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| CMS-PAS-BPH-13-002 | ||
| Measurement of production cross sections times branching fraction of $\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi^+$ and $\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+$ in pp collisions at $\sqrt{s}= $ 7 TeV at CMS | ||
| CMS Collaboration | ||
| June 2018 | ||
| Abstract: Measurements of the differential production cross section times branching fraction of the $\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi^+$ and $\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+$ processes are presented as a function of the $\mathrm{B_c}^+$ ($\mathrm{B}^+$) transverse momentum $p_{\mathrm{T}}$ and absolute rapidity $|y|$. The measurements are based on data collected by CMS in 2011 in pp collisions at $\sqrt{s}= $ 7 TeV, corresponding to an integrated luminosity of 4.77 fb$^{-1}$. The integrated production cross sections times branching fraction in the kinematic region of $p_{\mathrm{T}}(\mathrm{B_c}^+, \mathrm{B}^+) > $ 10 GeV/$c$ and $|y|(\mathrm{B_c}^+, \mathrm{B}^+) < $ 1.5 are measured to be 40.8 $\pm$ 4.7 (stat) $\pm$ 2.8 (syst) pb for $\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi^+$ and 5851.3 $\pm$ 37.1 (stat) $\pm$ 446.4 (syst) pb for $\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+$. The $\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+$ production is found to be described reasonably well by FONLL theoretical calculations, while the shape of $\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi^+$ production is described well by BCVEGPY theoretical predictions. | ||
| Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Invariant mass distribution of $\mathrm{J/\psi} \pi ^{\pm}$ (left) and $\mathrm{J/\psi} \mathrm{K}^{\pm}$ (right) for 2011 CMS data. The curves show the best maximum likelihood fit for the sample. |
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Figure 1-a:
Invariant mass distribution of $\mathrm{J/\psi} \pi ^{\pm}$ (left) and $\mathrm{J/\psi} \mathrm{K}^{\pm}$ (right) for 2011 CMS data. The curves show the best maximum likelihood fit for the sample. |
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Figure 1-b:
Invariant mass distribution of $\mathrm{J/\psi} \pi ^{\pm}$ (left) and $\mathrm{J/\psi} \mathrm{K}^{\pm}$ (right) for 2011 CMS data. The curves show the best maximum likelihood fit for the sample. |
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Figure 2:
Differential production cross sections times BR of $\mathrm{d}\sigma (\mathrm{B_c}^+)/\mathrm{d}p_{\mathrm{T}}(\mathrm{B_c}^+) \times \mathcal {B}(\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi ^+)$ (left) and $\mathrm{d}\sigma (\mathrm{B_c}^+)/\mathrm{d}|y|(\mathrm{B_c}^+) \times \mathcal {B}(\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi ^+)$ (right) at $\sqrt {s}= $ 7 TeV pp collisions. Solid points with error bars are the CMS measurements and the uncertainties are statistical and systematic, respectively. The prediction of the $\mathrm{B_c}^{+}$ production cross section by BCVEGPY times the branching fraction $\mathcal {B}(\mathrm{B_c}\rightarrow \mathrm{J/\psi} \pi)=3.3\times 10^{-03}$ [54] is scaled by 2.75 for display purposes. |
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Figure 2-a:
Differential production cross sections times BR of $\mathrm{d}\sigma (\mathrm{B_c}^+)/\mathrm{d}p_{\mathrm{T}}(\mathrm{B_c}^+) \times \mathcal {B}(\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi ^+)$ (left) and $\mathrm{d}\sigma (\mathrm{B_c}^+)/\mathrm{d}|y|(\mathrm{B_c}^+) \times \mathcal {B}(\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi ^+)$ (right) at $\sqrt {s}= $ 7 TeV pp collisions. Solid points with error bars are the CMS measurements and the uncertainties are statistical and systematic, respectively. The prediction of the $\mathrm{B_c}^{+}$ production cross section by BCVEGPY times the branching fraction $\mathcal {B}(\mathrm{B_c}\rightarrow \mathrm{J/\psi} \pi)=3.3\times 10^{-03}$ [54] is scaled by 2.75 for display purposes. |
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Figure 2-b:
Differential production cross sections times BR of $\mathrm{d}\sigma (\mathrm{B_c}^+)/\mathrm{d}p_{\mathrm{T}}(\mathrm{B_c}^+) \times \mathcal {B}(\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi ^+)$ (left) and $\mathrm{d}\sigma (\mathrm{B_c}^+)/\mathrm{d}|y|(\mathrm{B_c}^+) \times \mathcal {B}(\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi ^+)$ (right) at $\sqrt {s}= $ 7 TeV pp collisions. Solid points with error bars are the CMS measurements and the uncertainties are statistical and systematic, respectively. The prediction of the $\mathrm{B_c}^{+}$ production cross section by BCVEGPY times the branching fraction $\mathcal {B}(\mathrm{B_c}\rightarrow \mathrm{J/\psi} \pi)=3.3\times 10^{-03}$ [54] is scaled by 2.75 for display purposes. |
