High Energy Physics Seminar Series

SPRING 2025 

 

APRIL 16

“TBD”

DAVID POLAND – Yale University

Abstract: TBD

 

APRIL 9

“TBD”

SAM LEUTHEUSSER – IAS

Abstract: TBD

 

APRIL 2

“TBD”

ZHENGDI SUN – UCLA

Abstract: TBD

 

MARCH 19

Spring Break

 

FEBRUARY 26

“The Gravitational Index of 5d Black Holes and Black Strings”

LUCA ILIESIU – UC Berkeley

Abstract: 

In this talk, I will discuss how one can use the gravitational path integral to compute the supersymmetric index of black holes as well as other black objects in string theory. The saddles that I shall describe admit a non-zero temperature, consequently lacking an infinitely long AdS throat that separates the horizon from the asymptotic region, and also admit periodic boundary conditions for fermionic fields around the thermal circle, consequently counting bosonic and fermionic states with an opposite sign. Since the microscopic calculation of these indices is oftentimes well understood yet the saddles that I shall describe now lack the conventional decoupling limit taken in AdS/CFT, our analysis represents a first step towards understanding holography for supersymmetric observables in flat space.

 

FEBRUARY 19

“AdS_3/RMT_2 Beyond the Ramp “

GABRIELE DI UBALDO – UC Berkeley

Abstract: 

In 2307.03707 we introduced a framework for random matrix theory (RMT) in AdS_3 quantum gravity and chaotic 2D CFTs that is manifestly conformal and modular invariant. On the CFT side this leads to a 2d CFT trace formula, analogous to the Gutzwiller trace formula for chaotic quantum systems, which we use to derive necessary and sufficient conditions for an individual 2d CFT to have RMT statistics. Applied to pure 3D gravity, we obtained a microscopic CFT understanding of the off-shell Cotler-Jensen torus wormhole. This wormhole is shown to be exactly dual to RMT_2: the minimal modular invariant completion of the RMT two-point correlator. In work to appear soon, we construct and establish RMT_2 as a modular invariant RMT ensemble which minimally uplifts to 3D the near-extremal dynamics of 2D theories like JT gravity. We construct a modular invariant spectral form factor describing the full ramp-plateau transition. Seen as a candidate SFF of pure 3D gravity, it describes the chaos and discreteness of black hole microstates. We give predictions for n-boundary wormholes in pure 3D gravity and in the n=3 case we exhibit matching with a gravitational ansatz.

 

FEBRUARY 12

“String Perturbation Theory of Klebanov-Strassler Throat “

MANKI KIM – Stanford University

Abstract: 

In this talk, I will explain how to study string perturbation theory of the Klebanov-Strassler solution in the large radius approximation based on open-closed superstring field theory. Combining the large radius expansion and a double scaling limit, we find a perturbative background solution of open-closed superstring field theory that corresponds to the Klebanov-Strassler solution. To illustrate the utilities of this approach, we break supersymmetry of the background by placing a stack of anti-D3-branes at the tip of the throat. We then find a perturbative open string background solution to the third order in the large radius approximation, which agrees with the well-known supergravity analysis of Kachru-Pearson-Verlinde (KPV) on the stability of the anti- D3-brane supersymmetry breaking. The perturbative background solution to the open string field theory we found is expected to be dual to an NS5-brane probing the KS solution.

 

FEBRUARY 5

“Localized Black Holes in AdS3: Thermodynamics and Entanglement Entropy”

ZIXIA WEI – Harvard University

Abstract: 

A holographic conformal field theory (CFT) is a CFT whose low-energy behavior can be described by Einstein gravity in anti-de Sitter spacetime (AdS) with one higher dimension. For a 2D holographic CFT, modular invariance largely determines the spectrum at both low and high energies, leaving only a medium-energy range undetermined. In the corresponding 3D AdS, this implies that the low-energy statistics are described by global AdS plus matter, while the high-energy statistics are governed by the BTZ black hole, independent of the details of the underlying 2D CFT. The specific details of the spectrum are reflected only in the configurations within the medium-energy range, which are not well understood on the AdS3 side. In this talk, we present a class of non-supersymmetric localized black holes in Type IIB supergravity in AdS3 × S3 × T4, which is dual to a 2D CFT (the D1-D5 CFT) in the strong coupling limit. We first study the thermodynamics of these localized black holes and observe that they can dominate over the BTZ black hole and thermal AdS in the medium-energy range left undetermined by the modular bootstrap. This suggests that these solutions provide a pathway to analytically study this “enigmatic” energy window. We then estimate the holographic entanglement entropy associated with these solutions and, surprisingly, find that it is almost identical to that in the BTZ solutions at the same energy. This suggests that certain geometric details are obscured within the “entanglement shadow.” Finally, we will discuss their implications on the CFT side.

