Production of e(+)e(-) pairs accompanied by nuclear dissociation in ultraperipheral heavy-ion collisions
Production of e(+)e(-) pairs accompanied by nuclear dissociation in ultraperipheral heavy-ion collisions
复制标题
DOI：
10.1103/physrevc.70.031902
复制
发表时间：
2004-04
影响因子：
3.1
通讯作者：
J. Adams;E. al.
中科院分区：
文献类型：
--
作者：
J. Adams;E. al.
我们提出的第一个数据e{sup +}e{sup -}对生产伴随着核分裂的超外围金-金碰撞的质量中心能量为200 GeV每核子对。核分裂的要求选择事件在小的影响参数，高阶修正对生产截面应加强。我们比较两个计算对运动学分布：一个基于等效光子近似，和其他使用最低阶量子电动力学（QED），后者包括光子虚拟。截面、对质量、快度和角分布与两种计算结果符合得很好。对横向动量，p{sub T}，频谱同意QED计算，但不与等效光子的方法。我们对截面的高阶贡献设置了限制。e{sup +}和e{sup -} p{sub T}光谱是相似的，没有证据表明由于高阶图的干扰效应。
We present the first data on e{sup +}e{sup -} pair production accompanied by nuclear breakup in ultra-peripheral gold-gold collisions at a center of mass energy of 200 GeV per nucleon pair. The nuclear breakup requirement selects events at small impact parameters, where higher-order corrections to the pair production cross section should be enhanced. We compare the pair kinematic distributions with two calculations: one based on the equivalent photon approximation, and the other using lowest-order quantum electrodynamics (QED); the latter includes the photon virtuality. The cross section, pair mass, rapidity and angular distributions are in good agreement with both calculations. The pair transverse momentum, p{sub T}, spectrum agrees with the QED calculation, but not with the equivalent photon approach. We set limits on higher-order contributions to the cross section. The e{sup +} and e{sup -} p{sub T} spectra are similar, with no evidence for interference effects due to higher-order diagrams.