论文标题
$ J/ψ$ Meson的生产：匹配高和低横向动量
$J/ψ$ meson production in SIDIS: matching high and low transverse momentum
论文作者
论文摘要
我们考虑横向动量光谱和$ \ cos 2ϕ $方位角分布的$ j/ψ$介中，这些分布在半包含的，深度无弹性的电子普罗顿散射中产生，其中电子和质子是脱光化的。在低横向动量下，我们建议根据横向动量依赖性的Gluon分布和形状函数提出分解表达式。我们表明，我们的公式按$α_s的顺序与高横向动量下的共线分解结果正确匹配。后者是在非依赖性QCD（NRQCD）框架内按$α_s^2 $计算的，其中包括中间$^3S_1^{[1]} $ color-singlet fock状态，以及$ v^4 $ $ v^4 $ $ v^4 $ $ v^4 $ nrq nrq in nrq y nr $ v^4 $ nrq nrq。我们表明，$^1 \！s_0^{[8]} $和$^3 \！p_j^{[8]} $（$ j = 0,1,1,2 $）的贡献在小横向动量区域中差异分歧，并让我们确定形状的扰动尾巴功能，具有相同的量子数。这些事实证明是相同的，除了适当的NRQCD长距离矩阵元素给出的整体幅度。
We consider the transverse momentum spectrum and the $\cos 2ϕ$ azimuthal distribution of $J/ψ$ mesons produced in semi-inclusive, deep-inelastic electron-proton scattering, where the electron and the proton are unpolarized. At low transverse momentum, we propose factorized expressions in terms of transverse momentum dependent gluon distributions and shape functions. We show that our formulae, at the order $α_s,$ correctly match with the collinear factorization results at high transverse momentum. The latter are computed at the order $α_s^2$ in the framework of nonrelativistic QCD (NRQCD), with the inclusion of the intermediate $^3S_1^{[1]}$ color-singlet Fock state, as well as the subleading color-octet ones that are relatively suppressed by a factor $v^4$ in the NRQCD velocity parameter $v$. We show that the $^1\!S_0^{[8]}$ and $^3\!P_J^{[8]}$ ($J = 0,1,2$) contributions diverge in the small transverse momentum region and allow us to determine the perturbative tails of the shape functions, which carry the same quantum numbers. These turn out to be identical, except for the overall magnitude given by the appropriate NRQCD long distance matrix element.
