High Energy Physics

We analyse models of Matrix Quantum Mechanics in the double scaling limit that contain non-singlet states. The finite temperature partition function of such systems contains non-trivial winding modes (vortices) and is expressed in terms of a group theoretic sum over representations. We then focus on the model of Kazakov-Kostov-Kutasov when the first winding mode is dominant. In the limit of large representations (continuous Young diagrams), and depending on the values of the parameters of the model such as the compactification radius and the string coupling, the dual geometric background corresponds either to that of a long string (winding mode) condensate or a 2d (non-supersymmetric) semi-classical Black Hole competing with the thermal linear dilaton background. In the matrix model we are free to tune these parameters and explore various regimes of this phase diagram. Our construction allows us to identify the origin of the microstates of the long string condensate/2d Black Hole arising from the non trivial representations.

Zoom Link: https://pitp.zoom.us/j/95764320439?pwd=L1E1cEREM29ORjZhK21WdFN0RVgyQT09

In this talk we combine integrability and conformal bootstrap to learn about correlation functions of planar maximally supersymmetric Yang- Mills theory. Focusing on correlators of four stress-tensor multiplets, we first introduce a set of dispersive sum rules that are only sensitive to single-traces in the OPE expansion (this is advantageous because this data is available from integrability). We then construct combinations of the sum rules which determine one-loop correlators. Further, we discuss how to employ the sum rules in numerical bootstrap to nonperturbatively bound planar OPE coefficients. As an example, we show a nontrivial upper bound on the OPE coefficient of the Konishi operator outside the perturbative regime. 

With no hints of dark matter in the "classical WIMP" region of parameter space, experimentalists have begun searching in earnest for low mass (MeV-GeV scale) dark matter. However, efforts to probe this region of parameter space have been hindered by an unexpected and mysterious source of background events, dubbed the "low energy excess." Recently, mechanical stress has been shown to create a "low energy excess"-like source of events, and a microphysical picture of how stress creates this background is emerging. In addition to providing a path forward for low mass dark matter searches, these results may address several outstanding problems limiting the performance of superconducting quantum computers.

Zoom Link:  https://pitp.zoom.us/j/92147233613?pwd=RW5PaUNUZlE3SUNnTlZHaVFrdnV3dz09

Observations indicate the existence of natural particle accelerators in the Milky Way, capable of producing PeV cosmic rays (“PeVatrons”). Observations also indicate the existence of extreme sources in the Milky Way, capable of producing gamma-ray radiations above 100 TeV. If these gamma-ray sources are hadronic cosmic-ray accelerators, then they must also be neutrino sources. However, no neutrino sources have been detected. How can we consistently understand the observations of cosmic rays, gamma rays, and neutrinos? We point out two extreme scenarios are allowed: (1) the hadronic cosmic-ray accelerators and the gamma-ray sources are the same objects, so that neutrino sources exist and improved telescopes can detect them, versus (2) the hadronic cosmic-ray accelerators and the gamma-ray sources are distinct, so that there are no detectable neutrino sources. We discuss the nature of Milky Way’s highest energy gamma-ray sources and outline future prospects toward understanding the origin of hadronic cosmic rays. 

Zoom link:  https://pitp.zoom.us/j/91390039665?pwd=dGJ2b3VCbVFhUVpSelpjYzJHdk1Gdz09

We consider four-point correlators in an arbitrary excited state of a quantum field theory.  We show that when the theory and state are holographic, such correlators can produce high-quality movies of point-like bulk particles, revealing the geometry in which they move. In some situations, Einstein’s equations amount to a local differential equation on the correlator data. In theories or states that are not holographic, images are too blurry to extract a bulk geometry. Calculations are performed by adapting formulas from conformal Regge theory, to excited states and out-of-time-order correlators.

Zoom link: https://pitp.zoom.us/j/94153545930?pwd=YUFsUW44S1Z5Ri83a2xQdEN0Vk9XZz09

Based on arXiv:2208.04334. We consider oscillons - localized, quasiperiodic, and extremely long-living classical solutions in models with real scalar fields. We develop their effective description in the limit of large size at finite field strength. Namely, we note that nonlinear long-range field configurations can be described by an effective complex field ψ(t, x) which is related to the original fields by a canonical transformation. The action for ψ has the form of a systematic gradient expansion. At every order of the expansion, such an effective theory has a global U(1) symmetry and hence a family of stationary nontopological solitons - oscillons. The decay of the latter objects is a nonperturbative process from the viewpoint of the effective theory. Our approach gives an intuitive understanding of oscillons in full nonlinearity and explains their longevity. Importantly, it also provides reliable selection criteria for models with long-lived oscillons. This technique is more precise in the nonrelativistic limit, in the notable cases of nonlinear, extremely long-lived, and large objects, and also in lower spatial dimensions. We test the effective theory by performing explicit numerical simulations of a (d+1)-dimensional scalar field with a plateau potential. 

