BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Alejandro Cabo-Bizet (King's College) DTSTART:20200604T140000Z DTEND:20200604T150000Z DTSTAMP:20260422T212938Z UID:HEPTUW/1 DESCRIPTION:Title: O n the large N limit of the 4d N=1 superconformal index\nby Alejandro C abo-Bizet (King's College) as part of HEP seminars TU Wien (Vienna)\n\n\nA bstract\nThe large N limit of the 4d N=1 superconformal index is\nargued t o be determined by competition among complex eigenvalue\nconfigurations. A t least some of these configurations correspond to\nembeddings of abelian discrete groups of order N upon a 2-torus. Via\nthe principles of AdS/CFT correspondence one of these configurations\nmaps to a regular Wick-rotated section of a supersymmetric rotating and\nelectrically charged Lorentzian AdS5 black hole. After an introduction\nto the problem\, that will includ e a survey over the analytic frame that\nallows us to quantify the competi tion among elements of a sub-family of\nthese complex eigenvalue configura tions\, I will end with an\ninterpretation of our results for SU(N) N=4 SY M\, and a comparison with\nrecently reported numerical studies.\n LOCATION:https://researchseminars.org/talk/HEPTUW/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Miguel Montero (Harvard U.) DTSTART:20200618T140000Z DTEND:20200618T150000Z DTSTAMP:20260422T212938Z UID:HEPTUW/2 DESCRIPTION:Title: N othing is certain in string compactifications\nby Miguel Montero (Harv ard U.) as part of HEP seminars TU Wien (Vienna)\n\n\nAbstract\nA bubble o f nothing is a spacetime instability where a compact dimension collapses. After nucleation\, it expands at the speed of light\, leaving "nothing" be hind. There are a couple of robust mechanisms that can prevent the existen ce of a bubble: Either it is not energetically favourable to produce them \, or there is a topological obstruction to their existence. The latter is often the case with SUSY-preserving boundary conditions. I will explain how to understand the topological obstruction in detail using bordism\, wh ich will show that it is very generically absent even for a SUSY-compatibl e spin structure. As a proof of principle\, we construct and embed in stri ng theory an explicit bubble of nothing for a T3 with completely periodic (SUSY-compatible) spin structure. There is a dynamical obstruction due to a positive energy theorem which is circumvented by higher-derivative cor rections. Our model can be embedded in string theory. Our techniques can be used to construct a plethora of bubbles of nothing for spaces of intere st like CY6's\, G2 manifolds\, or Sasaki-Einstein manifolds. We will expla in how to study and circumvent the topological and dynamical obstruction i n these cases. Avoiding the dynamical obstruction means avoiding a modifie d energy condition which might be related to the Weak Gravity Conjecture. Our results lend support to the conjecture that any \nnon-supersymmetric vacuum of quantum gravity is ultimately unstable.\n LOCATION:https://researchseminars.org/talk/HEPTUW/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Charles Marteau DTSTART:20200625T140000Z DTEND:20200625T150000Z DTSTAMP:20260422T212938Z UID:HEPTUW/3 DESCRIPTION:Title: N ew boundary conditions for AdS2\nby Charles Marteau as part of HEP sem inars TU Wien (Vienna)\n\n\nAbstract\nWe describe new boundary conditions for AdS2 in Jackiw-Teitelboim gravity. The asymptotic symmetry group is en hanced to Diff(S1)⋉C∞(S1) whose breaking to SL(2\,R)×U(1) controls th e near-AdS2 dynamics. The action reduces to a boundary term which is a gen eralization of the Schwarzian theory. It can be interpreted as the coadjoi nt action of the warped Virasoro group. We show that this theory is hologr aphically dual to the complex SYK model. We compute the Euclidean path int egral and derive its relation to the random matrix ensemble of Saad\, Shen ker and Stanford. We study the flat space version of this action\, and sho w that the corresponding path integral also gives an ensemble average\, bu t of a much simpler nature. We explore some applications to near-extremal black holes.