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| CMS-BPH-15-005 ; CERN-EP-2017-267 | ||
| Measurement of quarkonium production cross sections in pp collisions at $\sqrt{s} = $ 13 TeV | ||
| CMS Collaboration | ||
| 30 October 2017 | ||
| Phys. Lett. B 780 (2018) 251 | ||
| Abstract: Differential production cross sections of $\mathrm{J}/\psi$ and $\psi$(2S) charmonium and $\Upsilon$(nS) (n = 1, 2, 3) bottomonium states are measured in proton-proton collisions at $\sqrt{s} = $ 13 TeV, with data collected by the CMS detector at the LHC, corresponding to an integrated luminosity of 2.3 fb$^{-1}$ for the $\mathrm{J}/\psi$ and 2.7 fb$^{-1}$ for the other mesons. The five quarkonium states are reconstructed in the dimuon decay channel, for dimuon rapidity $| y | < $ 1.2. The double-differential cross sections for each state are measured as a function of $y$ and transverse momentum, and compared to theoretical expectations. In addition, ratios are presented of cross sections for prompt $\psi$(2S) to $\mathrm{J}/\psi$, $\Upsilon$(2S) to $\Upsilon$(1S), and $\Upsilon$(3S) to $\Upsilon$(1S) production. | ||
| Links: e-print arXiv:1710.11002 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
The product of the measured double-differential cross sections and the dimuon branching fractions for prompt $ {\mathrm{J}/\psi} $ and $ \psi $(2S) (left) and the $\Upsilon $(nS) (right) mesons as a function of $ {p_{\mathrm {T}}} $, in four and two rapidity regions, respectively, assuming unpolarized dimuon decays. For presentation purposes, the individual points in the measurements are scaled by the factors given in the legends. The inner vertical bars on the data points represent the statistical uncertainty, while the outer bars show the statistical and systematic uncertainties, not including the 2.3% uncertainty in the integrated luminosity, added in quadrature. For most of the data points, the uncertainties are comparable to the size of the symbols. |
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Figure 1-a:
The product of the measured double-differential cross sections and the dimuon branching fractions for prompt $ {\mathrm{J}/\psi} $ and $ \psi $(2S) mesons as a function of $ {p_{\mathrm {T}}} $, in four rapidity regions, assuming unpolarized dimuon decays. For presentation purposes, the individual points in the measurements are scaled by the factors given in the legends. The inner vertical bars on the data points represent the statistical uncertainty, while the outer bars show the statistical and systematic uncertainties, not including the 2.3% uncertainty in the integrated luminosity, added in quadrature. For most of the data points, the uncertainties are comparable to the size of the symbols. |
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Figure 1-b:
The product of the measured double-differential cross sections and the dimuon branching fractions for prompt $\Upsilon $(nS) mesons as a function of $ {p_{\mathrm {T}}} $, in two rapidity regions, assuming unpolarized dimuon decays. For presentation purposes, the individual points in the measurements are scaled by the factors given in the legends. The inner vertical bars on the data points represent the statistical uncertainty, while the outer bars show the statistical and systematic uncertainties, not including the 2.3% uncertainty in the integrated luminosity, added in quadrature. For most of the data points, the uncertainties are comparable to the size of the symbols. |
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Figure 2:
The measured double-differential cross sections times branching fractions of the prompt $ {\mathrm{J}/\psi} $ and $ \psi $(2S) (left) and the $\Upsilon $(nS) (right) mesons (markers), assuming unpolarized dimuon decays, as a function of $ {p_{\mathrm {T}}} $, for $ {| y |} < $ 1.2, compared to NLO NRQCD predictions| [42,43] (shaded bands). The inner vertical bars on the data points represent the statistical uncertainty, while the outer bars show the statistical and systematic uncertainties, including the integrated luminosity uncertainty of 2.3%, added in quadrature. The middle panels show the ratios of measurement to theory, where the vertical bars depict the total uncertainties in the measurement. The widths of the bands represent the theoretical uncertainty, added in quadrature with the uncertainties in the dimuon branching fractions| [35]. The lower panels show the ratios of cross sections measured at $\sqrt {s} = $ 13 TeV to those measured at 7 TeV | [25,26]. All uncertainties in the 7 and 13 TeV results are treated as uncorrelated. |
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Figure 2-a:
