Constraining unintegrated gluon distributions from inclusive photon production in proton-proton collisions at the LHC
Constraining unintegrated gluon distributions from inclusive photon production in proton-proton collisions at the LHC
复制标题
限制大型强子对撞机质子-质子碰撞中包容性光子产生的未积分胶子分布
DOI：
10.1016/j.physletb.2019.02.007
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发表时间：
2019
影响因子：
4.4
通讯作者：
Raju Venugopalan
中科院分区：
文献类型：
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作者：
Sanjin Benic;Kenji Fukushima;Oscar Garcia Montero;Raju Venugopalan
计算了LHC质子-质子（p+ p）碰撞中首阶（LO）gg → q γ和次首阶（NLO）gg → q <$γ对包含光子产生的贡献.这些通道在LO和NLO处对光子横动量k γ τ提供了主要贡献，对应于碰撞质子中x≤ 0.01的动量分数。我们的计算，在稀密框架下的彩色玻璃凝聚有效场理论（CGC EFT），表明非线性光学贡献占主导地位，在小x，因为它是敏感的k π-依赖的未积分胶子分布在两个质子。我们预测，在低k γ ε时，截面的最大10%的修改是违反k γ-因子分解的直接后果。负责这一修改的相干效应在核中得到增强，并可以从质子-核碰撞中的包容性光子测量中确定。我们提供了p+ p碰撞中k γ ε ≤ 20 GeV的孤立包含光子截面的数值结果，这些结果可以在将来的LHC上进行测试。
We compute the leading order (LO) q g→ q γ and next-to-leading order (NLO) g g→ q q¯ γ contributions to inclusive photon production in proton–proton (p+ p) collisions at the LHC. These channels provide the dominant contribution at LO and NLO for photon transverse momenta k γ⊥ corresponding to momentum fractions of x≤ 0.01 in the colliding protons. Our computations, performed in the dilute–dense framework of the Color Glass Condensate effective field theory (CGC EFT), show that the NLO contribution dominates at small-x because it is sensitive to k⊥-dependent unintegrated gluon distributions in both of the protons. We predict a maximal 10% modification of the cross section at low k γ⊥ as a direct consequence of the violation of k⊥-factorization. The coherence effects responsible for this modification are enhanced in nuclei and can be identified from inclusive photon measurements in proton–nucleus collisions. We provide numerical results for the isolated inclusive photon cross section for k γ⊥≤ 20 GeV in p+ p collisions that can be tested in the future at the LHC.