\n LOCATION:https://researchseminars.org/talk/HEPTUW/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Hiroshi Ooguri (Caltech & Kavli IPMU) DTSTART:20200709T140000Z DTEND:20200709T150000Z DTSTAMP:20260422T212938Z UID:HEPTUW/5 DESCRIPTION:Title: T esting Swampland Conjectures\nby Hiroshi Ooguri (Caltech & Kavli IPMU) as part of HEP seminars TU Wien (Vienna)\n\n\nAbstract\nOver the last fou rteen years\, a variety of swampland conditions have been proposed with va rious degrees of rigor. In this talk\, I will discuss tests of some of the se conjectures that do not rely on specific string theory constructions. T hey include constraints on symmetry\, strength of gravitational couplings\ , cobordism between theories\, and issues with lower dimensional theories. \n LOCATION:https://researchseminars.org/talk/HEPTUW/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Paul Steinhardt (Princeton) DTSTART:20201105T150000Z DTEND:20201105T160000Z DTSTAMP:20260422T212938Z UID:HEPTUW/6 DESCRIPTION:Title: S moothing and Flattening the Universe\nby Paul Steinhardt (Princeton) a s part of HEP seminars TU Wien (Vienna)\n\n\nAbstract\nThe most salient fe ature of the observable universe is that it is homogeneous and spatially f lat on large scales. This talk will argue why this may only be explained b y replacing the big bang with a big bounce preceded by a period of slow co ntraction\, a conclusion which has profound implications for cosmology and fundamental physics.\n LOCATION:https://researchseminars.org/talk/HEPTUW/6/ END:VEVENT BEGIN:VEVENT SUMMARY:Kévin Nguyen (King's College) DTSTART:20201008T140000Z DTEND:20201008T150000Z DTSTAMP:20260422T212938Z UID:HEPTUW/7 DESCRIPTION:Title: T he effective action of superrotation modes\nby Kévin Nguyen (King's C ollege) as part of HEP seminars TU Wien (Vienna)\n\n\nAbstract\nStarting f rom an analysis of four-dimensional asymptotically flat gravity in first o rder formulation\, we show that superrotation reparametrization modes are governed by an Alekseev--Shatashvili action on the celestial sphere. This two-dimensional conformal theory describes spontaneous symmetry breaking o f Virasoro superrotations together with the explicit symmetry breaking of more general Diff(S2) superrotations. We arrive at this result by first re formulating the asymptotic field equations and symmetries of the radiative vacuum sector in terms of a Chern--Simons theory at null infinity\, and s ubsequently performing a Hamiltonian reduction of this theory onto the cel estial sphere.\n LOCATION:https://researchseminars.org/talk/HEPTUW/7/ END:VEVENT BEGIN:VEVENT SUMMARY:Arthur Hebecker (U. Heidelberg\, ITP) DTSTART:20201015T130000Z DTEND:20201015T140000Z DTSTAMP:20260422T212938Z UID:HEPTUW/8 DESCRIPTION:Title: D e Sitter from String Theory: Control Issues of KKLT\nby Arthur Hebecke r (U. Heidelberg\, ITP) as part of HEP seminars TU Wien (Vienna)\n\n\nAbst ract\nAfter a brief introduction to the problem of realising de Sitter spa ce in string compactifications\, I will describe the specific proposal of Kachru\, Kallosh\, Linde and Trivedi (KKLT)\, including some of its critic ism. I will then explain why\, according our recent analysis\, extended si ngularities in the bulk of the compact space appear to generically threate n the construction. Possible escape routes from this "bulk singularity pro blem" will also be discussed.