from September 29, 2015 to October 2, 2015
DESY Hamburg
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Particle Phenomenology


Location: DESY Hamburg
Room: seminar rooms
Date: from 30 Sep 14:00 to 1 Oct 17:50

Timetable | Contribution List

Displaying 47 contributions out of 47
Lepton flavor violating Higgs decays can arise in flavor symmetry models where the Higgs sector is responsible for both the electroweak and the flavor symmetry breaking. Here we advocate an $S_4$ three-Higgs-doublet model where tightly constrained flavor changing neutral currents are suppressed by a remnant $Z_3$ symmetry. A small breaking of this $Z_3$ symmetry can explain the $2.4\,\sigma$ ... More
Presented by Mr. Erik SCHUMACHER on 30/9/2015 at 14:15
The ATLAS collaboration recently found a 3 sigma excess in the search for events with large missing transverse energy, jets, and a dilepton peaked on the Z mass region. We study this excess in the minimal supersymmetric standard model (MSSM), especially focusing on the well-motivated split supersymmetry (SUSY) spectrum. We consider the following decay chain: gluino to gluon and Higgsino which su ... More
Presented by Dr. Takahiro TERADA on 1/10/2015 at 16:35
We propose an adjoint $SU(5)$ GUT model with a $T_{7}$ family symmetry and an extra $Z_{2}\otimes Z_{2}^{\prime }\otimes Z_{3}\otimes Z_{4}\otimes Z_{12}$ discrete group, that successfully describes the prevailing Standard Model (SM) fermion mass and mixing pattern. The observed hierarchy of the charged fermion masses and the quark mixing angles arises from the $Z_{3}\otimes Z_{4}\otimes Z_{12}$ s ... More
Presented by Dr. Arbelaez CAROLINA on 30/9/2015 at 14:30
Session: Particle Phenomenology
Track: Particle Phenomenology
Run-II of the LHC is probing the Standard Model of particle physics at unprecedented energies and precision. At such large energy scales higher-order electroweak (EW) corrections are strongly enhanced due to the presence of large Sudakov logarithms. In my talk I will present a fully automated implementation of next-to-leading order (NLO) EW corrections in the OpenLoops matrix-element generato ... More
Presented by Jonas LINDERT on 30/9/2015 at 14:45
Transverse momentum spectra of massive bosons at hadron colliders provide important tests of the Standard Model. In the crucial region, where the boson's invariant mass M is much smaller than its transverse momentum qT, the spectra are very sensitive to initial state radiation. Applying soft-collinear effective theory, a universal framework for its description has been established and the relevan ... More
Presented by Dr. Thomas LÜBBERT on 30/9/2015 at 16:35
The Minimal Supersymmetric Standard Model (MSSM) is known for the possibility of creating (unwanted) charge and color breaking minima. Well-known bounds on MSSM parameters are known for special scenarios with an alignment of vacuum expectation values (vevs) in the direction of up-type or dow-type fields only. From the one-loop stability condition in the up-type Higgs direction, we find a new const ... More
Presented by Dr. Wolfgang Gregor HOLLIK on 1/10/2015 at 17:05
We present a general classification of minimal models where Dark Matter coannihilates with another particle, X. Besides this new particle, such coannihilation processes typically require the existence of a mediator, M. Assuming tree-level and renormalizable interactions we construct all possible Dark Matter, X and M field content which respects gauge and Lorentz invariance. Using our framework one ... More
Presented by Dr. Michael BAKER on 30/9/2015 at 16:50
We present theoretical predictions for the mono-$Z$ production in the search for dark matter at the LHC with next-to-leading order QCD corrections and parton-shower effects. The calculation is performed in the framework of {\tt MadGraph5$\_$aMC@NLO}. We find that the high order QCD corrections are sizable, and can reduce the theoretical uncertainties. We also investigate the discovery potenti ... More
Presented by Dr. Jian WANG on 30/9/2015 at 17:20
We revisit the singlet complex scalar Higgs portal model. We introduce the U(1)_{\phi} breaking terms. These terms make small mass splitting. The small mass splitting make the displaced decay which could be a non-SM background signal. We find feasible way to discover the displaced higgs portal dark matter at the LHC.
Presented by Mr. Dong Woo KANG on 30/9/2015 at 17:05
Effective field theory (EFT) provides an efficient framework to study the phenomenology of extended Higgs sectors at the LHC. One caveat is that assuming a clear hierarchy of scales strongly suppresses the size of new physics deviations in an environment where partonic processes can probe a wide range of scales. We consider several modifications of the Higgs sector: a singlet and doublet exten ... More
Presented by Dr. David LOPEZ-VAL on 1/10/2015 at 14:30
We calculate the electroweak corrections to the Higgs-Strahlung processes at the LHC, pp -> Vh, within the Two Higgs Doublet Model(THDM). The freedom in triple-Higgs couplings would give strong elevation to the cross section. Even for fairly heavy Higgs bosons, the relative corrections could also reach -20%.