Zoom link: https://pitp.zoom.us/j/98801138609?pwd=VUJsZm41bnpBQzFoUEFwcUV6SG5Xdz09

In general, observables in QFTs can only be computed perturbatively using Feynman integrals. In this talk, which is based on arXiv:2008.12310 and arXiv:2204.06414, I will address some questions on the computability of such observables. By looking at QFT through the lens of tropical geometry, one can see that the runtime of such computations is dominated by the time it takes to understand the structure of certain polytopes. In the case of scalar QFTs on Euclidean space the relevant polytopes turn out to be generalized permutahedra, whose structure is well-understood thanks to the works of Postnikov, Aguiar and Ardila.  Using these insights, results in a new algorithm for Feynman integral evaluation that exceeds the capabilities of existing methods by multiple orders of magnitude, while being easy to implement.  I will also briefly discuss current wip that extends these findings to QFTs on Minkowski spacetime.

Zoom link:  https://pitp.zoom.us/j/93629580865?pwd=WnJ6aUVpckFZWGVDL0NqMTFrWlhBQT09

The fact black holes carry statistical entropy proportional to their horizon area implies that quantum information concepts are geometrized in gravity. This idea obtains a particular manifestation in the AdS/CFT correspondence, where it is believed that the quantum information content in the dual field theory state can be used to reconstruct the bulk space-time geometry. The calculation of entanglement entropy from geodesics in the bulk space-time have clarified this idea to some extend.

In this talk, I will consider two aspects of quantum information theory in relation to holography: First, I will discuss a refinement of entanglement entropy for systems with conserved charges, the so-called symmetry resolved entanglement. It measures the entanglement in a sector of fixed charge. I will present how to calculate the symmetry-resolved entanglement entanglement in two-dimensional conformal field theories with Kac-Moody symmetry, and also within W_3 higher spin theory. I will also discuss the geometric realization in the dual AdS space-time, and how the independent calculation there leads to a new test of the AdS3/CFT2 correspondence.

Second, I will discuss the large N limit of Nielsen's operator complexity on the SU(N) manifold, with a particular choice of cost function based on the Laplacian on the Lie algebra, which leads to polynomial (instead of exponential) penalty factors. I will first present numerical results that hint to the existence of chaotic and hence ergodic geodesic motion on the group manifold, as well show the existence of conjugate points. I will then discuss a mapping between the Euler-Arnold equation which governs the geodesic evolution, to the Euler equation of two-dimensional idea hydrodynamics, in the strict large N limit.

We revamp the constructive enumeration of 1/16-BPS states in the maximally supersymmetric Yang-Mills in four dimensions, and search for ones that are not of multi-graviton form. A handful of such states are found for gauge group SU(2) at relatively high energies, resolving a decade-old enigma. Along the way, we clarify various subtleties in the literature, and prove a non-renormalization theorem about the exactness of the cohomological enumeration in perturbation theory. We point out a giant-graviton-like feature in our results, and envision that a deep analysis of our data will elucidate the fundamental properties of black hole microstates.

Zoom link:  https://pitp.zoom.us/j/96037678536?pwd=eGdhTWF3UVN1em5uZVpJbWYyM2tzUT09

In this talk, I will show that the action of soft graviton operators generates a w(1+infinity) symmetry in gravitational theories minimally coupled to massless and massive scalar matter in 4D asymptotically flat spacetimes.  I will discuss how the symmetry action follows from an infinite tower of soft graviton theorems in momentum space.  By generalizing the previous analyses of w(1+infinity) symmetry in massless amplitudes, these results clarify that the symmetry emerges in 4D asymptotically flat gravitational theories without any additional technical ingredients.  This talk is based on a forthcoming paper with Monica Pate. 

Zoom link:  https://pitp.zoom.us/j/91448920819?pwd=cFY0L1JPVFF2bDUwc3JiVlRlbE5ldz09

Celestial holography posits a duality between a theory of quantum gravity in asymptotically flat spacetime and a "celestial" conformal field theory that lives on its co-dimension two boundary. By studying soft theorems of scattering amplitudes in the bulk it was shown that there exist infinite towers of corresponding soft currents in cCFT and their algebra was calculated. In this talk I will consider a bulk theory of Yang-Mills coupled to a massive scalar and show, via soft limits, that the corresponding boundary algebra admits a level proportional to the strength of the background. I will comment on some other aspects of this deformation as well as potentially important subtleties we have encountered with our method of computing celestial amplitudes.

Zoom link:  https://pitp.zoom.us/j/95423960414?pwd=RVoxc1FRRGRmL2RIMXJpbXFKZVBFdz09