4 papers
Perturbation Theory for the Logarithm of a Positive Operator
Nima Lashkari, Hong Liu, Srivatsan Rajagopal
In various contexts in mathematical physics one needs to compute the logarithm of a positive unbounded operator. Examples include the von Neumann entropy of a density matrix and th…
Modular Flow of Excited States
Nima Lashkari, Hong Liu, Srivatsan Rajagopal
We develop new techniques for studying the modular and the relative modular flows of general excited states. We show that the class of states obtained by acting on the vacuum (or a…
Global Anomalies, Discrete Symmetries, and Hydrodynamic Effective Actions
Paolo Glorioso, Hong Liu, Srivatsan Rajagopal
We derive effective actions for parity-violating fluids in both and dimensions, including those with anomalies. As a corollary we confirm the most general constitut…
Ostrogradsky instability and Born-Infeld modified cosmology in Palatini formalism
Srivatsan Rajagopal, Ajit Kumar
The Ostrogradsky instability of higher derivative Lagrangians is derived from first principles using Control theory and Lyapunov Stability Analysis. This result is then used to arg…