We study the process e+e- -> pi+pi-pi+pi-gamma, with a photon emitted from the initial-state electron or positron, using 454.3 fb^-1 of data collected with the BABAR detector at SLAC, corresponding to approximately 260,000 signal events. We use these data to extract the non-radiative sigma(e+e- ->pi+pi-pi+pi-) cross section in the energy range from 0.6 to 4.5 Gev. The total uncertainty of the cross section measurement in the peak region is less than 3%, higher in precision than the corresponding results obtained from energy scan data.
The dressed and undressed cross sections for the reaction E+ E- --> PI+ PI- PI+ PI-. Statistical errors only.
The ALICE experiment has measured low-mass dimuon production in pp collisions at $\sqrt{s} = 7$ TeV in the dimuon rapidity region 2.5<y<4. The observed dimuon mass spectrum is described as a superposition of resonance decays ($\eta$, $\rho$, $\omega$, $\eta^{'}$, $\phi$) into muons and semi-leptonic decays of charmed mesons. The measured production cross sections for $\omega$ and $\phi$ are $\sigma_\omega$ (1<$p_{\rm T}$<5 GeV/$c$,2.5<y<4) = 5.28 $\pm$ 0.54 (stat) $\pm$ 0.50 (syst) mb and $\sigma_\phi$(1<$p_{\rm T}$<5 GeV/$c$,2.5<y<4)=0.940 $\pm$ 0.084 (stat) $\pm$ 0.078 (syst) mb. The differential cross sections $d^2\sigma/dy dp_{\rm T}$ are extracted as a function of $p_{\rm T}$ for $\omega$ and $\phi$. The ratio between the $\rho$ and $\omega$ cross section is obtained. Results for the $\phi$ are compared with other measurements at the same energy and with predictions by models.
Differential phi cross section from the di-muon channel as a function of transverse momentum, the first error is statistical, the first systematic error is the correlated one, the second is the non-correlated one.
Differential omega cross section from the di-muon channel as a function of transverse momentum, the first error is statistical, the first systematic error is the correlated one, the second is the non-correlated one.
Total phi cross section from the di-muon data. The first error is statistical, the second is a systematic error.
This paper reports a measurement of D*+/- meson production in jets from proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the CERN Large Hadron Collider. The measurement is based on a data sample recorded with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets with transverse momentum between 25 and 70 GeV in the pseudorapidity range |eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z < 1. Monte Carlo predictions fail to describe the data at small values of z, and this is most marked at low jet transverse momentum.
Percentage D*+- production rate R in Z and PT bins.
Percentage D*+- production rate R integrated over jet PT 25-70 GeV as a function of Z.
D*+- production rate R integrated over jet PT=25-70 GeV and Z=0.3-1.0.
Spectra of positively charged kaons in p+C interactions at 31 GeV/c were measured with the NA61/SHINE spectrometer at the CERN SPS. The analysis is based on the full set of data collected in 2007 with a graphite target with a thickness of 4% of a nuclear interaction length. Interaction cross sections and charged pion spectra were already measured using the same set of data. These new measurements in combination with the published ones are required to improve predictions of the neutrino flux for the T2K long baseline neutrino oscillation experiment in Japan. In particular, the knowledge of kaon production is crucial for precisely predicting the intrinsic electron neutrino component and the high energy tail of the T2K beam. The results are presented as a function of laboratory momentum in 2 intervals of the laboratory polar angle covering the range from 20 up to 240 mrad. The kaon spectra are compared with predictions of several hadron production models. Using the published pion results and the new kaon data, the K+/\pi+ ratios are computed.
The measured K+ production cross section and the K+/PI+ cross section ratio for the angular range 20 to 140 mrad. The errors on the ratios are statistical only.
The measured K+ production cross section and the K+/PI+ cross section ratio for the angular range 140 to 240 mrad. The errors on the ratios are statistical only.
Results are presented on the production of jets of particles in association with a Z/gamma* boson, in proton-proton collisions at sqrt(s) = 7 TeV with the ATLAS detector. The analysis includes the full 2010 data set, collected with a low rate of multiple proton-proton collisions in the accelerator, corresponding to an integrated luminosity of 36 pb^-1. Inclusive jet cross sections in Z/gamma* events, with Z/gamma* decaying into electron or muon pairs, are measured for jets with transverse momentum pT > 30 GeV and jet rapidity |y| < 4.4. The measurements are compared to next-to-leading-order perturbative QCD calculations, and to predictions from different Monte Carlo generators implementing leading-order matrix elements supplemented by parton showers.
Cross section for Inclusive Jet Multiplicity corrected to the lepton common fiducial region and for QED radiation effects.
Ratio of cross sections for N/N-1 inclusive jet multiplicities corrected to the lepton common fiducial region and for QED radiation effects.
Inclusive jet differential cross section dsigma/dpt corrected to the lepton common fiducial region and for QED radiation effects.
