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DTSTART:20070311T020000
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BEGIN:VEVENT
DTSTAMP:20250313T135823
DTSTART;TZID=America/Detroit:20250326T120000
DTEND;TZID=America/Detroit:20250326T130000
SUMMARY:Lecture / Discussion:Brown Bag Seminar | Comments on closed universes
DESCRIPTION:We study closed universes in simple models of two dimensional gravity\, such as Jackiw-Teiteilboim (JT) gravity coupled to matter\, and a toy topological model that captures the key features of the former. We find there is a stark contrast between the perturbative and non-perturbative aspects of the theory. Semi-classically there is rich physics. However\, when non-perturbative effects are included we see the puzzling feature that there is a unique closed universe state in each theory.
UID:130853-21867140@events.umich.edu
URL:https://events.umich.edu/event/130853
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20250331T083855
DTSTART;TZID=America/Detroit:20250402T120000
DTEND;TZID=America/Detroit:20250402T130000
SUMMARY:Lecture / Discussion:Brown Bag Seminar | Geometric Entropies and their Hamiltonian Flow
DESCRIPTION:THIS SEMINAR IS CANCELLED \n\nThe geometric entropy is a localized contribution to the entropy obtained using Euclidean gravity methods. In this talk\, I will discuss the Hamiltonian flow generated by the geometric entropy operator in general theories of gravity using Lorentzian methods of the Peierls/Poisson brackets. I will discuss examples with higher derivative corrections to illustrate the general features of the geometric flow. In the context of AdS/CFT\, I will discuss the connection to modular flow.
UID:130854-21867142@events.umich.edu
URL:https://events.umich.edu/event/130854
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20250327T102342
DTSTART;TZID=America/Detroit:20250409T120000
DTEND;TZID=America/Detroit:20250409T130000
SUMMARY:Lecture / Discussion:Brown Bag Seminar |  Effective $AdS_3/CFT_2$\; Life is simpler without black holes
DESCRIPTION:The holographic dual to string theory in $AdS_3 x N$ has always been a fundamental question in high-energy theoretical physics. To this day\, we don't know the answer to this question in full generality. In this talk\, I'll propose an effective holographic dual to type IIB string theory in $AdS_3 x N$ in the presence of pure NS-NS flux. The dual boundary CFT takes the form of a p-fold symmetric product of $(R_\phi \times N)$ deformed by a $\phi$-dependent $Z_2$-twisted marginal operator. I'll explain how an exact worldsheet computation allows us to identify this marginal operator. \n\nWhen the radius of $AdS_3$\, $R_{ads}$\, is sub-stringy\, the CFT spectrum doesn't contain neither a normalizable vacuum nor the BTZ black hole states. The proposed holographic duality in this case is an exact one. On the other hand\, when $R_{ads}/l_s >1$\, the full boundary CFT does have a normalizable vacuum and the BTZ black hole states at high energies. The proposed duality in this case is an effective one and holds only for the perturbative string states in the spectrum. Finally\, I'll quote some of the checks that have been performed to test this duality.
UID:130855-21867143@events.umich.edu
URL:https://events.umich.edu/event/130855
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20250905T125428
DTSTART;TZID=America/Detroit:20250910T120000
DTEND;TZID=America/Detroit:20250910T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | S-matrix Bootstrap: Present and Future
DESCRIPTION:The modern S-matrix bootstrap carves out the space of 4-point amplitudes compatible with unitarity\, causality\, and locality. In my talk\, I review the current standing and future goals of the bootstrap with an emphasis on three central questions: What features do legal amplitudes have? How can we determine when these 4-point amplitudes extend to n-point S-matrices? To what extent can the bootstrap be applied to amplitudes in the real-world?
UID:138890-21884196@events.umich.edu
URL:https://events.umich.edu/event/138890
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20251001T135719
DTSTART;TZID=America/Detroit:20250917T120000
DTEND;TZID=America/Detroit:20250917T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | BPS Black Holes in AdS3xS3xS3xS1 and Beyond
DESCRIPTION:The Bekenstein–Hawking formula gives a coarse-grained count of the number of microstates of a black hole\, and it is remarkable that it may sometimes be reproduced from a microscopic count in string theory. However\, the standard approach neglects quantum effects in the bulk which lead to pathologies for both supersymmetric and non-supersymmetric black holes\, such as the breakdown of thermodynamics at sufficiently low temperatures. \nIn this talk\, we will explain how a more careful treatment of the gravitational path integral resolves these tensions and leads to new and surprising effects that are completely invisible classically.\nFor extended supersymmetry\, we will find that physically sensible black holes can preserve at most 4 supercharges\, with the most exceptional example being black holes in AdS3xS3xS3xS1. This notoriously poorly understood background in string theory has a nonlinear large N=4 superconformal symmetry\, but we are nevertheless able to make novel predictions for the BPS and near-BPS spectrum from gravity. Notably\, we find discrete jumps in the BPS spectrum as a continuous parameter is adjusted-- a quantum gravity effect for which no microscopic derivation is currently known. This result is corroborated by constructing a family of non-extremal supersymmetric black holes that contribute to a supersymmetric index yet possess a temperature-dependent free energy.
