Speaker
Atsushi Nakamura
(Hiroshima Univ)
Description
We report a new way to extract the QCD phase transition from the net
baryon multiplicity. The method provides us not only a freeze-out temperature-
density point, but also the neighbour of the point. In other words, Beam Energy Scan
explores not only points, but also regions with the finite spreads in $\mu$-$T$
plane, where $\mu$ is the chemical potential, and $T$ is the temperature.
First, we develop a formula in which canonical partition functions are constructed
from multiplicities data
for a conserved quantity. From the canonical partition functions, we construct
the grand partition functions as a function of the fugacity, $\exp(\mu/T)$, from which
we can investigate the system when it goes near to the QCD phase transition line.
We discuss the applicability limit that comes from the maximum number of the
multiplicity measured in experiments.
We extend the fugacity to the complex number region, and show the Lee-Yang zero
structure, which allows us to see the statistical nature of the system.
We calculate the Lee-Yang zero structure by the lattice QCD simulations, and
find a very striking feature, i.e., the Roberge-Weiss transition at the deconfinement
regions.
We investigate the net-proton multiplicity data at RHIC, although it is not a conserved
quantity. Using the proposed method, we calculate the susceptibility and kurtosis
as a function of $\mu/T$ for each $T$, and the Lee-Yang zeros, and compare them
with those of the lattice QCD results.
Primary author
Atsushi Nakamura
(Hiroshima Univ)
Co-author
Dr
Keitaro Nagata
(KEK)
