3,956 research outputs found
Strange Particle Production Mechanisms in Proton-Proton Collisions at RHIC
We present data on strange particle production in elementary proton-proton
collisions at RHIC energies. Comparison to leading order and next-to-leading
order (NLO) calculations shows that the fragmentation process is flavor
dependent and that higherorder corrections are needed to describe all spectra,
in particular at these collision energies, which are modest compared to the
Tevatron energies. A model (EPOS) which takes into account multiple scattering
between projectile constituents seems to describe the data best.Comment: 4 pages, 4 figures, QM2005 poster proceedings, updated according to
referee repor
Formation and decay of hadronic resonances in the QGP
Hadronic resonances can play a pivotal role in providing experimental
evidence for partial chiral symmetry restoration in the deconfined quark-gluon
phase produced at RHIC. Their lifetimes, which are comparable to the lifetime
of the partonic plasma phase, make them an invaluable tool to study medium
modifications to the resonant state due to the chiral transition. In this paper
we show that the heavier, but still abundant, light and strange quark
resonances K*, phi, Delta and Lambda* have large probability to be produced
well within the plasma phase due to their short formation times. We demonstrate
that, under particular kinematic conditions, these resonances can be formed and
will decay inside the partonic state, but still carry sufficient momentum to
not interact strongly with the hadronic medium after the QCD phase transition.
Thus, K*, phi, Delta and Lambda* should exhibit the characteristic property
modifications which can be attributed to chiral symmetry restoration, such as
mass shifts, width broadening or branching ratio modifications.Comment: 8 pages, 7 figure
The QCD phase diagram from analytic continuation
We present the crossover line between the quark gluon plasma and the hadron
gas phases for small real chemical potentials. First we determine the effect of
imaginary values of the chemical potential on the transition temperature using
lattice QCD simulations. Then we use various formulas to perform an analytic
continuation to real values of the baryo-chemical potential. Our data set
maintains strangeness neutrality to match the conditions of heavy ion physics.
The systematic errors are under control up to MeV. For the
curvature of the transition line we find that there is an approximate agreement
between values from three different observables: the chiral susceptibility,
chiral condensate and strange quark susceptibility. The continuum extrapolation
is based on 10, 12 and 16 lattices. By combining the analysis for these
three observables we find, for the curvature, the value .Comment: 14 pages, 4 figures, revised versio
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