Talks

I will give an introduction to Gravitational Waves from the perspective of Field Theory. I will then go on to discuss soft-graviton theorems and memory effect. I will also cover the theory of Stochastic Gravitational Waves and derive the Dellings-Down relation.
 

In these two lectures, I shall discuss the generation of primary gravitational waves (GWs) during inflation and secondary GWs sourced by enhanced scalar perturbations during the epoch of radiation domination. In the first lecture, after a quick introduction to inflation and reheating, I shall describe the origin of GWs from the quantum vacuum during inflation and also discuss their evolution post inflation. I shall begin the second lecture by describing the generation of scalar spectra with enhanced power on small scales due to a brief phase of ultra slow roll during the later stages of inflation. Thereafter, I shall outline the manner in which the enhanced scalar power on small scales can generate secondary GWs of strengths comparable to the sensitivities of the ongoing and forthcoming GW observatories. I shall conclude by highlighting that the scalar-induced, secondary GWs generated during reheating can possibly explain the recent observations by the pulsar timing arrays that suggest a stochastic background of GWs.
 

I will give an introduction to Gravitational Waves from the perspective of Field Theory. I will then go on to discuss soft-graviton theorems and memory effect. I will also cover the theory of Stochastic Gravitational Waves and derive the Dellings-Down relation.
 

We construct a d-dimensional Eddy Damped Quasi-Normal Markovian (EDQNM) Closure Model to study dynamo action in arbitrary dimensions. In particular, we find lower and upper critical dimensions for sustained dynamo action in this incompressible problem. Our model is adaptable for future studies incorporating helicity, compressible effects and a wide range of magnetic Reynolds and Prandtl numbers.

A fundamental aspect crucial for the survival of various animal species is their ability to successfully return home, whether it involves migration, foraging for food, or locating a breeding site. This innate behavior, known as Homing, is surprisingly ubiquitous, allowing
animals to navigate back from seemingly unfamiliar locations over considerable distances. In this talk, I will try to shed some light on this phenomena from the perspective of stochastic resetting. This connection helps us to uncover universal characteristics of
Homing paths using a self-propelled Robotic Forager. 

I will present recent findings from the study of the Random Field Ising Model across various dimensions. The aim is to explore the existence of Universality and Dimensional Reduction within this model. Using results from large-scale numerical simulations, I will argue that
Dimensional Reduction holds true at D=5, and we observe the consequences of supersymmetry. 

Motivated by recent debates around the many-body localization (MBL) problem, and in particular its stability against systemwide resonances, we investigate long-distance spin-spin correlations across the phase diagram of the random-field XXZ model, with a particular focus on the strong disorder regime. Building on state-of-the-art shift-invert diagonalization techniques, we study the high-energy behavior of transverse and longitudinal correlation functions, computed at the largest possible distance, for a broad range of disorder and interaction strengths. Our results show that while transverse correlations display a fairly stable exponential decay over the entire XXZ phase diagram, longitudinal correlations exhibit markedly different behavior, revealing distinct physical regimes. More precisely, we identify an intermediate disorder region where standard observables show well-converged MBL behavior [J. Colbois et al., Phys. Rev. Lett. 133, 116502 (2024)] while the distributions of longitudinal correlations reveal unexpected fat-tails towards large values. These rare events strongly influence the average decay of longitudinal correlations, which we find to be algebraic in a broad region inside the supposed MBL phase, whereas the typical decay remains mostly exponential. At stronger disorder and weaker interactions, this intermediate regime is replaced by a more conventional exponential decay with short correlation lengths for both typical and average correlators, as expected for standard localization. Our findings shed light on the systemwide instabilities and raise important questions about the impact of such rare but large long-range correlations on the stability of the MBL phase. Finally, we discuss the possible fate of the intermediate region in the context of recent perspectives in the field.