Presented by Taoli CHENG on 30/9/2015 at 14:00
Grand unified theories have been with us for more than four decades. While attractive, the standard SU(5) and SO(10) models fail to shed light on the flavour problem since, just like the Standard Model, they too place the fermions in three copies of representations of the enlarged gauge group. What about the possibility of having family unification by putting all fermions in a single represent ... More
Presented by Dr. Renato FONSECA on 30/9/2015 at 15:00
The anomalous magnetic moment of the muon is, by today, one of the most appealing signs for Physics Beyond the Standard Model. In this work, we study the Two-Higgs-Doublet Model and compute, up to two-loop order, the complete set of fermionic contributions for the anomaly. We are able to fully reproduce some recent results found in the literature and we show that, for a large region of the parame ... More
Presented by Dr. Adriano LANA CHERCHIGLIA on 1/10/2015 at 14:15
We present GM2Calc, a stand-alone C++ program which calculates the supersymmetric contributions to the anomalous magnetic moment of the muon in the Minimal Supersymmetric Standard Model. Besides the one-loop contributions, two-loop corrections coming from SUSY one-loop diagrams with an additional photon exchange or a fermion/sfermion loop insertion as well as two-loop corrections to SM-like one-lo ... More
Presented by Mr. Markus BACH on 1/10/2015 at 14:00
We present a framework to generate the mass hierarchies and mixing angles of the fermionic sector of the Standard Model with two extra Higgs doublets and one right-handed neutrino. The masses of the first and second generation are generated by small quantum effects, explaining the hierarchy with the third generation. The model also generates a natural hierarchy between the first and second genera ... More
Presented by Ms. Ana SOLAGUREN-BEASCOA on 30/9/2015 at 14:00
Searches for supersymmetry (SUSY) often rely on a combination of hard physics objects (jets, leptons) along with large missing transverse energy to separate New Physics from Standard Model hard processes. We consider a class of ``double-invisible'' SUSY scenarios: where squarks, stops and sbottoms have a three-body decay into {\em two} (rather than one) invisible final-state particles. This occurs ... More
Presented by Dr. Jia LIU on 1/10/2015 at 15:15
Session: Particle Phenomenology
Track: Particle Phenomenology
I will present the calculation of the N3LO QCD correction to the production of a Higgs boson via gluon fusion at the LHC in the limit of infinite top mass. In particular I will give an overview of computational methods used and discuss the reduction of theoretical uncertainties.
Presented by Franz HERZOG on 30/9/2015 at 17:20
I present recent calculation of 2-loop corrections to the lightest Higgs boson mass in the minimal R-symmetric supersymmetric Standard Model using the effective potential approximation.
Presented by Mr. Wojciech KOTLARSKI on 1/10/2015 at 15:00
Session: Particle Phenomenology
Track: Particle Phenomenology
Higgs pair production is key to extract information on the Higgs potential as it consists the simplest process which is sensitive to the trilinear Higgs coupling. A considerable amount of work has been devoted recently towards providing accurate SM predictions and investigating the prospects of observing the process at the LHC. While the SM rates are small (35 fb) at 14 TeV, the process can receiv ... More
Presented by Eleni VRYONIDOU on 30/9/2015 at 17:05
I will talk about the more technical aspects of calculations of higher-order corrections to single and double Higgs boson production.
Presented by Dr. Jens HOFF on 30/9/2015 at 16:50
As the number of non-perturbative parameters appearing in the heavy quark expansion for inclusive decays proliferates at higher orders, one cannot extract all of these from data, but needs to rely on theoretical estimates. I will explain a systematic method to estimate these parameters.
