Observation of a Λ<sub>b</sub><SUP>0</SUP> - (Λ)over-bar<sub>b</sub><SUP>0</SUP> production asymmetry in proton-proton collisions at √<i>s</i>=7 and 8 TeV



Aaij, R, Abdelmotteleb, ASW, Ackernley, T, Adeva, B, Adinolfi, M, Afsharnia, H, Aidala, CA, Aiola, S, Ajaltouni, Z, Akar, S
et al (show 964 more authors) (2021) Observation of a Λ<sub>b</sub><SUP>0</SUP> - (Λ)over-bar<sub>b</sub><SUP>0</SUP> production asymmetry in proton-proton collisions at √<i>s</i>=7 and 8 TeV. JOURNAL OF HIGH ENERGY PHYSICS, 10 (10). 060-.

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Abstract

This article presents differential measurements of the asymmetry between $\Lambda_b^0$ and $\overline{\Lambda}_b^0$ baryon production rates in proton-proton collisions at centre-of-mass energies of $\sqrt{s}=7$ and $8\,\textrm{TeV}$ collected with the LHCb experiment, corresponding to an integrated luminosity of $3\,\textrm{fb}^{-1}$. The $\Lambda_b^0$ baryons are reconstructed through the inclusive semileptonic decay $\Lambda_b^0\rightarrow\Lambda_c^+\mu^-\overline{\nu}_{\mu}X$. The production asymmetry is measured both in intervals of rapidity in the range $2.15<y<4.10$ and transverse momentum in $2<p_T<27\,\textrm{GeV}/c$. The results are found to be incompatible with symmetric production with a significance of 5.8 standard deviations for both $\sqrt{s}=7$ and $8\,\textrm{TeV}$ data, assuming no $C\!P$ 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.

Item Type: Article
Additional Information: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2021-016.html (LHCb public pages)
Uncontrolled Keywords: Hadron-Hadron scattering (experiments), Heavy quark production, proton-proton scattering, Hard scattering, B physics
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 01 Sep 2021 08:43
Last Modified: 09 Oct 2023 08:51
DOI: 10.1007/JHEP10(2021)060
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3134952