The lecture notes of ST4 main talks can be accessed from here.

D-brane in string theory by Subhroneel Chakrabarti (IMSc)

Fluid-gravity correspondence by Debangshu Mukherjee (IISER Bhopal)

Matrix Models by Arghya Chattopadhyay (IISER Bhopal)

QFT in curved spacetime by Pratik Roy (CMI)

Stability of spacetimes in general relativity by Prashant Kocherlakota (TIFR)