UID:138990-21884495@events.umich.edu
URL:https://events.umich.edu/event/138990
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20250915T112541
DTSTART;TZID=America/Detroit:20250924T120000
DTEND;TZID=America/Detroit:20250924T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Living on the edge: a non perturbative resolution to the negativity of bulk entropies
DESCRIPTION:In this talk\, I will discuss two entropic puzzles in JT gravity and their resolution\, which requires taking into account non-perturbative effects in the gravitational path integral. In JT gravity\, which is dual to a random matrix ensemble\, the gravitational thermal entropy becomes negative at very low temperatures. This puzzle arises when computing the annealed (instead of quenched) entropy\, corresponding to an incorrect averaging procedure in the dual matrix model. After defining an “intermediate” quantity\, the semi-quenched entropy\, I will explain how the positivity of entropy can be rescued. From the bulk perspective\, both a resummation of higher-genus topologies and wormhole effects are crucial. From the matrix model perspective\, the resolution relies on the statistics of eigenvalues near the edge\, governed\, in different regimes\, by the Airy distribution or by 1-eigenvalue instantons. A related puzzle arises where the entanglement entropy across a two-sided black hole can become negative when inserting a large number of matter excitations behind the black hole horizon. First posed by Lin\, Maldacena\, Rosenberg\, and Shan in two-sided BPS black holes in SUSY JT gravity\, I will show this paradox extends to non-SUSY JT gravity with matter as well and demonstrate how positivity is rescued in both cases. Finally\, I will discuss a tensor network toy model with the same features.
UID:138994-21884497@events.umich.edu
URL:https://events.umich.edu/event/138994
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20250923T004903
DTSTART;TZID=America/Detroit:20251001T120000
DTEND;TZID=America/Detroit:20251001T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Bootstrapping Holographic Theories
DESCRIPTION:Holographic conformal field theories provide a window into quantum gravity. However\, these field theories are difficult in their own right\, and to make progress on them we need new non-perturbative methods. I will describe a general technique for combining the conformal bootstrap method with constraints from supersymmetric localization. This dramatically improves the ability of the bootstrap to constrain holographic theories. I will describe results for N = 4 super-Yang-Mills theory\, for which this technique enables qualitatively new studies of observables as a function of the Yang-Mills coupling. I will also describe substantial improvements in the bootstrap of 3D ABJM theory\, which enables a precise numerical study of higher-derivative corrections in M-theory.
UID:138997-21884500@events.umich.edu
URL:https://events.umich.edu/event/138997
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20250930T164209
DTSTART;TZID=America/Detroit:20251008T120000
DTEND;TZID=America/Detroit:20251008T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Exploring QCD-like Dynamics from Supersymmetry
DESCRIPTION:Understanding the mechanisms of confinement and the dynamics of low-energy QCD remains one of the central open problems in the Standard Model. In this talk\, I will describe how these issues can be explored in a close relative of QCD\, constructed by starting from supersymmetric QCD and systematically breaking supersymmetry through anomaly mediation. These models reproduce the same phases as ordinary QCD\, while allowing us to probe confinement from a different dynamical perspective. Within this framework\, one can compute the η′ potential\, study θ-dependence\, and analyze the phase structure associated with spontaneous CP violation at θ = π. Moreover\, the construction permits a derivation of the analog of the chiral Lagrangian\, enabling explicit tests of the size of a dynamically generated up-quark mass. Strikingly\, we find that in these models the generated contribution could be large enough to account for the full observed up-quark mass.
