Jet fragmentation function and groomed substructure of bottom quark jets in proton-proton collisions at 5.02 TeV
Journal Article
Overview
abstract
; A; bstract; ; ; A measurement of the substructure of bottom quark jets (b jets) in proton-proton (pp) collisions is presented. The measurement uses data collected in pp collisions at; ; ; $$ sqrt{s}=5.02 $$; ; ; s; ; =; 5.02; ; ; ; TeV, with a low number of simultaneous interactions per bunch crossing, recorded by the CMS experiment in 2017, corresponding to an integrated luminosity of 301 pb; ; −; 1; ; . An algorithm to identify and cluster the charged decay daughters of b hadrons is developed for this analysis, which facilitates the exposure of the gluon radiation pattern of b jets using iterative Cambridge-Aachen declustering. The soft-drop-groomed jet radius,; R; g; , and momentum balance,; z; g; , of b quark jets are presented. These observables can be used to test perturbative quantum chromodynamics predictions that account for mass effects. Because the b hadron is partially reconstructed from its charged decay daughters, only charged particles are used for the jet substructure studies. In addition, a jet fragmentation function,; z; b,ch; , is measured, which is defined as the distribution of the ratio of the transverse momentum (; p; T; ) of the partially reconstructed b hadron with respect to the charged-particle component of the jet; p; T; . The substructure variable distributions are unfolded to the charged-particle level. The b jet substructure is compared to the substructure of jets in an inclusive jet sample that is dominated by light-quark and gluon jets in order to assess the role of the b quark mass. A strong suppression of emissions at small; R; g; values is observed for b jets when compared to inclusive jets, consistent with the dead-cone effect. The measurement is also compared with theoretical predictions from Monte Carlo event generators. This is the first substructure measurement of b jets that clusters together the b hadron decay daughters independent of the b hadron species and decay channel.;