Presented by Dr. Johannes HEINONEN on 1/10/2015 at 17:05
Fermion dark matter interacting with the standard model through a Higgs portal suggests the presence of new mediator states at the electroweak scale. Collider searches for the mediators are a powerful tool to experimentally probe the Higgs-portal interactions, complementary to direct dark matter detection searches. In this talk, I discuss search strategies and the discovery range for the mediators ... More
Presented by Susanne WESTHOFF on 30/9/2015 at 15:15
The interpretation of LHC searches for additional Higgs bosons has so far been restricted to cases without interference between close-by states. Phenomenological consequences of such interference terms will be presented. In the MSSM, the two heavier neutral Higgs bosons have similar masses in a wide part of the parameter space. Therefore, especially in the presence of CP-violating complex phases, ... More
Presented by Elina FUCHS on 1/10/2015 at 16:20
We present a variety of dark matter models with mediator particles, ranging from simplified setups to elaborated models with definite predictions. We explore the parameter space regions not excluded by cosmological observations. We show that there is an important complementarity between these bounds and LHC searches for the mediators themselves. These include monojet and dijet searches, as well as ... More
Presented by Dr. Mikael CHALA on 30/9/2015 at 16:20
R-Symmetry is an additional symmetry which can be imposed on a supersymmetric model, leading to interesting phenomenological consequences like the prediction of Dirac Gauginos. A model with a minimal implementation of this symmetry is the MRSSM and in this talk an analysis of its Higgs sector, as well as its dark matter and LHC phenomenology will be presented. This model includes a singlet ... More
Presented by Mr. Philip DIESSNER on 1/10/2015 at 15:15
In this talk I will discuss an azimuthal angle correlation between the two hardest jets in the top quark pair production at the LHC. The event samples are generated by merging the tree level matrix elements for the ttbar plus up to 2 or 3 partons with parton showers. I show that the generated event samples reproduce a strong correlation in the azimuthal angle difference between the two hardest jet ... More
Presented by Junya NAKAMURA on 1/10/2015 at 16:35
In this talk we give an overview over recent developments within GoSam, a publicly available package for the automated calculation of next-to-leading order corrections within and beyond the Standard Model. Besides the current developments we discuss the latest phenomenological applications and present results that are relevant for the Run 2 of the LHC.
Presented by Mr. Nicolas GREINER on 30/9/2015 at 13:00
The idea that dark matter forms part of a larger dark sector is very intriguing, given the high degree of complexity of the visible sector. In this paper, we discuss lepton jets as a promising signature of an extended dark sector. As a simple toy model, we consider an O(GeV) DM fermion coupled to a new U(1)' gauge boson (dark photon) with a mass of order GeV and kinetically mixed with the Standar ... More
Presented by Mr. Malte BUSCHMANN on 30/9/2015 at 16:35
We present an interpretation of searches for dark matter in a simplified model approach. Considering Majorana fermion dark matter and neutral vector mediators with axial-vector interaction we compare the limits obtained in mono-jet searches at the LHC with limits on the spin-dependent scattering cross-section set by the IceCube collaboration. We discuss the validity of the EFT limit and place new ... More
Presented by Dr. Jan HEISIG on 30/9/2015 at 16:05
We present the calculation, in a completely automated approach, of the NLO EW corrections to ttH, ttZ and ttW production at hadron colliders within the MadGraph5_aMC@NLO framework. We discuss also the impact of NLO QCD corrections on ttH, ttV and ttVV production with V=W, Z, gamma. Relevant distributions for the 13-TeV LHC are considered and inclusive results from 8 to 100 TeV are shown, also for ... More
Presented by Dr. Davide PAGANI on 30/9/2015 at 14:30
The MSSM with complex parameters has emerged as an attractive SUSY candidate providing new sources of CP-violation, which are well motivated in the context of the observed imbalance between matter and antimatter in the universe. In order to study the effects of the complex parameters, which enter via loop contributions, an accurate prediction for the Higgs production cross-section is required. In ... More
Presented by Shruti PATEL on 1/10/2015 at 16:05
Weak boson pair production processes are very sensitive to the gauge structure of the electroweak (EW) Standard Model. In certain regions of phase space EW corrections lead to significant distortions of differential distributions and their omission could easily be misinterpreted as signs of new physics. Providing not only QCD but also EW corrections for weak boson pair production processes in a fu ... More
Presented by Lukas SALFELDER on 30/9/2015 at 14:15
The spectroscopy of charmonium and exotic states with hidden charm together with the spectroscopy of charmed and strange baryons is discussed. It is a good testing tool for the theories of strong interactions, including: QCD in both the perturbative and non-perturbative regimes, LQCD, potential models and phenomenological models [1, 2, 3]. An understanding of the baryon spectrum is one of the prim ... More
Presented by Dr. Barabanov MIKHAIL on 1/10/2015 at 17:20
The NMSSM represents an elegant and well motivated alternative description for the observed phenomenology in high energy physics. In this theory a scalar singlet together with its superpartner is added to the Higgs-sector of the Minimal Supersymmetric Standard Model (MSSM). In order to allow significant testing of the NMSSM by experiments precise predictions for the parameters of the theory are a ... More
Presented by Peter DRECHSEL on 1/10/2015 at 14:45
