Measurement of beauty production via non-prompt charm hadrons in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

Abstract

The production cross sections of ${\mathrm{D}}^0$, ${\mathrm{D}}^{+}$, and ${\mathrm{\Lambda }}_{\mathrm{c}}^{+}$ hadrons originating from beauty-hadron decays (i.e. non-prompt) were measured for the first time at midrapidity in proton$-$lead (p$-$Pb) collisions at the center-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. Nuclear modification factors ($R_{\mathrm{pPb}}$) of non-prompt ${\mathrm{D}}^0$, ${\mathrm{D}}^{+}$, and ${\mathrm{\Lambda }}_{\mathrm{c}}^{+}$ are calculated as a function of the transverse momentum ($p_{\mathrm{T}}$) to investigate the modification of the momentum spectra measured in p$-$Pb collisions with respect to those measured in proton$-$proton (pp) collisions at the same energy. The $R_{\mathrm{pPb}}$ measurements are compatible with unity and with the measurements in the prompt charm sector, and do not show a significant $p_{\mathrm{T}}$ dependence. The $p_{\mathrm{T}}$-integrated cross sections and $p_{\mathrm{T}}$-integrated $R_{\mathrm{pPb}}$ of non-prompt ${\mathrm{D}}^0$ and ${\mathrm{D}}^{+}$ mesons are also computed by extrapolating the visible cross sections down to $p_{\mathrm{T}}$ = 0. The non-prompt D-meson $R_{\mathrm{pPb}}$ integrated over $p_{\mathrm{T}}$ is compatible with unity and with model calculations implementing modification of the parton distribution functions of nucleons bound in nuclei with respect to free nucleons. The non-prompt ${\mathrm{\Lambda }}_{\mathrm{c}}^{+}/{\mathrm{D}}^0$ and ${\mathrm{D}}^{+}/{\mathrm{D}}^0$ production ratios are computed to investigate hadronisation mechanisms of beauty quarks into mesons and baryons. The measured ratios as a function of $p_{\mathrm{T}}$ display a similar trend to that measured for charm hadrons in the same collision system.

32 pages, 8 captioned figures, 5 tables, authors from page 26, published version, figures at http://alice-publications.web.cern.ch/node/11237

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