Lessons from the first phase of the LHC

25 Sept 2012, 14:00 → 28 Sept 2012, 13:00 Europe/Berlin

DESY Main Auditorium (DESY Hamburg)

The annual DESY Theory Workshop is organized by the elementary particle physics community in Germany. The focus is on a topical subject in theoretical particle physics and related fields. More details can be found on the conference homepage, http://th-workshop2012.desy.de

Tuesday 25 September

14:00 → 14:15 Welcome J. Mnich (DESY)

Slides desy-map.pdf

14:15 → 16:00 Plenary Session

Convener: Georg Weiglein (DESY)

14:15 Results on the SM Higgs boson search at LHC

Speaker: C. Mariotti (Torino, CERN)

Slides Mariotti.pdf

14:50 The nature of the 125 GeV boson: SM or else ?

Speaker: M. Grazzini (Zurich)

Slides Grazzini.pdf

15:25 Searches for Higgs Bosons Beyond the SM at the LHC in Comparison to the Tevatron

Speaker: M. Schumacher (Freiburg)

Slides Schumacher.pdf Schumacher.pptx

16:00 → 16:30 Coffee break

16:30 → 17:45 Plenary Session

Convener: Wilfried Buchmuller (DESY)

16:30 SUSY Higgs Phenomenology

Speaker: R. Harlander (Wuppertal)

Slides Harlander.pdf

17:05 Electroweak Symmetry Breaking after the 4th of July

Speaker: A. Pomarol (Barcelona)

Slides Pomarol.pdf

17:45 → 19:00 RECEPTION

Wednesday 26 September

09:00 → 10:45 Plenary Session

Convener: Ahmed Ali

09:00 The Experimental Status of QCD

Speaker: Z. Marshall (CERN)

Slides Marshall.pdf

09:35 Theory of Heavy Quarkonium Production

Speaker: M. Butenschoen (Hamburg)

Slides Butenschoen.pdf

10:10 Parton distribution functions at the first phase of the LHC

Speaker: P. Jimenez Delgado (Zurich)

Slides JimenezDelgado.pdf

10:45 → 11:15 Coffee break

11:15 → 13:00 Plenary Session

Convener: Dr Stefan Dittmaier (MPI Munich)

11:15 NLO calculations for hard QCD processes

Speaker: S. Pozzorini (Zurich)

Slides Pozzorini.pdf

11:50 Precision Measurements in the Electroweak Sector

Speaker: M. Schott (CERN)

Slides Schott.pdf Schott.pptx

12:25 Electroweak precision physics from the theoretical viewpoint

Speaker: D. Wackeroth (Buffalo)

Slides Wackeroth.pdf

13:00 → 14:00 Lunch

14:00 → 15:20 Parallel Session 1: Particle Phenomenology: Flavor Physics

Convener: Dr Thomas Mannel (Siegen University)

14:00 Extracting B --> K* Form Factors from Data

Form factors for hadronic transitions are a leading error source in the theoretical estimate of observables whose experimental measurements might eventually uncover BSM physics. Two theoretical approaches, depending on the kinematic region, for the determination of hadronic form factors are available, namely LCSR and Lattice QCD. We extract ratios of $B \to K^*$ form factors at low hadronic recoil from recent data on $B \to K^* \mu^+ \mu^-$ decays in a model-independent way, building a bridge between the two theoretical determinations and the recently available data on this decays. In the talk this new method will be presented, based on the publication "Extracting B --> K* Form Factors from Data" arXiv:1204.4444 in collaboration with Gudrun Hiller.

Speaker: Christian Hambrock (TU Dortmund)

Slides Hambrock.pdf

14:20 Squark Flavor Implications from B --> K^(*) l^+ l^−

Recent experimental and theoretical progress regarding B --> K^(*) l^+ l^− decays led to improved bounds on the Wilson coefficients C_9 and C_10 of four-fermion operators of the |∆B| = |∆S| = 1 effective Hamiltonian. We analyze the resulting implications on squark flavor violation in the MSSM and obtain new constraints on flavor-changing left-right mixing in the up-squark-sector. We find the dimensionless flavor mixing parameter (δu^23)_LR, depending on the flavor-diagonal MSSM masses and couplings, to be as low as ≲ 0.1. This has implications for models based on radiative flavor violation and leads to BR(B_s --> μ^+ μ^−) ≳ 1×10^−9. Rare top decays t --> c γ, t --> c g, t --> c Z have branching ratios predicted to be below ≲ few × 10^−8, 10^−6 and 10^−7, respectively.

Speaker: Dr Christian Gross (Uni Basel)

Slides Gross.pdf

14:40 Minimal Flavor Violation without R-parity

We study the extension of the MFV hypothesis to the MSSM without R-parity. The novelty of our approach lies in the observation that supersymmetry enhances the global symmetry of the kinetic term and in the fact that we consider as irreducible sources of flavor breaking all the couplings of the superpotential, including the R-parity violating ones. When R-parity violation is responsible for neutrino masses, our setup can be seen as an extension of MFV to the lepton sector.

Speaker: Dr Luca Di Luzio (Karlsruhe Institute of Technology)

Slides DiLuzio.pdf

15:00 \theta^PMNS_13 = \theta_C / \sqrt2 from GUTs

The recent observations of the leptonic mixing angle \theta^PMNS_13 are consistent with \theta^PMNS_13 = \theta_C / \sqrt2 (with \theta_C being the Cabibbo angle \theta^CKM_12). We discuss how this relation can emerge in Grand Unified Theories (GUTs) via charged lepton corrections. The key ingredient is that in GUTs the down-type quark Yukawa matrix and the charged lepton Yukawa matrix are generated from the same set of GUT operators, which implies that the resulting entries are linked and differ only by group theoretical Clebsch factors. This allows a link \theta^e_12 = \theta_C to be established, which can induce \theta^PMNS_13 = \theta_C / \sqrt2 provided that the 1-3 mixing in the neutrino mass matrix is much smaller than \theta_C. We find simple conditions under which \theta^PMNS_13 = \theta_C / \sqrt2 can arise via this link in SU(5) GUTs and Pati-Salam models. We also discuss possible corrections to this relation. Using lepton mixing sum rules different neutrino mixing patterns can be distinguished by their predictions for the Dirac CP phase \delta^PMNS.

Speaker: Mr Vinzenz Maurer (Universität Basel)

Slides Maurer.pdf

14:00 → 15:20 Parallel Session 1: Particle Phenomenology: Radiative Corrections

Convener: Prof. Thorsten Ohl (University of Wuerzburg)

14:00 Associated ZH production in gluon fusion at NLO QCD

The associated production of a Higgs boson and one of the weak gauge bosons W or Z at hadron colliders can be understood mainly as the Drell-Yan production of a virtual vector boson, which subsequently radiates a Higgs. QCD corrections affect only the Drell-Yan part and are known through NNLO (alpha_S^2), leading to a small remaining dependence on the renormalization and factorization scale for the case of WH. For ZH however, another important contribution comes into play at this order, namely from diagrams with gluons in the initial state. Since alpha_S^2 corresponds only to the leading order for this channel, it increases the scale uncertainties for the ZH cross section. In this work, NLO corrections to gg to ZH are obtained by calculating the K factor in the limit of infinite top quark mass. We find large corrections and reduced scale uncertainties. This allows for a more reliable prediction of the ZH production cross section.

Speaker: Tom Zirke (University of Wuppertal)

Slides Zirke.pdf

14:20 Top-mass effects in differential Higgs production through gluon fusion at order αs^4

Effects from a finite top quark mass on differential distributions in the Higgs+jet production cross section through gluon fusion are studied at next-to-leading order in the strong coupling, i.e. O(αs^4). Terms formally subleading in 1/mTop are calculated, and their influence on the transverse momentum and rapidity distribution of the Higgs boson are evaluated. We find that, for the differential K-factor, the heavy-top limit is valid at the 2-3% level as long as the transverse momentum of the Higgs remains below about 150 GeV.

Speaker: Mr Tobias Neumann (Bergische Universität Wuppertal)

Slides Neumann.pdf

14:40 Neutralino Decays in the Complex MSSM at One-Loop: a Comparison of On-Shell Renormalization Schemes

We evaluate two-body decay modes of neutralinos in the Minimal Supersymmetric Standard Model with complex parameters (cMSSM). Assuming heavy scalar quarks we take into account all two-body decay channels involving charginos, neutralinos, (scalar) leptons, Higgs bosons and Standard Model gauge bosons. The evaluation of the decay widths is based on a full one-loop calculation including hard and soft QED radiation. Of particular phenomenological interest are decays involving the Lightest Supersymmetric Particle (LSP), i.e. the lightest neutralino, or a neutral or charged Higgs boson. For the chargino/neutralino sector we employ two different renormalization schemes, which differ in the treatment of the complex phases. We concentrate on the decay of the heaviest neutralino and present the results in the two different schemes. These corrections are important for the correct interpretation of LSP and Higgs production at the LHC and at a future linear e+e- collider.