Despite of its tremendous success various theoretical and experimental issues seem to indicate the need to go beyond the Standard Model framework. One of the most promising ways to address the open questions is offered by the Grand Unification paradigm. Its main experimental signature is the prediction of proton decay and with the new generation of experiments under way (Hyper-K, DUNE, \ldots) an ... More
Presented by Timon MEDE on 30/9/2015 at 14:45
We discuss an improved determination of the up- and down-quark distributions in the proton using recent data on charged lepton asymmetries from $W^\pm$ gauge-boson production at the LHC and Tevatron. The analysis is performed in the framework of a global fit of parton distribution functions. The results are consistent with a non-zero iso-spin asymmetry of the sea, $x(\bar d - \bar u)$, at small va ... More
Presented by Sergey ALEKHIN on 1/10/2015 at 16:05
LHC measurements involve cuts on several observables. Some lead to widely separated energy scales and require resummation. I will present an extension of SCET which enables the resummation of a class of double-differential measurements. Two prototypical application are 1) pp → Z + 0 jets, where the jet veto is imposed through the beam thrust event shape T, and the transverse momentum pT of the Z ... More
Presented by Lisa ZEUNE on 30/9/2015 at 16:20
We propose a framework of supersymmetric standard models that can ameliorate both the SUSY Higgs mass problem and the missing superpartner problem. New vectorlike matter fields couple to the Higgs and provide new loop contributions to its mass. To avoid a Landau pole for new Yukawa couplings, these fields are charged under a new gauge group, which confines and leads to a Hidden Valley-like phenome ... More
Presented by Dr. Yuichiro NAKAI on 1/10/2015 at 15:00
Due to the unknown stop, sbottom and neutralino masses, very different event shapes for squark pair production are imaginable, ranging from unboosted top/bottom quarks and low missing energy to highly boosted top/bottom quarks and large missing energy in the final state. In order to cover a wide range of possible event shapes and consequently stop, sbottom, and neutralino masses, we combined sever ... More
Presented by Mr. Matthias SCHLAFFER on 1/10/2015 at 16:50
In this talk, I will describe how kinematic distributions in the Higgs to four lepton channel can be used to probe the Standard Model (SM) as well as new physics scenarios. Higher order electroweak corrections make this channel sensitive to anomalous tensor structures in Higgs couplings, making this one of the best direct probes of several types of deviations from the SM including CP violation in ... More
Presented by Prof. Daniel STOLARSKI on 1/10/2015 at 14:15
Two-loop calculations with non-trivial renormalization are necessary for the determination of high-precision theory predictions of experimentally well-known quantities. A famous example is the mass of a Higgs-like particle which has been measured at the LHC with a precision at the sub-percent level. A possible interpretation of this particle is given by the Minimal Supersymmetric Standard Model (M ... More
Presented by Dr. Sebastian PAßEHR on 1/10/2015 at 14:30
A number of LHC resonance search channels display an excess in the invariant mass region of 1.8 - 2.0 TeV. Among them is a 3.4 sigma excess in the fully hadronic decay of a pair of Standard Model electroweak gauge bosons, in addition to potential signals in the HW and dijet final states. We present a model-independent cross-section fit to the results of all ATLAS and CMS searches sensitive to thes ... More
Presented by Mr. Johann BREHMER on 1/10/2015 at 14:00
Session: Particle Phenomenology
Track: Particle Phenomenology
The Matrix Element Method (MEM) has proven beneficial to make maximal use of the information available in experimental data. However, so far it has been formulated only in Born approximation. In this talk we discuss the extension to NLO accuracy. As a prerequisite we present an efficient method to calculate event weights for jet events at NLO accuracy. As illustration and proof of concept we app ... More
Presented by Till MARTINI on 1/10/2015 at 14:50
We discuss transverse momentum dependent (un)polarized gluon distributions (gluon TMDs) and their proper definitions in the context of factorization theorems. All the gluon TMDs have a scale evolution driven by a universal evolution kernel which is resummed to NNLL. By an explicit NLO calculation of the three gluon TMDs which are matched onto leading twist parton distribution functions (PDFs) we d ... More
Presented by Tomas KASEMETS on 1/10/2015 at 16:20
With increasing statistics at the LHC an important observable of the Higgs-like boson is its transverse momentum distribution. Its dominant contributions arise at small pT, where large logarithms log(pT/mH) need to be resummed to all orders to obtain a reliable theoretical prediction. This resummation is conveniently performed in the impact parameter space, which is Fourier conjugate to transve ... More
Presented by Markus EBERT on 30/9/2015 at 16:05
CheckMATE is a framework that allows the user to conveniently test simulated BSM physics events against current LHC data in order to derive exclusion limits. For this purpose, the data runs through a detector simulation and is then processed by a user chosen number of experimental analyses. These analyses determine event predictions of the signal for various kinematic regions of interest that can ... More
Presented by Mr. Daniel SCHMEIER on 1/10/2015 at 14:45
In this work we report on a next-to-leading order calculation of WW + jet production at hadron colliders, with subsequent leptonic decays of the W-bosons included. The calculation of the one-loop contributions is performed using generalized unitarity methods in order to derive analytic expressions for the relevant amplitudes. These amplitudes have been implemented in the parton-level Monte Carlo g ... More
Presented by Dr. Tania ROBENS on 30/9/2015 at 15:15
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