CMS-PAS-HIN-16-011

CMS-PAS-HIN-16-011
Study of $\mathrm{B}^+$ meson production in pp and PbPb collisions at $\sqrt{s_{_{\mathrm{NN}}}}= $ 5.02 TeV using exclusive hadronic decays
CMS Collaboration
September 2016

Abstract: The production cross section of the $\mathrm{B}^+$ meson, and of its charge conjugate, are measured via exclusive hadronic decays in pp and PbPb collisions at the center-of-mass energy $\sqrt{s_{_{\mathrm{NN}}}}= $ 5.02 TeV with the CMS detector at the LHC. The PbPb dataset used for this analysis corresponds to an integrated luminosity of 350.68 $\mu$b$^{-1}$. The production cross sections are measured in the transverse momentum range between 7 and 50 GeV/$c$. A significant suppression of the $\mathrm{B}^+$ production is observed compared to measured pp cross-section, scaled by the number of incoherent nucleon-nucleon collisions.
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; These preliminary results are superseded in this paper, PRL 119 (2017) 152301. The superseded preliminary plots can be found here.

Figures	Summary	Additional Figures	References	CMS Publications

Figures
png pdf	Figure 1: Invariant mass distributions of $\mathrm{B}^{+} + \mathrm{B}^{-} $ candidates in pp (left) and PbPb (right) collisions in the transverse momentum regions 10-15 GeV/$c$, respectively.
png pdf	Figure 1-a: Invariant mass distributions of $\mathrm{B}^{+} + \mathrm{B}^{-} $ candidates in pp collisions in the transverse momentum regions 10-15 GeV/$c$, respectively.
png pdf	Figure 1-b: Invariant mass distributions of $\mathrm{B}^{+} + \mathrm{B}^{-} $ candidates in PbPb collisions in the transverse momentum regions 10-15 GeV/$c$, respectively.
png pdf	Figure 2: The $ {p_{\mathrm {T}}} $-differential production cross section of $\mathrm{B}^{+}$ in pp collisions at $ {\sqrt {s_{_{\mathrm {NN}}}}} = $ 5.02 TeV. The vertical bars (boxes) correspond to statistical (systematic) uncertainties. The global systematic uncertainty, listed in the legend, comprises the uncertainties in the integrated luminosity measurement and the B meson branching fractions. Results are compared to FONLL calculations [29,30,31] represented by the orange boxes with its width indicating the theory uncertainty.
png pdf	Figure 3: The nuclear modification factor $ {R_\mathrm {AA}} $ of $\mathrm{B}^{+}$ measured in PbPb collisions at $ {\sqrt {s_{_{\mathrm {NN}}}}} = $ 5.02 TeV. The statistical and systematic uncertainties on the pp and PbPb data are shown as cross bars and boxes around the data points, respectively. The global systematic uncertainties are shown as full grey boxes at unity, and are not included in the data points. A few theory predictions are also plotted for comparison (M. Djordjevic et al.( [34]), M. He et al.( [35]), and CUJET3.0( [36,37,38]).

Summary

In summary, the first measurement of the $\mathrm{B}^+$ meson production cross section in PbPb collisions at $\sqrt{s_{_{\mathrm{NN}}}}= $ 5.02 TeV is presented. The mesons are measured in $ | y_{\text{lab}} | < $ 2.4 and 7 $ < p_{\mathrm{T}} < $ 50 GeV/$c$ via the reconstruction of one of their exclusive hadronic decay channels. The nuclear modification factor of $\mathrm{B}^+$ is measured as a function of the transverse momentum. The production cross section is found to be strongly suppressed in PbPb collisions when compared to the measured pp reference, scaled by the number of incoherent nucleon-nucleon collisions. These measurements provide strong constraints on the phenomenological models which aim to describe the flavor dependence of the in-medium parton energy loss.

Additional Figures
png pdf	Additional Figure 1: Summary plots of the systematic uncertainties for the pp collisions (left), PbPb collisions in 0-100% (right) analyses.
png	Additional Figure 1-a: Summary plots of the systematic uncertainties for the pp collision analysis.
png	Additional Figure 1-b: Summary plots of the systematic uncertainties for the PbPb collision in 0-100% analysis.
png pdf	Additional Figure 2: Nuclear modification factor $\rm {R_\mathrm {AA}} $ as a function of ${p_{\mathrm {T}}}$ in the centrality range 0-100%, for ${\mathrm {B}^{+}}$
png pdf	Additional Figure 3: Nuclear modification factor $\rm {R_\mathrm {AA}} $ as a function of ${p_{\mathrm {T}}}$ in the centrality range 0-100%, for ${\mathrm {B}^{+}} $, $\mathrm{D}$ and charged particles.

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