Abstract
A measurement of beauty hadron production at mid-rapidity in proton-lead collisions at a nucleon–nucleon centre-of-mass energy sqrt{s_text {NN}}=5.02 TeV is presented. The semi-inclusive decay channel of beauty hadrons into hbox {J}/psi is considered, where the hbox {J}/psi mesons are reconstructed in the dielectron decay channel at mid-rapidity down to transverse momenta of 1.3 GeV/c. The hbox {b}bar{hbox {b}} production cross section at mid-rapidity, hbox {d}sigma _{hbox {b}bar{hbox {b}}}/hbox {d}y, and the total cross section extrapolated over full phase space, sigma _{text {b}bar{text {b}}}, are obtained. This measurement is combined with results on inclusive hbox {J}/psi production to determine the prompt hbox {J}/psi cross sections. The results in p–Pb collisions are then scaled to expectations from pp collisions at the same centre-of-mass energy to derive the nuclear modification factor R_{text {pPb}}, and compared to models to study possible nuclear modifications of the production induced by cold nuclear matter effects. R_{text {pPb}} is found to be smaller than unity at low p_{mathrm{T}} for both hbox {J}/psi coming from beauty hadron decays and prompt hbox {J}/psi .
Highlights
IntroductionIn high-energy hadronic collisions the production of beautyflavoured hadrons, referred to as b-hadrons (hb) in the following, represents a challenging testing ground for models based on quantum chromodynamics (QCD)
In high-energy hadronic collisions the production of beautyflavoured hadrons, referred to as b-hadrons in the following, represents a challenging testing ground for models based on quantum chromodynamics (QCD).In proton–proton collisions the production cross sections can be computed with a factorisation approach [1,2], as a convolution of the parton distribution functions (PDFs) of the incoming protons, the partonic hard-scattering cross sections, and the fragmentation functions.Measurements in proton–nucleus (p–A) collisions and their comparison to pp results provide a tool to constrain the cold nuclear matter (CNM) effects
The EPS09 parameterisation was used in the Monte Carlo simulation to derive the central value of A × ε, but the alternative assumptions that have been considered produce larger deviations in the pT distributions than those obtained using either EPPS16 or nCTEQ15 instead of EPS09
Summary
In high-energy hadronic collisions the production of beautyflavoured hadrons, referred to as b-hadrons (hb) in the following, represents a challenging testing ground for models based on quantum chromodynamics (QCD). Results at midrapidity have been reported from the ATLAS and CMS experiments, based on either exclusively reconstructed beauty mesons [19], or semi-inclusive decays hb → J/ψ + X [20– 22] or beauty jets [23] These measurements do not cover, at mid-rapidity, the low pT region where the nuclear effects are expected to be the largest and the bulk of the total b-hadron production is concentrated. The precise vertexing capabilities of the ALICE detector allow us to determine the non-prompt component at mid-rapidity, which is discussed in this work This measurement is combined with results on inclusive J/ψ production to determine the prompt J/ψ cross sections, which allow a more direct comparison with models describing the charmonium production in hadronic interactions as compared to the inclusive J/ψ production
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