Speaker: Dr Aoife Bharucha (Uni Hamburg)

Slides Bharucha.pdf

15:00 Impact of QCD and SUSY-QCD corrections on the neutralino dark matter relic density

A powerful method to constrain the parameter space of theories beyond the Standard Model is to compare the predicted dark matter relic density with data from cosmological precision measurements, in particular from the WMAP and in future also from the PLANCK satellite. On the particle physics side, the main uncertainty in the relic density calculation arises from the (co-)annihilation cross sections of the dark matter particle. While dedicated public tools like DarkSUSY and micrOMEGAs compute the relic abundance using an effective tree-level calculation, it is, however, crucial to take into account higher order corrections in order to meet the future experimental precision. We will present the numerical package DM@NLO, which allows to compute the (co-)annihilation cross sections of the neutralino including the full one-loop QCD and SUSY-QCD corrections. We will show recent results illustrating the significant impact of the one-loop corrections on the neutralino (co-)annihilation cross-section and, in consequence, on the dark matter relic density.

Speaker: Julia Harz (DESY Hamburg)

Slides Harz.pdf

14:00 → 15:20 Parallel Session 2: Cosmology & Astroparticle Physics

14:00 The 130GeV gamma-ray line and dark matter model building constraints from continuum gamma rays, radio and antiproton data

An analysis of the Fermi gamma ray space telescope data has recently revealed a resolved gamma-ray feature close to the galactic center which is consistent with monochromatic photons at an energy of about 130 GeV. If interpreted in terms of dark matter (DM) annihilating into gamma gamma (gamma Z,gamma H), this would correspond to a DM article mass of roughly 130 GeV (145 GeV, 155 GeV). The rate for these loop-suppressed processes, however, is larger than typically expected for thermally produced DM. Correspondingly, one would generically expect even larger tree level production rates of standard model fermions or gauge bosons. Here, we quantify this expectation in a rather model-independent way by relating the tree level and loop amplitudes with the help of the optical theorem. As an application, we consider bounds from continuum gamma rays, radio and antiproton data on the tree level amplitudes and translate them into constraints on the loop amplitudes. We find that, independently of the DM production mechanism, any DM model aiming at explaining the line signal in terms of charged standard model particles running in the loop is in strong tension with at least one of these constraints.

Speakers: Mr Martin Vollmann (PhD student), Dr Masaki Asano (Post-doc)

Slides Vollmann.pdf

14:20 Dark matter constraints from box-shaped gamma-ray features

The observation of a sharp spectral feature in the gamma-ray sky would be one of the cleanest ways to identify dark matter and pinpoint its properties. Over the years a lot of attention has been paid to two specific features, namely gamma-ray lines and internal bremsstrahlung. Here, we explore a third class of spectral signatures, box-shaped gamma-ray spectra, that naturally arise in dark matter cascade annihilations or decays into intermediate particles that in turn decay into photons. Using Fermi-LAT data, we derive constraints on the dark matter parameter space for both annihilating and decaying dark matter, and show explicitly that our limits are competitive to strategies employing standard spectral features. More importantly, we find robust limits even in the case of non-degenerate dark matter and intermediate particle masses. This result is particularly relevant in constraining dark matter frameworks with gamma-ray data. We conclude by illustrating the power of box-shaped gamma-ray constraints on concrete particle physics scenarios.

Speaker: Mr Sergio Lopez Gehler (TU München)

Slides LopezGehler.pdf

14:40 Closing in on mass-degenerate dark matter scenarios with antiprotons and direct detection

Over the last years both cosmic-ray antiproton measurements and direct dark matter searches have proved particularly effective in constraining the nature of dark matter candidates. The present work focusses on these two types of constraints in a minimal framework which features a Majorana fermion as the dark matter particle and a scalar that mediates the coupling to quarks. We derive antiproton and direct detection constraints using the latest data and paying close attention to astrophysical and nuclear uncertainties. Interestingly, these limits are orthogonal to ongoing collider searches at the Large Hadron Collider, making it feasible to close in on degenerate dark matter scenarios within the next years.

Speaker: Mr Stefan Vogl (TUM)

Slides Vogl.pdf

15:00 PAMELA and FERMI limits on the neutralino-chargino mass degeneracy

Searches for Dark Matter particles with indirect detection techniques have reached an important milestone with the measurements of the anti-proton and positron spectra by the PAMELA experiment and the gamma-ray fluxes by the FERMI-LAT experiment. While the γ-ray results have been used to test the thermal Dark Matter hypothesis and constrain the Dark Matter annihilation cross section into Standard Model particles, the anti-proton flux measured by the Pamela experiment remains relatively unexploited. Here we show that the latter can be used to set a constraint on the mass spectrum in the dark sector that can be as strong as that derived from the Fermi-LAT data. To illustrate our point we use a Supersymmetric model in which the gauginos are light, the sfermions are heavy and the lightest particle is the neutralino. In this framework the WW production is expected to be very significant, thus leading to large p and γ-ray fluxes. We show that the neutralino-chargino mass difference can be constrained up to 20 GeV for a mixed neutralino, using PAMELA data. As a result, we can safely rule out the pure wino neutralino hypothesis if it constitutes all the Dark Matter.

Speaker: Mr Jonathan Da Silva (LAPTh)

Slides DaSilva.pdf

14:00 → 15:20 Parallel Session 3: Strings & Mathematical Physics

Convener: Jan Plefka

14:00 Towards a metric-like higher-spin gauge theory in 2+1 dimensions

Higher-spin gauge theories become particularly simple in 2+1 dimensions, where there are no propagating degrees of freedom. Nevertheless they are useful toy models to study e.g. higher-spin generalisations of black holes or holographic dualities. Most of the research on this subject has been done in the frame-like formalism with generalised vielbeins and spin connections. I will report on recent progress on the metric-like formulation. Such a formulation might shed light on the geometric structure of higher-spin gauge theories, and it allows to apply standard field theoretic techniques like the computation of the Wald entropy for higher spin black holes.

Speaker: Dr Stefan Fredenhagen (MPI for Gravitational Physics)

Slides Fredenhagen.pdf

14:30 Maximal R-symmetry violating amplitudes in type IIB superstring theory.

Calculating scattering amplitudes in a flat background is one of the first things to learn in string theory: the subject started after all with Veneziano's amplitude. Beyond four external legs however explicit computations get prohibitively complex quickly using standard world-sheet methods. In this talk I will show how one can use on-shell super-symmetry in type IIB superstring theory to bypass the complexity and arrive at astonishingly compact answers for a particular class of amplitudes. This class violates in a precise sense the R-symmetry maximally.

Speaker: Dr Rutger Boels (II. institut für theoretische physik)

Slides Boels.pdf

15:00 The superconducting QCD vacuum at large magnetic field from holography

It has been shown by Chernodub et al. that the rho meson of QCD in the presence of a very large magnetic field condenses, giving a superconducting ground state. The solution takes on a lattice form of an Abrikosov type. We calculate the holographic dual of this phenomenon. In particular we show that for magnetic fields close to the critical value, the lattice takes on a triangular form, in agreement with the field theory calculations.

Speaker: Dr Jonathan Shock (Max Planck Institute)

Slides Shock.pdf

15:20 → 15:50 Coffee break

15:50 → 17:10 Parallel Session 1: Particle Phenomenology: Flavor Physics

Convener: Dr Thomas Mannel (Siegen University)

15:50 New Physics Patterns in non-leptonic Charm Decays

New Physics patterns of D decays to two pseudoscalars are studied in the framework of SU(3) flavor symmetry including breaking effects.

Speaker: Mr Stefan Schacht (TU Dortmund)

Slides Schacht.pdf

16:10 One-loop approximation of Lattice HQET parameters

We present a one-loop order lattice perturbation theory calculation of a subset of Heavy Quark Effective Theory parameters. HQET being an effective theory is defined through a set of parameters which should be fixed in a process called matching, order by order in 1/m. We consider 6 matching conditions which are needed for the determination of, for example, the f_B decay constant and which include the 1/m corrections. The one-loop approximation of the matching conditions is obtained using the pastor package for automated lattice perturbation theory calculations in the Schrodinger functional. We can study the discretization effects and the effects of higher orders in 1/m due to the matching. Our results are complementary to the non-perturbative determination of HQET parameters by the ALPHA collaboration.

