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| CMS-BPH-15-004 ; CERN-EP-2016-198 | ||
| Measurement of the differential inclusive $\mathrm{B^{+}}$ hadron cross sections in pp collisions at $\sqrt{s} = $ 13 TeV | ||
| CMS Collaboration | ||
| 4 September 2016 | ||
| Phys. Lett. B 771 (2017) 435 | ||
| Abstract: The differential cross sections for inclusive production of $\mathrm{B^{+}}$ hadrons are measured as a function of the $\mathrm{B^{+}}$ transverse momentum ${p_{\mathrm{T}}}^{\mathrm{B}}$ and rapidity $y^{\mathrm{B}}$ in pp collisions at a centre-of-mass energy of 13 TeV, using data collected by the CMS experiment that correspond to an integrated luminosity of 48.1 pb$^{-1}$. The measurement uses the exclusive decay channel $\mathrm{B^{+}} \to \mathrm{J}/\psi \mathrm{K^{+}}$, with $\mathrm{J}/\psi$ mesons that decay to a pair of muons. The results show a reasonable agreement with theoretical calculations within the uncertainties. | ||
| Links: e-print arXiv:1609.00873 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Invariant mass distribution of $\mathrm{B^{+}} \to \mathrm{J}/\psi \mathrm{K^{+}} $ candidates, integrated over the phase-space region of 10 $ \le {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 17 GeV and $ { | y^{{\mathrm{B}}} | } < 1.45$, and of $17 \le {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV and $ { | y^{{\mathrm{B}}} | } < 2.1$. The solid curve shows the result of the fit. The shaded and hatched areas represent, respectively, the $\mathrm{J}/\psi \mathrm{K^{+}} $ signal and the $\mathrm{J}/\psi \pi^{+} $ component, while the dashed and dotted curves represent the combinatorial and misreconstructed ${\mathrm{B}} \to \mathrm{J}/\psi $ + hadrons backgrounds, respectively. |
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Figure 2:
Invariant mass distributions of the $\mathrm{B^{+}} \to \mathrm{J}/\psi \mathrm{K^{+}} $ candidates in the regions of (a) 17 $ \le {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 24 GeV, $ { | y^{{\mathrm{B}}} | } < $ 2.1, and (b) 10 $ \le {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV, 0.4 $ \le { | y^{{\mathrm{B}}} | } < $ 0.6. The solid curve shows the result of the fit. The shaded (hatched) area represents the signal ($\mathrm{B^{+}} \to \mathrm{J}/\psi \pi^{+} $) component, while the dashed and dotted curves represent the combinatorial and misreconstructed $ {\mathrm{B}} \to \mathrm{J}/\psi $ + hadrons background components, respectively. |
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Figure 2-a:
Invariant mass distributions of the $\mathrm{B^{+}} \to \mathrm{J}/\psi \mathrm{K^{+}} $ candidates in the regions of 17 $ \le {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 24 GeV, $ { | y^{{\mathrm{B}}} | } < $ 2.1. The solid curve shows the result of the fit. The shaded (hatched) area represents the signal ($\mathrm{B^{+}} \to \mathrm{J}/\psi \pi^{+} $) component, while the dashed and dotted curves represent the combinatorial and misreconstructed $ {\mathrm{B}} \to \mathrm{J}/\psi $ + hadrons background components, respectively. |
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Figure 2-b:
Invariant mass distributions of the $\mathrm{B^{+}} \to \mathrm{J}/\psi \mathrm{K^{+}} $ candidates in the regions of 10 $ \le {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV, 0.4 $ \le { | y^{{\mathrm{B}}} | } < $ 0.6. The solid curve shows the result of the fit. The shaded (hatched) area represents the signal ($\mathrm{B^{+}} \to \mathrm{J}/\psi \pi^{+} $) component, while the dashed and dotted curves represent the combinatorial and misreconstructed $ {\mathrm{B}} \to \mathrm{J}/\psi $ + hadrons background components, respectively. |
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Figure 3:
$\mathrm{B^{+}} $ differential production cross sections (a) $ {\mathrm {d}}\sigma / {\mathrm {d}} {p_{\mathrm {T}}} ^{{\mathrm{B}}}$ for $ { | y^{{\mathrm{B}}} | } < $ 1.45 or $ { | y^{{\mathrm{B}}} | } < $ 2.1, and (b) $ {\mathrm {d}}\sigma / {\mathrm {d}}y^{{\mathrm{B}}}$ for 10 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV or 17 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV, at $\sqrt {s} = $ 13 TeV (squares, this measurement). The previous CMS measurements from $\sqrt {s} = $ 7 TeV data [11] (circles) are also presented as a function of $ {p_{\mathrm {T}}} ^{{\mathrm{B}}}$ ($y^{{\mathrm{B}}}$), scaled to the phase-space region of $ { | y^{{\mathrm{B}}} | } < $ 2.1 or $ { | y^{{\mathrm{B}}} | } < $ 1.45 (10 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV or 17 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV). The vertical bars show the total uncertainty in the measured cross sections, and the horizontal bars represent the bin width. The calculations from FONLL and PYTHIA are shown as shaded boxes and dashed lines, respectively. The bottom panels display the ratio of the data at 13 TeV to the FONLL predictions (points) and the ratios of the PYTHIA to the FONLL calculations (dashed lines), with the shaded region displaying the uncertainties in the FONLL predictions. |
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Figure 3-a:
$\mathrm{B^{+}} $ differential production cross sections $ {\mathrm {d}}\sigma / {\mathrm {d}} {p_{\mathrm {T}}} ^{{\mathrm{B}}}$ for $ { | y^{{\mathrm{B}}} | } < $ 1.45 or $ { | y^{{\mathrm{B}}} | } < $ 2.1, at $\sqrt {s} = $ 13 TeV (squares, this measurement). The previous CMS measurements from $\sqrt {s} = $ 7 TeV data [11] (circles) are also presented as a function of $ {p_{\mathrm {T}}} ^{{\mathrm{B}}}$ ($y^{{\mathrm{B}}}$), scaled to the phase-space region of $ { | y^{{\mathrm{B}}} | } < $ 2.1 or $ { | y^{{\mathrm{B}}} | } < $ 1.45 (10 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV or 17 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV). The vertical bars show the total uncertainty in the measured cross sections, and the horizontal bars represent the bin width. The calculations from FONLL and PYTHIA are shown as shaded boxes and dashed lines, respectively. The bottom panels display the ratio of the data at 13 TeV to the FONLL predictions (points) and the ratios of the PYTHIA to the FONLL calculations (dashed lines), with the shaded region displaying the uncertainties in the FONLL predictions. |
png pdf |
Figure 3-b:
$\mathrm{B^{+}} $ differential production cross sections $ {\mathrm {d}}\sigma / {\mathrm {d}}y^{{\mathrm{B}}}$ for 10 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV or 17 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV, at $\sqrt {s} = $ 13 TeV (squares, this measurement). The previous CMS measurements from $\sqrt {s} = $ 7 TeV data [11] (circles) are also presented as a function of $ {p_{\mathrm {T}}} ^{{\mathrm{B}}}$ ($y^{{\mathrm{B}}}$), scaled to the phase-space region of $ { | y^{{\mathrm{B}}} | } < $ 2.1 or $ { | y^{{\mathrm{B}}} | } < $ 1.45 (10 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV or 17 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV). The vertical bars show the total uncertainty in the measured cross sections, and the horizontal bars represent the bin width. The calculations from FONLL and PYTHIA are shown as shaded boxes and dashed lines, respectively. The bottom panels display the ratio of the data at 13 TeV to the FONLL predictions (points) and the ratios of the PYTHIA to the FONLL calculations (dashed lines), with the shaded region displaying the uncertainties in the FONLL predictions. |
png pdf |
Figure 4:
Ratios of $\mathrm{B^{+}} $ differential production cross sections at $\sqrt {s} = $ 13 TeV and at $\sqrt {s} = $ 7 TeV as (a) a function of $ {p_{\mathrm {T}}} ^{{\mathrm{B}}}$ for $ { | y^{{\mathrm{B}}} | } < $ 1.45 or $ { | y^{{\mathrm{B}}} | } < $ 2.1 and (b) as a function of $ { | y^{{\mathrm{B}}} | }$ for 10 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV or 17 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV. The vertical bars show the total uncertainty in the measured ratios of the cross sections, and the horizontal bars represent the bin width. The calculations from FONLL and PYTHIA are shown as shaded boxes and dashed lines, respectively. |