The measured double-differential cross sections times branching fractions of the prompt $ {\mathrm{J}/\psi} $ and $ \psi $(2S) mesons (markers), assuming unpolarized dimuon decays, as a function of $ {p_{\mathrm {T}}} $, for $ {| y |} < $ 1.2, compared to NLO NRQCD predictions| [42,43] (shaded bands). The inner vertical bars on the data points represent the statistical uncertainty, while the outer bars show the statistical and systematic uncertainties, including the integrated luminosity uncertainty of 2.3%, added in quadrature. The middle panel shows the ratios of measurement to theory, where the vertical bars depict the total uncertainties in the measurement. The widths of the bands represent the theoretical uncertainty, added in quadrature with the uncertainties in the dimuon branching fractions| [35]. The lower panel shows the ratios of cross sections measured at $\sqrt {s} = $ 13 TeV to those measured at 7 TeV | [25,26]. All uncertainties in the 7 and 13 TeV results are treated as uncorrelated. |
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Figure 2-b:
The measured double-differential cross sections times branching fractions of the prompt $\Upsilon $(nS) mesons (markers), assuming unpolarized dimuon decays, as a function of $ {p_{\mathrm {T}}} $, for $ {| y |} < $ 1.2, compared to NLO NRQCD predictions| [42,43] (shaded bands). The inner vertical bars on the data points represent the statistical uncertainty, while the outer bars show the statistical and systematic uncertainties, including the integrated luminosity uncertainty of 2.3%, added in quadrature. The middle panel shows the ratios of measurement to theory, where the vertical bars depict the total uncertainties in the measurement. The widths of the bands represent the theoretical uncertainty, added in quadrature with the uncertainties in the dimuon branching fractions| [35]. The lower panel shows the ratios of cross sections measured at $\sqrt {s} = $ 13 TeV to those measured at 7 TeV | [25,26]. All uncertainties in the 7 and 13 TeV results are treated as uncorrelated. |
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Figure 3:
Ratios of the $ {p_{\mathrm {T}}} $ differential cross sections times dimuon branching fractions of the prompt $ \psi $(2S) to $ {\mathrm{J}/\psi} $, $\Upsilon $(2S) to $\Upsilon $(1S), and $\Upsilon $(3S) to $\Upsilon $(1S) mesons for $ {| y |} < $ 1.2. The inner vertical bars represent the statistical uncertainty, while the outer bars show the statistical and systematic uncertainties added in quadrature. The ratio of the $ \psi $(2S) to $ {\mathrm{J}/\psi} $ meson cross sections is multiplied by a factor 5 for better visibility. |
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Figure A1:
Examples of fits of the dimuon invariant mass (left) and decay length (right) distributions for $ {\mathrm{J}/\psi} $ (upper row) and $ \psi $(2S) (lower row) candidate events in the $ {p_{\mathrm {T}}} $ and $ {| y |}$ ranges given in the plots. The results from the total fit and from the various components included in the fit are shown. |
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Figure A2:
Examples of a fit of the dimuon invariant mass distribution for the $\Upsilon $(nS) candidate events in the $ {p_{\mathrm {T}}} $ and $ {| y |}$ ranges given in the plot. The results from the total fit and for the background component are shown. |
| Tables | |
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Table A1:
Double-differential cross section times the dimuon branching fraction of the $ {\mathrm{J}/\psi} $ meson for different ranges of $ {p_{\mathrm {T}}} $, in bins of $ {| y |}$ and for the full $ {| y |}$ range, for the unpolarized decay hypothesis, with their statistical and systematic uncertainties in percent. The average $ {p_{\mathrm {T}}} $ value in each bin is also given. The global uncertainty in the integrated luminosity of 2.3% is not included in the systematic uncertainties. |
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Table A2:
Double-differential cross section times the dimuon branching fraction of the $ \psi $(2S) meson for different ranges of $ {p_{\mathrm {T}}} $, in bins of $ {| y |}$ and for the full $ {| y |}$ range, for the unpolarized decay hypothesis, with their statistical and systematic uncertainties in percent. The average $ {p_{\mathrm {T}}} $ value in each bin is also given. The global uncertainty in the integrated luminosity of 2.3% is not included in the systematic uncertainties. |
png pdf |
Table A3:
Double-differential cross section times the dimuon branching fraction of the $\Upsilon $(1S) meson for different ranges of $ {p_{\mathrm {T}}} $, in bins of $ {| y |}$ and for the full $ {| y |}$ range, for the unpolarized decay hypothesis, with their statistical and systematic uncertainties in percent. The average $ {p_{\mathrm {T}}} $ value in each bin is also given. The global uncertainty in the integrated luminosity of 2.3% is not included in the systematic uncertainties. |
png pdf |
Table A4:
Double-differential cross section times the dimuon branching fraction of the $\Upsilon $(2S) meson for different ranges of $ {p_{\mathrm {T}}} $, in bins of $ {| y |}$ and for the full $ {| y |}$ range, for the unpolarized decay hypothesis, with their statistical and systematic uncertainties in percent. The average $ {p_{\mathrm {T}}} $ value in each bin is also given. The global uncertainty in the integrated luminosity of 2.3% is not included in the systematic uncertainties. |