Speaker: Dr Piotr Korcyl (NIC DESY Zeuthen)

Slides Korcyl.pdf

16:30 Lorentz invariance in heavy particle effective theories

Based on my work arxiv:1208.0601 with R. Hill and M. Solon, I will present a formalism derived from Wigner's little group that allows the construction of heavy particle effective Lagrangians with a Lorentz invariant S-matrix. In contrast to some previous approaches this is achieved directly by field transformations without calculating the Lorentz charges and their commutation relations. I will show how this connects to what is known as "reparametrization" invariance (RPI) and point out a subtlety, that leads to a break down of RPI at order 1/M^4. Our approach is easily generalized to fields of arbitrary spin or self-conjugate fields and can also be modified to be used e.g. in theories of massless fields like SCET.

Speaker: Dr Johannes Heinonen Heinonen (University of Chicago)

Slides Heinonen.pdf

16:50 Sterile neutrinos in flavor symmetry models

In this talk, I will briefly review the phenomenology of light sterile neutrinos. Then I will concentrate on the theoretical realizations of light sterile neutrinos, in particular a model based on flavor A4 symmetry and Froggatt-Nielsen mechanism.

Speaker: Dr He Zhang (MPIK)

Slides Zhang.pdf

15:50 → 17:30 Parallel Session 1: Particle Phenomenology: Radiative Corrections

Convener: Prof. Thorsten Ohl (University of Wuerzburg)

15:50 NNLL threshold resummation for the total top-pair production cross section

Results for the top-pair production cross section at the Tevtron and the LHC will be presented, including a combined resummation of threshold logarithms and Coulomb corrections at NNLL accuracy. The remaining theoretical and PDF uncertainties and prospects for the measurement of the top mass from the total cross section will be discussed.

Speaker: Dr Christian Schwinn (Freiburg University)

Slides Schwinn.pdf

16:10 Soft-gluon resummation for squark- and gluino hadroproduction

The production of SUSY particles at the LHC is dominated by processes involving coloured sparticles in the final state. Due to the high importance of these processes for SUSY searches at the LHC, precise theoretical predictions are needed. Higher-order QCD corrections are dominated by large logarithmic terms due to the emission of soft gluons from initial and final state particles. A systematic treatment of these logarithms to all orders in perturbation theory is provided by resummation methods. In this talk we discuss the resummation of soft gluon emission at next-to-leading-logarithmic (NLL) accuracy and beyond for squark and gluino pair-production processes. We present the analytical ingredients needed for the calculation and discuss numerical predictions for the LHC.

Speaker: Silja Christine Thewes (DESY)

Slides Thewes.pdf

16:30 Numerical evaluation of multi-loop integrals with SecDec

In this talk the new version of the public program SecDec 2.0 for the numerical evaluation of multi-loop integrals with several mass scales is presented. The program is based on sector decomposition to extract dimensionally regulated singularities. To deal with integrable singularities due to mass thresholds, the integration contour is deformed into the complex plane. As applications, numerical results for several two-loop integrals are given, including non-planar two-loop four-point functions entering heavy quark pair production at NNLO.

Speaker: Sophia Borowka (MPI Munich)

Slides Borowka.pdf

16:50 Automated one loop calculations with GoSam

In this talk I will present GoSam, a public package to compute one-loop corrections within and beyond the Standard Model. I will discuss how to use this package as well as phenomenological aspects and recent developments.

Speaker: Mr Nicolas Greiner (Max-Planck-Institut fuer Physik)

Slides Greiner.pdf

17:10 Recent results on NNLO Heavy Flavor Corrections to Deep-Inelastic Scattering

We present recent results on the 3-loop fermion-loop corrections to the asymptotic heavy flavor Wilson coefficients of the structure function $F_2(x,Q^2)$ in the asymptotic region $Q^2 \gg m^2$. This includes results on contributions with two different masses $m_c, m_b$ which first emerge at 3-loop level. We also obtained first results on more advanced toplogies of ladder- or benz-type using a method based on hyperlogarithms, a generalization of harmonic polylogarithms.

Speaker: Fabian Wissbrock (DESY)

Slides Wissbrock.pdf

15:50 → 17:10 Parallel Session 2: Cosmology & Astroparticle Physics

15:50 Prospects of antideuteron detection from dark matter annihilations/decays at AMS-02 and GAPS

The search for cosmic antideuterons has been proposed as a promising method to indirectly detect dark matter, due to the very small background flux from spallations expected at the energies relevant to experiments. The antideuteron flux from dark matter annihilation or decays is, however, severely constrained by the non-observation of an excess in the antiproton-to-proton fraction measured by PAMELA. In this talk we discuss, for various dark matter annihilation and decay channels, the prospects to observe a signal at AMS-02 and GAPS from requiring that the associated antiproton flux is in agreement with the PAMELA data.

Speaker: Mr Sebastian Wild (TU München)

Slides Wild.pdf

16:10 Multi-Component Dark Matter Systems and Their Observation Prospects

Conversions and semi-annihilations of dark matter (DM) particles in addition to the standard DM annihilations are considered in a three-component DM system. We find that the relic abundance of DM can be very sensitive to these non-standard DM annihilation processes, which has been recently found for two-component DM systems. To consider a concrete model of a three-component DM system, we extend the radiative seesaw model of Ma by adding a Majorana fermion \chi and a real scalar boson \phi, to obtain a Z_2 \times Z'_2 DM stabilizing symmetry, where we assume that the DM particles are the inert Higgs boson, \chi and \phi. It is shown how the allowed parameter space, obtained previously in the absence of \chi and \phi, changes. The semi-annihilation process in this model produces monochromatic neutrinos. The observation rate of these monochromatic neutrinos from the Sun at IceCube is estimated. Observations of high energy monochromatic neutrinos from the Sun may indicate a multi-component DM system. Based on arXiv:1207.3318.

Speaker: Mr Michael Duerr (MPIK, Heidelberg)

Slides Duerr.pdf

16:30 The universal density profile of the central region of dark matter haloes

We consider the density profile of the central region of dark matter haloes. It turns out that under very general conditions the profile is universal: it depends almost not at all on the properties of the initial perturbation and is very akin, but not identical, to the Einasto profile. We estimate the size of the 'central core' of the distribution, i.e., the extent of the very central region with a respectively gentle profile, and show that the cusp formation is unlikely, even if the dark matter is cold. We also indicate that the density profile of the outer part ($r>0.5 R_{vir}$) of the haloes significantly depends on the initial conditions and should not be universal, in contrast to the central area. All these results can be useful both to indirect search of the dark matter and to N-body simulations of the structure formation.

Speaker: Dr Anton Baushev (DESY Zeuthen)

Slides Baushev.pdf

16:50 Dark matter distribution in the Milky Way: microlensing and dynamical constraints

Dark matter searches are entering a particularly exciting phase where the complementarity between different signals may finally be explored. This situation calls for a more accurate description of the dark matter distribution in our Galaxy. In this context, I will show that gravitational microlensing and dynamical observables can be combined to set interesting constraints on the dark matter local density and profile slope. The most commonly discussed dark matter profiles are found compatible with microlensing and dynamical observations, while the local dark matter density is constrained to be in the range 0.20-0.56 GeV/cm^3. Future directions will be discussed.

Speaker: Miguel Pato (TU Munich)

Slides Pato.pdf

15:50 → 17:10 Parallel Session 3: Strings & Mathematical Physics

Convener: Prof. Jan Plefka (Humboldt University Berlin)

15:50 Special class of SU(2) two-point functions on the torus

I discuss two-point functions on the torus in the SU(2) Wess-Zumino-Witten model. I construct an explicit expression for the current blocks of the spin-k/2-spin-k/2 torus two-point function. As a first check, I consider the factorization limits of the current blocks as well as their monodromy properties. I then prove that the current blocks solve the corresponding Knizhnik-Zamolodchikov-like equations, which are constructed by the method of Mathur, Mukhi and Sen.

Speaker: Dr Ingo Kirsch (DESY Hamburg)

Slides Kirsch.pdf Kirsch.ppt

16:10 Motivic multiple zeta values and superstring amplitudes

String corrections to open superstring tree level amplitudes take a striking and elegant form once the contributions from different classes of multiple zeta values are appropriately disentangled. This novel organization of the alpha prime expansion makes use of a Hopf algebra structure underlying the motivic version of multiple zeta values: It induces an isomorphism which casts the amplitudes into a very symmetric form and represents the generalization of the symbol of a transcendental function. Equipped with these open string results, we can better understand the decoupling of even and higher depth zeta values from closed superstring tree amplitudes.

Speaker: Dr Oliver Schlotterer (AEI Potsdam)

Slides Schlotterer.pdf

16:30 Supersound diffusion constants from black hole physics

We describe the holographic computation of supercharge diffusion constants in theories dual to gravitational theories on the background of AdS black brane solutions (of arbitrary dimension and at vanishing chemical potential for R charges). The computation is performed via the low frequency, low momentum pole of the correlator of supercurrents, which describes the hydrodynamic "phonino" mode, and via the dual transversal gravitino mode using a Kubo formula. Furthermore, the connection to a universal absorption cross section result is drawn analogous to the famous proof of the universality of eta / s. Similarities and differences to this result are discussed.

