Search Talks

We suggest a framework for cosmology based on gravitational effective field theories with a negative fundamental cosmological constant, which may exhibit accelerated expansion due to the positive potential energy of rolling scalar fields. The framework postulates an exact time-reversal symmetry of the quantum state (with a time-symmetric big bang / big crunch background cosmology) and an analyticity property that relates cosmological observables to observables in a Euclidean gravitational theory defined with a pair of asymptotically AdS planar boundaries. The latter can be given a microscopic definition using holography, so the model is UV complete. While it is not yet clear whether the framework can give realistic predictions, it has the potential to resolve various naturalness puzzles without the need for inflation.

Zoom Link: https://pitp.zoom.us/j/95099004342?pwd=OWZoanJJMHNzMXF4S3VYM2Vxcklodz09

The volume of the interior of a two-sided eternal black hole classically grows forever. I will derive a microscopic formula for this volume in JT gravity by summing the non-perturbative contribution of higher topologies. The non-perturbative corrections lead to the saturation of the volume of the interior at times exponential in the entropy of the black hole. I will connect the microscopic formula for the volume with properties of a "thermo-averaged" density matrix, in particular with its second Renyi entropy, which I argue to measure the number of nearly orthogonal states visited by time evolution. I will discuss various problems with this interpretation.

Zoom Link: https://pitp.zoom.us/j/99880539557?pwd=VWZiMFI5Rk5pdnNZRE5kalRvUk1Zdz09

Direct detection searches for dark matter are typically optimized to search for weakly interacting particles with masses on the ~GeV scale. But these experiments are, in principle, sensitive to masses as large as approximately the Planck mass, for cross sections much larger than typical Weak-scale cross sections. However, certain assumptions typically made in direct detection analyses break down at such large cross sections, and must be reexamined. In my talk, I will discuss the theoretical considerations that become important for heavy, strongly interacting dark matter, as well as new types of dark matter search that become possible at such high masses and cross sections.

Zoom Link: https://pitp.zoom.us/j/98807962972?pwd=UXFWLzA0N2dPQ3JrVUo4TStmSGtWUT09

JT gravity in AdS was shown by Saad, Shenker and Stanford to be described by a matrix ensemble of random hamiltonians. We couple JT to a bulk scalar field and extend the matrix ensemble to include a second matrix, dual to the scalar field. We therefore consider a 2-matrix model that can be thought of as a (better defined) generalization of Eigenstate Thermalization Hypotheses: it is a coupled matrix model of a random hamiltonian and a random operator. The 2-matrix model has an interesting integrability structure: correlation functions are expressed via SL(2,R) 6j-symbols that obey unlacing rules and Yang-Baxter equations. We compute the two-sided 2-point function on the double-trumpet geometry from the matrix model and find agreement with the matter loop contribution in the bulk. Based on work in progress with Jafferis, Kolchmeyer and Sonner.

Zoom Link: https://pitp.zoom.us/j/92268935307?pwd=dytCdTJlWVc3QXkweWxzcy83Sk9PZz09

I will describe 4pt conformal blocks for scalar operators in diverse dimensions by using a single unified formalism, and explain a property of the conformal blocks known as stability. This stability implies that when writing conformal blocks as certain multivariate series, the coefficients of this expansion only depend on Young diagrams. In particular, we can bosonise the conformal computation and simply focus on compact groups. In this framework the blocks are polynomials of the BC root system after we apply complementation. I will then explain the connection with mathematics and show how to formulate a superconformal Cauchy identity which yields the CPW of any free theory diagram in any dimension. For discussion, I will finally mention q-deformations results.

Zoom Link: https://pitp.zoom.us/j/96912692269?pwd=TE8vT01mam9lQjhVV3VSYUtWR2d5Zz09

I review the main mechanisms that convert fundamental CP-violating parameters (theta_QCD and Kobayashi-Maskawa phase) to the observable electric dipole moments (EDMs). Given recent progress, the EDMs connected to electron spin (paramagnetic EDMs) are calculated. The limit on QCD theta angle is 3 * 10^(-8) and  somewhat subdominant to neutron EDM, but can be improved. The Kobayashi-Maskawa phase contributes to paramagnetic EDMs at the level of 10^{-35} e cm in units of equivalent electron EDM, which is much larger than what was previously expected.  