 

JANUARY 29

“Chiral Boson at the Edge of Lattice Chern-Simons Theory”

THEO JACOBSON – UCLA

Abstract: 

Regulating chiral quantum field theories on the lattice has been an outstanding problem since the inception of lattice gauge theory. In this talk, I describe a Hamiltonian lattice realization of the 1+1d chiral boson, which is one of the simplest examples of a chiral theory. This theory (both in the continuum and on the lattice) does not exist in isolation, but only as the boundary of a non-trivial topologically ordered 2+1d phase. We describe how to realize (Maxwell) Chern-Simons theory as a Hamiltonian lattice gauge theory, and show that it hosts a chiral edge mode on spatial lattices with boundary.

 

JANUARY 22 

“3D Modularity Revisited”

DAVIDE PASSARO – Caltech

Abstract: 

In this introductory, self-contained talk, I will present some recent developments concerning the modular properties of Ẑ invariants—quantum invariants of three-manifolds originally defined as half-indices of strongly coupled N=2 theories in three dimensions on a solid torus. After motivating the research, and a brief overview of their construction, I will focus on the intricate modular relations that emerge, with a focus on quantum modularity, mock modularity, and Weil representations. The discussion is based on results from arXiv:2403.14920 and aims to be accessible to a broad mathematical and physical audience.

 

______________________

FALL 2024

 

NOVEMBER 27 – 

THANKSGIVING HOLIDAY

 

*TUESDAY, NOVEMBER 19 – 

“Derivation of TQFT Gravity/Ensemble Holography”

TOLYA DYMARSKY– University of Kentucky

Abstract:

We outline a general derivation of holographic duality between “TQFT gravity” – the path integral of a 3d TQFT summed over different topologies – and an ensemble of boundary 2d CFTs. The key idea is to place the boundary ensemble on a Riemann surface of very high genus, where the duality trivializes. The duality relation at finite genus is then obtained by genus reduction. Our derivation is generic and does not rely on an explicit form of the bulk or boundary partition functions. It guarantees unitarity and suggests that the bulk sum should include all possible topologies. In the case of Abelian Chern-Simons theory with compact gauge group we show that the weights of the boundary ensemble are equal, while the bulk sum reduces to a finite sum over equivalence classes of topologies, represented by handlebodies with possible line defects.

 

NOVEMBER 13 – via ZOOM

“Conformally Invariant Chern-Simons Actions in 3+1 Dimensions: Holographic Shadows of 2T-Physics”

SOPHIA SINGH– Brown University

Abstract:

TBA

 

*TUESDAY, NOVEMBER 12 – 

“Classical Double Copy: Solutions, Horizons, and Penrose Limits”

CYNTHIA KEELER– Arizona State University

Abstract:

We will review the classical double copy, which maps exact solutions of classical gauge theories like electromagnetism, to solutions of general relativity. We will cover both the Kerr-Schild and Weyl formulations of this map.  Following a survey of known exact solutions, we will review why a position-space classical solution double copy is even feasible.  We will briefly discuss some perturbative approaches, and then close by relating several gravitational objects (including horizons and Penrose limits) to their gauge theory analogues.

 

NOVEMBER 6 – 

“Black Holes from Weak Jacobi Forms”

SUZANNE BINTANJA– UCLA

Abstract:

In this talk I will revisit the connection between modular forms and black hole entropy. I will introduce the notion of a weak Jacobi form (wJf), and use modular crossing kernels to extract asymptotic expansions of the Fourier coefficients of wJfs. When combined with conditions inspired by AdS/CFT we find a broad range of parameters in which the leading order behaviour is universal and Cardy-like, while the first sub-leading logarithmic correction depends on the “light” data of the wJf. When there is a dual gravity description we can match the asymptotic expansion to the black hole entropy. By doing so we find a precise microscopic interpretation to the logarithmic corrections to the entropy of BPS black holes in N=2,4 ungauged supergravity in four and five dimensions.

 

OCTOBER 30 – 

“A Bootstrap Principle for the Uniqueness of String Amplitudes”

AARON HILLMAN– Caltech

Abstract:

Ordinary consistency conditions on 2->2 scattering will not yield string amplitudes as the unique answer. This has motivated new work on the constraints from consistent multi-particle scattering. Still in the 2->2 world, one can ask whether there exists a principle which might uniquely constrain the spectrum and scattering of strings. We identify a principle dubbed level truncation which, when paired with the usual constraints, defines an infinite set of polynomial equations in terms of a set of free set of dual-resonant Ansatz parameters. The spectrum is unconstrained in the Ansatz and its unique solution is the Coon spectrum. When imposing superpolynomial boundedness and strict dual resonance, only Veneziano remains as a solution.  We present the generalization of this bootstrap to a closed-string type Ansatz, and the one-parameter deformation of the Virasoro-Shapiro amplitude that it admits. We discuss possible avenues for future work.