Speaker: Mr Stephan Steinfurt (Max-Planck-Institute for Physics, Munich)

Slides Steinfurt.pdf

16:50 Light-cone lattice from the universal R-matrix

I will discuss a systematic approach to the construction of lattice regularizations of a certain class of 1+1 dimensional integrable quantum field theories. The method is based on the identification of the relevant algebraic structure combined with a systematic analysis of its representations. I will focus on the example of affine Toda theories. Remarkable factorization/fusion properties of some degenerate representations of the underlying quantum affine algebra are connected to the separation/recombination of left- and right-movers in 1+1 dimensional conformal field theory. I will present a derivation of the so called quantum discrete-time evolution equations on a light-cone lattice for affine Toda theories. I will conclude with some considerations on the construction of Baxter's Q-operators for these models.

Speaker: Dr carlo Meneghelli (Fachbereich Mathematik uni hamburg and DESY)

Slides Meneghelli.pdf

17:30 → 19:00 HEINRICH HERTZ LECTURE

Speaker: Bryan Webber (Cambridge)

Slides Webber-Hertz.key Webber-Hertz.pdf

19:00 → 22:00 Dinner

Thursday 27 September

09:00 → 10:45 Plenary Session

Convener: Dr Steffen Schumann (ITP Heidelberg)

09:00 Top Quark Physics at Hadron Colliders

Speaker: C. Schwanenberger (Manchester)

Slides Schwanenberger.pdf

09:35 Top-quark pair production: New results and recent developments

Speaker: P. Uwer (Berlin)

Slides Uwer.pdf Uwer.ppt

10:10 The theory of single top production

Speaker: E. Laenen (Amsterdam, Utrecht)

Slides Laenen.pdf

10:45 → 11:15 Coffee break

11:15 → 13:00 Plenary Session

Convener: Prof. Gudrun Hiller (TU Dortmund)

11:15 Heavy flavour physics at the LHC

Speaker: T. Gershon (Warwick, CERN)

Slides Gershon.pdf

11:50 Interpreting 2012 flavor data

Speaker: A. Lenz (CERN)

Slides Lenz.pdf

12:25 Flavor physics: open problems, recent progress, and future prospects

Speaker: G. Isidori (Frascati)

Slides Isidori.pdf

13:00 → 14:00 Lunch

14:00 → 15:20 Parallel Session 1: Particle Phenomenology: Collider Physics, Higgs etc.

Convener: Prof. Thorsten Ohl (University of Wuerzburg)

14:00 2HDM+S effective potential approach to some Higgs decays

We consider the most general CP-conserving renormalizable effective scalar potential involving two doublets plus one singlet Higgs and satisfying the electroweak gauge symmetry. After deriving the electroweak-symmetry breaking conditions, we focus our attention on specific cases, characterized by specific symmetry properties and/or relations to supersymmetry-inspired extensions of the Standard Model (e.g. n/NMSSM, UMSSM). We then investigate the question of the reconstruction of the potential parameters from the Higgs masses and mixing angles and show that in some specific cases, such as the one of an underlying NMSSM, an accuracy at the order of leading-logarithms is achievable with minimal effort. We finally study a few phenomenological consequences for this latter model: noteworthy effects in Higgs-to-Higgs decays indeed develop, with an impact on collider constraints or the Dark-Matter relic density. We performed a comparison of our procedure with two public codes, NMSSMTools and micromegas, and found some improvement in particular regions of parameter space.

Speaker: Dr Guillaume Chalons (TTP-KIT)

Slides Chalons.pdf

14:20 Higgs Decays in the Low Scale Type I See-Saw Model

The couplings of the low scale type I See-Saw model are severely constrained by the requirement of reproducing the correct neutrino mass and mixing parameters, by the non-observation of lepton number and charged lepton flavour violating processes and by electroweak precision data. We show that all these constraints still allow for the possibility of an exotic Higgs decay channel into a light neutrino and a heavy neutrino with a sizable branching ratio. We also estimate the prospects to observe this decay at the LHC and discuss its complementarity to the indirect probes of the low scale type I see-saw model from experiments searching for the $\mu\to e\gamma$ decay.

Speaker: Mr Camilo A. Garcia Cely (Phd Student)

Slides GarciaCely.pdf

14:40 Impact of the Higgs Discovery on the Standard Model with Three and Four Fermion Generations

In this talk I present results of a global analysis of electroweak precision data and Higgs signal strengths in the context of the Standard Model with three and four fermion generations. I re-examine the SM electroweak fit with the new input on the Higgs mass and discuss the effect of a fourth fermion generation on the Higgs signal strengths. To quantify the level at which a fourth fermion generation is ruled out one must deal with the statistics of so-called non-nested models, because the three-family case is not recovered in any limit of the four-family model. To this end the computer package myFitter has been developed, which I will describe in my talk.

Speaker: Dr Martin Wiebusch (Karlsruhe Institute of Technology)

Slides Wiebusch.pdf

15:00 Flavor violating Higgs decays

As experimental evidence for a Higgs boson with a mass around 125 GeV is mounting, the question whether its couplings are Standard Model-like is becoming more and more important. Deviations from the Standard Model predictions could for example point to the existence of secondary mechanism of electroweak symmetry breaking such as additional Higgs doublets, or to other types of new physics not too far above the electroweak scale. The flavor structure of such scenarios can be non-trivial, leading to the interesting observation that decays of the 125 GeV Higgs boson can be flavor-violating. In this paper, we derive constraints on flavor-violating Higgs decays into both leptons and quarks using data on rare decays, electric and magnetic dipole moment searches, and meson oscillations. We find that in some flavor-violating Higgs decay channels, for instance H -> \tau\mu, there is significant room for discoveries at the LHC, and we outline possible search strategies. We conclude that flavor violating Higgs decay may present an opportunity for discovery of new physics and in some cases may be easier to access experimentally than flavor conserving deviations from the Standard Model Higgs framework.

Speaker: Joachim Kopp (Max Planck Institute for Nuclear Physics)

Slides Kopp.pdf

14:00 → 15:20 Parallel Session 1: Particle Phenomenology: Supersymmetry

Convener: Dr Thomas Mannel (Siegen University)

14:00 NLO corrections to squark-squark production and decay at the LHC

We present an analysis of the signature 2j + ETmiss (+X) via squark-squark production and direct decay into the lightest neutralino, pp -> squark squark -> j j chi_1^0 chi_1^0 (+X), in next-to-leading order QCD within the framework of the minimal supersymmetric standard model. In our approximation the produced squarks are treated on shell. Thus, the calculation of production and decay factorizes. In this way, we provide a consistent, fully differential calculation of NLO QCD factorizable corrections to the given processes. Clustering final states into partonic jets, we investigate the experimental inclusive signature 2j + ETmiss for several benchmark scenarios. We compare resulting differential distributions with leading-order approximations rescaled by a flat K-factor and examine a possible impact for cut-and-count searches for supersymmetry at the LHC.

Speaker: Mr Jonas Lindert (MPP)

Slides Lindert.pdf

14:20 QCD threshold resummation for Gluino-pair production at NNLL

We present improved predictions for the total hadronic cross section of gluino pair production at hadron colliders including NNLO threshold corrections. Here, we give analytic formulas for the color-decomposed NLO and (approximated) NNLO scaling functions, which allow for a resummation of Sudakov logarythms up to NNLL. We perform the resummation in Mellin space and give analytic results for the hard matching coefficients.

Speaker: Dr Torsten Pfoh (DESY Zeuthen)

Slides Pfoh.pdf

14:40 NLL soft and Coulomb resummation for squark and gluino production at the LHC

We present predictions of the total production cross sections of pairs of squarks and gluinos at the LHC, which incorporate a combined resummation of soft logarithms and Coulomb singularities, including bound-state contributions. These terms dominate the threshold region of the partonic cross section and are resummed directly in momentum space using an effective-theory framework based on SCET and pNRQCD. This differs from the more conventional approach where soft logarithms are exponentiated in Mellin-moment space. The combined resummation of soft and Coulomb corrections can lead to much bigger effects than soft resummation alone, with corrections of up to 150% to the fixed-order NLO result for gluino-gluino production at 8 TeV, and smaller (but still sizeable) effects for the other production processes. The theoretical uncertainty of the cross sections is typically reduced to about \pm 10%. The finite widths of the squarks and gluinos have a small, negligible effect on the soft and Coulomb corrections of the total SUSY production cross section.

