Watt B J A, Motylinski P, Thorne R S
Department of Physics and Astronomy, University College London, Gower Place, London, WC1E 6BT UK.
Eur Phys J C Part Fields. 2014;74(7):2934. doi: 10.1140/epjc/s10052-014-2934-z. Epub 2014 Jul 1.
We consider the effect on LHC jet cross sections on partons distribution functions (PDFs), in particular the MSTW2008 set of PDFs. We first compare the published inclusive jet data to the predictions using MSTW2008, finding a very good description. We also use the parton distribution reweighting procedure to estimate the impact of these new data on the PDFs, finding that the combined ATLAS 2.76 and 7 TeV data, and CMS 7 TeV data have some significant impact. We then also investigate the impact of ATLAS, CMS and DØ dijet data using the same techniques. In this case we investigate the effect of using different scale choices for the NLO cross section calculation. We find that the dijet data is generally not completely compatible with the corresponding inclusive jet data, often tending to pull PDFs, particularly the gluon distribution, away from the default values. However, the effect depends on the dijet dataset used as well as the scale choice. We also note that conclusions may be affected by limiting the pull on the data luminosity chosen by the best fit, which is sometimes a number of standard deviations. Finally we include the inclusive jet data in a new PDF fit explicitly. This enables us to check the consistency of the exact result with that obtained from the reweighting procedure. There is generally good, but not full quantitative agreement. Hence, the conclusion remains that MSTW2008 PDFs already fit the published jet data well, but the central values and uncertainties are altered and improved, respectively, to a significant, but not dramatic extent by inclusion of these data.
我们考虑了大型强子对撞机（LHC）喷注截面对于部分子分布函数（PDFs）的影响，特别是MSTW2008这套部分子分布函数。我们首先将已发表的包容性喷注数据与使用MSTW2008的预测结果进行比较，发现其描述非常好。我们还使用部分子分布重加权程序来估计这些新数据对部分子分布函数的影响，发现ATLAS的2.76和7 TeV数据以及CMS的7 TeV数据的组合有一些显著影响。然后我们也使用相同技术研究了ATLAS、CMS和DØ双喷注数据的影响。在这种情况下，我们研究了在计算NLO截面时使用不同标度选择的效果。我们发现双喷注数据通常与相应的包容性喷注数据不完全兼容，常常倾向于使部分子分布函数，特别是胶子分布，偏离默认值。然而，这种影响取决于所使用的双喷注数据集以及标度选择。我们还注意到，结论可能会受到限制最佳拟合所选择的数据光度拉拽的影响，这有时是几个标准差。最后，我们明确地将包容性喷注数据纳入新的部分子分布函数拟合中。这使我们能够检查精确结果与从重加权程序获得的结果的一致性。总体上有良好但不完全的定量一致性。因此，结论仍然是MSTW2008部分子分布函数已经很好地拟合了已发表的喷注数据，但是通过纳入这些数据，中心值和不确定性分别在显著但并非巨大的程度上被改变和改善。
