Gauge cooling for the singular-drift problem in the complex Langevin method - an application to finite density QCD
K. Nagata, H. Matsufuru, J. Nishimura, S. Shimasaki
We study full QCD at finite density and low temperature
with light quark mass using the complex Langevin method.
Since the singular drift problem turns out to be mild
on a $4^3 \times 8$ lattice we use,
the gauge cooling is performed only to control the unitarity norm
in this exploratory study.
We report on our preliminary data obtained
from the complex Langevin simulation up to certain Langevin time.
While the data are still noisy due to lack of statistics,
the onset of the baryon number density seems to occur
at larger $\mu$ than half the pion mass, which is
the value for the phase quenched QCD.
The validity of our simulation is tested by
the recently proposed criterion based on
the probability distribution of the drift term.