A measurement of the J/psi and psi(2S) production cross sections in pp collisions at sqrt(s)=7 TeV with the CMS experiment at the LHC is presented. The data sample corresponds to an integrated luminosity of 37 inverse picobarns. Using a fit to the invariant mass and decay length distributions, production cross sections have been measured separately for prompt and non-prompt charmonium states, as a function of the meson transverse momentum in several rapidity ranges. In addition, cross sections restricted to the acceptance of the CMS detector are given, which are not affected by the polarization of the charmonium states. The ratio of the differential production cross sections of the two states, where systematic uncertainties largely cancel, is also determined. The branching fraction of the inclusive B to psi(2S) X decay is extracted from the ratio of the non-prompt cross sections to be: BR(B to psi(2S) X) = (3.08 +/- 0.12(stat.+syst.) +/- 0.13(theor.) +/- 0.42(BR[PDG])) 10^-3
The (unpolarised) acceptance corrected J/PSI cross section times branching ratio to MU+ MU- for (PROMPT) and NON-PROMPT) production in the |rapidity| bin 0.0-0.9.
The (unpolarised) acceptance corrected J/PSI cross section times branching ratio to MU+ MU- for (PROMPT) and NON-PROMPT) production in the |rapidity| bin 0.9-1.2.
The (unpolarised) acceptance corrected J/PSI cross section times branching ratio to MU+ MU- for (PROMPT) and NON-PROMPT) production in the |rapidity| bin 1.2-1.6.
The production of Kshort and Lambda hadrons is studied in inelastic pp collisions at sqrt(s) = 0.9 and 7 TeV collected with the ATLAS detector at the LHC using a minimum-bias trigger. The observed distributions of transverse momentum, rapidity, and multiplicity are corrected to hadron level in a model-independent way within well defined phase-space regions. The distribution of the production ratio of Lambdabar to Lambda baryons is also measured. The results are compared with various Monte Carlo simulation models. Although most of these models agree with data to within 15% in the Kshort distributions, substantial disagreements with data are found in the Lambda distributions of transverse momentum.
The corrected transverse momentum distribution of KS mesons at 7000 GeV.
The corrected rapidity distribution of KS mesons at 7000 GeV.
The corrected multiplicity distribution of KS mesons at 7000 GeV.
A measurement of the exclusive two-photon production of muon pairs in proton-proton collisions at sqrt(s)= 7 TeV, pp to p mu^+ mu^- p, is reported using data corresponding to an integrated luminosity of 40 inverse picobarns. For muon pairs with invariant mass greater than 11.5 GeV, transverse momentum pT(mu) > 4 GeV and pseudorapidity |eta(mu)| < 2.1, a fit to the dimuon pt(mu^+ mu^-) distribution results in a measured cross section of sigma(pp to p mu^+ mu^- p) = 3.38 [+0.58 -0.55] (stat.) +/- 0.16 (syst.) +/- 0.14 (lumi.) pb, consistent with the theoretical prediction evaluated with the event generator Lpair. The ratio to the predicted cross section is 0.83 [+0.14-0.13] (stat.) +/- 0.04 (syst.) +/- 0.03 (lumi.). The characteristic distributions of the muon pairs produced via photon-photon fusion, such as the muon acoplanarity, the muon pair invariant mass and transverse momentum agree with those from the theory.
Cross section for the for the process P P --> P MU+ MU- P.
This Letter presents a measurement of WZ production in 1.02 fb^-1 of pp collision data at sqrt(s) = 7 TeV collected by the ATLAS experiment in 2011. Doubly leptonic decay events are selected with electrons, muons and missing transverse momentum in the final state. In total 71 candidates are observed, with a background expectation of 12.1 +/- 1.4(stat.) +4.1/-2.0(syst) events. The total cross section for WZ production for Z gamma^* masses within the range 66 GeV to 116 GeV is determined to be sigma_WZ^tot = 20.5 +3.1/-2.8(stat.) +1.4/-1.3(syst.) +0.9/-0.8(lumi.)pb, which is consistent with the Standard Model expectation of 17.3 +1.3/-0.8 pb. Limits on anomalous triple gauge boson couplings are extracted.
Total fiducial cross-section $WZ\to\ell\nu\ell\ell$.
We report on double-differential inclusive cross-sections of the production of secondary protons, charged pions, and deuterons, in the interactions with a 5% {\lambda}int thick stationary aluminium target, of proton and pion beams with momentum from \pm3 GeV/c to \pm15 GeV/c. Results are given for secondary particles with production angles between 20 and 125 degrees. Cross-sections on aluminium nuclei are compared with cross-sections on beryllium, carbon, copper, tin, tantalum and lead nuclei.
Ratio of deuterons to protons for polar angle 20-30 deg.
Ratio of deuterons to protons for polar angle 30-45 deg.
Ratio of deuterons to protons for polar angle 45-65 deg.
Forum