Using a data sample corresponding to an integrated luminosity of $2.0\,fb^{-1}$, collected by the LHCb experiment, the production of the $\eta_c(1S)$ state in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13 \text{ TeV}$ is studied in the rapidity range ${2.0 < y < 4.5}$ and in the transverse momentum range ${6.5 < p_{T} < 14.0\text{ GeV}}$. The cross-section for prompt production of $\eta_c(1S)$ mesons relative to that of the $J/\psi$ meson is measured using the ${p\bar{p}}$ decay mode and is found to be ${\sigma_{\eta_c(1S)}/\sigma_{J/\psi} = 1.69 \pm 0.15 \pm 0.10 \pm 0.18}$. The quoted uncertainties are, in order, statistical, systematic and due to uncertainties on the branching fractions of the ${J/\psi\to p \bar{p}}$ and ${\eta_c\to p \bar{p}}$ decays. The prompt $\eta_c(1S)$ production cross-section is determined to be ${\sigma_{\eta_c(1S)} = 1.26 \pm 0.11\pm 0.08 \pm 0.14 \,\mu b}$, where the last uncertainty includes that on the ${J/\psi}$ meson cross-section. The ratio of the branching fractions of $b$-hadron decays to the $\eta_c(1S)$ and ${J/\psi}$ states is measured to be ${\mathcal{B}_{b\to\eta_c X}/\mathcal{B}_{b\to J/\psi X} = 0.48 \pm 0.03 \pm 0.03 \pm 0.05}$, where the last uncertainty is due to those on the branching fractions of the ${J/\psi \to p \bar{p}}$ and ${\eta_c\to p \bar{p}}$ decays. The difference between the ${J/\psi}$ and $\eta_c(1S)$ masses is also determined to be ${113.0 \pm 0.7 \pm 0.1\text{ MeV}}$, which is the most precise single measurement of this quantity to date.
Relative $\eta_c$ to $J/\psi$ differential production cross-sections for prompt production. The uncertainties are statistical, systematic, and due to the ${\eta_c\to p\bar{p}}$ and ${J/\psi\to p\bar{p}}$ branching fractions, respectively.
Differential production cross-sections of $\eta_c$ for prompt production. The uncertainties are statistical, systematic, and due to the $\eta_c\to p \bar{p}$ and $J/\psi\to p \bar{p}$ branching fractions and $J/\psi$ production cross-section.
Relative $\eta_c$ to $J/\psi$ differential production cross-sections for production in $b$-hadron inclusive decays. The uncertainties are statistical, systematic, and due to the ${\eta_c\to p\bar{p}}$ and ${J/\psi\to p\bar{p}}$ branching fractions, respectively.
A narrow pentaquark state, $P_c(4312)^+$, decaying to $J/\psi p$ is discovered with a statistical significance of $7.3\sigma$ in a data sample of ${\Lambda_b^0\to J/\psi p K^-}$ decays which is an order of magnitude larger than that previously analyzed by the LHCb collaboration. The $P_c(4450)^+$ pentaquark structure formerly reported by LHCb is confirmed and observed to consist of two narrow overlapping peaks, $P_c(4440)^+$ and $P_c(4457)^+$, where the statistical significance of this two-peak interpretation is $5.4\sigma$. Proximity of the $\Sigma_c^+\bar{D}^{0}$ and $\Sigma_c^+\bar{D}^{*0}$ thresholds to the observed narrow peaks suggests that they play an important role in the dynamics of these states.
Distribution of $(J/\psi p)$ system invariant mass from the decay of $\Lambda_{b}^{0}$ candidates in the channel $\Lambda_{b}^{0} \to J/\psi p K^{-}$.
Distribution of $(J/\psi p)$ system invariant mass from the decay of $\Lambda_{b}^{0}$ candidates in the channel $\Lambda_{b}^{0} \to J/\psi p K^{-}$. $\Lambda_{b}^{0}$ candidates are selected after the suppression of the dominant $\Lambda^{*} \to p K^{-}$ contributions using the $m_{Kp} > 1.9$ GeV$/c^2$ requirement.
$\cos \theta_{P_c}$-weighted ditribution of $(J/\psi p)$ system invariant mass from the decay of $\Lambda_{b}^{0}$ candidates in the channel $\Lambda_{b}^{0} \to J/\psi p K^{-}$. Here $\theta_{P_c}$ is the helicity angle of the pentaquark exotic state (the angle between $K^-$ and $J/\psi$ in the pentaquark state rest frame).
