Enhanced Production of Λ_b<SUP>0</SUP> Baryons in High-Multiplicity pp Collisions at √s=13 TeV

The production rate of Lambda(0)(b) baryons relative to B-0 mesons in pp collisions at a center-of-mass energy root s = 13 TeV is measured by the LHCb experiment. The ratio of Lambda(0)(b) to B-0 production cross sections shows a significant dependence on both the transverse momentum and the measured charged-particle multiplicity. At low multiplicity, the ratio measured at LHCb is consistent with the value measured in ethorne- collisions, and increases by a factor of similar to 2 with increasing multiplicity. At relatively low transverse momentum, the ratio of Lambda(0)(b) to B-0 cross sections is higher than what is measured in e(+)e(-) collisions, but converges with the ethorne- ratio as the momentum increases. These results imply that the evolution of heavy b quarks into finalstate hadrons is influenced by the density of the hadronic environment produced in the collision. Comparisons with several models and implications for the mechanisms enforcing quark confinement are discussed.