Seminars

The IMSc Foundation Series 2025 in Theoretical Physics is a week-long academic initiative organized by the Outreach Team at the Institute of Mathematical Sciences (IMSc), Chennai. The program is scheduled from 23rd to 27th June 2025 and will offer three intensive short-term courses at the MSc Physics level tailored for early-stage physics students from Chennai and nearby regions. The courses will be delivered by renowned academicians from IMSc Chennai, aiming to bridge the gap between coursework and research. Through these engaging lectures, participants will gain insights into the Master's level topics from a research perspective. Our goal is to inspire the next generation of physicists and encourage them to pursue careers in academic research. https://indico.imsc.res.in/e/fstp2025

Tutorials

Tutorials

N=2, 4 and 8 supersymmetric string theories in four dimensional flat space-time have moduli space of vacua. We argue that starting from a theory where the moduli approach a particular moduli space point A at infinity, we can construct a classical solution that contains an arbitrarily large space-time region where the moduli take values corresponding to any other moduli space point B of our choice to any desired accuracy. Therefore the observables of a theory with a given set of asymptotic values of the moduli will have complete information on the observables for any other asymptotic values of the moduli. Also it is physically impossible for any experiment, performed over a finite time, to determine the asymptotic values of the moduli. We point out the difference between asymptotically flat space-time and asymptotically AdS space-time in this regard and discuss the possible implication of these results for holographic duals of string theories in flat space-time. For N=2 supersymmetric theories, A and B could correspond to compactifications on topologically distinct Calabi-Yau manifolds related by flop or conifold transitions.

The IMSc Foundation Series 2025 in Theoretical Physics is a week-long academic initiative organized by the Outreach Team at the Institute of Mathematical Sciences (IMSc), Chennai. The program is scheduled from 23rd to 27th June 2025 and will offer three intensive short-term courses at the MSc Physics level tailored for early-stage physics students from Chennai and nearby regions. The courses will be delivered by renowned academicians from IMSc Chennai, aiming to bridge the gap between coursework and research. Through these engaging lectures, participants will gain insights into the Master's level topics from a research perspective. Our goal is to inspire the next generation of physicists and encourage them to pursue careers in academic research. https://indico.imsc.res.in/e/fstp2025

For any Boolean function f:{0,1}^n -> {0,1} with a complexity measure k << n, is it possible to restrict the function f to \Theta(k) variables while keeping the complexity preserved at \Theta(k)? This question, in the context of query complexity, was recently studied by G{\"{o}}{\"{o}}s, Newman, Riazanov and Sokolov (STOC 2024). They showed, among other results, that query complexity can not be condensed losslessly. They asked if complexity measures like block sensitivity or unambiguous certificate complexity can be condensed losslessly? In this work, we show that a host of decision tree measures like block sensitivity, certificate complexity, unambiguous certificate complexity, etc., cannot be condensed losslessly. That is, there exists a Boolean function f such that any restriction of f to O(M(f)) variables has M(.)-complexity at most M(f)^{2/3}, where M \in {(fractional) block sensitivity, (unambiguous) certificate complexity, query complexity}. This also improves upon a result of G{\"{o}}{\"{o}}s, Newman, Riazanov and Sokolov (STOC 2024). We also complement the negative results on lossless condensation with positive results about lossy condensation. In particular, we show that for every Boolean function f there exists a restriction of f to M(f) variables such that its M(.)-complexity is at least \sqrt{M(f)}. This is based on a joint work with Chandrima Kayal (IRIF, Paris).

Perturbative amplitudes of N=4 SYM can be written down as integrals over an auxiliary space of k-planes in n-dimensions, Gr(k,n). These developments led to the Amplituhedron description for the massless (planar) N=4 SYM amplitudes. However, N=4 SYM contains massive W-bosons (and their superpartners) at non-trivial points in its moduli space, called the Coulomb branch. Amplitudes for these massive supersymmetric states have been studied well using the on-shell methods. Here, we discuss the use of symplectic Grassmannian spGr(n,2n) to describe the Coulomb branch amplitudes. Focusing on the simple cases of three and four-point tree-level amplitudes, we demonstrate that the kinematic spaces are equivalent to spGr(n,2n), and express the amplitudes as integrals over the space of spGr(n,2n). Building on the four-dimensional analysis, we also express the six-dimensional N = (1,1) SYM amplitude in terms of four-dimensional variables in a form that makes its symplectic Grassmannian structure manifest. We discuss how the six-dimensional variables reduce to four-dimensional ones.

The direct detection of gravitational waves about a decade ago heralded a new era of multi-messenger astronomy. The world also subsequently witnessed the first simultaneous observation of gravitational and electromagnetic radiations from a single astronomical event. The ongoing observations from the second-generation ground-based detectors, advanced LIGO-Virgo-KAGRA, have delivered several key scientific discoveries. In this talk, I will provide a bird's eye view of the detection techniques behind some of these key discoveries. In the last part, I will highlight the implications of multi-messenger observations from ultra-dense compact objects, e.g., neutron stars on the unexplored territory of fundamental physics.