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star focus: Charmed hadron production at low transverse momentum at RHIC
Highlights from the STAR paper Charmed hadron production at low transverse momentum in Au+Au collisions at RHIC submitted recently to Physical Review Letters.
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Posted: Jun 27, 2008
Charm quarks are likely to be produced only in
the early stages and can be a unique tool to
probe the partonic matter created in relativistic
heavy-ion collisions at RHIC energies. Studies of
the number of binary collision (calculated using
Glauber model) scaling of the total charm cross
section from d+Au to Au+Au collisions can be used
to test if charm production is exclusively at the initial
impact of colliding heavy ions.
The total charm production cross section is also
an important input in models of J/Psi production
via charm quark coalescence in a Quark Gluon
Plasma.
STAR experiment has reported measurements of charmed
hadron production at mid-rapidity from analysis
of D0 --> K pi, muon(electron) from semileptonic
charm decays in minimum bias and central Au+Au
collisions and d+Au collisions at center of mass
energy of 200 GeV at RHIC. The mid-rapidity charm
cross section per nucleon-nucleon collisions are
extracted from a combination of the above three
measurements covering the transverse momentum
range which contributes to ~ 90% of the integrated
cross section. The charm production cross section
at mid-rapidity is observed to scale with number
of binary interactions from d+Au to central Au+Au
collisions. This is shown in the figure. This
confirms the expected scaling of hard production
processes with binary interactions among incoming
nucleons so that charm quarks can be used as a
calibrated probe of the early stage dynamics of
the system. The FONLL calculation is the band in
figure. The ratio of the minimum bias data over
theory calculation is 4.3 +/- 0.5(stat.) +/- 1.2(syst.)
+9.4(theory) -3.3(theory). The upper
theory value reproduces our result.
Further details can be found in the following STAR paper -
Charmed hadron production at low transverse momentum in Au+Au collisions at RHIC
- arXiv:0805.0364.
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