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arXiv 1407.5887hep-ph
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在LHC上作为夸克色电和色磁偶极矩探针的直接光子产生

Direct photon production as a probe of quarks chromoelectric and chromomagnetic dipole moments at the LHC

Hoda Hesari, Mojtaba Mohammadi Najafabadi

摘要:

本文证明了在LHC质子-质子碰撞中,$γ+$喷流不变质量分布对夸克色电($κ$)和色磁($\tildeκ$)偶极矩的敏感性。结果表明,$κ$或$\tildeκ$的存在导致了$γ+$喷流过程截面的增加,特别是在$γ+$喷流不变质量分布的尾部.利用CMS实验在质心能量为8 TeV时测得的$γ+$喷流不变质量分布,我们导出了夸克色电和色磁偶极矩的界.在提取的限制,我们考虑理论和系统的不确定性。重归一化/因式分解尺度的变化和质子部分子分布函数的选择所产生的不确定性被考虑作为$γ+$喷流不变质量的函数。在95 $\%$置信水平下,我们排除了高于$10^{-5}$的$κ$或$\tildeκ$。这是$κ$或$\tildeκ$最严格的直接上限。

英文摘要:

In this paper we show that the $γ+$jet invariant mass distribution in proton-proton collisions at the LHC is significantly sensitive to the quarks chromoelectric ($κ$) and chromomagnetic ($\tildeκ$) dipole moments. It is shown that the presence of $κ$ or $\tildeκ$ leads to an increment of the cross section of $γ+$jet process in particular in the tail of $γ+$jet invariant mass distribution. Using the measured $γ+$jet invariant mass distribution by the CMS experiment at the center-of-mass energy of 8 TeV, we derive bounds on the quarks chromoelectric and chromomagnetic dipole moments. In extraction of the limits, we consider both theoretical and systematic uncertainties. The uncertainties originating from variation of the renomalization/factorization scales and the choice of proton parton distribution functions are taken into account as a function of the $γ+$jet invariant mass. We exclude $κ$ or $\tildeκ$ above $10^{-5}$ at 95$\%$ confidence level. This is the most stringent direct upper limit on $κ$ or $\tildeκ$.

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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