arXiv 1407.44812014-07hep-phhep-ex

W^+W^-测量中的横向动量重算效应

Transverse momentum resummation effects in W^+W^- measurements

Patrick Meade, Harikrishnan Ramani, Mao Zeng

备注：: 21 pages, 9 figures, v2: minor changes/refs updated
发表信息：: Phys. Rev. D 90, 114006 (2014)
DOI：: 10.1103/PhysRevD.90.114006

摘要：

在7 TeV和8 TeV的能量下，ATLAS和CMS测量到的W^+W^-截面与LHC的SM预测相比，仍然是最不一致的通道之一。开发一个更好的通道模型对于理解希格斯粒子的性质和潜在的新物理学至关重要。本文研究了NNLL横动量修正在测量W^+W^-截面中的作用。在我们所采用的形式中，横动量重算并不改变总包含截面，但对双玻色子系统的p_T分布给出了更精确的预言。通过重新加权由蒙特卡罗发生器产生的事件的p_T分布，我们发现一个系统的移动，减少了约3-7%的实验与SM预测的差异取决于MC发生器和部分子簇射使用。主要效果来自两个实验所使用的射流否决切割。我们评论的连接到喷流否决重申，和其他方法的实验可以用来测试这种效果。我们还讨论了该通道与其他双玻色子通道的再结晶效应的相关性。最终，p_T重算改善了大多数发电机的SM和实验测量之间的一致性，但不能解释与SM的测量差异约20%，需要对该通道进行进一步研究。

英文摘要：

The W^+W^- cross section has remained one of the most consistently discrepant channels compared to SM predictions at the LHC, measured by both ATLAS and CMS at 7 and 8 TeV. Developing a better modeling of this channel is crucial to understanding properties of the Higgs and potential new physics. In this paper we investigate the effects of NNLL transverse momentum resummation in measuring the W^+W^- cross section. In the formalism we employ, transverse momentum resummation does not change the total inclusive cross section, but gives a more accurate prediction for the p_T distribution of the diboson system. By re-weighting the p_T distribution of events produced by Monte Carlo generators, we find a systematic shift that decreases the experimental discrepancy with the SM prediction by approximately 3-7% depending on the MC generator and parton shower used. The primary effect comes from the jet veto cut used by both experiments. We comment on the connections to jet veto resummation, and other methods the experiments can use to test this effect. We also discuss the correlation of resummation effects in this channel with other diboson channels. Ultimately p_T resummation improves the agreement between the SM and experimental measurements for most generators, but does not account for the measured ~20% difference with the SM and further investigations into this channel are needed.

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