UID:138998-21884502@events.umich.edu
URL:https://events.umich.edu/event/138998
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20251001T135836
DTSTART;TZID=America/Detroit:20251015T120000
DTEND;TZID=America/Detroit:20251015T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Testing quantum gravity
DESCRIPTION:I will give an overview of proposals to test the quantization of the gravitational field using terrestrial experiments. This will include entanglement experiments\, searches for noise in gravitational wave interferometers\, and \"single-graviton detection\" experiments. As a particular example of a non-standard gravity model that could be tested\, I will discuss a recent phenomenological model of \"entropic gravity\" and its experimental signatures.
UID:137597-21880446@events.umich.edu
URL:https://events.umich.edu/event/137597
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20251002T085120
DTSTART;TZID=America/Detroit:20251022T120000
DTEND;TZID=America/Detroit:20251022T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Love number matching: uncovering the simplest EFT
DESCRIPTION:At wavelengths large compared to the source size\, any compact object admits a point-particle EFT whose finite-size effects are encoded by Love numbers. In this talk I will discuss a novel method to compute gravitational wave amplitudes by reinterpreting the Feynman diagram expansion as a Born series\, solution of an effective wave equation. This method enables efficient\, systematic calculations of scattering amplitudes off any compact object\, yielding new predictions for scalar black-hole Love numbers and their renormalization-group equations up to O(G^7).
UID:139047-21884679@events.umich.edu
URL:https://events.umich.edu/event/139047
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20251021T120431
DTSTART;TZID=America/Detroit:20251029T120000
DTEND;TZID=America/Detroit:20251029T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | AdS3 Quantum Gravity and Finite N Chiral Primaries
DESCRIPTION:String theory on AdS3 x S3 x M4 provides a well-studied realization of AdS3/CFT2 holography\, but its non-perturbative structure at finite N ~ 1/G_N is largely unknown. A long-standing puzzle concerns the stringy exclusion principle: what bulk mechanism can reproduce the boundary expectation that the chiral primary Hilbert space of the symmetric orbifold contains only a finite number of states at finite N?\n\nIn this talk\, we present a bulk prescription for computing the finite N spectrum of chiral primary states in symmetric orbifolds of T4 or K3. We show that the integer spectrum at any N is reproduced exactly by summing over one-loop supersymmetric partition functions of the IIB theory on (AdS3 x S3)/Z_k x M4 orbifolds and their spectral flows. Using the worldsheet in the tensionless limit\, we verify that the terms appearing in our proposal coincide with the supersymmetric partition functions of these orbifold geometries. These partition functions contribute with alternating signs due to BPS modes with negative conformal dimensions and charges in twisted sectors. The resulting alternating sum collapses via large cancellations to the finite N polynomials observed in symmetric orbifold CFTs\, providing a bulk explanation of the stringy exclusion principle. We identify different Stokes sectors where different infinite subsets of these geometries contribute to the path integral\, and propose a classification as functions of the chemical potentials.
UID:139048-21884681@events.umich.edu
URL:https://events.umich.edu/event/139048
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20251024T122844
DTSTART;TZID=America/Detroit:20251112T120000
DTEND;TZID=America/Detroit:20251112T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Broadening direct searches for light dark matter
DESCRIPTION:Direct searches for low-mass DM were originally designed using the same conceptual picture as WIMP searches. However\, over the last five years\, the crucial role of in-medium effects has come into sharp focus. A new theoretical framework in the language of condensed matter physics has emerged for understanding the relationship between the properties of detector systems and their sensitivity to DM interactions. I will report on three recent advances that leverage this formalism to substantially broaden the design considerations for the next generation of experiments\, and even extract new constraints from existing data. First\, for DM–electron interactions\, large new datasets generated by the materials science community have enabled the first data-driven search for optimal detector materials\, which promises to significantly enhance the sensitivity of near-future experiments. Second\, just as detectors designed to detect nuclear scattering have been used to study electronic scattering\, I will explain how in-medium effects make the reverse possible as well\, allowing us to set new limits on DM–nucleon scattering using the low-threshold detectors designed to detect electronic scattering. Third\, with the advent of low-threshold detectors sensitive to energy deposits as low as 50 meV\, we have finally entered the regime where the interaction rate can be significantly enhanced due to the geometry of the detector system. These three considerations promise to substantially accelerate the search for light DM in both mass and cross section over the coming years.
