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.
Double-differential production cross-sections for prompt $J/\psi$ mesons in ($p_\text{T},y$) intervals. The first uncertainties are statistical, the second are correlated systematic uncertainties shared between intervals, the third are uncorrelated systematic uncertainties, and the last are correlated between $p_\text{T}$ intervals and uncorrelated between $y$ intervals.
Double-differential production cross-sections for nonprompt $J/\psi$ mesons in ($p_\text{T},y$) intervals. The first uncertainties are statistical, the second are correlated systematic uncertainties shared between intervals, the third are uncorrelated systematic uncertainties, and the last are correlated between $p_\text{T}$ intervals and uncorrelated between $y$ intervals.
Single-differential production cross-sections for prompt $J/\psi$ mesons as a function of $p_\text{T}$. The first uncertainties are statistical, the second are correlated systematic uncertainties shared between intervals, and the last are uncorrelated systematic uncertainties.
We present the first measurements of the differential cross section $d\sigma/dp_{T}^{\gamma}$ for the production of an isolated photon in association with at least two $b$-quark jets. The measurements consider photons with rapidities $|y^\gamma| < 1.0$ and transverse momenta $30 < p_{T}^{\gamma} < 200$~\GeV. The $b$-quark jets are required to have $p_T^{jet}>15$ GeV and $| y^{jet}| < 1.5$. The ratio of differential production cross sections for $\gamma+2~b$-jets to $\gamma+b$-jet as a function of $p_{T}^{\gamma}$ is also presented. The results are based on the proton-antiproton collision data at $\sqrt{s}=$1.96~\TeV collected with the D0 detector at the Fermilab Tevatron Collider. The measured cross sections and their ratios are compared to the next-to-leading order perturbative QCD calculations as well as predictions based on the $k_{T}$-factorization approach and those from the SHERPA and PYTHIA Monte Carlo event generators.
The differential GAMMA+2BJET production cross section, DSIG/DPT(GAMMA), in bins of PT(GAMMA).
The differential GAMMA+BJET production cross section, DSIG/DPT(GAMMA), in bins of PT(GAMMA).
The SIG(GAMMA 2BJET)/SIG(GAMMA BJET) cross section ratio in bins of PT(GAMMA).
The production of $J/\psi$ mesons with rapidity $1.5<y<4.0$ or $-5.0<y<-2.5$ and transverse momentum $p_\mathrm{T}<14 \mathrm{GeV}/c$ is studied with the LHCb detector in proton-lead collisions at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{NN}}=5 \mathrm{TeV}$. The analysis is based on a data sample corresponding to an integrated luminosity of about $1.6 \mathrm{nb}^{-1}$. For the first time the nuclear modification factor and forward-backward production ratio are determined separately for prompt $J/\psi$ mesons and $J/\psi$ from $b$-hadron decays. Clear suppression of prompt $J/\psi$ production with respect to proton-proton collisions at large rapidity is observed, while the production of $J/\psi$ from $b$-hadron decays is less suppressed. These results show good agreement with available theoretical predictions. The measurement shows that cold nuclear matter effects are important for interpretations of the related quark-gluon plasma signatures in heavy-ion collisions.
Single differential production cross sections of prompt J/PSI mesons and of J/PSI from B decay as a function of transverse momentum in the FORWARD region. The errors shown are statistical and the uncorrelated and correlated components of the systematic uncertainties.
Single differential production cross sections of prompt J/PSI mesons and of J/PSI from B decay as a function of transverse momentum in the BACKWARD region. The errors shown are statistical and the uncorrelated and correlated components of the systematic uncertainties.
Single differential production cross sections of prompt J/PSI mesons and of J/PSI from B decay as a function of rapidity in the FORWARD region. The errors shown are statistical and the uncorrelated and correlated components of the systematic uncertainties.
