#### Alladi Ramakrishnan Hall

#### Non-linear Fluctuation Dissipation Relation via holography

#### Chandan Kumar Jana

##### ICTS-TIFR, Bangalore

*In this talk I will discuss Langevin effective theory of a heavy quark moving through a strongly coupled CFT plasma. In AdS/CFT, this system can be identified with that of a string stretched between the boundary and the horizon of an asymptotically AdS black-hole solution. I will show that the Feynam-Vernon influence functional for a heavy quark can be obtained by evaluating the Nambu-Goto action on a doubled string configuration. The expression for the influence phase passes non-trivial consistency conditions arising from the underlying unitarity and thermality of the bath. The local effective theory obeys the recently proposed non-linear FDR relating the non-Gaussianity of thermal noise to the thermal jitter in the damping constant.*

This talk is bases on a paper (arxiv:1906.07762) done in collaboration with Bidisha Chakrabarti, Joydeep Chakraborti, Soumyadeep Chaudhuri, R. Loganayagam, Akhil Sivakumar.

Done