Speaker: Mr Chris Wever (ITF Utrecht University)

Slides Wever.pdf

15:00 Updates on the anomalous magnetic moment of the muon in the MSSM

The anomalous magnetic moment of the muon, aμ , is an important quantity to test the Standard Model. The highly precise experimental and theoretical determination of aμ leads to a discrepancy of 3 to 4σ. This deviation could be explained by contributions of the MSSM. To be competitive to the high accuracy of the experiment, in particular the future improved measurements, and the SM theory prediction, also high accuracy of the MSSM theory prediction is necessary. Therefore, two-loop corrections to aμ need to be evaluated. I present recent updates on this issue, in particular corrections to MSSM one-loop diagrams by a closed fermion–sfermion–loop. I introduce the class of Feynman diagrams and explain some details of their renormalisation. Finally, I show numerical results for interesting parts of the MSSM parameter space. in collaboration with Helvecio Fargnoli, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil Christoph Gnendiger, Dominik Stöckinger and Hyejung Stöckinger-Kim, Institute for Nuclear and Particle Physics, TU Dresden, Dresden, Germany

Speaker: Mr Sebastian Paßehr (Max Planck Institute for Physics)

Slides Passehr.pdf

14:00 → 15:20 Parallel Session 2: Cosmology & Astroparticle Physics

Convener: Miguel Pato (TU Munich)

14:00 Nonequilibrium QFT approach to leptogenesis

The observed baryon asymmetry of the Universe can be elegantly explained in the leptogenesis scenario, where a net lepton asymmetry produced by the decay of heavy right-handed neutrinos is then transfered to the baryon number through the Standard Model sphalerons. Being an intrinsicly quantum effect the generation of such an asymmetry in the hot early Universe can be described systematically only using nonequilibrium quantum field theory tools. Starting from first principles one derives a quantum Boltzmann equation which is free of the double counting problem and which incorporates consistently the medium corrections to the masses and decay widths. Medium corrections are particularly large for the CP-violating parameters. The total decay widths are affected to a lesser extent. Moreover thermal corrections to the heavy neutrino mass play an important role in the case of quasi-degenerate and mildly-degenerate mass spectrum, and can even lead to an avoided level crossing. Therefore a resonant enhancement of the CP-violating parameter can be present at high temperature but absent in the vacuum case.

Speaker: Mr Tibor Frossard (Max-Planck-Institut für Kernphysik Heidelberg)

Slides Frossard.pdf

14:20 Towards a quantum treatment of leptogenesis

Leptogenesis is an attractive mechanism for explaining the baryon asymmetry of the universe, and provides interesting links between cosmology and neutrino physics. In addition, within the scenario of resonant leptogenesis, models with implications for LHC and future colliders have been proposed. However, the predictions depend on a correct calculation of the generated asymmetry in terms of the fundamental masses and couplings. Typically, classical Boltzmann equations with vacuum matrix elements are used. Since the lepton asymmetry results from a quantum interference process that is out of equilibrium, it is desirable to study the mechanism within a purely quantum field theoretical description. We present a calculation of the resonant enhancement based on a first principle approach. We identify the correct behaviour when the mass difference of the right-handed neutrinos is of the order of their width, and show that the generated asymmetry is smaller compared to the Boltzmann approach.

Speaker: Mr Mathias Garny (Desy)

Slides Garny.pdf

14:40 WIMP Dark Matter from Gravitino Decays and Leptogenesis

The spontaneous breaking of B-L symmetry naturally accounts for the small observed neutrino masses via the seesaw mechanism. We have recently shown that the cosmological realization of B-L breaking in a supersymmetric theory can successfully generate the initial conditions of the hot early universe, i.e. entropy, baryon asymmetry and dark matter, if the gravitino is the lightest superparticle (LSP). This implies relations between neutrino and superparticle masses. Here we extend our analysis to the case of very heavy gravitinos which are motivated by the discovery of the Higgs boson at the LHC. We find that the nonthermal production of `pure' wino or higgsino LSPs, i.e. weakly interacting massive particles (WIMPs), in heavy gravitino decays can account for the observed amount of dark matter while simultaneously fulfilling the constraints imposed by primordial nucleosynthesis and leptogenesis within a range of LSP, gravitino and neutrino masses. For instance, a mass of the lightest neutrino of 0.05 eV would require a higgsino mass below 900 GeV and a gravitino mass of at least 10 TeV.

Speaker: Kai Schmitz (DESY)

Slides Schmitz.pdf

15:00 From Dirac neutrino masses to baryonic and dark matter asymmetries

In this talk I will introduce a unified picture of Dirac neutrino masses, baryon asymmetry and dark matter relic density. Specifically, we consider an $SU(3)'_c\times SU(2)'_L\times U(1)'_Y$ dark sector, parallel to the $SU(3)_c\times SU(2)_L\times U(1)_Y$ ordinary sector. The hypercharges, baryon numbers and lepton numbers in the dark sector are opposite to those in the ordinary sector. We further introduce three types of messenger sectors: (i) two or more gauge-singlet Dirac fermions, (ii) two or more $[SU(2)_L\times SU(2)'_L]$-bidoublet Higgs scalars, (iii) at least one gauge-singlet Dirac fermion and at least one $[SU(2)_L\times SU(2)'_L]$-bidoublet Higgs scalar. The lepton number conserving decays of the heavy fermion singlet(s) and/or Higgs bidoublet(s) can simultaneously generate a lepton asymmetry in the $[SU(2)_L]$-doublet leptons and an opposite lepton asymmetry in the $[SU(2)'_L]$-doublet leptons to account for the cosmological baryon asymmetry and dark matter relic density, respectively. The dark proton and/or neutron as the dark matter particle thus should have a mass about $5\,\textrm{GeV}$. By integrating out the heavy fermion singlet(s) and/or Higgs bidoublet(s), we can obtain three light Dirac neutrinos composed of the ordinary and dark left-handed neutrinos. If a mirror symmetry is further imposed, our models will not require more parameters than the traditional type-I, type-II or type-I+II seesaw models.

Speaker: Dr Peihong GU (Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany)

Slides Gu.pdf

14:00 → 15:20 Parallel Session 3: Strings & Mathematical Physics

14:00 From rigid D-branes to particle physics

D6-brane models provide a geometrically intuitive picture for string model building. Rigid D-branes on orbifolds with discrete torsion are of particular interest due to the absence of (some) moduli on the one hand and the power of CFT tools on the other hand. In this talk, recent progress on constructing the Standard and GUT Models in such D-brane scenarios will be presented.

Speaker: Prof. Gabriele Honecker (Johannes-Gutenberg-Universität Mainz)

Slides Honecker.pdf

14:30 String theory on Determinantal Calabi-Yau Manifolds

String compactifications and string model building have mainly been pursued on Calabi–Yau manifolds of a certain type: complete intersections in toric varieties. A powerful tool to study such Calabi-Yau manifolds is provided by the two-dimensional gauged linear sigma model with abelian gauge groups. In this talk I consider gauged linear sigma models with non-abelian gauge groups so as to describe the propagation of strings on determinantal Calabi-Yau manifolds, which furnish another broad class beyond complete intersection Calabi-Yau geometries. I demonstrate that the presented techniques provide a direct and powerful method to compute the spacetime Kähler potential exact in alpha'. Calabi-Yau threefolds and for determinantal Calabi-Yau threefolds

Speaker: Hans Jockers (BCTP, Bonn)

Slides Jockers.pdf

15:00 New Dualities in Three-dimensional Scattering

In recent years a host of new structures, such as Yangian symmetries and the duality between color and kinematics, have been discovered in the study of maximally supersymmetric scattering amplitudes. It is natural to question whether these structures can be found in a wider class of theories. In this talk we provide evidence for analogous structures in three-dimensional supersymmetric Chern-Simons matter theories. Specifically we show that the tree-level amplitudes can be written so that the kinematic factors satisfy the fundamental identity of three-algebras. We further show that the amplitudes can be squared into the amplitudes of three-dimensional supergravity, thus providing evidence for a hidden three-algebra structure in the dynamics of the supergravity. We also study the Chern-Simons planar amplitudes at one-loop, demonstrating that their explicit form is consistent with, and determined by, their Yangian symmetry.

Speaker: Tristan McLoughlin (MPI Potsdam)

Slides McLoughlin.pdf

15:20 → 15:50 Coffe break

15:20 → 15:50 Coffee break

15:20 → 15:50 Coffee break

15:20 → 15:50 Coffee break

15:50 → 17:10 Parallel Session 1: Particle Phenomenology: Collider Physics, Higgs etc.

Convener: Prof. Thorsten Ohl (University of Wuerzburg)

15:50 Constraining SUSY models beyond vanilla supersymmetry at the LHC

ATLAS and CMS collaborations have searched for multi-jet plus large missing energy signatures and their null results have put a stringent constraint on the CMSSM parameter space. Such "vanilla" supersymmetry with squark/gluino mass below 1-1.4 TeV have already excluded. However in some scenarios, for example split generation, compressed SUSY and R-parity violation scenarios, low energy supersymmetry below 1 TeV is still allowed. Excluding such possibilities would be one of the next important goals of the LHC. I would like to talk about our recent study to exclude the compressed SUSY models using leptonic signatures. I would also like to mention our recent work on RPV model exclusion using a large jet multiplicity search.

