Nuclear-modification factor for open-heavy-flavor production at forward rapidity in Cu+Cu collisions atsNN=200GeV

Abstract

Background: Heavy-flavor production in p + p collisions is a good test of perturbative-quantumchromodynamics (pQCD) calculations. Modification of heavy-flavor production in heavy-ion collisions relative to binary-collision scaling from p + p results, quantified with the nuclear-modification factor (R AA ), provides information on both cold-and hot-nuclear-matter effects. Midrapidity heavy-flavor R AA measurements at the 024909-2 NUCLEAR-MODIFICATION FACTOR FOR OPEN-HEAVY-. . . PHYSICAL REVIEW C 86, 024909 (2012) Relativistic Heavy Ion Collider have challenged parton-energy-loss models and resulted in upper limits on the viscosity-entropy ratio that are near the quantum lower bound. Such measurements have not been made in the forward-rapidity region. Purpose: Determine transverse-momentum (p T ) spectra and the corresponding R AA for muons from heavy-flavor meson decay in p + p and Cu + Cu collisions at √ s NN = 200 GeV and y = 1.65. Method: Results are obtained using the semileptonic decay of heavy-flavor mesons into negative muons. The PHENIX muon-arm spectrometers measure the p T spectra of inclusive muon candidates. Backgrounds, primarily due to light hadrons, are determined with a Monte Carlo calculation using a set of input hadron distributions tuned to match measured-hadron distributions in the same detector and statistically subtracted. Results: The charm-production cross section in p + p collisions at √ s = 200 GeV, integrated over p T and in the rapidity range 1.4 < y < 1.9, is found to be dσ cc /dy = 0.139 ± 0.029 (stat) +0.051 −0.058 (syst) mb. This result is consistent with a perturbative fixed-order-plus-next-to-leading-log calculation within scale uncertainties and is also consistent with expectations based on the corresponding midrapidity charm-production cross section measured by PHENIX. The R AA for heavy-flavor muons in Cu + Cu collisions is measured in three centrality bins for 1 < p T < 4 GeV/c. Suppression relative to binary-collision scaling (R AA < 1) increases with centrality. Conclusions: Within experimental and theoretical uncertainties, the measured charm yield in p + p collisions is consistent with state-of-the-art pQCD calculations. Suppression in central Cu + Cu collisions suggests the presence of significant cold-nuclear-matter effects and final-state energy loss.

Transverse momentum dependence of D-meson production in Pb-Pb collisions at s N N = 2.76 $$ \sqrt{{\mathrm{s}}_{\mathrm{NN}}}=2.76 $$ TeV

“…The PHENIX and STAR Collaborations reported measurements using heavy-flavour decay electrons and muons in Au-Au and Cu-Cu collisions at centre-of-mass energy per nucleon pair, √ s NN = 200 GeV [27][28][29][30]. A suppression…”

Elliptic flow of electrons from heavy-flavour hadron decays at mid-rapidity in Pb-Pb collisions at s N N = 2.76 $$ \sqrt{{\mathrm{s}}_{\mathrm{NN}}}=2.76 $$ TeV

“…A strong suppression of open charm hadrons and heavy-flavour decay leptons is observed for p T > 3 GeV/c in central collisions, both at RHIC ( √ s NN = 200 GeV) [12][13][14][15][16] -1 -…”

“…Heavy-quark energy loss in strongly-interacting matter can be studied via the modification of the transverse momentum (p T ) spectra of heavy-flavour hadrons and their decay products in heavy-ion collisions with respect to the proton-proton yield scaled by the number of binary nucleon-nucleon collisions, quantified by the nuclear modification factor (R AA ). A strong suppression of open charm hadrons and heavy-flavour decay leptons is observed for p T > 3 GeV/c in central collisions, both at RHIC ( √ s NN = 200 GeV) [12][13][14][15][16] -1 - …”

Measurement of electrons from heavy-flavour hadron decays in p-Pb collisions at $\\sqrt{s_{NN}} = 5.02$ TeV using TPC and EMCal detectors with ALICE at LHC

“…In the STAR, the azimuthal angle between electrons from heavy-flavour decays and hadrons were measured and PYTHIA simulations were used to extract the relative contributions from charm and beauty decays. heavy-flavour hadron decay to electrons at mid rapidity and to muons at forward rapidity [69]. The FONLL pQCD prediction is shown in the figure and the experimental data are closer to the upper limit of the calculations.…”