Study of QCD at low temperature and finite density with a new technique for lattice fermions

2017 Fiscal Year Final Research Report

• Project/Area Number: 26800154
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Kochi University (2016-2017); High Energy Accelerator Research Organization (2014-2015)
• Principal Investigator: Nagata Keitaro 高知大学, 教育研究部医療学系連携医学部門, 助教 (00586901)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 符号問題 / 低温有限密度QCD

Outline of Final Research Achievements

We have studied finite density lattice QCD, which is a longstanding issue in particle and nuclear physics, by using new techniques for lattice fermions. We first employed an approach based on a reduction formula of the lattice Wilson fermions, but it turned out to be difficult to solve an eigenvalue problem for the reduced matrix at low temperatures and finite densities. Then, we started using the Complex Langevin method(CLM), which was also a new development around 2015. We conducted theoretical studies of CLM: proof of the gauge cooling, reduction of criteria of correctness of CL simulations, and also developed a new technique with the generalization of the gauge cooling method. Based on those studies, we conducted CL simulations of QCD at low temperatures and finite densities, and achieved to simulate a targeted domain, chemical potential beyond half the pion mass, with satisfying criteria of correctness. Thus, we accomplished the purpose of this project.

Free Research Field

QCD