Speaker: Dr Kazuki Sakurai (DESY)

Slides sakurai_9_27_DESY.pdf

16:10 A generalised narrow-width approximation for interference effects in the MSSM

The ``narrow-width approximation'' is a convenient tool for the factorisation of a more complicated process into production and subsequent decay of a particle with a small width compared to its mass. However, this approximation cannot be applied in the case of sizable interferences between propagator contributions of different particles that are close to their mass shell. The spectrum of the MSSM may contain particles with a mass difference of the order of their decay widths. In order to deal with such a situation, a generalisation of the usual narrow-width approximation is analysed which allows for a consistent treatment of interference effects between such nearly mass-degenerate particles. This can be useful for the application to processes for which the factorisation into different sub-processes will be essential to enable the computation of higher-order contributions. Phenomenological consequences with interference effects between neutral MSSM Higgs bosons will be discussed for the example process of Higgs boson production and subsequent decay from the decay of a heavy neutralino. Vertex corrections are included at the one-loop level in an on-shell renormalisation of the neutralino sector.

Speaker: Elina Fuchs (DESY)

Slides Fuchs.pdf

16:30 Spin Correlations in Double-Parton Scattering

In double parton interactions the two hard scatterings are correlated via double parton densities. We study the double Drell-Yan process and investigate the impact of the correlations on the differential cross section. In particular the spin of the quarks originating from the same proton can be correlated, affecting both the magnitude and the distributions of the cross section. We set upper limits on such spin-correlations following from positivity conditions on parton densities.

Speaker: Tomas Kasemets (DESY)

Slides Kasemets.pdf

16:50 S_hat_min resurrected

We discuss the use of the variable s_hat_min, which has been proposed in order to measure the hard scale of a multi parton final state event using inclusive quantities only, on a SUSY data sample for a 14TeV LHC. In its original version, where this variable was proposed on calorimeter level, the direct correlation to the hard scattering scale does not survive when effects from soft physics are taken into account. We here show that when using reconstructed objects instead of calorimeter energy and momenta as input, we manage to actually recover this correlation for the parameter point considered here. We furthermore discuss the effect of including W + jets and t¯t+ jets background in our analysis and the use of pˆsmin for the suppression of SM induced background in new physics searches.

Speaker: Dr Tania Robens (IKTP, TU Dresden)

Slides trobens_desy12.pdf

15:50 → 17:10 Parallel Session 1: Particle Phenomenology: Supersymmetry

Convener: Dr Thomas Mannel (Siegen University)

15:50 Pure Gravity Mediation: Why do I believe in low energy SUSY more strongly than before the LHC?

I will explain why I belive in low energy SUSY more strongly than before the LHC.

Speaker: Prof. Tsutomu Yanagida (University of Tokyo / IPMU)

Slides Yanagida.pdf Yanagida.pptx

16:10 Naturalness of the Non-Universal MSSM in the light of the recent Higgs results

We analyse the naturalness of the Minimal Supersymmetric Standard Model (MSSM) in the light of recent LHC results from the ATLAS and CMS experiments. We study non-universal boundary conditions for the scalar and the gaugino sector, with fixed relations between some of the soft breaking parameters, and find a significant reduction of fine-tuning for non-universal gaugino masses. For a Higgs mass of about 125 GeV, as observed recently, we find parameter regions with a fine-tuning of O(10), taking into account experimental and theoretical uncertainties. These regions also survive after comparison with simplified model searches in ATLAS and CMS. For a fine-tuning less than 20 the lightest neutralino is expected to be lighter than about 400 GeV and the lighter stop can be as heavy as 3.5 TeV. On the other hand, the gluino mass is required to be above 1.5 TeV. For non-universal gaugino masses, we discuss which fixed GUT scale ratios can lead to a reduced fine-tuning and find that the recent Higgs results have a strong impact on which ratio is favoured. We also discuss the naturalness of GUT scale Yukawa relations, comparing the non-universal MSSM with the CMSSM.

Speaker: Dr Martin Spinrath (SISSA)

Slides Spinrath.pdf

16:30 Phenomenological Aspects of the GNMSSM

I will discuss phenomenological aspects of the GNMSSM.

Speaker: Dr Kai Schmidt-Hoberg (Oxford University)

Slides Schmidt-Hoberg.pdf

16:50 Long-lived staus in a simplified model approach

We present the phenomenology of the gravitino dark matter scenario at the LHC. We consider the case that the next-to-lightest supersymmetric particle (NLSP) is the lighter stau. For a wide range of gravitino masses the lighter stau is stable on the scale of a detector. Such a particle will give rise to a prominent signature as a ’slow muon’. The dominant production channel of staus depends strongly on the hierarchy of the mass spectrum. However, due to the directly detectable stau one is not forced to rely solely on the observation of highly energetic standard model particles coming either from decay chains or from initial state radiation. This is why in a long-lived stau scenario there are barely any regions in parameter space where the theory is hidden from observation, compared to the neutralino LSP scenario where compressed spectra as well as highly stretched spectra are very hard to observe. We study the LHC sensitivity and examine its dependence on the spectrum with an emphasis on the strong production and decay. Unlike most existing studies we do not restrict ourselves to specific supersymmetry breaking models and benchmark points but aim for a signature driven analysis along the lines of the so-called simplified models. We will show that simplified models are particularly suitable in these classes of scenarios and, in fact, allow us to derive conservative model-independent limits on the SUSY mass parameters from the current LHC data.

Speaker: Mr Jan Heisig (University of Hamburg)

Slides Heisig.pdf

15:50 → 17:10 Parallel Session 2: Cosmology & Astroparticle Physics

Convener: Mr Mathias Garny (Desy)

15:50 Relaxed Dark Matter

In standard cosmology the present ratio of the dark matter (DM) and baryon energy densities is set by two completely unrelated mechanisms: the DM production mechanism and baryogenesis. Therefore, the fact that the observed value for this ratio is close to one may appear as a puzzling coincidence. A scalar field interacting differently with DM and baryons can explain dynamically why the ratio of their cosmic densities is of order unity today: In the model presented in this talk, the initial DM and baryon densities "relax" to a ratio of coupling constants, which can be naturally of the order of one. Implications of this scenario for cosmology (e.g. structure formation and gravity tests) and particle physics (e.g. impact on SUSY parameter space) will be also discussed.

Speaker: Dr Riccardo Catena (Institut fuer Theoretische Physik Goettingen)

Slides Catena.pdf

16:10 Smooth Hybrid Inflation and Non-Thermal Type II Leptogenesis

We consider a smooth hybrid inflation scenario based on a supersymmetric SU(2)_L x SU(2)_R x U(1)_(B-L) model. The Higgs triplets involved in the model play a key role in inflation as well as in explaining the observed baryon asymmetry of the universe. We show that the baryon asymmetry can originate via non-thermal triplet leptogenesis from the decay of SU(2)_(B−L) triplets, whose tiny vacuum expectation values also provide masses for the light neutrinos.

Speaker: Dr ARUNANSU SIL (Indian Institute of Technology, Guwahati, INDIA)

Slides Sil.pdf Sil.ppt

16:30 Superconformal D-Term Inflation

In superconformal D-term inflation, dangerous supergravity corrections to the scalar potential are controlled by a superconformal symmetry of the matter sector of the Lagrangian, a concept which has received recent interest in the context of Higgs inflation. Working out this idea in the context of D-term inflation, we find an interesting phenomology, in particular a two-field inflationary phase once one allows for a breaking of the exact superconformal symmetry and predictions for the observables of the primordial power spectrum within current experimental bounds for reasonable values of the model parameters. Furthermore, we show that this simple model can be embedded in the context of Grand Unified Theories, with the U(1) symmetry broken at the end of D-term inflation identified as the U(1)_{B-L}.

Speaker: Valerie Domcke (DESY)

Slides Valerie_Domcke_desy_theory_workshop_2012.pdf

16:50 Observational degeneracy between non-canonical and canonical single field inflation

We discuss observational degeneracy between non-canonical and canonical single field inflation. We map the dynamics of the non-canonical inflationary trajectory to a Lagrangian with canonically normalized kinetic term and a scalar potential. At the level of the two-point function, the two theories are observationally degenerate at all times. To obtain observationally degeneracy at the level of the three-point function, we add sinusodial contributions to the scalar potential. These give rise to resonant non-Gaussianities, whose superpositions are shown to approximately match equilateral non-Gaussianity which is characteristic for non-canonical inflation. We discuss explicit examples such as DBI-inflation.