\n LOCATION:https://researchseminars.org/talk/HEPTUW/8/ END:VEVENT BEGIN:VEVENT SUMMARY:Shubham Maheshwari (Groningen) DTSTART:20201022T140000Z DTEND:20201022T150000Z DTSTAMP:20260422T212938Z UID:HEPTUW/9 DESCRIPTION:Title: S table\, ghost-free solutions in UV non-local gravity\nby Shubham Mahes hwari (Groningen) as part of HEP seminars TU Wien (Vienna)\n\n\nAbstract\n I consider higher derivative\, UV modifications to GR. In particular\, I w ill focus on a specific kind of string theory-inspired higher derivative g ravity where one includes derivatives to all orders in the action. First\, I will discuss how such a non-local theory of gravity admits stable\, non -singular bouncing solutions in the absence of matter. Moreover\, around t his bouncing background\, there exists only one propagating (and ghost-fre e) scalar mode\, and no vector or tensor modes. Next\, I will discuss the general analysis of scalar-vector-tensor perturbations in non-local gravit y - in particular\, I will show how non-local gravity is ghost-free around (A)dS and certain non-maximally symmetric backgrounds\, and how certain ( A)dS backgrounds have special physical spectra in that the propagating deg rees of freedom are different from usual expectations.\n LOCATION:https://researchseminars.org/talk/HEPTUW/9/ END:VEVENT BEGIN:VEVENT SUMMARY:Bret Underwood (Pacific Lutheran University) DTSTART:20201029T150000Z DTEND:20201029T160000Z DTSTAMP:20260422T212938Z UID:HEPTUW/10 DESCRIPTION:Title: Cosmological Chaos\, Complexity\, and the OTOC\nby Bret Underwood (Pac ific Lutheran University) as part of HEP seminars TU Wien (Vienna)\n\n\nAb stract\nSeveral approaches to investigating quantum chaos have recently em erged\, including quantum circuit complexity and the out-of-time-order cor relator (OTOC). In this talk\, I will briefly introduce these ideas and ap ply them to squeezed states\, including the squeezed state description of cosmological perturbations on a variety of cosmological backgrounds\, such as de Sitter accelerated expansion. Some intriguing results from this inv estigation include a bound on the growth rate of cosmological complexity r eminiscent of a similar bound on the quantum Lyapunov exponent\, and the o bservation that among all cosmological backgrounds\, only de Sitter space leads to the exponential growth of the OTOC that is a signature of quantum chaos.\n LOCATION:https://researchseminars.org/talk/HEPTUW/10/ END:VEVENT BEGIN:VEVENT SUMMARY:Ashish Shukla (Perimeter) DTSTART:20201119T150000Z DTEND:20201119T160000Z DTSTAMP:20260422T212938Z UID:HEPTUW/11 DESCRIPTION:Title: The Effective Field Theory for Hydrodynamics and its Analytic Properties\nby Ashish Shukla (Perimeter) as part of HEP seminars TU Wien (Vienna)\ n\n\nAbstract\nHydrodynamics provides an effective description for many-bo dy systems near thermal equilibrium. The success of the paradigm rests on the idea that the dynamics of such near-equilibrium systems can be capture d by a very small number of parameters\, such as the temperature and fluid velocity\, and their derivatives. For instance\, relativistic hydrodynami cs\, which is applicable to systems which respect the Lorentz symmetry\, h as been immensely successful in understanding the properties of the Quark- Gluon plasma that is produced in heavy-ion collisions at RHIC and CERN. In this talk\, I will start by reviewing the construction of hydrodynamics i n terms of a derivative expansion\, followed by a discussion of the equili brium generating functional and its properties. Interestingly\, though the standard formulation of hydrodynamics captures the dissipative aspects of the system quite well\, it does not take into account the effects of the underlying thermal fluctuations efficiently. One can remedy the situation to some extent by using the stochastic approach\, where one can introduce random Gaussian fluctuations and derive an effective action. However\, thi s approach has its limitations\, as the structure of the interaction terms in the effective action is quite restricted. Recently\, an effective fiel d theory (EFT) approach based on the Schwinger-Keldysh (SK) formalism has been proposed\, which systematically captures the effects of the underlyin g fluctuations\, making use of symmetries. In the second part of the talk\ , I will review the construction of the stochastic as well as the SK effec tive actions for a theory of charge diffusion. I will then discuss a simpl ifying limit of the SK diffusive EFT\, where the sound modes effectively d ecouple from the dynamics. I will discuss one-loop corrections to the reta rded and symmetric correlators in this model\, with special emphasis on th e role played by the KMS symmetry in ensuring the correct analytic structu re for the theory as required by the limit of thermal equilibrium\, provid ing a strong consistency check on the EFT framework.