"Table 5" of "Measurement of t-tbar production with additional jet activity, including b quark jets, in the dilepton channel using pp collisions at sqrt(s) = 8TeV"

Jet multiplicity distributions in top quark pair (ttbar) events are measured in pp collisions at a centre-of-mass energy of 8 TeV with the CMS detector at the LHC using a data set corresponding to an integrated luminosity of 19.7 inverse-femtobarns. The measurement is performed in the dilepton decay channels (e+ e-, mu+ mu-, and e+/- mu-/+). The absolute and normalized differential cross sections for t-tbar production are measured as a function of the jet multiplicity in the event for different jet transverse momentum thresholds and the kinematic properties of the leading additional jets. The differential t-tbar-b and t-tbar-b-bbar cross sections are presented for the first time as a function of the kinematic properties of the leading additional b jets. Furthermore, the fraction of events without additional jets above a threshold is measured as a function of the transverse momenta of the leading additional jets and the scalar sum of the transverse momenta of all additional jets. The data are compared and found to be consistent with predictions from several perturbative quantum chromodynamics event generators and a next-to-leading order calculation.

本研究利用大型强子对撞机（LHC）上CMS探测器采集的、质心系能量为8 TeV的质子-质子碰撞数据（对应积分亮度19.7反飞靶恩），测量了顶夸克对（tt̄）事件的喷注多重数分布。测量针对双轻子衰变道（e⁺e⁻、μ⁺μ⁻及e±μ∓）开展。针对不同喷注横向动量阈值以及领头额外喷注的运动学特性，我们测量了顶夸克对产生的绝对微分截面与归一化微分截面，其随事件内喷注多重数变化。我们首次给出了顶夸克对加单个b夸克喷注以及顶夸克对加成对b夸克喷注的微分截面，其随领头额外b喷注的运动学特性演化。此外，我们还测量了阈值以上无额外喷注的事件占比，其随领头额外喷注的横向动量以及所有额外喷注横向动量的标量和变化。将本数据集与多个微扰量子色动力学事件产生器的预言结果以及次领头阶（NLO）计算结果进行对比后发现，二者具有良好的一致性。