This article presents differential measurements of the asymmetry between Lambda(0)(b) and (Lambda) over bar (0)(b) baryon production rates in proton-proton collisions at centre-of-mass energies of root s = 7 and 8 TeV collected with the LHCb experiment, corresponding to an integrated luminosity of 3 fb(-1). The Lambda(0)(b) baryons are reconstructed through the inclusive semileptonic decay Lambda(0)(b) -> Lambda(+)(c) mu(-)(nu) over bar X-mu. The production asymmetry is measured both in intervals of rapidity in the range 2:15 < y < 4:10 and transverse momentum in 2 < p T < 27 GeV/c. The results are found to be incompatible with symmetric production with a significance of 5.8 standard deviations for both root s = 7 and 8 TeV data, assuming no CP violation in the decay. There is evidence for a trend as a function of rapidity with a significance of 4 standard deviations. Comparisons to predictions from hadronisation models in Pythia and heavy-quark recombination are provided. This result constitutes the first observation of a particle-antiparticle asymmetry in b-hadron production at LHC energies.
Aaij, R., Abdelmotteleb, A., Ackernley, T., Adeva, B., Adinolfi, M., Afsharnia, H., et al. (2021). Observation of a Lambda(0)(b) - (Lambda)over-bar(b)(0) production asymmetry in proton-proton collisions at root s=7 and 8 TeV. JOURNAL OF HIGH ENERGY PHYSICS(10) [10.1007/JHEP10(2021)060].
Observation of a Lambda(0)(b) - (Lambda)over-bar(b)(0) production asymmetry in proton-proton collisions at root s=7 and 8 TeV
Adinolfi, M.;Archilli, F.;Carbone, A.;Carboni, G.;Cattaneo, M.;Chen, S.;D'Ambrosio, C.;De Capua, S.;Ferrari, F.;Fontana, M.;Gao, Y.;Li, Y.;Li, Y.;Mariani, S.;Pastore, A.;Petrucci, S.;Santovetti, E.Membro del Collaboration Group
;Wang, C.;Wang, J.;Wang, J.;Wang, J.;Wang, J.;Wang, Z.;Wang, Z.;Zhang, L.;Zhou, Y.;
2021-01-01
Abstract
This article presents differential measurements of the asymmetry between Lambda(0)(b) and (Lambda) over bar (0)(b) baryon production rates in proton-proton collisions at centre-of-mass energies of root s = 7 and 8 TeV collected with the LHCb experiment, corresponding to an integrated luminosity of 3 fb(-1). The Lambda(0)(b) baryons are reconstructed through the inclusive semileptonic decay Lambda(0)(b) -> Lambda(+)(c) mu(-)(nu) over bar X-mu. The production asymmetry is measured both in intervals of rapidity in the range 2:15 < y < 4:10 and transverse momentum in 2 < p T < 27 GeV/c. The results are found to be incompatible with symmetric production with a significance of 5.8 standard deviations for both root s = 7 and 8 TeV data, assuming no CP violation in the decay. There is evidence for a trend as a function of rapidity with a significance of 4 standard deviations. Comparisons to predictions from hadronisation models in Pythia and heavy-quark recombination are provided. This result constitutes the first observation of a particle-antiparticle asymmetry in b-hadron production at LHC energies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
