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Time: 2pm
Location: 2N26

Title: Topological sectors, supersymmetric localization, and holography

Time: 1:30pm
 
Location: 4N12
 
Title: Many-body localization: breakdown of thermalization in quantum matter

Abstract: Until recently interacting many-particle systems governed by the laws of quantum mechanics were assumed to eventually reach thermal equilibrium, being described by equilibrium statistical physics. Rapid developments in theory and experiments in the last decade have established a phase of matter where this assumption is false, due to a phenomenon known as many-body localization (MBL). In this phase, the system undergoing unitary time dynamics retains memory of the initial state in local observables for infinitely long times. I will give an overview of the theoretical and experimental progress in this growing field at the intersection of condensed matter physics, quantum information science and atomic physics.
I will describe the emergent integrability of the MBL phase which gives rise to area-law entanglement for the full many-body spectrum of eigenstates. This structure of the eigenstates allows for an efficient description of the system using shallow quantum circuits. MBL also gives rise to novel forms of quantum phase transitions even in states at finite energy densities. I will conclude with some of the open questions in this field.

Time: 2pm
Location: 2N36

Title: A toy model of axion gauge field inflation
 
 Abstract: We present a toy model of an axion gauge field inflation scenario that yields viable density and gravitational wave spectra. The scenario consists of an axionic inflaton in a steep potential that is effectively flattened by a coupling to a collection of non-Abelian gauge fields. The model predicts a blue-tilted gravitational wave spectrum that is dominated by one circular polarization, resulting in unique observational targets for cosmic microwave background (CMB) and gravitational wave experiments. The handedness of the gravitational wave spectrum is incorporated in a model of leptogenesis through the axial-gravitational anomaly. In order to explain the matter-antimatter asymmetry of the Universe, we obtain an approximate lower bound on the tensor-to-scalar ratio that is within reach of current CMB experiments.

Time: 1:30pm

Location: 4N12

Title: Digging Deeper for New Physics in the LHC Data

Time: 2pm

Location: 2N36

Title: Thermal Equivariance and its applications

Time: 2pm
Location: 2N36
Title: Markovian property of vacuum state and the a-theorem

Time: 2pm
 
Location: 2N36
 
Title: Generalized Parallelizable Spaces, Consistent Truncations and DualitiesAbstract: While only three sphere, S^1, S^3 and S^7, are parallelizable,  it was recently shown that all spheres are generalized parallelizable. In addition to its beautiful mathematical structure, this extended notion of parallelizability allows to identify certain maximal gauged supergravities as consistent truncations of 10/11D supergravity. In this talk, I present the first systematic construction of generalized parallelize spaces and demonstrate how this string theory inspired concept captures T-duality in a natural way.

Time: 1:30pm
Location: 4N12
Title:  Applications of the Average Null Energy Condition
Abstract:  Local energy conditions are key hypothesis in many classical results in general relativity.  In quantum theory these local energy conditions are invalidated due to quantum fluctuations.  Nevertheless a weaker condition, the so-called average null energy condition still holds in quantum field theory.  I will explain how this this condition constrains the data of conformal field theories such as operator product coefficients and scaling dimensions.

Time: 10am - 6:30pm
Location: 4N12
Webpage: https://web.sas.upenn.edu/penn-jcppm/

Time: 2pm
Location: 2N36
 
TITLE: The re-emergance of spontaneously broken space-time symmetries without Goldstones or Inverse Higgs
 
ABSTRACT: In this talk I will discuss how broken space-time symmetries can emerge in the IRafter being spontaneously broken in the UV, even though there may be no Goldstonebosons. Given that there has been a large body of work on trying to get space-timesymmetry (e.g. Lorentz) to be emergent in the IR via an RG attractive basin, this may seemlike a very surprising and non-generic result. However, I will show that in the context ofFermi liquid theory it is quite natural, and even required to preserve Fermi liquid behavioras the existence of Goldstone bosons (in this case they would be non-derivative coupled) would lead to shortened life-times for quasi-particles. I will also consider the spontaneous breaking of Schrodingersymmetry whose emergence (with no dilaton) in the IR leads to very strong constraintson Fermi liquids at unitarity.

Time: 2pm
Location: 2N36
 
Title: Entanglement Entropy in Chern-Simons Theory and Link Invariants

Abstract: We will study the entanglement structure of states in Chern-Simons (CS) theory obtained by performing the Euclidean path-integral on certain highly non-trivial 3-manifolds, namely link complements in S^3. The corresponding entanglement entropies in fact provide framing independent link-invariants. In U(1) CS theory, we will give a general formula for the entanglement entropy across a bi-partition of a generic n-link into sub-links. In the non-Abelian case, we study various interesting 2 & 3-links including the Whitehead link & Borromean rings, both of which have non-trivial entanglement structures. If time permits, we will mention connections with gravity and hyperbolic geometry. 

Time: 2pm 
Location: 2N36
Title: Large N Tensor Models
 
Abstract: We review the double line notation for the Feynman diagram expansion of N by N matrix models. In the ‘t Hooft large N limit only the planar diagrams survive, and the dual graphs may be thought of as discretized random surfaces. We proceed to theories where the dynamical degrees of freedom are rank-3 tensors with distinguishable indices, each of which takes N values. Their Feynman diagrams may be drawn using colored triple lines (red, blue, green), while the dual graphs are made out of tetrahedra glued along their triangular faces. Such theories possess a special solvable large N limit dominated by the “melon” diagrams. We discuss quantum mechanical models of fermionic rank-3 tensors and their similarity with the Sachdev-Ye- Kitaev disordered model. We then use the large N Schwinger-Dyson equations to study the conformal dimensions of certain composite operators. Gauging the global symmetry in the quantum mechanical models removes the non-singlet states; therefore, one can search for their well-defined gravity duals. We note that the models possess a vast number of gauge-invariant operators involving higher powers of the tensor field. Finally, we discuss similar models of a commuting rank-3 tensor in dimension d. While the quartic interaction is not positive definite, we study the large N Schwinger-Dyson equations and show that their solution is consistent with conformal invariance.

Time: 12pm (Special Seminar)
Location: 2N36
 
Title: Black Holes in Massive Gravity: Time-Dependent Solutions
Abstract: When starting with a static, spherically-symmetric ansatz, there are two types of black hole solutions in massive gravity: (i) exact Schwarzschild solutions which exhibit no Yukawa suppression at large distances and (ii) solutions which contain coordinate-invariant singularities at the horizon.  In this talk, I will present new black hole solutions which have a nonsingular horizon and can potentially be matched to Yukawa asymptotics at large distances.  These solutions recover Schwarzschild black holes in the limit of zero graviton mass and are thus observationally viable.  At finite mass they depend explicitly on time.  However, the location of the apparent horizon is time-independent indicating that these black holes are neither accreting or evaporating (classically).