png pdf |
Figure 4-a:
Ratios of $\mathrm{B^{+}} $ differential production cross sections at $\sqrt {s} = $ 13 TeV and at $\sqrt {s} = $ 7 TeV as a function of $ {p_{\mathrm {T}}} ^{{\mathrm{B}}}$ for $ { | y^{{\mathrm{B}}} | } < $ 1.45 or $ { | y^{{\mathrm{B}}} | } < $ 2.1. The vertical bars show the total uncertainty in the measured ratios of the cross sections, and the horizontal bars represent the bin width. The calculations from FONLL and PYTHIA are shown as shaded boxes and dashed lines, respectively. |
png pdf |
Figure 4-b:
Ratios of $\mathrm{B^{+}} $ differential production cross sections at $\sqrt {s} = $ 13 TeV and at $\sqrt {s} = $ 7 TeV as a function of $ { | y^{{\mathrm{B}}} | }$ for 10 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV or 17 $ < {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV. The vertical bars show the total uncertainty in the measured ratios of the cross sections, and the horizontal bars represent the bin width. The calculations from FONLL and PYTHIA are shown as shaded boxes and dashed lines, respectively. |
| Tables | |
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Table 1:
Summary of the relative systematic uncertainties in the measured $\mathrm{B^{+}} $ production cross sections. The ranges given reflect the uncertainties over the $ {p_{\mathrm {T}}} ^{{\mathrm{B}}}$ and $y^{{\mathrm{B}}}$ bins. |
png pdf |
Table 2:
The ranges in $ {p_{\mathrm {T}}} ^{{\mathrm{B}}}$ and $ { | y^{{\mathrm{B}}} | }$, signal yields $n_\text {sig}$, acceptance times efficiency $A\epsilon $, and measured differential cross sections ${{{\mathrm {d}}}\sigma}/{{{\mathrm {d}}} {p_{\mathrm {T}}} ^{{\mathrm{B}}}}$ and ${{{\mathrm {d}}}\sigma}/{{{\mathrm {d}}}y^{{\mathrm{B}}}}$, compared to the FONLL and PYTHIA predictions. The three uncertainties in the measured cross sections refer to the statistical, systematic, and integrated luminosity uncertainties, respectively. The uncertainties in $A\epsilon $ and in the FONLL predictions are the total uncertainties. The last row ("Inclusive bin") presents the measured total cross section and the FONLL and PYTHIA predictions for the phase-space region of $10 \le {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 17 GeV and $ { | y^{{\mathrm{B}}} | } < $ 1.45, and 17 $ \le {p_{\mathrm {T}}} ^{{\mathrm{B}}} < $ 100 GeV and $ { | y^{{\mathrm{B}}} | } < $ 2.1. |
| Summary |
| The differential cross sections for $\mathrm{B^{+}}$ meson production in ${\mathrm{p}}{\mathrm{p}}$ collisions at $\sqrt{s} = $ 13 TeV have been measured for the first time by the CMS experiment using the decay channel $\mathrm{B^{+}} \to \mathrm{J}/\psi \mathrm{K^{+}}$, with $\mathrm{J}/\psi \to \mu^+\mu^-$, as a function of ${p_{\mathrm{T}}}^{{\mathrm{B}}}$ for $| {y^{{\mathrm{B}}}} | < $ 1.45 or $ | {y^{{\mathrm{B}}}} | < 2.1$, and as a function of $y^{{\mathrm{B}}}$ for 10 $ < {p_{\mathrm{T}}}^{{\mathrm{B}}} < $ 100 GeV or 17 $ < {p_{\mathrm{T}}}^{{\mathrm{B}}} < $ 100 GeV. The total cross section summed over all bins is measured to be 15.3 $\pm$ 0.4 (stat.) $\pm$ 2.1 (syst.) $\pm$ 0.4 (lumi.) $\mu$b. The measured distributions show reasonable agreement in terms of shape, as well as normalization, with FONLL calculations and with the prediction of the PYTHIA event generator, within the uncertainties. The ratios between the measurements at 13 and at 7 TeV tend to prefer higher values compared to the predictions. This study provides the first measurement of a b hadron cross section through the $ \mathrm{B^{+}} \to \mathrm{J}/\psi \mathrm{K^{+} } $ exclusive decay channel at the centre-of-mass energy of 13 TeV. |
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