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

30/09/2015, 14:00

Phenomenologically appealing string vacua with either the Standard Model or some GUT spectrum and suitable orders of magnitudes of matter couplings are essential to establish string theory as the framework that unifies all fundamental interactions. I will present here recent results on the quest for such vacua based on Type II string theory with D-branes, and I will discuss their impact on new...

Dr
Patrick Vaudrevange
(TUM Munich)

30/09/2015, 14:25

Two approaches to heterotic string model building are discussed and compared: first toroidal orbifolds and secondly Calabi-Yau manifolds with line bundle gauge backgrounds.

Raffaele Savelli
(Saclay)

30/09/2015, 15:15

Strings & Mathematical Physics

I will discuss the effective action of F-theory at order \alpha'^3 from a 12 dimensional perspective. Upon compactification on elliptic Calabi-Yau fourfolds, I will show how the non-trivial vacuum profile for the axio-dilaton leads to a new, genuinely N=1 correction to the 4-dimensional effective action.

Paul Oehlmann
(Univ. Bonn)

30/09/2015, 16:05

We give an overview on all F-theory fibrations with the 16 classical 2D polytopes as the fiber.
These models include Abelian, discrete and quotient symmetries as well as the exact standard model of particle physics that we construct explicitly in four dimensions.

Mr
Andreas Gerhardus
(Bethe Center for Theoretical Physics)

30/09/2015, 16:20

Two-dimensional gauged linear sigma models with N=(2,2) supersymmetry are a powerful tool for studying the worldsheet theories of type II string compactifications. We construct a certain class of non-Abelian gauged linear sigma models that exhibit an interesting phase structure emerging from non-Abelian strong coupling dynamics. The observed phase structure leads to a duality proposal amongst...

Mr
Thorsten Schimannek
(University of Bonn)

30/09/2015, 16:35

The topological string theory partition function captures non-trivial invariants of Calabi-Yau threefolds. In general, target space symmetries acting on the cohomology induce an automorphic structure on the free energies. For non-compact geometries with spectral curve of genus one this allowed to re-express the physical constraints in terms of modular forms. The construction, however, relied...

Mrs
Ioana Coman-Lohi
(DESY)

30/09/2015, 16:50

Non-perturbative aspects of N=2 SUSY gauge theories of class S are encoded in the algebra of functions on the moduli space M-flat of flat SL(N)-connections on Riemann surfaces. Expectation values of Wilson and 't Hooft line operators are related to holonomies of flat connections and, in the low-energy effective theory, to Fock-Goncharov coordinates on M-flat.
We determine the non-commutative...

Jules Lamers
(Utrecht University)

30/09/2015, 17:05

Strings & Mathematical Physics

Solid-on-solid (SOS) models in statistical physics describe the
(two-dimensional) interface between two media. To model the shape of the interface we assign a (discrete) height variable to each vertex of a square lattice. The surface tension is taken into account by interactions between these height variables. In case the nearest-neighbouring heights differ by one unit, and the interactions...

Dr
Igor Bogolubsky
(JINR, Dubna)

30/09/2015, 17:20

Strings & Mathematical Physics

First I will give a short comparison of topological defects and topological solitons for various space dimensions (D=1,2,3).
Then I will discuss properties of 2-dimensional solitons for
U(1) gauged easy-axis Heisenberg antiferromagnet, compare these
solitons both with 2D Nielsen-Olesen strings in the Abelian Higgs model and with 2D Belavin-Polyakov solitons in isotropic antiferromagnet...

David Ciupke
(DESY)

30/09/2015, 17:35

Strings & Mathematical Physics

Models of 4D $\mathcal{N}=1$ supergravity coupled to chiral multiplets with vanishing scalar potential have been denoted as no-scale. Of particular interest in the context of string theory are models which additionally possess a shift-symmetry. In this case there exists a dual description of chiral models in terms of real linear multiplets. We classify all shift-symmetric no-scale...

