High Energy / Nuclear Theory / RIKEN Seminars

[Riken Seminar] Sign problem in Monte Carlo simulations and the tempered Lefschetz thimble method

by Masafumi Fukuma (Kyoto U.)


The tempered Lefschetz thimble method (TLTM) [arXiv:1703.00861] is a parallel-tempering algorithm towards solving the numerical sign problem. It uses the deformation parameter of integration surface (the flow time of the antiholomorphic gradient flow) as a tempering parameter, and is expected to tame both the sign and ergodicity problems simultaneously that exist intrinsically in thimble methods. In this talk, I explain the basics of TLTM, and apply the method to various problems, including the quantum Monte Carlo simulation of the Hubbard model away from half filling and the chiral random matrix models with finite temperature and finite chemical potential. This talk is based on collaboration with Nobuyuki Matsumoto and Naoya Umeda [arXiv: 1703.00861, 1906.04243, 1912.13303].

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