\n LOCATION:https://researchseminars.org/talk/HEPTUW/11/ END:VEVENT BEGIN:VEVENT SUMMARY:Francesco Alessio (Naples) DTSTART:20201126T150000Z DTEND:20201126T160000Z DTSTAMP:20260422T212938Z UID:HEPTUW/12 DESCRIPTION:Title: Weyl symmetry and anomaly in asymptotically locally AdS_3\nby Francesc o Alessio (Naples) as part of HEP seminars TU Wien (Vienna)\n\n\nAbstract\ nI will discuss an enhancement of Brown-Henneaux boundary conditions in 3d AdS General Relativity to encompass Weyl transformations of the boundary metric. The consequences on the asymptotic symmetry algebra and the dual t heory of imposing a conformally flat boundary condition are explored. In p articular\, I will show that the corresponding asymptotic symmetries inclu de a new sector of Weyl rescalings with integrable but not conserved surfa ce charges. The holographic counterpart of this result can be consistently described by an anomalous Ward-Takahashi identity in the boundary.\n LOCATION:https://researchseminars.org/talk/HEPTUW/12/ END:VEVENT BEGIN:VEVENT SUMMARY:Juan Margalef-Bentabol (UCM) DTSTART:20201203T153000Z DTEND:20201203T163000Z DTSTAMP:20260422T212938Z UID:HEPTUW/13 DESCRIPTION:Title: Geometric formulation of covariant phase methods with boundary\nby Jua n Margalef-Bentabol (UCM) as part of HEP seminars TU Wien (Vienna)\n\n\nAb stract\nIn physics\, one standard way to study and understand a theory is through its dynamical formulation. Whenever possible\, this is obtained by considering some initial conditions and evolving them through the dynamic al equations of the theory. One gets then a curve over the space of initia l conditions which codifies the evolution. This approach is useful in many settings\, including General Relativity (ADM\, numerical relativity\, gra vitational waves...)\, however\, it also has some limitations. Namely\, to understand some non-local concepts such as black holes and their properti es (e.g. spin\, energy\, or entropy) one runs into some complications. Ano ther approach is to study the space of solutions where each point represen ts a whole solution of the theory. For well-posed problems\, this space is equivalent to the space of initial conditions (each initial condition giv es rise to one and only one solution) although in general there would be s ome gauge degeneracy (the solution is determined up to some gauge transfor mation). In this talk\, I will present this latter approach in what is kno wn as the Covariant Phase Space methods. In particular\, I will show how t o construct a presymplectic structure over the space of solutions canonica lly associated with the action of the theory. The novelty of our work is t hat we consider the manifold with boundary\, which adds several difficulti es that had not been solved before.\n LOCATION:https://researchseminars.org/talk/HEPTUW/13/ END:VEVENT BEGIN:VEVENT SUMMARY:Roberto Valandro (Trieste U.) DTSTART:20201217T153000Z DTEND:20201217T163000Z DTSTAMP:20260422T212938Z UID:HEPTUW/14 DESCRIPTION:Title: De Sitter vacua from anti-D3-branes in type IIB LVS compactifications\ nby Roberto Valandro (Trieste U.) as part of HEP seminars TU Wien (Vienna) \n\n\nAbstract\nWe will begin with an introduction on moduli stabilisation in type IIB compactifications on CY orientifolds\, with de Sitter uplift due to an anti-D3 brane. We consider a concrete setup where an anti D3-bra ne sits at the tip of a warped throat and the stabilised volume is exponen tially large as in the large volume scenario (LVS). We analyse the conditi ons on the parameters of the EFT such that they are in the region of valid ity. We illustrate our results with an explicit choice of Calabi-Yau manif old and D-brane configuration\, where moduli stabilisation gives rise to a de Sitter minimum.