Any color singlet or octet ccbar pair is created at short distances and then expands to a full size of J/psi. Such a dynamical evolution process is included here in calculations for the J/psi number distribution as a function of transverse momentum and rapidity in central Au-Au collisions at both RHIC and LHC energies. The ccbar pairs are produced in the initial collision and in the partonic system during the prethermal and thermal stages through the partonic channels ab to ccbar [{2S+1}L_J] and ab to ccbar [{2S+1}L_J]x, and then they dissociate in the latter two stages. Dissociation of ccbar in the medium occurs via two reactions: (a) color singlet ccbar plus a gluon turns to color octet ccbar, (b) color octet ccbar plus a gluon persists as color octet. There are modest yields of ccbar in the prethermal stage at RHIC energy and through the reactions ab to ccbar [{2S+1}L_J] at LHC energy for partons with large average momentum in the prethermal stage at both collider energies and in the thermal stage at LHC energy. Production from the partonic system competes with the suppression of the initial yield in the deconfined medium. Consequently, a bulge within -1.5<y<1.5 has been found for the J/psi number distribution and the ratio of J/psi number distributions for Au-Au collisions to nucleon-nucleon collisions. This bulge is caused by the partonic system and is thus an indicator of a deconfined partonic medium. Based on this result we suggest the rapidity region worth measuring in future experiments at RHIC and LHC to be -3<y<3.
Prompt J/Psi production at LHC: new evidence for the kt-factorization
在kt-因子分解方法的框架下，研究了在7 TeV LHC能量下pp碰撞中J/Psi瞬发介子的产生和极化.考虑了直接产生机制以及chic 1、chic 2和psi'衰变的反馈贡献。我们的考虑是基于色单重模型补充相应的部分子过程的离壳矩阵元素。质子中未积分的胶子密度使用CCFM演化方程以及Kimber-Martin-Ryskin公式来确定。我们将我们的数值预测与CMS，ATLAS和LHCb合作的第一个实验数据进行比较。对决定J/Psi自旋密度矩阵的所有极化参数进行了估计。
Towards an automated tool to evaluate the impact of the nuclear modification of the gluon density on quarkonium, D and B meson production in proton-nucleus collisions
我们提出了一个简单的和模型无关的程序来解释核修改的胶子密度编码在核共线PDF集上的两到两个部分子硬过程中的质子-核碰撞的影响。这适用于对夸克偶素、D和B介子产生的良好近似，一般称为H。我们的程序包括参数化的部分子散射振幅的平方，A_{gg -> H X}和约束它从质子-质子数据。这样，我们已经能够以模型无关的方式计算在各种LHC实验的运动学中，在sqrt（s_NN）=5和8 TeV时，J/psi，Upperdance和D^0作为y和P_T的函数的相应核修改因子。这当然是合理的，因为在这种评估中最重要的成分是每个运动学配置的概率。我们对D介子的计算也可以推广到B介子的产生。为了进一步说明该工具的潜力，我们提供了-第一次-预测的核修改因子的eta_c的生产在LHC的pPb碰撞。
