University of Colorado, Boulder, Colorado 80309, USA.
Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003-9337, USA.
Phys Rev Lett. 2016 Mar 25;116(12):122301. doi: 10.1103/PhysRevLett.116.122301. Epub 2016 Mar 24.
Jet production rates are measured in p+p and d+Au collisions at sqrt[s_{NN}]=200 GeV recorded in 2008 with the PHENIX detector at the Relativistic Heavy Ion Collider. Jets are reconstructed using the R=0.3 anti-k_{t} algorithm from energy deposits in the electromagnetic calorimeter and charged tracks in multiwire proportional chambers, and the jet transverse momentum (p_{T}) spectra are corrected for the detector response. Spectra are reported for jets with 12<p_{T}<50 GeV/c, within a pseudorapidity acceptance of |η|<0.3. The nuclear-modification factor (R_{dAu}) values for 0%-100% d+Au events are found to be consistent with unity, constraining the role of initial state effects on jet production. However, the centrality-selected R_{dAu} values and central-to-peripheral ratios (R_{CP}) show large, p_{T}-dependent deviations from unity, challenging the conventional models that relate hard-process rates and soft-particle production in collisions involving nuclei.
在 2008 年使用相对论重离子对撞机上的 PHENIX 探测器，在 p+p 和 d+Au 碰撞中测量了喷注产生率，这些碰撞的质心能量为 sqrt[s_{NN}]=200 GeV。使用电磁量能器中的能量沉积和多丝正比室中的带电径迹，采用 R=0.3 的反-k_{t}算法来重建喷注，并对探测器响应进行了喷注横动量（p_{T}）谱的修正。报道了在|η|<0.3 的赝快度接受度内，具有 12<p_{T}<50 GeV/c 的喷注的谱。发现 0%-100% d+Au 事件的核修正因子（R_{dAu}）值与 1 一致，限制了初始状态效应对喷注产生的作用。然而，中心度选择的 R_{dAu}值和中心到边缘比（R_{CP}）与 1 有很大的、依赖于 p_{T}的偏离，这对涉及原子核的碰撞中硬过程速率与软粒子产生相关的传统模型提出了挑战。