The production fractions of $\overline{B}_s^0$ and $\Lambda_b^0$ hadrons, normalized to the sum of $B^-$ and $\overline{B}^0$ fractions, are measured in 13 TeV pp collisions using data collected by the LHCb experiment, corresponding to an integrated luminosity of 1.67/fb. These ratios, averaged over the $b$-hadron transverse momenta from 4 to 25 GeV and pseudorapidity from 2 to 5, are $0.122 \pm 0.006$ for $\overline{B}_s^0$, and $0.259 \pm 0.018$ for $\Lambda_b^0$, where the uncertainties arise from both statistical and systematic sources. The $\Lambda_b^0$ ratio depends strongly on transverse momentum, while the $\overline{B}_s^0$ ratio shows a mild dependence. Neither ratio shows variations with pseudorapidity. The measurements are made using semileptonic decays to minimize theoretical uncertainties. In addition, the ratio of $D^+$ to $D^0$ mesons produced in the sum of $\overline{B}^0$ and $B^-$ semileptonic decays is determined as $0.359\pm0.006\pm 0.009$, where the uncertainties are statistical and systematic.
Values of $f_s/(f_u+f_d)$ and $f_{\mathit{\Lambda}_b^0}/(f_u+f_d)$ in each $p_\mathrm{T}(H_b)$ bin.
The production of $B^+$, $B^0$ and $\Lambda_b^0$ hadrons is studied in proton-lead collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_\mathrm{NN}}=8.16\,{\rm TeV}$ recorded with the LHCb detector at the LHC. The measurement uses a dataset corresponding to an integrated luminosity of $12.2\pm0.3\,\mathrm{nb}^{-1}$ for the case where the proton beam is projected into the LHCb detector (corresponding to measuring hadron production at positive rapidity) and $18.6\pm0.5\,\mathrm{nb}^{-1}$ for the lead beam projected into the LHCb detector (corresponding to measuring hadron production at negative rapidity). Nuclear effects are probed through double-differential cross-sections, forward-to-backward cross-section ratios and nuclear modification factors of the beauty hadrons. The double-differential cross-sections are measured as a function of the beauty-hadron transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame. Forward-to-backward cross-section ratios and nuclear modification factors indicate a significant nuclear suppression at positive rapidity. The ratio of $\Lambda_b^0$ over $B^0$ production cross-sections is reported and is consistent with the corresponding measurement in $pp$~collisions.
Differential cross-section of $B^+$ production in bins of $p_\mathrm{T}$ and $y$, $\frac{\mathrm{d}^2\sigma}{\mathrm{d}p_\mathrm{T}\,\mathrm{d}y}$ ($\mu\mathrm{b}/[\mathrm{GeV}/c]$).
Differential cross-section of $B^0$ production in bins of $p_\mathrm{T}$ and $y$, $\frac{\mathrm{d}^2\sigma}{\mathrm{d}p_\mathrm{T}\,\mathrm{d}y}$ ($\mu\mathrm{b}/[\mathrm{GeV}/c]$).
Differential cross-section of $\mathit{\Lambda}_b^0$ production in bins of $p_\mathrm{T}$ and $y$, $\frac{\mathrm{d}^2\sigma}{\mathrm{d}p_\mathrm{T}\,\mathrm{d}y}$ ($\mu\mathrm{b}/[\mathrm{GeV}/c]$).
The production of $\Upsilon (nS)$ mesons ($n=1,2,3$) in $p$Pb and Pb$p$ collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{NN}}=8.16$ TeV is measured by the LHCb experiment, using a data sample corresponding to an integrated luminosity of 31.8 nb$^{-1}$. The $\Upsilon (nS)$ mesons are reconstructed through their decays into two opposite-sign muons. The measurements comprise the differential production cross-sections of the $\Upsilon (1S)$ and $\Upsilon (2S)$ states, their forward-to-backward ratios and nuclear modification factors, performed as a function of the transverse momentum $p_{\mathrm{T}}$ and rapidity in the nucleon-nucleon centre-of-mass frame $y^*$ of the $\Upsilon (nS)$ states, in the kinematic range $p_{\rm{T}}<25$ GeV/$c$ and $1.5
$\Upsilon(1S)$ production cross-section in $p$Pb, as a function of $p_{T}$ and $y*$. The uncertainty is the sum in quadrature of the statistical and systematic components.
