雷 扬  副教授学术报告

Title: Critical dimension in d-matrix theory and its application in SU(2) subsector of N=4 SYM

Speaker: Yang Lei（雷扬）

Affiliation: Soochow University（苏州大学）

Time: 16:00-17:00, Friday, April 24th, 2026 (UTC+8, Beijing Time)

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

Inviter: Hai Lin（林海）

Abstract

Supersymmetric sectors of N=4 super-Yang-Mills theory motivate the study of the partition function for the counting of gauge-invariant functions of d=2,3 matrices transforming under the adjoint action of U(N). The partition function \mathcal{Z}_d(x) in the large N limit has a known Hagedorn phase transition at x=d^{−1} which provides a simple model for the phase structure of the thermal partition function of SYM. We study the all-orders asymptotic expansion of \mathcal{Z}_d(x) based on a geometric picture of concentric circles of poles in the complex plane accumulating in a natural boundary at ∣x∣=1. We find that the order by order structure has a precise combinatorial interpretation organized in terms of increasing cycle size of permutations arising in the enumeration of the invariants. We refer to this organization as small-cycle dominance, and find that it extends to refined versions of the partition functions depending on several complex variables. An analysis of the coefficients in the asymptotic expansion of \mathcal{Z}_d(x) using the modular property of the Dedekind eta function reveals that the asymptotic expansion is actually convergent for d≥d_crit=13.

Speaker

Prof. Yang Lei is an associate professor in Soochow University. He received PhD degree in Durham University, UK, and after that did postdoc researches in Chinese Academy of Science, University of Witwatersrand, and in Niels Bohr Institute, Copenhagen. His recent research interests included using combinatorics method to study quantum gravity and supersymmetric field theory, and also non-relativistic holography, and black hole physics.

The seminar will be broadcasted online by Zoom.

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

The Zoom info is

URL: https://us02web.zoom.us/j/3854420225?pwd=SXY4eWJKOTBFZWJDaE16aXpTamY1QT09

Meeting ID: 385 442 0225

Passcode: yauc