标题： charm产生机制的新观点 显示英文标题

标题： New mechanisms of charm production

摘要： 我们讨论了在RHIC的$pp$散射过程中粲夸克、介子以及非光子电子的产生。采用$k_t$因子化方法计算了重夸克及其反粒子在快速度和横向动量上的分布。重夸克的强子化通过具体的碎裂函数实现，而半轻子衰变函数则通过对半轻子衰变数据拟合得到。我们获得了对于高横向动量电子包容数据的良好描述，并发现了低横向动量电子的缺失强度。此外，我们还讨论了不同机制产生的带电轻子之间的动力学关联。 包含纯QED$\gamma^*\gamma^*$融合的弹性及非弹性$pp$碰撞反应，以及特异性$c \bar c$产生的衍射机制都被纳入讨论范围。PHENIX合作组的双轻子不变质量谱得到了很好的描述。展示了双轻子对横向动量和电子与正电子之间方位角角度的分布。讨论了一种新的特异性$c \bar c$的特异性产生机制，并给出了相应结果且探讨了其可识别性。 我们还利用双重部分子散射（DPS）的简单形式讨论了两对$c \bar c$的产生。 预计对于LHC能量，横截面非常大，与单个$c \bar c$生产相当。展示了总包络横截面作为能量的函数以及微分分布。我们讨论了如何识别双散射贡献的一个前景。 显示英文摘要

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 $\gamma^*\gamma^*$-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.