Baltz Anthony J, Klein Spencer R, Nystrand Joakim
Brookhaven National Laboratory, Upton, New York 11973, USA.
Phys Rev Lett. 2002 Jul 1;89(1):012301. doi: 10.1103/PhysRevLett.89.012301. Epub 2002 Jun 14.
Relativistic heavy ions are copious sources of virtual photons. The large photon flux gives rise to a substantial photonuclear interaction probability at impact parameters where no hadronic interactions can occur. Multiple photonuclear interactions in a single collision are possible. In this Letter, we use mutual Coulomb excitation of both nuclei as a tag for moderate-impact-parameter collisions. We calculate the cross section for coherent vector-meson production accompanied by mutual excitation and show that the median impact parameter is much smaller than for untagged production. The vector-meson rapidity and transverse-momentum distribution are very different from untagged exclusive vector-meson production.
相对论重离子是虚光子的丰富来源。大量的光子通量在强子相互作用无法发生的碰撞参数处产生了可观的光核相互作用概率。单次碰撞中可能发生多次光核相互作用。在本信函中，我们将两个原子核的相互库仑激发用作中等碰撞参数碰撞的标记。我们计算了伴随相互激发的相干矢量介子产生的截面，并表明中位碰撞参数比未标记产生的情况小得多。矢量介子的快度和横向动量分布与未标记的排他性矢量介子产生非常不同。