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Figure 3:
Top: Differential production cross sections $\mathrm{d}\sigma /\mathrm{d} {p_{\mathrm {T}}} \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ for $\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+$ at $\sqrt {s}= $ 7 TeV pp collisions for 0.0 $ < |y|(\mathrm{B}^{+}) < $ 0.75 (left) and 0.75 $ < |y|(\mathrm{B}^{+}) < $ 1.5 (right). Solid points with error bars are the CMS measurements and the uncertainties are statistical and systematic, respectively. Bottom: Differential production cross sections of $\mathrm{d}\sigma (\mathrm{B}^+)/\mathrm{d}p_{\mathrm{T}}(\mathrm{B}^+) \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ and $\mathrm{d}\sigma (\mathrm{B}^+)/\mathrm{d}|y|(\mathrm{B}^+) \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ at $\sqrt {s}= $ 7 TeV pp collisions. Solid points with uncertainty bar are the CMS measurements and the uncertainties are statistical and systematic, respectively. The shaded region shows the theoretical uncertainty due to the mass of the b-quark, renormalization and factorization scales. The ratio of the measurement to the predictions from FONLL is shown in the lower part of the plots. |
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Figure 3-a:
Top: Differential production cross sections $\mathrm{d}\sigma /\mathrm{d} {p_{\mathrm {T}}} \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ for $\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+$ at $\sqrt {s}= $ 7 TeV pp collisions for 0.0 $ < |y|(\mathrm{B}^{+}) < $ 0.75 (left) and 0.75 $ < |y|(\mathrm{B}^{+}) < $ 1.5 (right). Solid points with error bars are the CMS measurements and the uncertainties are statistical and systematic, respectively. Bottom: Differential production cross sections of $\mathrm{d}\sigma (\mathrm{B}^+)/\mathrm{d}p_{\mathrm{T}}(\mathrm{B}^+) \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ and $\mathrm{d}\sigma (\mathrm{B}^+)/\mathrm{d}|y|(\mathrm{B}^+) \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ at $\sqrt {s}= $ 7 TeV pp collisions. Solid points with uncertainty bar are the CMS measurements and the uncertainties are statistical and systematic, respectively. The shaded region shows the theoretical uncertainty due to the mass of the b-quark, renormalization and factorization scales. The ratio of the measurement to the predictions from FONLL is shown in the lower part of the plots. |
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Figure 3-b:
Top: Differential production cross sections $\mathrm{d}\sigma /\mathrm{d} {p_{\mathrm {T}}} \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ for $\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+$ at $\sqrt {s}= $ 7 TeV pp collisions for 0.0 $ < |y|(\mathrm{B}^{+}) < $ 0.75 (left) and 0.75 $ < |y|(\mathrm{B}^{+}) < $ 1.5 (right). Solid points with error bars are the CMS measurements and the uncertainties are statistical and systematic, respectively. Bottom: Differential production cross sections of $\mathrm{d}\sigma (\mathrm{B}^+)/\mathrm{d}p_{\mathrm{T}}(\mathrm{B}^+) \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ and $\mathrm{d}\sigma (\mathrm{B}^+)/\mathrm{d}|y|(\mathrm{B}^+) \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ at $\sqrt {s}= $ 7 TeV pp collisions. Solid points with uncertainty bar are the CMS measurements and the uncertainties are statistical and systematic, respectively. The shaded region shows the theoretical uncertainty due to the mass of the b-quark, renormalization and factorization scales. The ratio of the measurement to the predictions from FONLL is shown in the lower part of the plots. |
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Figure 3-c:
