The production of $J/\psi$ mesons in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV is studied with the \lhcb detector. Cross-section measurements are performed as a function of the transverse momentum $p_\mathrm{T}$ and the rapidity $y$ of the $J/\psi$ meson in the region $p_\mathrm{T}<14\mathrm{GeV}/c$ and $2.0<y<4.5$, for both prompt $J/\psi$ mesons and $J/\psi$ mesons from $b$-hadron decays. The production cross-sections integrated over the kinematic coverage are $15.03\pm 0.03\pm 0.94$ $\mu$b for prompt $J/\psi$ and $2.25\pm 0.01\pm 0.14$ $\mu$b for $J/\psi$ from $b$-hadron decays, assuming zero polarization of the $J/\psi$ meson. The first uncertainties are statistical and the second systematic. The cross-section reported for $J/\psi$ mesons from $b$-hadron decays is used to extrapolate to a total $b\bar{b}$ cross-section. The ratios of the cross-sections with respect to $\sqrt{s}=8$ TeV are also determined.
A measurement of the production cross-section of Z bosons in pp collisions at $\sqrt{s} = 13$ TeV is presented using dimuon and dielectron final states in LHCb data. The cross-section is measured for leptons with pseudorapidities in the range $2.0 < \eta < 4.5$, transverse momenta $p_\text{T} > 20$ GeV and dilepton invariant mass in the range $60<m(\ell\ell)<120$ GeV. The integrated cross-section from averaging the two final states is \begin{equation*}\sigma_{\text{Z}}^{\ell\ell} = 194.3 \pm 0.9 \pm 3.3 \pm 7.6\text{ pb,}\end{equation*} where the first uncertainty is statistical, the second is due to systematic effects, and the third is due to the luminosity determination. In addition, differential cross-sections are measured as functions of the Z boson rapidity, transverse momentum and the angular variable $\phi^*_\eta$.
A study is presented of central exclusive production of $\Upsilon(nS)$ states, where the $\Upsilon(nS)$ resonances decay to the $\mu^+\mu^-$ final state, using $pp$ collision data recorded by the LHCb experiment. The cross-section is measured in the rapidity range $2<y(\Upsilon)<4.5$ where the muons are reconstructed in the pseudorapidity range $2<\eta(\mu^\pm)<4.5$. The data sample corresponds to an integrated luminosity of 2.9 fb$^{-1}$ and was collected at centre-of-mass energies of $7$ TeV and $8$ TeV. The measured $\Upsilon(1S)$ and $\Upsilon(2S)$ production cross-sections are \begin{eqnarray} \sigma(pp \to p\Upsilon(1S)p) &=& 9.0 \pm 2.1 \pm 1.7\textrm{ pb and}\nonumber\\ \sigma(pp \to p\Upsilon(2S)p) &=& 1.3 \pm 0.8 \pm 0.3\textrm{ pb},\nonumber \end{eqnarray} where the first uncertainties are statistical and the second are systematic. The $\Upsilon(1S)$ cross-section is also measured as a function of rapidity and is found to be in good agreement with Standard Model predictions. An upper limit is set at 3.4 pb at the 95\% confidence level for the exclusive $\Upsilon(3S)$ production cross-section, including possible contamination from $\chi_b(3P)\to\Upsilon(3S)\gamma$ decays.
Measurements are presented of electroweak boson production using data from $pp$ collisions at a centre-of-mass energy of $\sqrt{s} = 8\mathrm{\,Te\kern -0.1em V}$. The analysis is based on an integrated luminosity of $2.0\mathrm{\,fb}^{-1}$ recorded with the LHCb detector. The bosons are identified in the $W\rightarrow\mu\nu$ and $Z\rightarrow\mu^{+}\mu^{-}$ decay channels. The cross-sections are measured for muons in the pseudorapidity range $2.0 < \eta < 4.5$, with transverse momenta $p_{\rm T} > 20{\mathrm{\,Ge\kern -0.1em V\!/}c}$ and, in the case of the $Z$ boson, a dimuon mass within $60 < M_{\mu^{+}\mu^{-}} < 120{\mathrm{\,Ge\kern -0.1em V\!/}c^{2}}$. The results are \begin{align*} \sigma_{W^{+}\rightarrow\mu^{+}\nu} &= 1093.6 \pm 2.1 \pm 7.2 \pm 10.9 \pm 12.7{\rm \,pb} \, , \sigma_{W^{-}\rightarrow\mu^{-}\bar{\nu}} &= \phantom{0}818.4 \pm 1.9 \pm 5.0 \pm \phantom{0}7.0 \pm \phantom{0}9.5{\rm \,pb} \, , \sigma_{Z\rightarrow\mu^{+}\mu^{-}} &= \phantom{00}95.0 \pm 0.3 \pm 0.7 \pm \phantom{0}1.1 \pm \phantom{0}1.1{\rm \,pb} \, , \end{align*} where the first uncertainties are statistical, the second are systematic, the third are due to the knowledge of the LHC beam energy and the fourth are due to the luminosity determination. The evolution of the $W$ and $Z$ boson cross-sections with centre-of-mass energy is studied using previously reported measurements with $1.0\mathrm{\,fb}^{-1}$ of data at $7\mathrm{\,Te\kern -0.1em V}$. Differential distributions are also presented. Results are in good agreement with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics.
