Beijing Institute of Mathematical Sciences and Applications

Kimyeong Lee , Antons Pribitoks

Shahin Sheikh-Jabbari

Thursday, April 10, 2025 2:55 PM - 4:30 PM

A3-4-301

Zoom 462 110 5973 (BIMSA)

Worldsheet theory of strings is a generic Weyl-invariant 2d gravity and is customarily quantized by requiring vanishing of Virasoro constraints on physical string states up to spurious states. This customary choice obscures WQEP, Equivalence Principle at the Quantized Worldsheet theory level. We discuss that QWEP for closed strings can be made explicit by requiring Sandwich Virasoro Constraints (SVC), requiring vanishing of Virasoro constraints sandwiched between any two physical states. We show solutions to SVC come in four classes which are specified with whether they keep or break worldsheet parity P and/or time reversal T. The class which makes P and T manifest is associated with the usual Minkoswki worldsheet observer discussed in the string theory textbooks. The three other classes constitute Hilbert spaces of generic non-inertial worldsheet observers in which P or T or both are not broken. We apply our formulation to an accelerated worldsheet with horizons, initiating the worldsheet formulation of a thermal string theory and strings probing horizon of black holes.

M.M. Sheikh-Jabbari (Shahin) is a professor at School of Theoretical Physics of IPM, Tehran. He completed his PhD at physics department of Sharif Uni. in Tehran in 1998. He spent 7 years of postdoc at IPM, ICTP (Trieste) and Stanford ITP before becoming an associate professor at IPM in 2005 and then a full professor there since 2006. Shahin has a wide research interest, from early and late universe cosmology to various areas in theoretical high energy and black hole physics. He is the author of a graduate textbook black hole physics, from collapse to evaporation (https://link.springer.com/book/10.1007/978-3-031-10343-8) and in recent years has been working on Einstein GR in spacetimes with boundaries, from covariant space viewpoint.