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Measurement of the $B^{\pm}$ production cross-section in pp collisions at $\sqrt{s} =$ 7 and 13 TeV

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Abstract

The production of $B^{\pm}$ mesons is studied in $pp$ collisions at centre-of-mass energies of 7 and 13 TeV, using $B^{\pm}\rightarrow J/\psi K^{\pm}$ decays and data samples corresponding to 1.0 fb$^{-1}$ and 0.3 fb$^{-1}$, respectively. The production cross-sections summed over both charges and integrated over the transverse momentum range $0<p_{\text{T}}< 40$ GeV/$c$ and the rapidity range $2.0<y<4.5$ are measured to be $\sigma(pp \rightarrow B^{\pm} X, \sqrt{s} = \text{7 TeV}) = 43.0 \pm 0.2 \pm 2.5 \pm 1.7\mu b,$ $\sigma(pp \rightarrow B^{\pm} X, \sqrt{s} = \text{13 TeV}) = 86.6 \pm 0.5 \pm 5.4 \pm 3.4\mu b,$ where the first uncertainties are statistical, the second are systematic, and the third are due to the limited knowledge of the $B^{\pm}\rightarrow J/\psi K^{\pm}$ branching fraction. The ratio of the cross-section at 13 TeV to that at 7 TeV is determined to be $2.02\pm0.02\text{(stat)}\pm0.12\text{(syst)}$. Differential cross-sections are also reported as functions of $p_{\text{T}}$ and $y$. All results are in agreement with theoretical calculations based on the state-of-art fixed next-to-leading order quantum chromodynamics.

Figures and captions

Invariant mass distributions of $ B ^\pm$ candidates in the range ${3.5< p_{\mathrm{ T}} <4.0 {\mathrm{\,GeV\!/}c} }$ and ${2.5<y<3.0}$ using (left) $7\mathrm{\,TeV} $ and (right) $13\mathrm{\,TeV} $ data. The black points are the number of selected candidates in each bin, the blue curve represents the fit result, the red-dotted line represents the $ B ^\pm \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^\pm $ signal, and the green- and brown-dashed lines are contributions from the combinatorial and the Cabibbo-suppressed backgrounds. The Cabibbo-suppressed background contribution $ B ^\pm \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^\pm $ is only just visible at masses above the signal peak.

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Measured $ B ^\pm$ double-differential production cross-sections at (top) $7\mathrm{\,TeV} $ and (bottom) $13\mathrm{\,TeV} $ as a function of $p_{\mathrm{ T}}$ and $y$. The black points represent the measured values, and the cyan bands are the FONLL predictions [28]. Each set of measurements and predictions in a given rapidity bin is offset by a multiplicative factor $10^{-m}$, where the offset factor is shown after the rapidity range. The error bars include both the statistical and systematic uncertainties.

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Measured $ B ^\pm$ differential cross-section at $7\mathrm{\,TeV} $ as a function of (left) $p_{\mathrm{ T}}$ or (right) $y$. The black points represent the measured values, the blue-dashed line and cyan band represent the central values and uncertainties of the FONLL prediction [28]. The error bars include both the statistical and systematic uncertainties.

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Measured $ B ^\pm$ differential cross-section at $13\mathrm{\,TeV} $ as a function of (left) $p_{\mathrm{ T}}$ or (right) $y$. The black points represent the measured values, the blue-dashed line and cyan band represent the central values and uncertainties of the FONLL prediction [28]. The error bars include both the statistical and systematic uncertainties.

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Ratio of the $ B ^\pm$ cross-section at $13\mathrm{\,TeV} $ to that at $7\mathrm{\,TeV} $ as a function of (left) $p_{\mathrm{ T}}$ or (right) $y$. The black points represent the measured values, the blue-dashed line and cyan band represent the central values and uncertainties of the FONLL prediction [28].

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Measured acceptance efficiency of $ B ^\pm$ events at (left) $7\mathrm{\,TeV} $ and (right) $13\mathrm{\,TeV} $ as a function of $p_{\mathrm{ T}}$ in different $y$ regions.

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Tables and captions

Summary of relative systematic uncertainties on the integrated production cross-sections at {$\sqrt{s}=$ 7} and $13\mathrm{\,TeV} $, and the ratio of the cross-sections $R(13\mathrm{\,TeV} /7\mathrm{\,TeV} )$.

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Measured $\varepsilon_{\text{tot}}$ of $ B ^\pm$ events at $7\mathrm{\,TeV} $, in the bins of $ B ^\pm$ $p_{\mathrm{ T}}$ and $y$. The efficiencies and uncertainties are in percent.

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Measured $\varepsilon_{\text{tot}}$ of $ B ^\pm$ events at $13\mathrm{\,TeV} $, in the bins of $ B ^\pm$ $p_{\mathrm{ T}}$ and $y$. The efficiencies and uncertainties are in percent.

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Measured $ B ^\pm$ double-differential cross-section (in units of $\mathrm{ \,nb}$ ) at $7\mathrm{\,TeV} $, as a function of $p_{\mathrm{ T}}$ and $y$, in the rapidity regions of $2.0<y<2.5$, $2.5<y<3.0$, and $3.0<y<3.5$.

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Measured $ B ^\pm$ double-differential cross-section (in units of $\mathrm{ \,nb}$ ) at $7\mathrm{\,TeV} $, as a function of $p_{\mathrm{ T}}$ and $y$, in the rapidity regions of $3.5<y<4.0$ and $4.0<y<4.5$.

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Measured $ B ^\pm$ double-differential cross-section (in units of $\mathrm{ \,nb}$ ) at $13\mathrm{\,TeV} $, as a function of $p_{\mathrm{ T}}$ and $y$, in the rapidity regions of $2.0<y<2.5$, $2.5<y<3.0$, and $3.0<y<3.5$.

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Measured $ B ^\pm$ double-differential cross-section (in units of $\mathrm{ \,nb}$ ) at $13\mathrm{\,TeV} $, as a function of $p_{\mathrm{ T}}$ and $y$, in the rapidity regions of $3.5<y<4.0$ and $4.0<y<4.5$.

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Measured $ B ^\pm$ differential cross-sections (in units of $\mathrm{ \,nb} $) at $7\mathrm{\,TeV} $ and $13\mathrm{\,TeV} $ as functions of $p_{\mathrm{ T}}$ in the range $2.0<y<4.5$. The cross-section ratio between $13\mathrm{\,TeV} $ and $7\mathrm{\,TeV} $ is also presented.

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Measured $ B ^\pm$ differential cross-sections (in units of $ {\mathrm{ \,\upmu b}} $) at $7\mathrm{\,TeV} $ and $13\mathrm{\,TeV} $ as functions of $y$ in the $p_{\mathrm{ T}}$ range $0< p_{\mathrm{ T}} <40 {\mathrm{\,GeV\!/}c} $. The cross-section ratio between $13\mathrm{\,TeV} $ and $7\mathrm{\,TeV} $ is also presented.

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Created on 09 December 2018.Citation count from INSPIRE on 09 December 2018.