Study of $B$ Meson Production in $p+\mathrm{Pb}$ Collisions at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$ Using Exclusive Hadronic Decays

The production cross sections of the $B^{+}$, $B^0$, and $B_s^0$ mesons, and of their charge conjugates, are measured via exclusive hadronic decays in $p+\mathrm{Pb}$ collisions at the center-of-mass energy $\sqrt{s_{NN}}=5.02\mathrm{TeV}$ with the CMS detector at the CERN LHC. The data set used for this analysis corresponds to an integrated luminosity of $34.6{\mathrm{nb}}^{-1}$. The production cross sections are measured in the transverse momentum range between 10 and $60\mathrm{GeV}/c$. No significant modification is observed compared to proton-proton perturbative QCD calculations scaled by the number of incoherent nucleon-nucleon collisions. These results provide a baseline for the study of in-medium $b$ quark energy loss in $\mathrm{Pb}+\mathrm{Pb}$ collisions.

Figure 1

Invariant-mass distributions of $B^{+}+B^{-}$ (left panel), $B^0+{\overline{B}}^0$ (center panel), and $B_s^0+{\overline{B}}_s^0$ (right panel) candidates in the transverse momentum regions 10–15, 10–15, and $10–60\mathrm{GeV}/c$, respectively. See the text for details.

Figure 2

The $p_T$-differential production cross section of $B^{+}$ (left panel), $B^0$ (center panel), and $B_s^0$ (right panel) measured in $p+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$. The vertical bars (boxes) correspond to statistical (systematic) uncertainties. The global systematic uncertainty, listed in each panel and not included in the data points, comprises the uncertainties in the integrated luminosity measurement and the $B$ meson branching fractions. Results are compared to FONLL calculations [37, 38, 39], scaled by the number of binary $NN$ collisions, represented by a continuous histogram. The dashed histograms represent the theoretical uncertainties for the FONLL reference.

Figure 3

The nuclear modification factors $R_{p+A}^{\mathrm{FONLL}}(p_T)$ of $B^{+}$ (left panel), $B^0$ (center panel), $B_s^0$ (right panel) measured in $p+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$. The statistical and systematic uncertainties on the $p+\mathrm{Pb}$ data are shown as bars and yellow boxes around the data points, respectively. The systematic uncertainties from the FONLL predictions are plotted separately as open blue boxes. The global systematic uncertainties are shown as full grey boxes at unity, and are not included in the data points.

Figure 4

(Left panel) The $y_{\mathrm{CM}}$-differential production cross section of $B^{+}$ measured in $p+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$. Vertical bars (the boxes) correspond to statistical (systematic) uncertainties. The listed global systematic uncertainty is not included in the data points. The result is compared to a FONLL calculation [37, 38, 39] represented by a continuous histogram. The dashed histograms represent the theoretical uncertainties for the FONLL reference. (Right panel) The nuclear modification factor $R_{p+A}^{\mathrm{FONLL}}(y_{\mathrm{CM}})$ of $B^{+}$ as a function of $y_{\mathrm{CM}}$. The statistical and systematic uncertainties on the $p+\mathrm{Pb}$ data are shown as bars and yellow boxes around the data points, respectively. The systematic uncertainty from the FONLL reference is plotted separately as open blue boxes. The global systematic uncertainty is shown as a full grey box at unity, and it is not included in the data points.