UID:137598-21880447@events.umich.edu
URL:https://events.umich.edu/event/137598
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20251105T090437
DTSTART;TZID=America/Detroit:20251119T120000
DTEND;TZID=America/Detroit:20251119T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Form factors in the large-N bootstrap
DESCRIPTION:Well after 50 years since the discovery of QCD\, we are still lacking a description of the theory of strong interactions at low energies. For instance\, we do not know how to produce the rich meson spectrum out of the handful of parameters in the QCD Lagrangian\, other than by brute-force lattice simulations. This has prompted a revival of the S-matrix bootstrap\, which aims to single out the theory as the unique set of scattering amplitudes consistent with certain self-consistency conditions. This approach has led to sharp\, rigorous bounds for pion scattering in the large N limit. But these bounds are completely agnostic about the UV completion of the theory. In this talk I will explain how\, by enlarging the system to include form factors and two-point functions\, one can input UV information (computed with perturbative QCD) into the bootstrap. We will see how this improves upon the previous bounds.
UID:139049-21884682@events.umich.edu
URL:https://events.umich.edu/event/139049
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20251117T120151
DTSTART;TZID=America/Detroit:20251203T120000
DTEND;TZID=America/Detroit:20251203T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar |  Supermassive Black Holes\, Dark Matter\, and the Relativistic Instability.
DESCRIPTION:The gravothermal core collapse of self-interacting dark matter halos provides a compelling mechanism for seeding supermassive black holes in the early Universe. In this scenario\, a small fraction of a halo\, approximately 1% of its mass\, collapses into a dense core\, which could further evolve into a black hole. In addition\, I describe how the relativistic onset of dynamical instability can be diagnosed by exploiting Chandrasekhar’s criterion in both classical and quantum gases. Finally\, I highlight the crucial role of space dimensionality and cosmological constant regarding the general-relativistic instability.
UID:139050-21884683@events.umich.edu
URL:https://events.umich.edu/event/139050
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20251204T140057
DTSTART;TZID=America/Detroit:20251210T120000
DTEND;TZID=America/Detroit:20251210T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar |  Log soft graviton theorem from BMS superrotation symmetry
DESCRIPTION:In four spacetime dimensions\, the soft graviton theorem exhibits a term that arises exclusively from one-loop diagrams and is logarithmic in the soft graviton energy. In this talk\, we demonstrate that this term\, known as the log soft graviton theorem\, can be derived as the Ward identity of BMS superrotation symmetry\, once long-range interactions are properly taken into account. We carry out a systematic analysis to all orders in the coupling and confirm that the log soft theorem is indeed one-loop exact.
UID:142385-21890782@events.umich.edu
URL:https://events.umich.edu/event/142385
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20251212T094501
DTSTART;TZID=America/Detroit:20251217T120000
DTEND;TZID=America/Detroit:20251217T130000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Higher-derivative Kerr-Sen black holes
DESCRIPTION:In this talk\, I will discuss recent developments in the use of solution-generating techniques for computing higher-derivative corrections. In particular\, I will show how to use an O(2\,1) boost to obtain the four-derivative corrections to the Kerr-Sen solution for two choices of higher-derivative action. The resulting solution\, much like the case for Kerr\, is perturbative in the spin parameter\, but I will show how to get the exact thermodynamics and discuss a\nconjectural BPS limit. Time allowing\, I will also discuss ongoing work on the extremal non-supersymmetric Kerr-Sen black hole.
UID:142625-21891233@events.umich.edu
URL:https://events.umich.edu/event/142625
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20260125T183710
DTSTART;TZID=America/Detroit:20260128T130000
DTEND;TZID=America/Detroit:20260128T140000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Cardy limit of the 3d superconformal index
DESCRIPTION:Cardy limit of SUSY indices in diverse dimensions are of interest for studying black hole microstates and supersymmetric gauge dynamics\, among other things. This talk will review recent results on the Cardy limit of the superconformal index of rank-one 3d N=2 gauge theories. We shall encounter mathematical structures reminiscent of those in Seiberg-Witten theory. This motivates future attempts at applying some of the new 3d N=2 techniques to 4d N=2 theories.
UID:143767-21893988@events.umich.edu
URL:https://events.umich.edu/event/143767
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20260203T141419
DTSTART;TZID=America/Detroit:20260130T130000
DTEND;TZID=America/Detroit:20260130T140000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Negative energies and the breakdown of bulk lengths in JT gravity
DESCRIPTION:One central puzzle in quantum gravity is to understand how and why predictions from semiclassical gravity can sometimes break down in a regime where we naively expect the semiclassical approximation to be valid. In particular\, overlaps among states that are orthonormal in the semiclassical approximation can receive large corrections from quantum fluctuations of the geometry. I will examine such overlaps among states of fixed length in the theory of pure JT gravity\, which is dual to the random matrix ensemble of Saad-Shenker-Stanford. Previously\, it has been discussed that the discreteness of the boundary spectrum must cause a breakdown of the bulk length basis for lengths proportional to the boundary inverse level spacing\, e^{S_0}.  I will discuss how the sum over quantum fluctuations at all orders in the bulk genus expansion indicates a more dramatic breakdown than previously expected\, at shorter lengths of O(e^{S_0/3}). From the perspective of the boundary spectrum\, these corrections arise from the presence of negative energies in rare members of the random matrix ensemble. Work in progress with John Preskill and Mykhaylo Usatyuk.