Top: Differential production cross sections $\mathrm{d}\sigma /\mathrm{d} {p_{\mathrm {T}}} \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ for $\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+$ at $\sqrt {s}= $ 7 TeV pp collisions for 0.0 $ < |y|(\mathrm{B}^{+}) < $ 0.75 (left) and 0.75 $ < |y|(\mathrm{B}^{+}) < $ 1.5 (right). Solid points with error bars are the CMS measurements and the uncertainties are statistical and systematic, respectively. Bottom: Differential production cross sections of $\mathrm{d}\sigma (\mathrm{B}^+)/\mathrm{d}p_{\mathrm{T}}(\mathrm{B}^+) \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ and $\mathrm{d}\sigma (\mathrm{B}^+)/\mathrm{d}|y|(\mathrm{B}^+) \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ at $\sqrt {s}= $ 7 TeV pp collisions. Solid points with uncertainty bar are the CMS measurements and the uncertainties are statistical and systematic, respectively. The shaded region shows the theoretical uncertainty due to the mass of the b-quark, renormalization and factorization scales. The ratio of the measurement to the predictions from FONLL is shown in the lower part of the plots. |
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Figure 3-d:
Top: Differential production cross sections $\mathrm{d}\sigma /\mathrm{d} {p_{\mathrm {T}}} \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ for $\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+$ at $\sqrt {s}= $ 7 TeV pp collisions for 0.0 $ < |y|(\mathrm{B}^{+}) < $ 0.75 (left) and 0.75 $ < |y|(\mathrm{B}^{+}) < $ 1.5 (right). Solid points with error bars are the CMS measurements and the uncertainties are statistical and systematic, respectively. Bottom: Differential production cross sections of $\mathrm{d}\sigma (\mathrm{B}^+)/\mathrm{d}p_{\mathrm{T}}(\mathrm{B}^+) \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ and $\mathrm{d}\sigma (\mathrm{B}^+)/\mathrm{d}|y|(\mathrm{B}^+) \times \mathcal {B}(\mathrm{B}^+\rightarrow \mathrm{J/\psi} \mathrm{K}^+)$ at $\sqrt {s}= $ 7 TeV pp collisions. Solid points with uncertainty bar are the CMS measurements and the uncertainties are statistical and systematic, respectively. The shaded region shows the theoretical uncertainty due to the mass of the b-quark, renormalization and factorization scales. The ratio of the measurement to the predictions from FONLL is shown in the lower part of the plots. |
| Tables | |
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Table 1:
Measurements of integrated and differential cross section times branching fraction for $ {p_{\mathrm {T}}} (\mathrm{B_c}^+) > $ 10 GeV/$c$ and $|y| < $ 1.5. The first uncertainties are statistical and the second are systematic. The branching ratio (BR) $\mathcal {B}(\mathrm{B_c}\rightarrow \mathrm{J/\psi} \pi)$, used to evaluate the prediction from BCVEGPY, is $ 3.3\times 10^{-3}$ [54]. |
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Table 2:
Measurement of integrated and differential cross section times branching fraction for $ {p_{\mathrm {T}}} (\mathrm{B}^{+}) > $ 10 GeV/$c$ and $|y| < $ 1.5. The first uncertainties are statistical and the second are systematic. |
| Summary |
| The production cross section times branching fractions $\sigma(\mathrm{B_c}^+)\times\mathcal{B}(\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi^+)$ and $\sigma(\mathrm{B}^+)\times\mathcal{B}(\mathrm{B}^{+}\rightarrow\mathrm{J/\psi} \mathrm{K}^+)$ are measured at CMS. The measurement uses a dataset collected by the CMS detector in 2011 at $\sqrt{s} = $ 7 TeV, which corresponds to an integrated luminosity of 4.77 fb$^{-1}$. The differential measurements $\mathrm{d}\sigma(\mathrm{B_c}^+)\times\mathcal{B}(\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi^+)$ and $\mathrm{d}\sigma(\mathrm{B}^+)\times\mathcal{B}(\mathrm{B}^{+}\rightarrow\mathrm{J/\psi} \mathrm{K}^+)$ are reported with respect to $p_{\mathrm{T}}(\mathrm{B_c}^+, \mathrm{B}^+)$ and rapidity $|y|$. The shape of $\sigma(\mathrm{B_c}^+)\times\mathcal{B}(\mathrm{B_c}^+ \rightarrow \mathrm{J/\psi} \pi^+)$ measurement has been compared with the normalised theoretical predictions based on BCVEGPY and is found to be in good agreement. The $\sigma(\mathrm{B}^+)\times\mathcal{B}(\mathrm{B}^{+}\rightarrow\mathrm{J/\psi} \mathrm{K}^+)$ measurements have also been compared with the predictions based on PYTHIA, FONLL and NLO calculations. The predictions from the NLO and FONLL theoretical framework have also been quoted with the theoretical uncertainty from the renormalization and factorization scale and b-quark mass ($ 35%$). The measurements are found to be consistent with the theoretical predictions within uncertainty. We hope the measurements may be helpful for theorists to understand and investigate the $\mathrm{B_c}^{+}$ and $\mathrm{B}^{+}$ production and decay mechanism further. |
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Compact Muon Solenoid LHC, CERN |
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