1.Debabrata Sahu 

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Title : Off-shell phase diagram of BPS black holes in AdS5

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Abstract :- We construct the off-shell free energy of supersymmetric black holes in AdS5,

and study the phase diagram in various limiting cases, with particular emphasis on BPS

thermodynamics. The changes to the free energy following from the four-derivative

corrections to five-dimensional minimal gauged supergravity action are computed, and

the modifications to the phase diagram are studied. An exact method is systematically

developed to construct the off shell BPS free energy, which in certain limiting cases, can

be rearranged in terms of an effective energy and entropy of the system, with the later

being conjugate to an effective BPS temperature. The off-shell BPS phase diagram

shows features which resemble the phases of general AdS Schwarzschild black holes,

with some nuances in the asymptotic structure, modified by four-derivative corrections.

Using AdS/CFT, phenomenological effective potentials in the boundary gauge theory are

proposed, dual to both general black holes and their BPS counterparts. The saddle

points of the effective potential capture the various locally stable and unstable phases of

the gauge theory at finite temperature and chemical potentia

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2. Somnath Maity

 

Title: Integrability and Non-hermitian quantum systems

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Abstract: The search for regular solutions to the Yang-Baxter equation (YBE) has

become an emerging area of interest in the integrability community. These regular

solutions are spectral parameter-dependent, and they reduce to a form proportional to

the permutation operator at a specific value of the spectral parameter. In this work, we

construct such solutions by applying the Baxterization process to non-invertible constant

Yang-Baxter operators. The solutions are algebraic, indicating that once we derive the

algebraic expression for these solutions, we can easily obtain any higher-dimensional

representations associated with them. They are formulated using supersymmetry

(SUSY) algebras. The resulting regular R-matrices give rise to local non-hermitian spin

chains expressed in terms of the SUSY generators. Notably, many of these solutions are

not only non-Hermitian but also non-diagonalizable, resulting in interesting spectra. As a

concrete example, we demonstrate the exact counting of zero modes in one such

solution.

 

Pre-requisites: The lectures are pedagogical and assume only basic QFT as a pre-requisite. Only the last lecture uses some string amplitudes, but the knowledge of the string

theory is not crucial to follow the lecture.

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3. Lakshita Bageja

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Title: Cosmology From Branes In AdS

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Abstract: Holography(AdS/CFT correspondence) has proved to be quite useful in under-

standing field theory at the boundary from the information in the bulk and vice-

versa, the goal is to see if such a prescription can help us understand our universe

and provide a mapping between cosmology and a CFT defined on a manifold with

boundary(BCFT). The bulk geometry is taken to be AdS with an additional End-Of-the-World (EOW) brane along with the asymptotic AdS boundary such that the boundary in the dual BCFT theory corresponds to EOW brane on gravity. The advantage of this construction is that although the bulk geometry is taken to be AdS, the space-time on the brane could be dS and thus could pave a way to study dS/CFT

by embedding in higher dimensional AdS/CFT.

4. Shivam Singh Kushwah

Title: Bulk Viscosity, speed of sound, and contact structure

at intermediate coupling

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Abstract: My talk explores the connection between the differential geometry of 7-folds

and transport coefficients in M-theory duals of thermal QCD-like theories at intermediate

coupling, incorporating O(R^4) corrections ( partly based on Phys. Rev. D 110 (2024) 12,

126010; arXiv:2403.10541).

 

It is divided into two parts:

1) Physics: An overview of the M-theoretic uplift including higher-derivative corrections,

deviation of the square of speed of sound (c_s^2) from its conformal value (1/3), bulk

viscosity( ζ) via Kubo’s formula, and a lattice-compatible ζ/η using the Eling-Oz relation.

The key result is a novel expression for ζ/η at intermediate coupling that interpolates

between weak and strong coupling limits.

2) Mathematics: (Almost) Contact-3 (Metric) Structure(s) arising from G_2 structure,

connection between Contact Structures, and ζ⁄η. The main takeaway is the connection

between the fractional (temperature-dependent) gauge-coupling-power-dependence of

ζ⁄η at large temperatures when ζ/η∝(1/3−c_s^2)^n (with n=1,2), and Contact

3-Structures induced from the G_2 structure of the 7-fold relevant to the M-theory uplift

of thermal QCD-like theories.

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5. Pronoy Chakroborty

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Title: Boundary Carrollian conformal field theories and open null strings

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Abstract: We consider Carrollian conformal field theories in two dimensions and

construct the boundary Carrollian conformal algebra (BCCA), opening up innumerable

possibilities for further studies, given the growing relevance of Carrollian symmetries.

We prove that the BCCA emerges by contracting a single copy of the Virasoro algebra.

As an application, we construct, for the first time, open null strings and show that, for

Dirichlet boundary conditions, we recover the BCCA as the algebra of constraints. We

finally reconstruct our string results by taking the null limit of tensile open strings.