D0-meson-tagged jet axes difference in proton-proton collisions at √s = 5.02 TeV

Abstract

Heavy-flavor quarks produced in proton-proton (pp) collisions provide a unique opportunity to investigate the evolution of quark-initiated parton showers from initial hard scatterings to final-state hadrons. By examining jets that contain heavy-flavor hadrons, this study explores the effects of both perturbative and nonperturbative QCD on jet formation and structure. The angular differences between various jet axes, ΔR<inf>axis</inf>, offer insight into the radiation patterns and fragmentation of charm quarks. The first measurement of D0-tagged jet axes differences in pp collisions at √s = 5.02 TeV by the ALICE experiment at the LHC is presented for jets with transverse momentum pch jet<inf>T</inf> ≥ 10 GeV/c and D0 mesons with pD0<inf>T</inf> ≥ 5 GeV/c. In this D0-meson-tagged jet measurement, three jet axis definitions, each with different sensitivities to soft, wide-angle radiation, are used: the standard axis, soft drop groomed axis, and winner-takes-all axis. Measurements of the radial distributions of D0 mesons with respect to the jet axes, ΔR<inf>axis-D0</inf>, are reported, along with the angle, ΔR<inf>axis</inf>, between the three jet axes. The D0 meson emerges as the leading particle in these jets, closely aligning with the winner-takes-all axis and diverging from the standard jet axis. The results also examine how varying the sensitivity to soft radiation with grooming influences the orientation of the soft drop jet axis and uncover that charm-jet structure is more likely to survive grooming when the soft drop axis is further from the D0 direction, providing further evidence of the dead-cone effect recently measured by ALICE. © 2025 CERN, for the ALICE Collaboration