 

OCTOBER 23 – 

“Quantum Information Scrambling of Algebras and Quantum Mereology”

PAOLO ZANARDI– USC

Abstract:

I will give an informal and gentle whiteboard introduction to our work on quantum scrambling  of observable algebras and (perhaps, time permitting) to its application to quantum mereology. Here below a few references:

https://quantum-journal.org/papers/q-2022-03-11-666/

https://quantum-journal.org/papers/q-2024-07-11-1406/ 

https://journals.aps.org/pra/abstract/10.1103/PhysRevA.107.042217

 

OCTOBER 16 – 

“Bootstrapping BFSS at infinite N”

HENRY LIN – Stanford University

Abstract:

I will discuss analytical and numerical bootstrap bounds on simple correlators in the BFSS model/D0-brane quantum mechanics. I will present strong evidence that the bootstrap method is dramatically more efficient than Monte Carlo at large N and low temperatures. This talk is based on http://arxiv.org/abs/2302.04416 and work in progress with Zechuan Zheng.

 

*TUESDAY, OCTOBER 8 – 3:00 PM*

“Strings Near the Conformal Boundary of AdS3”

VIT SRIPRACHYAKUL – ETH Zurich

Abstract:

I will discuss recent development in AdS3/CFT2 duality with pure, non-minimal NSNS flux. This comes from adopting a certain approximation. I will describe how such an approximation allows us to calculate generic n-point ground state amplitudes in bosonic string theory. This then enables us to deduce the bosonic dual CFT. I will also discuss what happens when we add supersymmetry and when we consider excited states.

 

OCTOBER 2 – NO SEMINAR

 

SEPTEMBER 25 – 

“Quantum Scrambling, Operator Entanglement and Operator Algebras”

Faidon Andreadakis – USC

Abstract:

Complex quantum dynamics lead to the generation of non-local correlations that delocalize information initially stored in local degrees of freedom, a phenomenon referred to as scrambling. In this talk, I will motivate and describe the concept of quantum information scrambling, demonstrating the role of non-commutativity and entanglement. Some connections with quantum thermalization and information propagation in local quantum many-body systems will be briefly mentioned. Then, I will show how the on-average scrambling caused by a unitary evolution is directly related to information-theoretic properties of the dynamics, like operator entanglement and entropy production. Finally, a more general algebraic framework of scrambling will be discussed, which incorporates a wider range of properties of quantum evolutions, like coherence generation, depending on the algebra of observables of interest.

 

SEPTEMBER 18 – 

“Universality of 2D CFT Phase Diagram at Large Central Charge”

SRIDIP PAL – Caltech

Abstract:

In a modular invariant 2D CFT with a fixed central charge, the Cardy formula gives a universal density of states at asymptotically high energy (E \rightarrow\infty). Hartman, Keller, and Stoica (HKS) extended the regime of validity of this formula for states with E \propto c with c \rightarrow \infty, assuming a sparseness condition on the spectrum below E < 0. In the canonical ensemble, this is equivalent to the familiar statement, as expected from holography, that for \beta < 2\pi, the BTZ black hole dominates, and for \beta > 2\pi, thermal AdS dominates. Upon turning on the temperature for both the left and right movers, assuming the spectrum is sparse below twist ( = 2 min(h,\bar{h})) c/12, HKS conjectured and produced numerical evidence that the free energy is universal except for the hyperbola \beta_L \beta_R = 4\pi^2; i.e., for \beta_L \beta_R > 4\pi^2, thermal AdS dominates and for \beta_L \beta_R< 4\pi^2, the black hole dominates. We analyze the modular bootstrap equation at large central charge and prove this conjecture. Our formalism allows us to explore the consequence of sparseness by taking the spectrum to be sparse below twist \alpha (c-1)/12, where \alpha is a tunable parameter in (0,1]. The \alpha = 1 is the case related to the HKS conjecture. We show that for \alpha \rightarrow 0,, the region where the free energy is universal reduces in a quantifiable manner.

 

SEPTEMBER 11 – 

“Classification of Generalized Gaugings in 2d QFT”

CONGHUAN LUO – USC

Abstract:

Gaugings are powerful tools for creating new theories, studying general properties of symmetry and relating known theories that have very different appearances. Crucially, the notion of discrete gauging generalizes to various versions of generalized symmetries, especially non-invertible symmetry which I will briefly review. After that, I will introduce a way of systematically bootstrapping all the possible discrete generalized gaugings of a 2d QFT equipped with (non-invertible) global symmetry, which makes use of the relation between discrete gaugings and topological interfaces. As an example, I will briefly illustrate a specific symmetry in 2d c=1 CFT on the orbifold branch.