Strings: Monday, 09/12/2024, 14:00, Room 226
Pietro Benetti Genolini (University of Geneva, Geneva)
Equivariant localization for AdS/CFT
Equivariant localization may be applied to AdS/CFT to compute various BPS observables in gravity without solving the supergravity equations. The key ingredient is that supersymmetric solutions with an R-symmetry are equipped with a set of equivariantly closed forms. These may in turn be used to calculate observables including free energy, entropy, scaling dimensions of operators, anomalies.
Cosmo: Wednesday, 11/12/2024, 11:00, Lecture Room
Ilia Musco (INFN, Rome)
Primordial Black Holes: threshold, self similarity and cosmological impact
Primordial black holes have received in the recent years lots of attention, being considered interesting candidates for cold dark matter and signals from black hole mergers in the solar mass range detected by LIGO/Virgo. The formation of primordial black holes in naturally enhanced during the QCD phase transition, because of the softening of he equation of state. A fundamental quantity to understand the cosmological impact of such objects is the threshold for primordial black hole formation, defined as the peak of the compaction function on super horizon scales, when the curvature profile for adiabatic perturbations is time independent. This quantity, depends both on the equation state and the shape of the initial configurations. Performing detailed numerical simulations we have computed the modified mass function for such black holes, showing that the minimum of the QCD transition works as an attractor solution. Making then a confrontation with the LVK phenomenological models describing the GWTC-3 catalog, we have found that a sub-population of such PBHs formed in the solar mass range is compatible with the current observational constraints and could explain some of the interesting sources emitting gravitational waves detected by LIGO/VIRGO in the black hole mass gap, such as GW190814, and other light events. Finally I will discuss a new idea introducing a generalised definition of the threshold using the self similar regime of the collapse, when the black hole is almost formed, getting an universal value of the threshold depending only on the equation of state.
Strings: Monday, 16/12/2024, 14:00, Room 226
Cihan Pazarbasi (Okinawa Institute of Science and Technology, Okinawa)
Exact WKB in all sectors
Exact WKB (EWKB) is one of the most powerful tools to study differential equations and has many applications including quantum mechanics, SUSY gauge theories, integrable models, topological string theory etc. Being an incorporation of resurgence theory and the traditional WKB method, EWKB method reveals the exact quantization of the physical systems. However, in its standard treatment, the EWKB techniques are restricted to only a single sector which is bounded by singular points on the moduli space. In this talk, I will introduce a novel EWKB approach which displays the continuous connection between different sectors via an analytical continuation preventing the singularities. My focus will be on one dimensional potentials with degenerate saddles. With the Airy-type EWKB method, I will show the smooth transition of the spectrum between different sectors. In addition to that with the Weber-type EWKB method, I will present exact estimations to WKB actions in relation with multi-instanton configurations. This reveals the S-duality between minima and maxima of the degenerate potentials in the language of EWKB method. I also show an S-transformation of resurgence relations of genus-1 potentials.
Cosmo: Wednesday, 18/12/2024, 11:00, Lecture Room
Francesco Serra (Johns Hopkins University)
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Cosmo: Wednesday, 05/02/2025, 11:00
Tanja Rindler-Daller (University of Vienna - Institute for Astronomy)
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Strings: Monday, 10/02/2025, 14:00, Room 226
Karapet Mkrtchyan (Imperial College, London)
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Cosmo: Wednesday, 19/02/2025, 11:00
Jens C. Niemeyer (Institute for Astrophysics, Georg-August-University Gottingen, Gottingen)
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Strings: Monday, 24/02/2025, 14:00, Room 226
Nicolo Petri (INFN, Turin)
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Strings: Monday, 10/03/2025, 14:00, Room 226
Paul Luis Roehl (DAMTP, Cambridge)
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Strings: Monday, TBA, 14:00, Room 226
Saebyeok Jeong (CERN, Geneva)
Miura operators as R-matrices from M-brane Intersections
I will discuss how M2-M5 intersections in the twisted M-theory background yield R-matrices of quantum toroidal algebra of gl(1). These intersections are also identified as Miura operators, providing the Miura transformation for the q-deformed W- and Y-algebras. Consequently, the intertwining relation of the q-deformed Maulik-Okounkov R-matrix is illuminated as a Yang-Baxter equation, in particular. Also, I will explain the M2-M5 intersection (equivalently the Miura operator) gives rise to the qq-characters of the 5d N=1 gauge theory, illuminating an algebraic meaning of the latter.
Strings: Monday, 26/05/2025, 14:00, Room 226
Seyed Morteza Hosseini (Queen Mary University of London, London)
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Strings: Monday, 02/06/2025, 14:00, Room 226
Kiril Hristov (Sofia University & INRNE, Bulgarian Academy of Sciences, Sofia)
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