The production of $B^{+}$, $B^0$ and ${\mathrm{\Lambda }}_b^0$ hadrons is studied in proton-lead collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=8.16\mathrm{TeV}$ recorded with the LHCb detector at the LHC. The measurement uses a dataset corresponding to an integrated luminosity of $12.2\pm 0.3{\mathrm{nb}}^{-1}$ for the case where the proton beam is projected into the LHCb detector (corresponding to measuring hadron production at positive rapidity) and $18.6\pm 0.5{\mathrm{nb}}^{-1}$ for the lead beam projected into the LHCb detector (corresponding to measuring hadron production at negative rapidity). Double-differential cross sections are measured and used to determine forward-backward ratios and nuclear modification factors, which directly probe nuclear effects in the production of beauty hadrons. The double-differential cross sections are measured as a function of the beauty-hadron transverse momentum and rapidity in the nucleon-nucleon center-of-mass frame. Forward-to-backward cross section ratios and nuclear modification factors indicate a significant nuclear suppression at positive rapidity. The ratio of ${\mathrm{\Lambda }}_b^0$ over $B^0$ production cross sections is reported and is consistent with the corresponding measurement in $pp$ collisions.

• Received 18 February 2019

DOI:https://doi.org/10.1103/PhysRevD.99.052011

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© 2019 CERN, for the LHCb Collaboration