Zoom Link: https://pitp.zoom.us/j/96502704646?pwd=ZThQWGU2dEZPWjdPQnp2ZEpPVXRIdz09

In this talk, I will discuss the duality between the two-dimensional type 0B string theory and its dual matrix quantum mechanics. This duality has been a source of motivation and a useful toy model to explore many new features of string theory. I will first revisit the computation of closed string scattering amplitudes in string perturbation theory, using new numerical methods to compute Virasoro conformal blocks in 2d supersymmetric conformal field theories. Then, I will describe a worldsheet formalism to include non-perturbative corrections to closed string scattering amplitudes, mediated by D-instantons. This formalism is of general applicability, and can be straightforwardly implemented in other string models. In the type 0B string theory, this will allow us to extend the duality dictionary beyond perturbation theory.

The possibility of having DM (or a fraction of it) charged under a dark U(1) which mixes with the U(1)EM has been of interest for many years. Many different experiments search for such a millicharged DM (MCDM), under the assumption that its velocity would be distributed according to MB. However, our galaxy and local environment have a variety of effects that make this assumption highly non trivial. In this talk, I will discuss the effects of galactic magnetic fields, collisions with Cosmic rays, acceleration from Supernovae remnants, and energy losses due collisions with particles in the interstellar medium on the velocity distribution of MCDM outside the solar system. Furthermore, to arrive at an underground detector, the MCDM would need to pass through the solar wind, not be deflected by earth's magnetic field, and pass through earth's crust to reach the underground lab. We will discuss these effects as well. I will end the talk by discussing the importance of these effects on Direct Detection experiments, and whether MCDM could explain the XENON excess.

Zoom Link: https://pitp.zoom.us/j/92701168758?pwd=UlY5Smlrd1MzWmI4ZkNyNVI5d3JIUT09

In holographic duality an eternal AdS black hole is described by two copies of the boundary CFT in the thermofield double state. We provide explicit constructions in the boundary theory of infalling time evolutions which can take bulk observers behind the horizon. The constructions also help to illuminate the boundary emergence of the black hole horizons, the interiors, and the associated causal structure. A key element is the emergence, in the large N limit of the boundary theory, of a type III1 von Neumann algebraic structure and the half-sided modular translation structure associated with it.

Zoom Link: https://pitp.zoom.us/j/99458239757?pwd=YTBRdXdwTjltMkdZc0Q4WW1jQjA3QT09

I will describe an approach to extracting the physical consequences of S-duality of four-dimensional N = 4 super Yang-Mills (SYM) and its string theory dual based on SL(2,Z) spectral theory. I will show that processing S-duality in this way leads to strong consequences for the CFT data, both perturbatively and non-perturbatively in all parameters. In large-N limits, I will argue for the existence and scaling of non-perturbative effects, both at large N and at strong 't Hooft coupling. An elegant benchmark for these techniques is a certain integrated stress-tensor multiplet four-point function, whose form I will elucidate. I will explain how the ensemble average of CFT observables over the N = 4 supersymmetric conformal manifold with respect to the Zamolodchikov measure is cleanly isolated by the spectral decomposition, and will show that the large-N limit of the ensemble average is equal to the strong-coupling limit of the observable in the planar theory, which is its value in type IIB supergravity on AdS_5 x S^5. This embeds an emergent averaged holographic duality within the conventional holographic paradigm.

Zoom link:  https://pitp.zoom.us/j/95197874062?pwd=QU4vbXNNeFVmS0hNbTVLL24wdDBndz09

Quasi-sterile neutrinos are a natural consequence of dark sectors interacting with the Standard Model (SM) sector via neutrino- and vector-portals. Essentially, quasi-sterile neutrinos are light dark sector fermions with two generic properties: (i) they mix with the active neutrinos of the SM, and (ii) they are charged under a vector mediator that couples feebly to SM matter. Various interesting phenomenological consequences result from this class of particles. In this talk, I will discuss one such consequence: new, beyond the SM matter effects that can alter in-medium neutrino oscillations. In particular, for special windows of energy and matter densities, active neutrinos can resonantly oscillate into sterile neutrinos. I will discuss how this feature could be exploited to build a quasi-sterile neutrino model that can explain the MiniBooNE and LSND anomalies, while remaining compatible with observations from long-baseline reactor- and accelerator-based neutrino experiments. I will also discuss the implications to this model from the recent MicroBooNE results, and, time permitting, from solar neutrino measurements.

Zoom Link: https://pitp.zoom.us/j/95362454210?pwd=RzNCeDRkMjJXb2xNbHNkcEc1ZTdkUT09

Zoom link:  https://pitp.zoom.us/j/96132106700?pwd=L3ZMOXltZks4Y25abUl5TTdhZTVKUT09