$\Upsilon(1S)$ production cross-section in Pb$p$, as a function of $p_{T}$ and $y^*$. The uncertainty is the sum in quadrature of the statistical and systematic components.
$\Upsilon(1S)$ production cross-section in $p$Pb and Pb$p$, as a function of $p_{T}$. The uncertainty is the sum in quadrature of the statistical and systematic components.
The cross-section for prompt antiproton production in collisions of protons with an energy of $6.5$ TeV incident on helium nuclei at rest is measured with the LHCb experiment from a data set corresponding to an integrated luminosity of $0.5\,nb^{-1}$. The target is provided by injecting helium gas into the LHC beam line at the LHCb interaction point. The reported results, covering antiproton momenta between $12$ and $110\,\mathrm{GeV/}c$, represent the first direct determination of the antiproton production cross-section in ${\rm p He}$ collisions, and impact the interpretation of recent results on antiproton cosmic rays from space-borne experiments.
Double-differential cross-section in antiproton momentum and transverse momentum for antiproton production in collisions of 6.5 TeV protons on He nuclei at rest. The antiproton momentum is defined in the laboratory frame. Results are averaged over the given kinematic range of each bin. The uncertainty is split into an uncertainty delta_uncorr, uncorrelated among the kinematic bins, and an uncertainty delta_corr, fully correlated among the kinematic bins. For both uncertainties, the systematic uncertainty, dominant for most bins, and the statistical uncertainty, are added in quadrature. The average value within each bin is also reported for the antiproton momentum, the transverse momentum. These average values are obtained from simulation (based on EPOS LHC), to avoid biases from reconstruction effects and given the good agreement with data observed for the simulated kinematic spectra. Projections of Table1 distribution in antiproton $p_T$ bins.
The average value of antiproton x-Feynman $x_F=2 p_{Z}^{*}/\sqrt{s}$ in bins of antiproton momentum and transverse momentum in collisions of 6.5 TeV protons on He nuclei at rest, where $p_{Z}^{*}$ is the longitudinal antiproton momentum in the center-of-mass system and $\sqrt{s}$ the nucleon-nucleon center-of-mass energy. In each bin the average value is reported for the antiproton momentum and transverse momentum. These average values are obtained from simulation (based on EPOS LHC), to avoid biases from reconstruction effects and given the good agreement with data observed for the simulated kinematic spectra. Projections of Table 3 distribution in antiproton $p_T$ bins.
The inclusive $D_s^{\pm}$ production asymmetry is measured in $pp$ collisions collected by the LHCb experiment at centre-of-mass energies of $\sqrt{s} =7$ and 8 TeV. Promptly produced $D_s^{\pm}$ mesons are used, which decay as $D_s^{\pm}\to\phi\pi^{\pm}$, with $\phi\to K^+K^-$. The measurement is performed in bins of transverse momentum, $p_{\rm T}$, and rapidity, $y$, covering the range $2.5
Values of the $D_s^+$ production asymmetry in percent, including, respectively, the statistical and systematic uncertainties for each of the $D_s^+$ kinematic bins using the combined $\sqrt{s} =7$ and 8 TeV data sets. The statistical and systematic uncertainties include the corresponding contributions from the detection asymmetries, and are therefore correlated between the bins. ASYM is defined as ASYM = ((SIG(D/S+)-SIG(D/S-))/(SIG(D/S+)+SIG(D/S+)).
Values of the $D_s^+$ production asymmetry in percent, including, respectively, the statistical and systematic uncertainties for each of the $D_s^+$ kinematic bins using the $\sqrt{s} =7$ TeV data set. The statistical and systematic uncertainties include the corresponding contributions from the detection asymmetries, and are therefore correlated between the bins. ASYM is defined as ASYM = ((SIG(D/S+)-SIG(D/S-))/(SIG(D/S+)+SIG(D/S+)).
Values of the $D_s^+$ production asymmetry in percent, including, respectively, the statistical and systematic uncertainties for each of the $D_s^+$ kinematic bins using the $\sqrt{s} =8$ TeV data set. The statistical and systematic uncertainties include the corresponding contributions from the detection asymmetries, and are therefore correlated between the bins. ASYM is defined as ASYM = ((SIG(D/S+)-SIG(D/S-))/(SIG(D/S+)+SIG(D/S+)).