\n LOCATION:https://researchseminars.org/talk/HEPTUW/14/ END:VEVENT BEGIN:VEVENT SUMMARY:Pedro Aniceto (IST Lisbon) DTSTART:20210114T153000Z DTEND:20210114T163000Z DTSTAMP:20260422T212938Z UID:HEPTUW/15 DESCRIPTION:Title: R^2 corrected AdS_2 holography\nby Pedro Aniceto (IST Lisbon) as part of HEP seminars TU Wien (Vienna)\n\n\nAbstract\nWe approach the problem of constructing the holographic dictionary for AdS_2/CFT_1 in the context of higher derivative gravitational actions in AdS_2. We focus on S_2 reducti ons of four-dimensional N=2 Wilsonian effective actions with Weyl squared interactions restricted to constant scalar backgrounds. BPS black hole nea r-horizon spacetimes fall into this class of backgrounds and\, by identify ing the boundary operators dual to the bulk fields\, we explicitly show ho w the Wald entropy of the BPS black hole is holographically encoded in the anomalous transformation of the operator dual to a composite bulk field. Additionally\, using a 2d/3d lift\, we show that the CFT holographically d ual to AdS_2 is naturally embedded in the chiral half of the CFT_2 dual to the AdS_3 spacetime\, and we identify the specific CFT_1 operator that en codes the chiral central charge of the CFT_2.\n LOCATION:https://researchseminars.org/talk/HEPTUW/15/ END:VEVENT BEGIN:VEVENT SUMMARY:Jakob Salzer (Harvard) DTSTART:20210128T153000Z DTEND:20210128T163000Z DTSTAMP:20260422T212938Z UID:HEPTUW/17 DESCRIPTION:Title: Limits of JT gravity\nby Jakob Salzer (Harvard) as part of HEP seminar s TU Wien (Vienna)\n\n\nAbstract\nJackiw—Teitelboim (JT) gravity is a mo del of two-dimensional dilaton gravity that has been central to many inter esting developments (e.g.\, SYK model\, random matrix models\, island prop osal) in the last couple of years. In this talk I will discuss various lim its of JT gravity\, including Newton—Cartan (non-relativistic) and Carro llian (ultra-relativistic) versions of two-dimensional dilaton gravity. Af ter defining suitable boundary conditions\, I will then discuss the issue of constructing boundary actions that capture the non-trivial dynamics at the boundary of these models.\n LOCATION:https://researchseminars.org/talk/HEPTUW/17/ END:VEVENT BEGIN:VEVENT SUMMARY:Sukruti Bansal (Chulangkorn University\, Bangkok) DTSTART:20210304T153000Z DTEND:20210304T163000Z DTSTAMP:20260422T212938Z UID:HEPTUW/18 DESCRIPTION:Title: Unimodular vs Nilpotent Superfield Approach to Pure dS Supergravity\nb y Sukruti Bansal (Chulangkorn University\, Bangkok) as part of HEP seminar s TU Wien (Vienna)\n\n\nAbstract\nRecent progress in understanding de Sitt er spacetime in supergravity and string theory has led to the development of a 4D supergravity with spontaneously broken supersymmetry allowing for de Sitter vacua\, also called de Sitter supergravity. One approach makes use of constrained (nilpotent) superfields\, while an alternative one coup les supergravity to a locally supersymmetric generalization of the Volkov- Akulov goldstino action. These two approaches have been shown to give rise to the same 4D action.\nA novel approach to de Sitter vacua in supergravi ty involves the generalisation of unimodular gravity to supergravity usin g a super-Stückelberg mechanism. We make a connection between this new ap proach and the previous two. We show that upon appropriate field redefinit ions\, the 4D actions match up to the cubic order in the fields. This poin ts at the possible existence of a more general framework to obtain de Sitt er spacetimes from high-energy theories.