HERA硬光生过程中的光子产生

Production of Photon in Hard Photoproduction Processes at HERA

在领头级近似下计算了ＨＥＲＡ硬光生过程中直接光子和分解光子与质子作用的单、双光子产生截面．结果表明：当ｘＴ≤０．１５时，对单光子产生的主要贡献来自于分解光子过程；当ｘＴ≥０．１５时，主要贡献来自于直接光子过程．双光子的主要产生源则是分解光子的两个子过程：ｑｑ→γγ和ｇｇ→γγ，且双光子的产生截面与同等条件下，ｈ１ｈ２→γγＸ的截面在同一量级．研究双光子产生有助于探明分解光子的结构．

The cross sections of single and double photon production are calculated in both direct and resolved processes in hard photoproduction at HERA in the leading order(LO)of QCD.The results indicate that single photon production is dominated by direct processes while xT≤0.15.The main sources of double photons are the subprocesses of resolved processes gg→γγ and qq→γγ.Under the same condition,the double photon cross section is of the same order as those in h1h2→γγX.The study of double photon production may be helpful for exploring the structure of resolved photon.