Speaker: Mr Markus Rummel (University of Hamburg)

Slides Rummel.pdf

15:50 → 17:10 Parallel Session 3: Strings & Mathematical Physics

15:50 Multi-Regge Limit of Scattering Amplitudes in Strongly Coupled N=4 SYM

In this talk, I will investigate n-gluon scattering amplitudes in the multi-Regge region of N=4 supersymmetric Yang-Mills theory at strong coupling. To leading order, the amplitude at strong coupling is given in terms of a minimal surface in AdS5. The area of this surface can be calculated by a set of non-linear integral equations, which, however, do not allow an analytic solution for arbitrary kinematics. I will demonstrate that in the multi-Regge limit these equations simplify drastically and become algebraic equations. This result implies that there exists an auxiliary system of algebraic Bethe ansatz equations which encode valuable information on the analytical structure of amplitudes at strong coupling.

Speaker: Martin Sprenger (DESY Theory Group)

Slides Sprenger.pdf

16:10 Integrability and scattering amplitudes in N=4 SYM

In this talk I will present some work in progress on the interplay between scattering amplitudes in N=4 SYM and the Yang-Baxter equation. I will start by reviewing the notions of Yangian symmetry and Grassmannian formulation and recall the recently observed connection between the leading part of the dilatation operator for the integrable spin chain and the tree-level amplitudes. I will then merge these concepts and present the spectral parameter deformation of scattering amplitudes and the interpretation of the spectral parameter itself. Finally I will discuss the possibility of a new (spectral) regularization for loop amplitudes.

Speaker: Dr Livia Ferro (Humboldt University of Berlin)

Slides Ferro.pdf

16:30 Slow-Walking Inflation

We propose a new model of D3-brane inflation in a recently constructed class of warped throat backgrounds of Type IIB Supergravity, which are modifications of the Klebanov-Strassler background in the IR region. The dilaton has a non-trivial profile along the radial direction and induces a potential for the D3-brane. This contribution to the D3-brane potential generically features an inflection point near the tip of the throat and thus may provide a new possibility to address the eta-problem.

Speaker: Sebastian Halter (LMU & ASC, Munich)

Slides Halter.pdf

16:50 The Higgs from Remote Supersymmetry

We interpret the recently discovered Higgs candidate as a standard Higgs Boson originating from an underlying string-derived supersymmetric theory. The observed mass range of 124...126 GeV points towards a vanishing quartic coupling at intermediate to high scales. This compels us to study a class of String/F-Theory based models in which symmetries enforce a vanishing quartic Higgs coupling near the soft scale. We discuss the impact of radiative corrections to these symmetries and explore possible stringy realizations.

Speaker: Mr Alexander Knochel (ITP Heidelberg)

Slides Knochel.pdf

17:10 → 17:40 Coffee break

17:10 → 17:40 Coffee break

17:10 → 17:40 Coffee break

17:10 → 17:40 Coffee break

17:40 → 19:20 Parallel Session 1: Particle Phenomenology: Collider Physics, Higgs etc.

Convener: Prof. Thorsten Ohl (University of Wuerzburg)

17:40 Constraints on UED Models with LHC data

Models with a universal extra dimension (UED), in which all Standard Model fields propagate, predict a rich LHC phenomenology at the TeV scale. We present bounds on the minimal UED, split UED, and non-minimal UED models from the data taken in the first phase of the LHC. We compare our results with existing bounds from flavor physics and electroweak precision tests, thereby showing how much current LHC data has already improved the constraints.

Speaker: Dr Thomas Flacke (University of Wuerzburg and KAIST)

Slides 03FlackeDESY12.pdf

18:00 Strong Signatures of Right-handed compositeness

Right-handed light quarks could be largely composite compatibly with experimental searches at the LHC and precision tests on Standard Model couplings. In these scenarios, which are also motivated by flavor physics, one expects large cross-section for the production of new resonances coupled to light quarks. We study the possible experimental signatures of right-handed compositeness at the LHC and constrain the parameter space of these scenarios with recent results by Atlas and CMS. We show that the LHC sensitivity could significantly improve if dedicated searches were performed in particular in multi-jet signals.

Speaker: Mr Maikel de Vries (DESY)

Slides deVries.pdf

18:20 Chiral Superfluidity for the Heavy Ion Collisions

In this talk I will argue that the strongly coupled quark-gluon plasma formed at LHC and RHIC can be considered as a chiral superfluid. The 'normal' component of the fluid is the thermalized matter in common sense, while the 'superfluid' part consists of long wavelength (chiral) fermionic states moving independently. I use several nonperturbative techniques to demonstrate that. First, I analyze the fermionic spectrum in the deconfinement phase (Tc < T < 2 Tc) using lattice (overlap) fermions and observe a gap between near-zero modes and the bulk of the spectrum. Second, I use the bosonization procedure with a finite cut-off and obtain a dynamical axion-like field out of the chiral fermionic modes. Third, I use relativistic hydrodynamics for macroscopic description of the effective theory obtained after the bosonization. Finally, solving the hydrodynamic equations in gradient expansion, I find that in the presence of external electromagnetic fields the motion of the 'superfluid' component gives rise to the chiral magnetic, chiral electric and dipole wave effects. Latter two effects are specific for a two-component fluid, which provides us with crucial experimental tests of the model.

Speaker: Tigran Kalaydzhyan (DESY)

Slides Kalaydzhyan.pdf

18:40 New exact wavefunctions and generic 2-vertex processes, in two strong electromagnetic fields

In future linear colliders, ultrarelativistic charge bunches with associated electromagnetic fields approaching or exceeding the Schwinger limit, will interact at the IP. With such strong fields, vacuum polarisation becomes significant and, in order to quantify the effect on physics processes, new analytic calculations in the Furry interaction picture are necessary. Up to now, Furry picture calculations - most notably the beamstrahlung, only consider one external field, that of the oncoming bunch. However, for particles with significant transverse momentum, there is potentially an effect from both bunch fields. To that end we present here new solutions of the equations of motion obtained from the Furry picture Lagrangian for the exact interaction with the two electromagnetic fields associated with each interacting charge bunch. These enable more physically correct cross-section calculations to be performed.

Speaker: Anthony Hartin (DESY)

Slides Hartin_DESY_theory_ws_Sep2012.pdf

17:40 → 19:20 Parallel Session 1: Particle Phenomenology: Supersymmetry

Convener: Dr Thomas Mannel (Siegen University)

17:40 TeV scale Mirage Mediation in the NMSSM

We study the next-to-minimal supersymmetric standard model. We consider soft supersymmetry breaking parameters, which are induced by the mirage mediation mechanism of supersymmetry breaking. We concentrate on the mirage mediation, where the so-called mirage scale is the TeV scale. In this scenario, we can realize the effective mu-term the up-type Higgs soft mass of O(200) GeV, while other masses such as gaugino masses and stop masses are heavy such as 1 TeV or more. Cancellation between the effective mu-term and the down-type Higgs soft mass ameliorates the fine-tuning in the electroweak symmetry breaking even for mu=O(500) GeV. The lightest Higgs mass can be $115-130$ GeV. The higgsino and singlino are light and their linear combination is the lightest superparticle. We also discuss the new false vacua in the Higgs potential. The significant parameter region can be excluded by requiring the realistic vacuum to be deeper than false vacua and the couplings to be perturbative up to the GUT scale, which result in constraints on the properties of the lightest Higgs boson.

Speaker: Dr Takashi Shimomura (Niigata Univ., Japan/MPIK, Germany)

Slides Shimomura_DESY2012.pdf

18:00 Natural supersymmetric spectrum in mirage mediation

Current results of LHC experiments exclude large area of light new particle region, namely natural parameter space, in supersymmetric extension models. One of the possibilities for achieving the correct electroweak symmetry break- ing naturally is low scale messenger scenario. Actually, the next-to-minimal supersymmetric standard model with TeV scale mirage mediation realizes the natural electroweak symmetry breaking with various mass spectra. In this paper, we show the possible mass spectrum in the scenario, e.g. degenerate and/or hierarchical mass spectrum, and discuss these features.

Speaker: Dr Masaki Asano (University of Hamburg)

Slides Asano.pdf

18:20 A 125 Gev Higgs boson with enhanced gamma gamma rate in Supersymmetry

We confront the discovery of a boson decaying to two photons, as reported recently by ATLAS and CMS, with the corresponding predictions in the Minimal Supersymmetric Standard Model (MSSM) and the Next-to-Minimal Supersymmetric Standard Model (NMSSM). We show that a Higgs with a mass around 125 GeV and a significant enhancement of the rate in the two photon channel, compatible with the observed signal strenghts, is possible in both the MSSM and the NMSSM and we analyse in detail different mechanisms that can give rise to such an enhancement. We find that besides the interpretation of a possible signal at about 125 GeV in terms of the lightest CP-even Higgs boson, both the MSSM and the NMSSM permit also a viable interpretation where an observed state at about 125 GeV would correspond to the second-lightest CP-even Higgs boson in the spectrum.

