Speaker
Dr
David Alvarez-Castillo
(Joint Institute for Nuclear Research)
Description
In order to prove the existence of a critical end point (CEP) in the
QCD phase diagram it is sufficient to demonstrate that at zero
temperature $T=0$ a first order phase transition exists as a function
of the baryochemical potential $\mu$, since it is established
knowledge from ab-initio lattice QCD simulations that at $\mu=0$ the
transition on the temperature axis is a crossover.
We present the argument that the observation of a gap in the
mass-radius relationship for compact stars which proves the existence
of a so-called third family (aka "mass twins") will imply
that the $T=0$ equation of state of compact star matter exhibits a
strong first order transition with a latent heat that satisfies
$\Delta\epsilon/\epsilon_c >0.6$ [Alford et al., arxiv:1302.4732].
Since such a strong first order transition under compact
star conditions will remain first order when going to symmetric matter, the observation of a disconnected
branch (third family) of compact stars in the mass-radius diagram proves the existence of a CEP in QCD.
For the equation of state of the twins the quark matter description is based on a QCD-motivated chiral approach with higher-order quark interactions in the Dirac scalar and vector coupling channels. For hadronic matter we select a relativistic mean-filed equation of state with density-dependent couplings. Since the nucleons are treated in the quasi-particle framework, an excluded volume has been included for the nuclear equation of state at super-saturation density that takes into account the finite size of the nucleons.
Furthermore we show results of a Bayesian analysis (BA) using disjunct M-R constraints for
extracting probability measures for cold, dense matter equations of state. In particular this study reveals
that measuring radii of the neutron star twins has the potential to
support the existence of a first order phase transition for compact star matter.
Primary author
Dr
David Alvarez-Castillo
(Joint Institute for Nuclear Research)
Co-author
Prof.
David Blaschke
(University of Wroclaw)
