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arXiv 1711.07366hep-ph
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$k_T$ -因子分解中$χ_c$对的产生

Production of $χ_c$ pairs in $k_T$-factorization

Anna Cisek, Wolfgang Schäfer, Antoni Szczurek

摘要:

我们计算了所有可能的$J=0,1,2$组合的$χ_c(J)$介子对的产生。主要的产生机制是胶子-胶子熔合反应中的交叉通道胶子交换。构建基块是离壳胶子的顶点$g^* g^* \to χ_c(J)$。我们坚持色单重态模型,计算了束缚态非相对论运动重夸克极限下的胶子融合顶点。这些顶点用于构建$g^* g^* \to χ_c(J_1) χ_c(J_2)$振幅。然后,我们使用$k_T$ -因子分解方法计算强子级截面。在我们的数值预测中,我们使用KMR型未积分胶子分布。示出了在$pp$质心能量$\sqrt{s} = 8 \, {\rm TeV}$的几个微分分布。$t$和$u$通道胶子交换的显著特征是$χ_c$介子之间的快度差$Δy$的宽分布.

英文摘要:

We calculate the production of pairs of $χ_c(J)$ mesons with all possible combinations of $J=0,1,2$. The leading order production mechanism is the crossed-channel gluon exchange in the gluon-gluon fusion reaction. The building blocks are the vertices $g^* g^* \to χ_c(J)$ for off shell gluons. We stick to the color-singlet model and calculate the gluon fusion vertices in the limit of heavy quarks with nonrelativistic motion in the bound state. These vertices are used to construct the $g^* g^* \to χ_c(J_1) χ_c(J_2)$ amplitudes. We then calculate hadron-level cross sections using the $k_T$-factorization approach. In our numerical predictions, we use the KMR-type unintegrated gluon distributions. Several differential distributions at the $pp$ center of mass energy $\sqrt{s} = 8 \, {\rm TeV}$ are shown. The salient feature of the $t$ and $u$-channel gluon exchange are the broad distributions in rapidity difference $Δy$ between $χ_c$ mesons.

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