标题： 大 p_T 光子产生 ep 对撞中的 D~*+− 介子 显示英文标题

标题： Large-p_T Photoproduction of D^*+- Mesons in ep Collisions

摘要： 我们计算了大横动量 \( D^\{*\pm\} \) 介子的光致产生截面到次领头阶，并采用不同的方法描述粲夸克向 \( D^\{*\pm\} \) 介子的碎裂。 我们将粲夸克按照无质量因子化方案处理，假设它为质子和光子内部的一个活性味。 我们给出了包括直接光子和分辨光子贡献在内的横动量和快度上的单粒子综合分布。 我们比较并评估了各种碎裂实现方式。 我们认为，在高横动量区域，通过将Peterson等人演化后的Altarelli-Parisi碎裂函数与无质量部分子的硬散射截面卷积，并将与末态粲夸克相关的 collinear 奇异因子化转换到有质量粲夸克方案中，可以得到特别真实的描述。 由此得出的预测与DESY HERA上H1和ZEUS合作组最近的实验数据非常一致。 显示英文摘要

摘要： The cross section for the inclusive photoproduction of large-p_T D^*+- mesons is calculated at next-to-leading order, adopting different approaches to describe the fragmentation of charm quarks into D^*+- mesons. We treat the charm quark according to the massless factorization scheme, where it is assumed to be one of the active flavours inside the proton and the photon. We present inclusive single-particle distributions in transverse momentum and rapidity, including the contributions due to both direct and resolved photons. We compare and assess the various implementations of fragmentation. We argue that, in the high-p_T regime, a particularly realistic description can be obtained by convoluting the Altarelli-Parisi-evolved fragmentation functions of Peterson et al. with the hard-scattering cross sections of massless partons where the factorization of the collinear singularities associated with final-state charm quarks is converted to the massive-charm scheme. The predictions thus obtained agree well with recent experimental data by the H1 and ZEUS Collaborations at DESY HERA.