UC Berkeley

A measurement of beauty hadron production at mid-rapidity in proton-lead collisions at a nucleon–nucleon centre-of-mass energy sNN=5.02$$\sqrt{s_\text {NN}}=5.02$$ TeV is presented. The semi-inclusive decay channel of beauty hadrons into J/ψ$$\hbox {J}/\psi $$ is considered, where the J/ψ$$\hbox {J}/\psi $$ mesons are reconstructed in the dielectron decay channel at mid-rapidity down to transverse momenta of 1.3 GeV/c. The bb¯$$\hbox {b}\bar{\hbox {b}}$$ production cross section at mid-rapidity, dσbb¯/dy$$\hbox {d}\sigma _{\hbox {b}\bar{\hbox {b}}}/\hbox {d}y$$, and the total cross section extrapolated over full phase space, σbb¯$$\sigma _{\text {b}\bar{\text {b}}}$$, are obtained. This measurement is combined with results on inclusive J/ψ$$\hbox {J}/\psi $$ production to determine the prompt J/ψ$$\hbox {J}/\psi $$ 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 RpPb$$R_{\text {pPb}}$$, and compared to models to study possible nuclear modifications of the production induced by cold nuclear matter effects. RpPb$$R_{\text {pPb}}$$ is found to be smaller than unity at low pT$$p_{\mathrm{T}}$$ for both J/ψ$$\hbox {J}/\psi $$ coming from beauty hadron decays and prompt J/ψ$$\hbox {J}/\psi $$.