论文标题
LHC在UPC中对包含Dijet光生生产的衍射贡献有多大？
How large is the diffractive contribution to inclusive dijet photoproduction in UPCs at the LHC?
论文作者
论文摘要
使用近代领先的顺序（NLO）扰动QCD，我们计算LHC的PB-PB超疗法碰撞（UPC）的衍射贡献，并发现它在小$ x_a $ bin中的$ 5-10美元不超过$ 5-10 $％ $ \ sqrt {s_ {nn}} = 5.02 $ tev。它的较小性是受限运动学（$ p_ {t1}> 20 $ gev和$ x_a> 0.001 $）的结果，这是对核衍射的核能分布函数的大量核抑制核能阴影模型预测的核能分布功能，以及由于QCD分解而导致的额外抑制作用。同时，使用Looser $ p_t $ cuts，例如，$ p_ {t1}> 10 $ gev和$ p_ { \大约5 \ times 10^{ - 4} $。另外，将我们的框架应用于$ \ sqrt {s_ {nn}} = 13 $ tev的Proton-proton UPC，我们发现Dijet Photoproduction $（dσ_{\ rm diff}/dx_p）/dc y Inc/and ars（d dijet propoproduction $ rm and ass as as as as as as as as as ars and ars） $ 10-15 $％的$ x_p \ sim 5 \ times 10^{ - 4} $。在我们的分析中不包括Pomeron-Pomeron散射的贡献，应该使该比率更大。
Using next-to-leading order (NLO) perturbative QCD, we calculate the diffractive contribution to inclusive dijet photoproduction in Pb-Pb ultraperipheral collisions (UPCs) at the LHC and find that it does not exceed $5-10$% in small-$x_A$ bins in the ATLAS kinematics at $\sqrt{s_{NN}}=5.02$ TeV. Its smallness is a result of the restricted kinematics ($p_{T1} > 20$ GeV and $x_A > 0.001$), the large nuclear suppression of nuclear diffractive parton distribution functions predicted in the leading twist model of nuclear shadowing, and additional suppression due to QCD factorization breaking in diffraction. At the same time, using looser $p_T$ cuts, e.g., $p_{T1} > 10$ GeV and $p_{T i\neq 1} > 5-7$ GeV, we find that $(dσ_{\rm diff}/dx_A)/(dσ_{\rm inc}/dx_A)$ can reach $10-20$% at $x \approx 5 \times 10^{-4}$. Also, applying our framework to proton-proton UPCs at $\sqrt{s_{NN}}=13$ TeV, we find that the ratio of the diffractive and inclusive cross sections of dijet photoproduction $(dσ_{\rm diff}/dx_p)/(dσ_{\rm inc}/dx_p)$ is as large as $10-15$% for $x_p \sim 5 \times 10^{-4}$. An account of the contribution of Pomeron-Pomeron scattering, which is not included in our analysis, should make this ratio somewhat larger.