\n LOCATION:https://researchseminars.org/talk/HEPTUW/18/ END:VEVENT BEGIN:VEVENT SUMMARY:Jakob Moritz (Cornell) DTSTART:20210311T153000Z DTEND:20210311T163000Z DTSTAMP:20260422T212938Z UID:HEPTUW/19 DESCRIPTION:Title: Resolving spacetime singularities in flux compactifications and KKLT\n by Jakob Moritz (Cornell) as part of HEP seminars TU Wien (Vienna)\n\n\nAb stract\nI explain how string theory resolves ubiquitous singularities in t ype IIB flux compactifications (and eventually KKLT de Sitter vacua) via e ffects that are non-perturbative in the \\alpha' expansion of string theor y. I will show that these can be understood in detail by mapping them to w ell known gauge instanton effects in pure 4d N=2 Yang-Mills theory. A perh aps surprising consequence is that the naively 'elementary' D7 brane of ty pe IIB string theory is properly thought of as a bound state of two mutual ly non-local cosmic defects in six dimensions upon compactification on a c urved 4-manifold. Finally\, I will argue that the resolution described ind icates that KKLT de Sitter vacua can be controlled by a small flux superpo tential although the K\\"ahler potential may in general receive large corr ections which are difficult to compute.\n LOCATION:https://researchseminars.org/talk/HEPTUW/19/ END:VEVENT BEGIN:VEVENT SUMMARY:Kirill Boguslavski (TU Wien) DTSTART:20210325T153000Z DTEND:20210325T163000Z DTSTAMP:20260422T212938Z UID:HEPTUW/20 DESCRIPTION:by Kirill Boguslavski (TU Wien) as part of HEP seminars TU Wie n (Vienna)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/HEPTUW/20/ END:VEVENT BEGIN:VEVENT SUMMARY:Angel Uranga (IFT Madrid) DTSTART:20210415T143000Z DTEND:20210415T153000Z DTSTAMP:20260422T212938Z UID:HEPTUW/21 DESCRIPTION:Title: Rolling down to the end of the world\nby Angel Uranga (IFT Madrid) as part of HEP seminars TU Wien (Vienna)\n\n\nAbstract\nWe discuss string the ory configurations sitting on the slope of scalar potentials (aka tadpoles ) and discuss properties of their spacetime dependent solutions. We argue that these solutions can extend only a finite distance away in the spaceti me dimensions\, scaling as \\Delta^{-n}\\sim {\\cal T} with the strength o f the tadpole {\\cal T}. We show that naive singularities arising at this distance scale are physically replaced by ends of spacetime\, related to t he cobordism defects of the swampland cobordism conjecture. We illustrate these phenomena in large classes of examples\, including susy and non-susy 10 string theories and a 6d string model whose tadpole triggers spontaneo us compactification to a semirealistic 3-family MSSM-like particle physics model.\n LOCATION:https://researchseminars.org/talk/HEPTUW/21/ END:VEVENT BEGIN:VEVENT SUMMARY:Sucheta Majumdar (Université Libre de Bruxelles) DTSTART:20210422T143000Z DTEND:20210422T153000Z DTSTAMP:20260422T212938Z UID:HEPTUW/22 DESCRIPTION:Title: BMS symmetry in light-cone gravity\nby Sucheta Majumdar (Université L ibre de Bruxelles) as part of HEP seminars TU Wien (Vienna)\n\n\nAbstract\ nThe aim of this talk is to discuss how the BMS symmetry appears in gravit y in the light-cone gauge\, a formulation where all unphysical degrees of freedom are integrated out. By checking the invariance of\nthe light-cone Hamiltonian\, we obtain a set of residual gauge transformations that satis fy the BMS algebra realized on the two physical fields in the theory. Henc e\, the BMS algebra appears as a consequence of residual gauge invariance in the bulk without any reference to asymptotic limits. Alternatively\, on e can also obtain the\nBMS algebra as a local extension of the Poincaré s ymmetry in light-cone gravity in four dimensions. In the light-cone formal ism\, the dynamical part of the Poincaré algebra is enhanced to accommoda te the supertranslations\, yielding the infinite-dimensional BMS algebra.\ n LOCATION:https://researchseminars.org/talk/HEPTUW/22/ END:VEVENT BEGIN:VEVENT SUMMARY:Kirill Boguslavski (TU Wien) DTSTART:20210429T143000Z DTEND:20210429T153000Z DTSTAMP:20260422T212938Z UID:HEPTUW/23 DESCRIPTION:Title: The imaginary part of the heavy-quark potential from real-time Yang-Mills dynamics\nby Kirill Boguslavski (TU Wien) as part of HEP seminars TU W ien (Vienna)\n\n\nAbstract\nThe suppression of heavy quark-antiquark bound states like bottomonium in heavy-ion collisions is an important observabl e for the quark-gluon plasma state. Theoretically\, this can be quantified by the heavy-quark potential. In this talk\, I will present our results o n extracting its imaginary part using classical-statistical simulations of real-time Yang-Mills dynamics in classical thermal equilibrium. We compar e our results to perturbation theory calculations in hard thermal loop for malisms. We find that\, when considered as a function of m_D r\, where m_D is the soft scale\, the imaginary part of the heavy-quark potential becom es independent of the lattice spacing at sufficiently small r and agrees w ell with perturbative results. We finally relate the short-distance behavi or of the potential to the heavy-quark transport coefficient κ\, providin g an estimate of the latter.