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arXiv 0901.1382nucl-thhep-ph
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相对论性重离子碰撞中的重子/介子比

Heavy baryon/meson ratios in relativistic heavy ion collisions

Yongseok Oh, Che Ming Ko, Su Houng Lee, Shigehiro Yasui

备注：
11 pages, 2 figures
发表信息：
Phys.Rev.C79:044905,2009
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摘要：

在夸克并合模型下研究了相对论性重离子碰撞中重子/介子比$Λ_c/D^0$和$Λ_b/\bar{B}^0$。对于重子，我们包括重夸克与自由轻夸克以及与有界轻双夸克的合并产生，这些双夸克可能存在于这些碰撞产生的强耦合夸克-胶子等离子体中。考虑到重强子共振衰变的贡献和合并后留在系统中的重夸克碎裂的贡献，计算了中快度的$Λ_c/D^0$和$Λ_b/\bar{B}^0$比在$\sqrt{s_{NN}}=200$ GeV的中心Au+Au碰撞产生的能量（$|y|\le 0.5$）分别比热模型给出的能量大5倍和10倍，大于PYTHIA模型中$pp$碰撞的相应比率。如果在夸克-胶子等离子体中没有双夸克，这些比值将减小约1.6倍。重子/介子比的横动量依赖性对重夸克质量敏感，其中$Λ_b/\bar{B}^0$比比$Λ_c/D^0$更平坦.后者在横向动量$p_T^{} \simeq 0.8$ GeV处达到峰值，但在没有双夸克的情况下，峰值移动到$p_T^{} \simeq 2$ GeV。

英文摘要：

Heavy baryon/meson ratios $Λ_c/D^0$ and $Λ_b/\bar{B}^0$ in relativistic heavy ion collisions are studied in the quark coalescence model. For heavy baryons, we include production from coalescence of heavy quarks with free light quarks as well as with bounded light diquarks that might exist in the strongly coupled quark-gluon plasma produced in these collisions. Including the contribution from decays of heavy hadron resonances and also that due to fragmentation of heavy quarks that are left in the system after coalescence, the resulting $Λ_c/D^0$ and $Λ_b/\bar{B}^0$ ratios in midrapidity ($|y|\le 0.5$) from central Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV are about a factor of five and ten, respectively, larger than those given by the thermal model, and about a factor of ten and twelve, respectively, larger than corresponding ratios in the PYTHIA model for $pp$ collisions. These ratios are reduced by a factor of about 1.6 if there are no diquarks in the quark-gluon plasma. The transverse momentum dependence of the heavy baryon/meson ratios is found to be sensitive to the heavy quark mass, with the $Λ_b/\bar{B}^0$ ratio being much flatter than the $Λ_c/D^0$ ratio. The latter peaks at the transverse momentum $p_T^{} \simeq 0.8$ GeV but the peak shifts to $p_T^{} \simeq 2$ GeV in the absence of diquarks.

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