(2024-03-19) Seminar: Sameer Murthy -- Gravitational index of the heterotic string


Sameer Murthy  教授学术报告

Title: Gravitational index of the heterotic string

Speaker: Sameer Murthy

Affiliation: King's College London, UK (英国伦敦国王学院)

Time: 20:00-21:00, Tuesday, 19th March, 2024 (UTC+8, Beijing Time)

Venue: Zoom Meeting (ID: 385 442 0225; Passcode: yauc)

Inviter: Tadashi Okazaki


The fundamental heterotic string has a tower of BPS states with an exponential growth in the charges. The fate of these BPS states at strong coupling is an old, much-debated topic: do they become a black hole or a string gas? I will discuss a new approach to this problem, i.e. the gravitational path integral corresponding to the supersymmetric index of these states. I will show that the saddle-point configuration of this path integral is a supersymmetric rotating non-extremal Euclidean black hole. This configuration is singular in the two-derivative theory but is resolved by higher-derivative terms from string theory. Remarkably, the one-loop, four-derivative F-term contribution to the prepotential leads to a precise match of the gravitational and microscopic index. Thus, the nature of the BPS string at strong coupling depends on the precise observable being probed. The thermal states transition to a winding condensate and a gas of strings without ever reaching a small black hole, while the index is captured by the rotating Euclidean black hole solution, is constant, and thus smoothly connected to the microscopic ensemble.


Professor Sameer Murthy graduated from the Indian Institute of Technology Bombay, and got his PhD at Princeton University under the supervision of Professor Nathan Seiberg. He subsequently held a research position at the Abdus Salam ICTP Trieste, a Marie Curie fellowship at the University of Paris, and a senior post-doctoral research position at Nikhef Amsterdam where he was awarded the NWO VIDI research grant by the Dutch organisation for scientific research. In 2015 he was awarded the prestigious ERC consolidator grant to lead a research team working on a research project involving quantum gravity, black holes, and modular forms. He moved to King's College London as a Lecturer in Theoretical Physics in September 2013, where he is currently Professor of Theoretical and Mathematical Physics.

His research interests lie broadly in quantum field theory and string theory, and their interactions with mathematics.

More information could be found on his personal page: https://www.kcl.ac.uk/people/sameer-murthy .


The seminar will be broadcasted online by Zoom.

Interested people are free to join, without registration in advance.

The Zoom info is


Meeting ID: 385 442 0225

Passcode: yauc