1,268 research outputs found
Thermal versus Direct Production in Ultrarelativistic Heavy-Ion Collisions
The production of mesons in central collisions of heavy nuclei is
investigated as a function of collision energy. Two contributions are
considered simultaneously: early (hard) production coupled with subsequent
suppression in a Quark-Gluon Plasma, as well as thermal recombination of
primordially produced and quarks at the hadronization transition.
Whereas the former still constitutes the major fraction of the observed
abundance at SpS energies, the latter dominates the yield at RHIC. The
resulting excitation function for the number of 's over open charm
pairs exhibits nontrivial structure around AGeV, evolving
into a significant rise towards maximal RHIC energy. We study this feature
within different (thermal) scenarios for suppression, including
parton-induced quasifree destruction as a novel mechanism.Comment: 6 pages ReVTeX, including 4 eps-figures; Revised version accepted for
publication in Phys. Lett.
Theoretical Overview on (Hidden) Charm in High-Energy Heavy-Ion Collisions
Recent developments in the theoretical evaluation of charmonium production in
ultrarelativistic heavy-ion collisions (URHIC's) are discussed. In particular,
the consequences of equilibrium properties of open and hidden charm states --
accessible, {\it e.g.}, in QCD lattice gauge calculations -- are assessed.
These include abundances as well as formation and dissociation rates of
charmonia in both hadronic and quark-gluon matter.Comment: Invited Talk at 7. Int. Conf. on Strangeness in Quark Matter
(Atlantic Beach, NC, USA, 12.-17.03.03); 10 pages LaTeX including 11 Figures
and iop style files; v3: Section 3.4 (Continuity) revise
The Leadership of Ulysses S. Grant: A General Who Will Fight
A Look at the General Who Won the War
Without a doubt he was the man who single handily won the war for the Union on the battlefield through his “uncommon drive and tenacity to not back down from a fight. General Ulysses S. Grant has been the study of hundreds of volumes in the past, b...
A Broken Regiment: The 16th Connecticut\u27s Civil War
War Without Glory: The Trials of the 16th Connecticut
Late in the afternoon of September 17, 1862 a regiment of green Connecticut soldiers marched headlong into Otto’s Cornfield at Antietam. Forming part of the extreme left flank of the Army of the Potomac, the Nutmeggers, only days remove...
Quark Coalescence for Charmed Mesons in Ultrarelativistic Heavy-Ion Collisions
We investigate effects of charm-quark interactions in a Quark-Gluon Plasma on
the production of and mesons in high-energy heavy-ion collisions.
Employing a previously constructed coalescence model that successfully
reproduces the transverse momentum () spectra and elliptic flow
() of light hadrons at RHIC from underlying light-quark distributions
at the phase transition temperature , -meson and spectra
are evaluated. For the charm-quark distributions, we consider two limiting
scenarios: (i) {\em no} rescattering, corresponding to perturbative QCD spectra
and (ii) {\em complete} thermalization including transverse expansion. With the
-meson spectra acquiring a minimal inherited from their light-quark
content, the corresponding semileptonic decay spectra of single electrons are
found to practically preserve the of the parent particles, exhibiting
marked differences between the pQCD and thermal scenarios for GeV.
Likewise, the -spectra and yields of 's differ appreciably in the
two scenarios.Comment: 6 pages, 4 figures, version published in PLB with updated figure
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