Mr
Alexander Zhiboedov
(Harvard University)

01/10/2015, 14:00

We study higher spin currents in the O(N) vector models using analytic conformal bootstrap. For large $N$ we compare the predictions of the bootstrap for anomalous dimensions of higher spin currents against the available perturbative computations. We then generalize to arbitrary loop order. For small $N$ our results can be tested using numerical bootstrap or future experiments.

Dr
Alexander Manashov
(University of Hamburg)

01/10/2015, 14:25

QCD evolution equations in MS-like schemes can be recovered from the same equations in a modified theory, QCD in non-integer d=4−2ϵ dimensions, which enjoys exact scale and conformal invariance at the critical point. Restrictions imposed by the conformal symmetry of the modified theory allow one to obtain complete evolution kernels in integer (physical) dimensions at the given order of...

Rolf Kappl
(Bethe Center for Theoretical Physics)

01/10/2015, 14:50

Natural (axionic) inflation provides a well-motivated and predictive scheme for the description of the early universe. It leads to sizeable primordial tensor modes and thus a high mass scale of the inflationary potential. Naively this seems to be at odds with low (TeV) scale supersymmetry, especially when embedded in string theory. I will outline in the talk that low scale supersymmetry is...

Dr
Lukas Witkowski
(Heidelberg University)

01/10/2015, 15:15

Strings & Mathematical Physics

We explore a recent proposal of Cosmological Relaxation, by Graham, Kaplan and Rajendran, for generating a hierarchically small Higgs vacuum expectation value. In particular, we discuss its capacity for solving the electroweak hierarchy problem. To do so, we study the dynamics of the model and determine the relation between the fundamental input parameters and the electroweak vacuum...

Mr
Edoardo Vescovi
(Humboldt-Universität zu Berlin)

01/10/2015, 16:05

We study the strong coupling behaviour of 1/4 BPS latitude Wilson loops in N=4 SYM theory, computing the one-loop corrections to the relevant classical string solution in AdS5xS5 in sigma-model perturbation theory.
The approach is based on the application of the Gel’fand-Yaglom method to compute the relevant functional determinants for the fluctuations of the type IIB Green-Schwarz action...

Dmitry Chicherin
(LAPTh, Annecy)

01/10/2015, 16:20

Strings & Mathematical Physics

Correlation functions of local gauge-invariant operators are natural
observables inany conformal quantum field theory.
In N=4 SYM a particular role is played by the multipoint supercorrelators
of thestress-tensor multiplet.
Their chiral truncation in the light-cone limit coincides with the scattering
superamplitudes.
We propose a novel approach to calculating such correlators based on...

Mrs
Lucila Zárate
(Hamburg University)

01/10/2015, 16:35

Strings & Mathematical Physics

In this work we consider a set of soft supersymmetry breaking terms within the NMSSM which leads to a small hierarchy between the supersymmetry breaking scale and the electroweak scale.
Specifically only the gaugino masses and the soft term in the Higgs sector are non-vanishing at the GUT scale. This pattern can be found in gaugino mediated models and in higher-dimensional orbifold GUTs....

Dr
Norimi Yokozaki
(INFN, Rome)

01/10/2015, 16:50

Strings & Mathematical Physics

We propose a focus point gauge mediation model based on the product group unification (PGU), which solves the double-triplet splitting problem of the Higgs multiplets. In the focus point gauge mediation, the electroweak symmetry breaking scale can be naturally explained even for multi-TeV stops. It is known that the focus point behavior appears if a ratio of the number of SU(2) doublet...

Mr
Julian Schweizer
(DESY)

01/10/2015, 17:20

Strings & Mathematical Physics

Recently, a model with SO(10) symmetry and bulk flux in 6d was constructed. Anomalies can be canceled and the flux leads to interesting features. Notably, a U(1) flux breaks supersymmetry at a high scale in the matter sector while leaving it intact on gauge and Higgs multiplets. On the other hand, the flux creates a multiplicity for the matter fields while protecting them from symmetry...