arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 0903.3399nucl-ex
收藏

sqrt(s_NN)= 200 GeV时p+p和Au+Au碰撞中的光子-强子喷注关联

Photon-Hadron Jet Correlations in p+p and Au+Au Collisions at sqrt(s_NN) = 200 GeV

PHENIX Collaboration, A. Adare

摘要:

报道了在相对论重离子对撞机(RHIC)上观测到的Au+Au中直接光子+喷流通道中的背靠背关联相对于p+p碰撞的抑制现象。通过统计扣除衰变光子-强子背景,得到了直接光子触发与伴随强子的两粒子关联。在微扰量子色动力学(pQCD)中,远离侧部分子的初始动量受到严格约束,因为部分子-光子对在首阶动量完全平衡,使得这种关联成为介质中部分子能量损失的有力探针。在中心碰撞中,当强子3 < p_T < 5,光子5 < p_T < 15 GeV/c时,离核抑制因子I_AA为0.32 +/-0.12(stat)+/-0.09(syst).这种抑制与高p_T单强子和双强子的抑制相当。p+p碰撞中的直接光子产额与动量平衡z_T = p_T^强子/p_T^光子近似成比例,正如对远离侧部分子碎裂函数的测量所预期的那样。我们比较金+金碰撞的动量平衡依赖的核修改应该是敏感的路径长度依赖的部分子能量损失。

英文摘要:

We report the observation at the Relativistic Heavy Ion Collider (RHIC) of suppression of back-to-back correlations in the direct photon+jet channel in Au+Au relative to p+p collisions. Two-particle correlations of direct photon triggers with associated hadrons are obtained by statistical subtraction of the decay photon-hadron background. The initial momentum of the away-side parton is tightly constrained, because the parton-photon pair exactly balance in momentum at leading order in perturbative quantum chromodynamics (pQCD), making such correlations a powerful probe of the in-medium parton energy loss. The away-side nuclear suppression factor, I_AA, in central Au+Au collisions, is 0.32 +/- 0.12(stat) +/- 0.09(syst) for hadrons of 3 < p_T < 5 in coincidence with photons of 5 < p_T < 15 GeV/c. The suppression is comparable to that observed for high-p_T single hadrons and dihadrons. The direct photon associated yields in p+p collisions scale approximately with the momentum balance, z_T = p_T^hadron/p_T^photon, as expected for a measure of the away-side parton fragmentation function. We compare to Au+Au collisions for which the momentum balance dependence of the nuclear modification should be sensitive to the path-length dependence of parton energy loss.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