Time: 2 pm

Place: DRL 2N36

# Events

Time: 2pm

Place: DRL 2N36

Time: 2 pm

Place: DRL 2N36

Time: 2pm

Place: DRL 2N36

Time: 2pm

Place: DRL 2N36

Time: 2pm

Place: DRL 2N36

Time: 2 pm

Place: DRL 2N36

Time: 2pm

Place: DRL 2N36

Title: Dark Energy phenomenology: the effective field theory approach

Time 2pm

Place: DRL 2N36

Abstract:

I will present recent and ongoing works that aim at a unifying description of dark energy and modified gravity models containing a scalar degree of freedom in addition to general relativity. Such an effective field theory approach allows, on the one hand, a transparent analysis of the possible theoretical mechanisms at the basis of cosmic acceleration; moreover, it provides a useful set of parameters that can be efficiently constrained with observations. I will show the present observational constraints based on the growth rate of cosmic structures and the forecasts for future surveys such as EUCLID.

Title: Building a social network of elliptic fibrations for F-Theory

Time: 2pm

Place DRL 2N36

Abstract:

We discuss the gauge groups and matter content for genus one fibrations with their fiber a hypersurface in one of the 16 2D reflexive polytopes, where some of these were already discussed in the literature. The polyhedrons are connected by geometric transitions on the geometry side which translates into a toric Higgs branch on the field theory side. This network structure is symmetric and reflects the mirror symmetry of the polytopes. This allows the identification of discrete symmetries.

Title: Healthy theories beyond Horndeski

Time: 2pm

Place: DRL 2N36

Title: Search for CP Violation in the Gamma Ray Sky

Time: 2pm

Place: 4N9

Abstract: Motivated by the possible existence of a cosmological magnetic field with non-trivial

helicity, we evaluate a CP odd statistic, $Q$, using gamma ray data obtained from

Fermi satellite observations at high galactic latitudes. Observed values of $Q$ arefound to be non-zero at the $2\sigma$ level ($3\sigma$ in the northern hemisphere)and also deviate at the same level from values obtained from simulated data. Contaminationfrom the Milky Way does not seem to be responsible for the excess since the signal ispresent even for data at very high galactic latitudes. Assuming that the excess is indeeddue to a helical cosmological magnetic field, our results indicate left-handed magnetic helicityand field strength $\sim 10^{-14}~{\rm G}$ on $\sim 10~{\rm Mpc}$ scales.

Title: Origin of probabilities and their application to the multiverse: Toward a resolution of cosmological measure problems

Time: 11am

Place: DRL 4N12

Abstract:

Increasing observational support for cosmic inflation motivates further scrutiny of the challenging open questions related to multiverse theories such as eternal inflation. Page and others have argued that such theories only make sense if classical probabilities are introduced separately from the quantum ones. I argue using simple models that all successful practical uses of probabilities originate in quantum fluctuations in the microscopic physical world around us, often propagated to macroscopic scales. Thus I claim there is no physically verified fully classical theory of probability. I comment on the general implications of this view, and specifically question the application of classical probability theory to cosmology in cases where key questions are known to have no quantum answer. I argue that the ideas developed here may offer a way out of the notorious measure problems of eternal inflation.

Title: Are Two Metrics Better than One?: The Cosmology of Massive Bigravity

Time: 2 pm

Place: DRL 4N9

Title: Scale Invariance, Radiative Symmetry Breaking and Dark Matter

Time: 2pm

Place: DRL 4N12

Abstact:

The discovery of the Higgs and the absence of any New Physics at the LHC

shifts the landscape of BSM model building. Is a natural theory just

pushed to higher scales or were we not careful enough, when interpreting

the argument of Naturalness?

In this talk I want to consider both possibilities. In case of a

high-scale UV completion of the SM, a heavy WIMP could be the first

thing we see. I will discuss new effective theories for such a scenario.

Theories which radiatively induce the Higgs mass parameter by a

Coleman-Weinberg mechanism in a Dark Sector allow to generate all mass

scales in the SM by quantum effects. In the absence of high scale new

physics these models could c

Title: Thermodynamics of gauged dyonic and Proca black holes

Time: 2pm

Place: DRL 4N12

Title: The Null Energy Condition from String Theory

Time: 2 pm

Place: DRL 2N36

Modeling quantum gravity effects in inflation

In this talk I will discuss the quantum structure of slow-roll inflation. Various examples in 3+1 and 1+1 dimensions show that the standard arguments leading to slow-roll eternal inflation (SREI) are not invariant under field redefinitions. A particular case in 1+1d, which by standard arguments should exhibit SREI, is related by a field redefinition to pure Liouville gravity coupled to a free scalar matter field. Aspects of the non-perturbative quantization of Liouville theory will be discussed, and quantum fluctuations of the scale factor will be seen to prevent SREI in this model.

Time: 2 p.m.

Place: 4N12

Time: 2 pm

Place: DRL 2N36

Title: Galileon Duality

Abstract: I will review how Galileon scalar fields arise in models of modified gravity. In the vicinity of matter, Galileons get screened via the Vainshtein mechanism which comes hand in hand with its own share of peculiarities: superluminalities, strong coupling and perturbative non-analyticity of the S-matrix to name a few. From a traditional effective field viewpoint such effects are typically disastrous but I will present the first hints in understanding these theories beyond the traditional perspective and their implications for modified theories of gravity.

**Math-Physics Joint Seminar**

Title: Singularities and phases of gauge theories

Time: 4:30 pm

Place: DRL 4E19

Abstract:

Motivated by M-theory compactification on elliptic Calabi-Yau threefolds, we present a correspondence between networks of small resolutions for singular elliptic fibrations and Coulomb branches of five-dimensional N=1 gauge theories. While resolutions correspond to subchambers of the Coulomb branch, partial resolutions correspond to higher codimension loci at which the Coulomb branch intersects the Coulomb-Higgs branches. Flops between different resolutions are identified with reflections on the Coulomb branch. Physics aside, this correspondence provides an interesting link between elliptic fibrations and representation theory.