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 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_\mathrm{g}, and momentum balance, z_\mathrm{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_\text{b,ch}, is measured, which is defined as the distribution of the ratio of the transverse momentum (p_\mathrm{T}) of the partially reconstructed b hadron with respect to the charged-particle component of the jet p_\mathrm{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_\mathrm{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.

Jet fragmentation function and groomed substructure of bottom quark jets in proton-proton collisions at 5.02 TeV

Abbrescia, M.;Colaleo, A.;D'Anzi, B.;Elmetenawee, W.;Louka, M.;Mastrapasqua, V.;My, S.;Nuzzo, S.;Pellecchia, A.;Pompili, A.;Radogna, R.;Simone, F. M.;Stamerra, A.;Troiano, D.;Venditti, R.;Zaza, A.;Tenchini, F.;
2026-01-01

Abstract

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 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_\mathrm{g}, and momentum balance, z_\mathrm{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_\text{b,ch}, is measured, which is defined as the distribution of the ratio of the transverse momentum (p_\mathrm{T}) of the partially reconstructed b hadron with respect to the charged-particle component of the jet p_\mathrm{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_\mathrm{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.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11586/581604
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