Charm production at the LHC in pp collisions at sqrt(s)=7 TeV is studied with the LHCb detector. The decays D0 -> K- pi+, D+ -> K- pi+ pi+, D*+ -> D0(K- pi+) pi+, D_s+ -> phi(K- K+) pi+, Lambda_c+ -> p K- pi+, and their charge conjugates are analysed in a data set corresponding to an integrated luminosity of 15 nb^{-1}. Differential cross-sections dsigma/dp_T are measured for prompt production of the five charmed hadron species in bins of transverse momentum and rapidity in the region 0 < p_T < 8 GeV/c and 2.0 < y < 4.5. Theoretical predictions are compared to the measured differential cross-sections. The integrated cross-sections of the charm hadrons are computed in the above p_T-y range, and their ratios are reported. A combination of the five integrated cross-section measurements gives sigma(c\bar{c})_{p_T < 8 GeV/c, 2.0 < y < 4.5} = 1419 +/- 12 (stat) +/- 116 (syst) +/- 65 (frag) microbarn, where the uncertainties are statistical, systematic, and due to the fragmentation functions.
The production of $J/\psi$ mesons in proton-proton collisions at $\sqrt{s}$= 7 tev is studied with the LHCb detector at the LHC. The differential cross-section for prompt $J/\psi$ production is measured as a function of the $J/\psi$ transverse momentum p_{\rm T}\ and rapidity $y$ in the fiducial region $p_{\rm T}\in[0;14]$ GeV/c and $y\in[2.0;4.5]$. The differential cross-section and fraction of \j psi\ from $b$-hadron decays are also measured in the same p_{\rm T}\ and $y$ range s. The analysis is based on a data sample corresponding to an integrated luminos ity of 5.2 pb$^{-1}$. The measured cross-sections integrated over the fiducial region are $10.52\pm 0. 04\pm 1.40^{+1.64}_{-2.20}\mu b$ for $\mathrm{prompt}~J/\psi$ production and $1.14 \pm 0. 01\pm 0.16 \mu b$ for $J/\psi$ from $b$-hadron decays, where the first uncertainty is statistical and the second systematic. The $\mathrm{prompt}~J/\psi$ production cross-section is obtained assuming no $J/\psi$ polarisation and the third error indicates the acceptance uncertainty due to this assumption.
The production of $J/\psi$ pairs in proton-proton collisions at a centre-of-mass energy of 7 TeV has been observed using an integrated luminosity of $37.5 pb^{-1}$ collected with the LHCb detector. The production cross-section for pairs with both \jpsi in the rapidity range $2<y^{J/\psi}<4.5$ and transverse momentum $p_{T}^{J/\psi}<10 GeV/c$ is $$ \sigma^{J/\psi J/\psi} = 5.1\pm1.0\pm1.1 nb,$$ where the first uncertainty is statistical and the second systematic.
The production cross-sections of $J/\psi$ mesons in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=5$ TeV are measured using a data sample corresponding to an integrated luminosity of $9.13\pm0.18~\text{pb}^{-1}$, collected by the LHCb experiment. The cross-sections are measured differentially as a function of transverse momentum, $p_{\text{T}}$, and rapidity, $y$, and separately for $J/\psi$ mesons produced promptly and from beauty hadron decays (nonprompt). With the assumption of unpolarised $J/\psi$ mesons, the production cross-sections integrated over the kinematic range $0<p_{\text{T}}<20~\text{GeV}/c$ and $2.0<y<4.5$ are $8.154\pm0.010\pm0.283~\mu\text{b}$ for prompt $J/\psi$ mesons and $0.820\pm0.003\pm0.034~\mu\text{b}$ for nonprompt $J/\psi$ mesons, where the first uncertainties are statistical and the second systematic. These cross-sections are compared with those at $\sqrt{s}=8$ TeV and $13$ TeV, and are used to update the measurement of the nuclear modification factor in proton-lead collisions for $J/\psi$ mesons at a centre-of-mass energy per nucleon pair of $\sqrt{s_{\text{NN}}}=5$ TeV. The results are compared with theoretical predictions.
The production of J/psi mesons is studied with the LHCb detector using data from pp collisions at sqrt(s)=2.76 TeV corresponding to an integrated luminosity of 71 nb^-1. The differential cross-section for inclusive J/psi production is measured as a function of its transverse momentum pT. The cross-section in the fiducial region 0<pT<12 GeV/c and rapidity 2.0<y<4.5 is measured to be 5.6 +/- 0.1(stat) +/- 0.4 (syst) mub, with the assumption of unpolarised J/psi production. The fraction of J/psi production from b-hadron decays is measured to be (7.1 +/- 0.6 (stat) +/- 0.7 (syst)) %.
The production of B+- mesons in proton-proton collisions at sqrt(s)=7 TeV is studied using 35 pb-1 of data collected by the LHCb detector. The B+- mesons are reconstructed exclusively in the B+- -> J/psi K+- mode, with J/psi -> mu+ mu-. The differential production cross-section is measured as a function of the B+- transverse momentum in the fiducial region 0 < pT < 40 GeV/c and with rapidity 2.0 < y < 4.5. The total cross-section, summing up B+ and B-, is measured to be sigma(pp -> B+- X, 0 < pT < 40 GeV/c, 2.0 < y < 4.5) = 41.4 +- 1.5 (stat.) +- 3.1 (syst.) mub.
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