\n LOCATION:https://researchseminars.org/talk/HEPTUW/23/ END:VEVENT BEGIN:VEVENT SUMMARY:Anthony Ashmore (Chicago U. & Paris LPTHE) DTSTART:20210520T143000Z DTEND:20210520T153000Z DTSTAMP:20260422T212938Z UID:HEPTUW/24 DESCRIPTION:Title: Calabi-Yau metrics: what are they good for?\nby Anthony Ashmore (Chica go U. & Paris LPTHE) as part of HEP seminars TU Wien (Vienna)\n\n\nAbstrac t\nCalabi-Yau manifolds have played a key role in both mathematics and phy sics\, and are particularly important for deriving realistic models of par ticle physics from string theory. Unfortunately\, very little is known abo ut the explicit metrics on these spaces\, leaving us unable\, for example\ , to compute particle masses or couplings in these models. I will review r ecent progress in this direction on using numerical approximations to comp ute the metric and the (p\,q)-form Laplacian on these spaces. I will finis h with some examples of what one can do with this new "data".\n LOCATION:https://researchseminars.org/talk/HEPTUW/24/ END:VEVENT BEGIN:VEVENT SUMMARY:Irene Valenzuela (Harvard) DTSTART:20210610T143000Z DTEND:20210610T153000Z DTSTAMP:20260422T212938Z UID:HEPTUW/25 DESCRIPTION:Title: Light Fermions and the Swampland\nby Irene Valenzuela (Harvard) as par t of HEP seminars TU Wien (Vienna)\n\n\nAbstract\nQuantum gravity can have important implications for Particle Physics and Cosmology. We consider co nstraints on D-dimensional theories in Minkowski\, dS and AdS backgrounds in the light of AdS swampland conjectures as applied to their compacticati on in a circle. In particular\, we consider the non-SUSY AdS instability c onjecture and the AdS distance conjecture. For Minkowski and dS vacua the results may be summarized by a light fermion conjecture which states that in theories with a positive first non-vanishing supertrace $(-1)^{k+1}Str( M^{2k}) > 0$\, a surplus of light fermions with mass $m_f < \\Lambda_D^{1/ D}$ must be present\, where $\\Lambda_D$ is the cosmological constant. The case of AdS can be made consistent with the mild but not the strong versi on of the AdS Distance conjecture. I will also apply the above constraints to the Standard Model of particle physics\, obtaining that it would be in consistent in Minkowski space but consistent in dS if the lightest neutrin o is Dirac and lighter than the cosmological constant scale. This may shed some light into the naturalness issues observed in our universe.\n LOCATION:https://researchseminars.org/talk/HEPTUW/25/ END:VEVENT BEGIN:VEVENT SUMMARY:Matthew Walters (EPF Lausanne) DTSTART:20210617T143000Z DTEND:20210617T153000Z DTSTAMP:20260422T212938Z UID:HEPTUW/26 DESCRIPTION:Title: Thermalization and Hydrodynamics in 2d QFTs\nby Matthew Walters (EPF L ausanne) as part of HEP seminars TU Wien (Vienna)\n\n\nAbstract\nI will di scuss the finite-temperature behavior of general 2d QFTs (obtained as rele vant deformations of CFTs). At long timescales (t >> 1/T)\, these theories all have an effective hydrodynamic description governed by the KPZ univer sality class. Using KPZ universality and causality\, I will derive a lower bound on the timescale characterizing the onset of this hydrodynamic beha vior. The resulting bound is typically much longer than the expected quant um equilibration time of 1/T. I will also show how causality can be used t o define a new thermodynamic C-function for 2d QFTs\, as well as constrain the sign of the "T-Tbar" term in EFTs.\n LOCATION:https://researchseminars.org/talk/HEPTUW/26/ END:VEVENT END:VCALENDAR