We present measurements of the differential cross section $d\sigma/dp_{T}^{\gamma}$ for the associated production of a $c$-quark jet and an isolated photon with rapidity $|y^{\gamma}|< 1.0$ and transverse momentum $30 < p_{T}^{\gamma} < 300$ GeV. The $c$-quark jets are required to have $|y^{jet}| < 1.5$ and $p_{T}^{jet} >15$ GeV. The ratio of differential cross sections for photon+ c and photon+ b production as a function of $p_{T}^{\gamma}$ is also presented. The results are based on data corresponding to an integrated luminosity of 8.7 fb$^{-1}$ recorded with the D0 detector at the Fermilab Tevatron $p\bar{p}$ Collider at $\sqrt{s}=$1.96 TeV. The obtained results are compared to next-to-leading order perturbative QCD calculations using various parton distribution functions, to predictions based on the $k_{T}$-factorization approach, and to predictions from the Sherpa and Pythia Monte Carlo event generators.
The differential cross section as a function of PT for the production of GAMMA+ Charmed JET in PBAR P collisions at a centre of mass energy of 1.96 TeV.
The ratio of the (GAMMA+ CJET) to (GAMMA+ BJET) cross section in bins of the GAMMA PT.
We have observed the reactions p+pbar --> p+X+pbar, with X being a centrally produced J/psi, psi(2S) or chi_c0, and gamma+gamma --> mu+mu-, in proton- antiproton collisions at sqrt{s} = 1.96 TeV using the Run II Collider Detector at Fermilab. The event signature requires two oppositely charged muons, each with pseudorapidity |eta| < 0.6, with M(mumu) in [3.0,4.0] GeV/c2, and either no other particles, or one additional photon, detected. The J/psi and the psi(2S) are prominent, on a continuum consistent with the QED process gamma+gamma --> mu+mu-. Events with a J/psi and an associated photon candidate are consistent with exclusive chi_c0 production through double pomeron exchange. The exclusive vector meson production is as expected for elastic photo- production, gamma+p --> J/psi(psi(2S)) + p, which is observed here for the first time in hadron-hadron collisions. The cross sections ds/dy(y=0) for p + pbar --> p + X + pbar with X = J/psi, psi(2S) orchi_c0 are 3.92+/-0.62 nb, 0.53+/-0.14 nb, and 75+/-14 nb respectively. The cross section for the continuum, with |eta(mu+/-)| < 0.6, M(mumu) in [3.0,4.0] GeV/c2, is [Integral ds/(dM.deta1.deta2)] = 2.7+/-0.5 pb, consistent with QED predictions. We put an upper limit on the cross section for odderon exchange in J/psi production: ds/dy(y=0) (J/psi_O/IP) < 2.3 nb at 95% C.L.
Prompt J/psi cross section from exclusive photoproduction at mid rapidity.
Prompt Psi(2S) cross section from exclusive photoproduction at mid rapidity.
Prompt photoproduction cross-section ratio Psi(2S)/(J/psi) at mid rapidity.
We present a measurement of the cross section for W-boson production in association with jets in pbarp collisions at sqrt(s)=1.96$ TeV. The analysis uses a data sample corresponding to an integrated luminosity of 320 pb^-1 collected with the CDF II detector. W bosons are identified in their electron decay channel and jets are reconstructed using a cone algorithm. For each W+>= n-jet sample ($n= 1 - 4$) we measure sigma(ppbar =>W+>=n$-jet)x BR(W => e nu) with respect to the transverse energy E_T of the n^th-highest E_T jet above 20 GeV, for a restricted W => e nu decay phase space. The cross sections, corrected for all detector effects, can be directly compared to particle level W+ jet(s) predictions. We present here comparisons to leading order and next-to-leading order predictions.
Measured ET differential cross section of the 1st jet in >= 1 JET plus W < E NU > events.
Measured ET differential cross section of the 2nd jet in >= 2 JET plus W < E NU > events.
Measured ET differential cross section of the 3rd jet in >= 3 JET plus W < E NU > events.
We report on measurements of the ϒ(1S), ϒ(2S), and ϒ(3S) differential, (d2σdPtdy)y=0, and integrated cross sections in pp¯ collisions at s=1.8 TeV using a sample of 16.6 ± 0.6 pb−1 collected by the Collider Detector at Fermilab. The three resonances were reconstructed through the decay ϒ→μ+μ−. Comparison is made to a leading order QCD prediction.
SIG*Br(UPSI --> MU+ MU-).
SIG*Br(UPSI --> MU+ MU-).
SIG*Br(UPSI --> MU+ MU-).
Forum