The production cross-sections of $\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(3S)$ mesons in proton-proton collisions at $\sqrt{s}$= 13 TeV are measured with a data sample corresponding to an integrated luminosity of $277 \pm 11$ $\rm pb^{-1}$ recorded by the LHCb experiment in 2015. The $\Upsilon$ mesons are reconstructed in the decay mode $\Upsilon\to\mu^{+}\mu^{-}$. The differential production cross-sections times the dimuon branching fractions are measured as a function of the $\Upsilon$ transverse momentum, $p_{\rm T}$, and rapidity, $y$, over the range $0 < p_{\rm T}< 30$ GeV/c and $2.0 < y < 4.5$. The ratios of the cross-sections with respect to the LHCb measurement at $\sqrt{s}$= 8 TeV are also determined. The measurements are compared with theoretical predictions based on NRQCD.
Double-differential cross-sections times dimuon branching fraction in different bins of $p_T$ and $y$ for $\Upsilon$(1S) (in pb). The first uncertainty is statistical and the second is systematic.
Double-differential cross-sections times dimuon branching fraction in different bins of $p_T$ and $y$ for $\Upsilon$(2S) (in pb). The first uncertainty is statistical and the second is systematic.
Double-differential cross-sections times dimuon branching fraction in different bins of $p_T$ and $y$ for $\Upsilon$(3S) (in pb). The first uncertainty is statistical and the second is systematic.
The cross-section for inelastic proton-proton collisions at a centre-of-mass energy of 13\,TeV is measured with the LHCb detector. The fiducial cross-section for inelastic interactions producing at least one prompt long-lived charged particle with momentum $p>2$\,GeV/$c$ in the pseudorapidity range $2<\eta<5$ is determined to be $\sigma_{\rm acc}= 62.2 \pm 0.2 \pm 2.5$\,mb. The first uncertainty is the intrinsic systematic uncertainty of the measurement, the second is due to the uncertainty on the integrated luminosity. The statistical uncertainty is negligible. Extrapolation to full phase space yields the total inelastic proton-proton cross-section $\sigma_{\rm inel}= 75.4 \pm 3.0 \pm 4.5$\,mb, where the first uncertainty is experimental and the second due to the extrapolation. An updated value of the inelastic cross-section at a centre-of-mass energy of 7\,TeV is also reported.
The cross-section for inelastic $pp$ collisions at a centre-of-mass energy $\sqrt{s} = 13$ TeV, yielding one or more prompt long-lived charged particles in the kinematic range $p > 2.0$ GeV/$c$ and $2.0 < \eta < 5.0$ (LHCb acceptance). The quoted uncertainty that is almost completely systematic in nature as the purely statistical uncertainty is found negligible. A particle is long-lived if its proper (mean) lifetime is larger than 30 ps, and it is prompt if it is produced directly in the $pp$ interaction or if none of its ancestors is long-lived.
The total cross-section for inelastic $pp$ collisions at a centre-of-mass energy $\sqrt{s} = 13$ TeV, extrapolated from Monte Carlo in similar way to measurement at $\sqrt{s}=7$ TeV.
Update of the total cross-section for inelastic $pp$ collisions at a centre-of-mass energy $\sqrt{s} = 7$ TeV due to improved calibration of the luminosity scale.
Forward top quark pair production is studied in $pp$ collisions in the $\mu eb$ final state using a data sample corresponding to an integrated luminosity of 1.93 fb$^{-1}$ collected with the LHCb experiment at a centre-of-mass energy of 13 TeV. The cross-section is measured in a fiducial region where both leptons have a transverse momentum greater than 20 GeV and a pseudorapidity between 2.0 and 4.5. The quadrature sum of the azimuthal separation and the difference in pseudorapidities, denoted $\Delta R$, between the two leptons must be larger than 0.1. The $b$-jet axis is required to be separated from both leptons by a $\Delta R$ of 0.5, and to have a transverse momentum in excess of 20 GeV and a pseudorapidity between 2.2 and 4.2. The cross-section is measured to be $$\sigma_{t\bar{t}}= 126\pm19\,(\mathrm{stat})\pm16\,(\mathrm{syst})\pm5\,(\mathrm{lumi})\,\,\mathrm{ fb}$$ where the first uncertainty is statistical, the second is systematic, and the third is due to the luminosity determination. The measurement is compatible with the Standard Model prediction.
The measured fiducial cross section. The uncertainty is split into statistical, systematic and uncertainty due to luminosity.
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