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arXiv 1302.4346hep-phhep-exnucl-th
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LHC的独家衍射光子韧致辐射

Exclusive diffractive photon bremsstrahlung at the LHC

Piotr Lebiedowicz, Antoni Szczurek

摘要:

我们计算了LHC能量为$\sqrt{s} = 14$ TeV的$p p \to p p γ$反应的微分分布。我们考虑衍射的经典韧致辐射机制,包括质子的非点状性质的影响。此外,我们首次考虑了(矢量介子)-坡密子、光子-π介子以及光子-坡密子交换过程。对总截面和与这些过程有关的几个观测量,如光子或质子的赝快度和横动量的微分分布进行了预测和讨论。积分衍射韧致辐射截面($E_γ>100$ GeV)仅为$μ$ b的量级。我们试图确定区域的相空间的机制之一占主导地位。经典的韧致辐射占主导地位,在大的前向/后向光子的赝快度,接近散射质子的赝快度。相比之下,光子-坡密子(坡密子-光子)机制在中等速度下占主导地位,但相关的截面相当小。相比之下,虚拟Ω再散射机制在较小的光子角度(较大的光子速率)下起作用。前向/后向区域的光子可以通过安装在LHC实验中的零度量热计(ZDC)测量,而中快度光子难以测量(小截面,小光子横动量)。质子可以通过CMS的ALFA检测器(ATLAS)或TOTEM检测器测量。可以在主要中央检测器的帮助下检查排他性。

英文摘要:

We calculate differential distributions for the $p p \to p p γ$ reaction at the LHC energy $\sqrt{s} = 14$ TeV. We consider diffractive classical bremsstrahlung mechanisms including effects of non point-like nature of protons. In addition, we take into account (vector meson)-pomeron, photon-pion as well as photon-pomeron exchange processes for the first time in the literature. Predictions for the total cross section and several observables related to these processes e.g. differential distributions in pseudorapidities and transverse momenta of photons or protons are shown and discussed. The integrated diffractive bremsstrahlung cross section ($E_γ>100$ GeV) is only of the order of $μ$b. We try to identify regions of the phase space where one of the mechanisms dominates. The classical bremsstrahlung dominates at large forward/backward photon pseudorapidities, close to the pseudorapidities of scattered protons. In contrast, the photon-pomeron (pomeron-photon) mechanism dominates at midrapidities but the related cross section is rather small. In comparison the virtual-omega rescattering mechanism contributes at smaller angles of photons (larger photon rapidities). Photons in the forward/backward region can be measured by the Zero Degree Calorimeters (ZDCs) installed in experiments at the LHC while the midrapidity photons are difficult to measure (small cross section, small photon transverse momenta). Protons could be measured by ALFA detector (ATLAS) or TOTEM detector at CMS. The exclusivity could be checked with the help of main central detectors.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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