2 research outputs found
The strange-quark chemical potential as an experimentally accessible "order parameter" of the deconfinement phase transition for finite baryon-density
We consider the change of the strange-quark chemical potential in the phase
diagram of nuclear matter, employing the Wilson loop and scalar quark
condensate order parameters, mass-scaled partition functions and enforcing
flavor conservation. Assuming the region beyond the hadronic phase to be
described by massive, correlated and interacting quarks, in the spirit of
lattice and effective QCD calculations, we find the strange-quark chemical
potential to change sign: from positive in the hadronic phase - to zero upon
deconfinement - to negative in the partonic domain. We propose this change in
the sign of the strange-quark chemical potential to be an experimentally
accessible order parameter and a unique, concise and well-defined indication of
the quark-deconfinement phase transition in nuclear matter.Comment: 22 pages, 14 figures within text, 2 figures(6,B3) as separate files.
To be published in J.Phys.G: Nucl.&Part.Phys. G28 (2002
Charged particle production in proton-, deuteron-, oxygen- and sulphur-nucleus collisions at 200 GeV per nucleon
The transverse momentum and rapidity distributions of net protons and
negatively charged hadrons have been measured for minimum bias
proton-nucleus and deuteron-gold interactions, as well as central
oxygen-gold and sulphur-nucleus collisions at 200 GeV per nucleon. The
rapidity density of net protons at midrapidity in central
nucleus-nucleus collisions increases both with target mass for sulphur
projectiles and with the projectile mass for a gold target. The shape of
the rapidity distributions of net protons forward of midrapidity for
d+Au and central S+Au collisions is similar. The average rapidity loss
is larger than 2 units of rapidity for reactions with the gold target.
The transverse momentum spectra of net protons for all reactions can be
described by a thermal distribution with ‘temperatures’ between 145+/-11
MeV (p+S interactions) and 244+/-43 MeV (central S+Au collisions). The
multiplicity of negatively charged hadrons increases with the mass of
the colliding system. The shape of the transverse momentum spectra of
negatively charged hadrons changes from minimum bias p+p and p+S
interactions to p+Au and central nucleus-nucleus collisions. The mean
transverse momentum is almost constant in the vicinity of midrapidity
and shows little variation with the target and projectile masses. The
average number of produced negatively charged hadrons per participant
baryon increases slightly from p+p, p+A to central S+S, Ag collisions