UID:144818-21895974@events.umich.edu
URL:https://events.umich.edu/event/144818
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20260209T103905
DTSTART;TZID=America/Detroit:20260211T130000
DTEND;TZID=America/Detroit:20260211T140000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Maximizing the Interaction Strength
DESCRIPTION:QCD remains intractable in the high-energy soft regime\, where all standard methods break down. This regime governs total hadronic cross-sections\, which have long been observed to grow with energy\, a phenomenon that is still very poorly understood today. In this talk\, I will argue that the modern S-matrix bootstrap provides a systematic way to tackle this regime of QCD. I will derive an upper bound on the total cross-section at finite energy and present the strongest interacting amplitude that the bootstrap outputs. I will compare these results with proton–proton experimental data.
UID:143765-21893986@events.umich.edu
URL:https://events.umich.edu/event/143765
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20260217T111612
DTSTART;TZID=America/Detroit:20260218T130000
DTEND;TZID=America/Detroit:20260218T140000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Bulk Locality from Infrared Entanglement
DESCRIPTION:For quantum field theories coupled to any massless fields\, one generally encounters “IR divergences” which arise due to the fact that the asymptotic description of the state contains an infinite number of soft radiative quanta. These quanta have recently gained interest due to their connections to unitarity\, asymptotic symmetries and the memory effect. However\, for the description of any bulk experiment\, these quanta are generally viewed as a nuisance with little physical relevance for the predictions of any bulk\, finite time observable.\n\nIn this talk\, I will explain that this is not the case. In fact\, the situation is quite the opposite: all local physical observables and phenomena depend on the entanglement and absorption of soft radiation. I will explain (1) how this phenomenon arises and (2) why it was missed in the literature and (3) why this result agrees with the predictions of collider experiments. I will primarily focus on the case of QED with and will comment on the analogous issues in QED with massless electrons\, Yang-Mills theories and Quantum Gravity.
UID:143132-21892189@events.umich.edu
URL:https://events.umich.edu/event/143132
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20260304T123637
DTSTART;TZID=America/Detroit:20260311T130000
DTEND;TZID=America/Detroit:20260311T140000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Near-extremal black hole evaporation
DESCRIPTION:Over the last few years it has been understood that black holes sufficiently close to extremality receive large quantum corrections that modify their thermodynamic properties. In this talk\, I will explain how these large corrections modify the real time dynamics of near-extremal black holes. As an example\, the spectrum of emitted Hawking radiation differs drastically from the standard predictions of QFT in curved spacetime for such black holes.
UID:144820-21895978@events.umich.edu
URL:https://events.umich.edu/event/144820
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20260310T154829
DTSTART;TZID=America/Detroit:20260318T130000
DTEND;TZID=America/Detroit:20260318T140000
SUMMARY:Lecture / Discussion:HET Brown Bag Seminar | Comments on the gravitational path integral approach to cosmology
DESCRIPTION:In this talk\, I will discuss various aspects of the gravitational path integral (GPI) approach to cosmology. First\, I will revisit the Hartle-Hawking no-boundary proposal taking into account the norms of states computed using the GPI\, and explain how this dramatically alters the predictions of the proposal. I will then propose an alternative prescription\, which relates cosmological initial conditions to asymptotically AdS boundary conditions. Preliminary results show this approach predicts a long inflationary period ending in a metastable de Sitter universe (modulo some technical issues I will discuss). Finally\, if time allows\, I will comment on recent results that the Hilbert space of closed universes is one-dimensional\, and discuss the role of an ingredient common to all proposed resolutions of this issue: ensemble averaging.
UID:144821-21895979@events.umich.edu
URL:https://events.umich.edu/event/144821
CLASS:PUBLIC
STATUS:CONFIRMED
CATEGORIES:Brown Bag Seminar
LOCATION:Randall Laboratory - 3481
CONTACT:
END:VEVENT
END:VCALENDAR