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arXiv 1204.2665hep-phhep-exnucl-th
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魅力生产的新机制

New mechanisms of charm production

Antoni Szczurek

摘要:

讨论了RHIC中$pp$散射中粲夸克、介子和非光子电子的产生。用$k_t$因子分解方法计算了粲夸克和底夸克/反夸克的快度和横动量分布.利用现象学碎裂函数研究了重夸克的强子化,并通过拟合半轻子衰变数据得到了半轻子衰变函数。在电子横动量大的情况下得到了较好的描述,在电子横动量小的情况下发现了一个缺失的强度,并讨论了不同机制的带电轻子之间的运动学关联。包括弹性和非弹性$pp$碰撞中由纯QED $γ^*γ^*$ -融合引发的反应以及$c \bar c$的衍射机制。实现了对PHENIX合作的双轻子不变质谱的良好描述。给出了双轻子对横动量和正负电子方位角的分布。探讨了$c \bar c$专一生成的新机理。给出了相应的结果,并讨论了其识别的可能性。我们还讨论了生产的两对$c \bar c$内的一个简单的形式主义的双部分子散射(DPS)。非常大的横截面,相当于单$c \bar c$生产,预测LHC的能量。总包含截面作为能量和微分分布的函数示出。我们讨论了如何识别的角度双散射的贡献。

英文摘要:

We discuss production of charm quarks, mesons as well as nonphotonic electrons in $pp$ scattering at RHIC. The distributions in rapidity and transverse momentum of charm and bottom quarks/antiquarks are calculated in the $k_t$-factorization approach. The hadronization of heavy quarks is done by means of fenomenological fragmentation functions and semileptonic decay functions are found by fitting semileptonic decay data. Good description of the inclusive data at large transverse momenta of electrons is obtained and a missing strength at small transverse momenta of electrons is found. In addition we discuss kinematical correlations between charged leptons from different mechanisms. Reactions initiated by purely QED $γ^*γ^*$-fusion in elastic and inelastic $pp$ collisions as well as diffractive mechanism of exclusive $c \bar c$ production are included. A good description of the dilepton invariant mass spectrum of the PHENIX collaboration is achieved. Distributions in the dilepton pair transverse momentum and in azimuthal angle between electron and positron are presented. A new mechanism of exclusive production of $c \bar c$ is discussed. Corresponding results are shown and the possibility of its identification is discussed. We discuss also production of two pairs of $c \bar c$ within a simple formalism of double-parton scattering (DPS). Very large cross sections, comparable to single-$c \bar c$ production, are predicted for LHC energies. Both total inclusive cross section as a function of energy and differential distributions are shown. We discuss a perspective how to identify the double scattering contribution.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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