Speaker: Lisa Zeune (DESY)

Slides Zeune.pdf

18:40 The Constrained MSSM and NMSSM in light of a 125 GeV Higgs and other constraints

We present an updated global analysis of the GUT-constrained models CMSSM and CNMSSM, taking into account the recent observation of a SM Higgs-like signal at the LHC. In both our analyses, we implement the CMS razor limit on supersymmetry, based on ~5/fb datasets, with an approximate but accurate likelihood map constructed through a simulation of the detector efficiency. In the CNMSSM we consider three possible scenarios: i) H1 is SM-like with mass around 125 GeV, ii) H2 is SM-like, with a mass of ~125 GeV and H1 escaped detection, and iii) H1 and H2 are almost degenerate in mass. We identify the 68% and 95% credible posterior probability regions in both models employing a Bayesian approach. We find that it is possible to accomodate the recent observation of the Higgs in both models, although a 125-GeV Higgs mass shows some tension with various constraints.

Speaker: Dr Enrico Maria Sessolo (NCBJ Warsaw)

Slides SessoloDESY27Sep12.pdf

19:00 Scattering in General Gauge Mediation, Vector Meson Dominance and Holography

We examine what scattering cross sections of Visible to Hidden sectors that break SUSY and are strongly coupled can tell us about supersymmetry breaking and its mediation. We apply Vector Meson Dominance and Holographic techniques to encode resonances in visible to hidden sector processes. We draw on analogies with QCD and the AdS/QCD programme.

Speaker: Dr Moritz McGarrie (DESY)

Slides McGarrie.key McGarrie.pdf

17:40 → 19:00 Parallel Session 2: Cosmology & Astroparticle Physics

Convener: Dr Riccardo Catena (Institut fuer Theoretische Physik Goettingen)

17:40 Cosmology challenges brane scenarios in AdS_5

We study a theory of dilaton gravity in a 5D brane scenario, with dilaton non-minimally coupled to the matter content of the universe localized on the brane. We investigate whether the observed large-scale structure of the universe can exist on the brane in the effective 4D dilaton gravity scenario with an exact anti de Sitter bulk. The corresponding constraint on the spatial derivative of the matter energy density is derived, and subsequently quantified using the current limits resulting from searches for variation of the Newton's constant. By confronting it with the observational data from galaxy surveys, we show that the derived bound does not allow for the existence of the large-scale structure as is observed today. Thus, such a dilaton gravity brane scenario is ruled out.

Speaker: Dr Dominika Konikowska (Bielefeld University)

Slides Konikowska.pdf

18:00 Electrically charged curvaton

We consider the possibility that the primordial curvature perturbation was generated through the curvaton mechanism from a scalar field with an electric charge, or precisely the Standard Model U(1) weak hypercharge. This links the dynamics of the very early universe concretely to the Standard Model of particle physics, and because the coupling strength is known, it reduces the number of free parameters in the curvaton model. We show that the model is compatible with CMB observations for large Hubble rate and large curvaton mass. Charge fluctuations generated during inflation are screened by electron-positron pairs, and therefore do not violate observational constraints. The interaction with the gauge field leads to interesting dynamics after inflation, including resonant preheating, with non-trivial observational consequences.

Speaker: Dr Rose Lerner (Helsinki University)

Slides Lerner.pdf

18:20 Dark radiation from the axino solution of the gravitino problem

Current CMB observations could confirm an increase of the effective neutrino degrees of freedom at photon decoupling. We show that, if the gravitino problem is solved by a light axino, dark (decoupled) radiation emerges naturally after nucleosynthesis but before CMB times leading to a new upper bound on the reheating temperature < 10^10 GeV. In turn, successful thermal leptogenesis predicts such an increase. The LHC might endorse this opportunity. We identify several consistent cosmologies.

Speaker: Dr Jasper Hasenkamp (Hamburg U.)

Slides Hasenkamp.pdf

18:40 Axions and saxions from the primordial supersymmetric plasma and extra radiation signatures

We calculate the rate for thermal production of axions and saxions via scattering of quarks, gluons, squarks, and gluinos in the primordial supersymmetric plasma. Systematic field theoretical methods such as hard thermal loop resummation are applied to obtain a finite result in a gauge-invariant way that is consistent to leading order in the strong gauge coupling. We calculate the thermally produced yield and the decoupling temperature for both axions and saxions. For the generic case in which saxion decays into axions are possible, the emitted axions can constitute extra radiation already prior to big bang nucleosynthesis and well thereafter.We update associated limits imposed by recent studies of the primordial helium-4 abundance and by precision cosmology of the cosmic microwave background and large scale structure. We show that the trend towards extra radiation seen in those studies can be explained by late decays of thermal saxions into axions and that upcoming Planck results will probe supersymmetric axion models with unprecedented sensitivity.

Speaker: Mr Peter Graf (Max-Planck-Institut fuer Physik)

Slides Graf.pdf

17:40 → 19:00 Parallel Session 3: Strings & Mathematical Physics

17:40 Loop corrections in certain (super) conformal Yang-Mills theories

In the talk I will motivate why direct perturbative calculations in N=4 SYM theory and in ist (super9 conformal deformations are of interest and I will summarize some of our recent results and work in progress.

Speaker: Mr Christoph Sieg (Humboldt U. Berlin)

Slides Sieg.pdf

18:00 Form factors at strong coupling via AdS/CFT

Form factors are very interesting observables to consider. For example, it has been shown that the two-loop form factor in N=4 SYM is equal to the leading transcendental part of a Higgs scattering amplitude in QCD. In this talk we report some progress on computing form factors in N=4 SYM at strong coupling based on AdS/CFT duality.

Speaker: Dr Gang Yang (University of Hamburg)

Slides Yang.pdf

18:20 Towards a Holographic Realization of Homes' Law

Gauge/gravity duality has proved to be a very successful tool for describing strongly coupled systems in particle physics and heavy ion physics. The application of the gauge/gravity duality to quantum matter is a promising candidate to explain questions concerning non-zero temperature dynamics and transport coefficients. To a large extent, the success of applications of gauge/gravity duality to the quark--gluon plasma is founded on the derivation of a universal result, the famous ratio of shear viscosity and entropy density. As a base for applications to condensed matter physics, it is highly desirable to have a similar universal relation in this context as well. A candidate for such a universal law is given by Homes' law: High Tc superconductors, as well as some conventional superconductors, exhibit a universal scaling relation between the superfluid density at zero temperature and the conductivity at the critical temperature times the critical temperature itself. In this work we describe progress in employing the models of holographic superconductors to realize Homes' law and to find a universal relation governing strongly correlated quantum matter. We calculate diffusive processes, including the backreaction of the gravitational matter fields on the geometry. We consider both holographic s-wave and p-wave superconductors. We show that a particular form of Homes' law holds in the absence of backreaction. Moreover, we suggest further steps to be taken for holographically realizing Homes' law more generally in the presence of backreaction.

Speaker: Mr Steffen Mueller (Max-Planck Institute for Physics)

Slides Mueller.pdf

18:40 D-brane superpotentials from a Landau-Ginzburg perspective

D-branes on Calabi-Yau manifolds can be described by matrix factorizations at the Landau-Ginzburg (LG) point. In this talk I will discuss methods for the study of D-brane moduli spaces and superpotentials within this framework. An emphasis will be put on non-toric complex structure deformations, which arise as bulk moduli from twisted sectors in the LG orbifold. I will outline how the contributions to the effective superpotential from these fields can be computed by considering appropriate defects in the unonrbifolded LG model.

Speaker: Mr Daniel Plencner (LMU Munich)

Slides Plencner.pdf

Friday 28 September

09:00 → 10:45 Plenary Session

Convener: Tsutomu Yanagida

09:00 Beyond the Standard Model from a Neutrino Perspective

Speaker: M. Lindner (MPI Heidelberg)

Slides Lindner.pdf

09:35 Direct Detectionof Dark Matter: WIMPs and Beyond

Speaker: T. Volansky (Tel Aviv)

Slides Volansky.pdf

10:10 Monte Carlo Programs for the LHC

Speaker: J. Reuter (DESY)

Slides Reuter.pdf

10:45 → 11:15 Coffee break

11:15 → 13:00 Plenary Session

Convener: Andreas Weiler (DESY-T)

11:15 Searches for Physics beyond the Standard Model

Speaker: F. Moortgat (Zurich)

Slides Moortgat.pdf

11:50 Where could SUSY be hiding?

Speaker: C. Csaki (Cornell)

Slides Csaki.pdf

12:25 Searches for new physics at the LHC: some frustration, but no despair...

Speaker: M. Kraemer (Aachen)

Slides Kraemer.pdf