png pdf |
Table A5:
Double-differential cross section times the dimuon branching fraction of the $\Upsilon $(3S) meson for different ranges of $ {p_{\mathrm {T}}} $, in bins of $ {| y |}$ and for the full $ {| y |}$ range, for the unpolarized decay hypothesis, with their statistical and systematic uncertainties in percent. The average $ {p_{\mathrm {T}}} $ value in each bin is also given. The global uncertainty in the integrated luminosity of 2.3% is not included in the systematic uncertainties. |
png pdf |
Table A6:
Multiplicative scaling factors to obtain the $ {\mathrm{J}/\psi} $ differential cross sections for different polarization scenarios ($ {\lambda _{\theta}^{\mathrm {HX}}}= +1$, $k$, $-1$) from the unpolarized cross section measurements given in Table A1. The value of $k$ is taken equal to $+0.10$, and corresponds to an average over $ {p_{\mathrm {T}}} $ of the CMS measurement [30]. |
png pdf |
Table A7:
Multiplicative scaling factors to obtain the $ \psi $(2S) differential cross sections for different polarization scenarios ($ {\lambda _{\theta}^{\mathrm {HX}}}= +1$, $k$, $-1$) from the unpolarized cross section measurements given in Table A1. The value of $k$ is taken equal to $+0.03$, and corresponds to an average over $ {p_{\mathrm {T}}} $ of the CMS measurement [30]. |
png pdf |
Table A8:
Multiplicative scaling factors to obtain the $\Upsilon $(1S) differential cross sections for different polarization scenarios ($ {\lambda _{\theta}^{\mathrm {HX}}}= +1$, $k$, $-1$) from the unpolarized cross section measurements given in Table A3. The parameter $k$ corresponds to a linear interpolation of the CMS measured value of $ {\lambda _{\theta}^{\mathrm {HX}}}$ [31] as a function of $ {p_{\mathrm {T}}} $ for $ {p_{\mathrm {T}}} < $ 50 GeV. For $ {p_{\mathrm {T}}} > $ 50 GeV, where no measurements of $ {\lambda _{\theta}^{\mathrm {HX}}} $ exist, $k$ is taken as the average of all the measured values of $ {\lambda _{\theta}^{\mathrm {HX}}} $ for $ {p_{\mathrm {T}}} < $ 50 GeV. |
png pdf |
Table A9:
Multiplicative scaling factors to obtain the $\Upsilon $(2S) differential cross sections for different polarization scenarios ($ {\lambda _{\theta}^{\mathrm {HX}}}= +1, k, -1$) from the unpolarized cross section measurements given in Table A4. The parameter $k$ corresponds to a linear interpolation of the CMS measured value of $ {\lambda _{\theta}^{\mathrm {HX}}}$| [31] as a function of $ {p_{\mathrm {T}}} $ for $ {p_{\mathrm {T}}} < $ 50 GeV. For $ {p_{\mathrm {T}}} > $ 50 GeV, where no measurements of $ {\lambda _{\theta}^{\mathrm {HX}}} $ exist, $k$ is taken as the average of all the measured values of $ {\lambda _{\theta}^{\mathrm {HX}}} $ for $ {p_{\mathrm {T}}} < $ 50 GeV. |
png pdf |
Table A10:
Multiplicative scaling factors to obtain the $\Upsilon $(3S) differential cross sections for different polarization scenarios ($ {\lambda _{\theta}^{\mathrm {HX}}}= +1$, $k$, $-1$) from the unpolarized cross section measurements given in Table A5. The parameter $k$ corresponds to a linear interpolation of the CMS measured value of $ {\lambda _{\theta}^{\mathrm {HX}}}$ [31] as a function of $ {p_{\mathrm {T}}} $ for $ {p_{\mathrm {T}}} < $ 50 GeV. For $ {p_{\mathrm {T}}} > $ 50 GeV, where no measurements of $ {\lambda _{\theta}^{\mathrm {HX}}} $ exist, $k$ is taken as the average of all the measured values of $ {\lambda _{\theta}^{\mathrm {HX}}} $ for $ {p_{\mathrm {T}}} < $ 50 GeV, which are all consistent with a single value. |
png pdf |
Table A11:
Ratios of the $ {p_{\mathrm {T}}} $ differential cross sections times dimuon branching fractions of the prompt $ \psi $(2S) to $ {\mathrm{J}/\psi} $, $\Upsilon $(2S) to $\Upsilon $(1S), and $\Upsilon $(3S) to $\Upsilon $(1S) mesons for $ {| y |} < $ 1.2, with their statistical and systematic uncertainties in percent. |
| Summary |
| The double-differential production cross sections of the $\mathrm{J}/\psi$, $\psi$(2S), and $\Upsilon$(nS) (n = 1, 2, 3) quarkonium states have been measured, using their dimuon decay mode, in pp collisions at $\sqrt{s} = $ 13 TeV with the CMS detector at the LHC. The production cross sections of all five S-wave states are presented in a single analysis. The measurement has been performed as a function of transverse momentum (${p_{\mathrm{T}}}$) in several bins of rapidity ($y$), covering a ${p_{\mathrm{T}}}$ range 20-120 GeV for the $\mathrm{J}/\psi$ meson and 20-100 GeV for the remaining states. The cross sections integrated over $| y | < $ 1.2 are also presented, and extend the ${p_{\mathrm{T}}}$ reach to 150 and 130 GeV, respectively. Also presented are the ratios of cross sections measured at $\sqrt{s} = $ 13 (this analysis) and 7 TeV (from Refs. [25,26]), as well as the cross sections of the prompt $\psi$(2S), $\Upsilon$(2S), and $\Upsilon$(3S) mesons relative to their ground states. These results will help in testing the underlying hypotheses of nonrelativistic quantum chromodynamics and in providing further input to constrain the theoretical parameters. |
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