# The 34th International Symposium on Lattice Field Theory (Lattice 2016)

Jul 24 – 30, 2016
Highfield Campus, University of Southampton
Europe/London timezone

## Gauge cooling for the singular-drift problem in the complex Langevin method - an application to finite density QCD

Jul 26, 2016, 5:50 PM
20m
Building 32 Room 1015 (Highfield Campus, University of Southampton)

### Building 32 Room 1015

#### Highfield Campus, University of Southampton

Talk Nonzero Temperature and Density

### Speaker

Dr Keitaro Nagata (KEK)

### Description

The complex Langevin method is a promising approach to complex action systems, which suffer from the sign problem. In particular, the use of gauge cooling enabled the studies of finite density QCD either in the deconfined phase or in the heavy dense limit. In the confined phase with light quarks, however, the method does not work as it is due to the singularities in the fermion drift term caused by small eigenvalues of the Dirac operator with the quark mass. In a previous paper, we proposed that this singular-drift problem can be overcome by the gauge cooling with different criteria for choosing the complexified gauge transformation, and showed that the method works in chiral Random Matrix Theory even at small quark mass. Here, we apply the same idea to QCD at finite density with light quarks and present some preliminary results.

### Co-authors

Prof. Hideo Matsufuru (KEK) Prof. Jun Nishimura (KEK Theory Center, SOKENDAI) Dr Shinji Shimasaki (Keio University)

 Slides