The Lambda(b) differential production cross section and the cross section ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Lambda(b) decays reconstructed in the exclusive final state J/Psi Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and Lambda to proton pion, using a data sample corresponding to an integrated luminosity of 1.9 inverse femtobarns. The product of the cross section times the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls faster than that of b mesons. The measured value of the cross section times the branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06 +/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are statistical and systematic, respectively.
The measured Lambda/B integrated cross section and the ratio of anti-Lambda/B to Lambda/B cross sections.
The measured Lambda/B differential cross section and the ratio of anti-Lambda/B to Lambda/B cross sections as a function of the Lambda/B transverse momentum The second and third systematic errors on the cross sections are the common luminosity and branching fraction uncertainties respectively.
The measured Lambda/B differential cross section and the ratio of anti-Lambda/B to Lambda/B cross sections as a function of the Lambda/B absolute rapidity. The second and third systematic errors on the cross sections are the common luminosity and branching fraction uncertainties respectively.
The reactions p p → K ∗ (890) X , p p →Σ ± (1385) X and p p → S ∗ (993) X at 12 GeV/ c incident momentum have been studied using 19 000 events with a visible V 0 decay in BEBC. Inclusive production cross sections of these resonances as a function of transverse momentum and rapidity are presented. The contribution of annihilation to the production of the K ∗ (890) is investigated from a comparison with the corresponding pp data.
COMBINDED K*+ AND K*- DATA IN THIS TABLE.
COMBINDED K*+ AND K*- DATA IN THIS TABLE.
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Results are presented on the inclusive reactions p p → K 0 X , p p → Λ X and p p → Λ X at an incident antiproton momentum of 12 GeV/ c in BEBC. The cross sections are studied as functions of the Feynman scaling variable x , the rapidity, the transverse momentum of the V 0 and the missing mass squared. The dependence of the Λ and Λ polarization on x are also studied. Comparisons with proton-proton data at 12 GeV/ c are also made. Finally, events with two detected V 0 are analyzed in order to study correlations arising from the production of two strange neutral particles.
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Inclusive non-diffractive photoproduction of rho(770)^0, K^*(892)^0 and phi(1020) mesons is investigated with the H1 detector in ep collisions at HERA. The corresponding average \gamma p centre-of-mass energy is 210 GeV. The mesons are measured in the transverse momentum range 0.5<p_T<7 GeV and the rapidity range |y_{lab}|<1. Differential cross sections are presented as a function of transverse momentum and rapidity, and are compared to the predictions of hadroproduction models.
Inclusive non-diffractive photoproduction cross sections in the specified kinematic region.
Ratios of cross sections.
Inclusive non-diffractive photoproduction invariant differential cross sections as a function of PT in the specified kinematic range.
We present data on the production of the baryons Λ,\(\bar \Lambda \),p and of the baryon resonances Σ*+ (1385) and Δ++ (1232) inK+p and π+p interactions at 250 GeV/c. Results are given on total and semi-inclusive cross sections, Feynman-x spectra, transverse momentum distributions and Λ polarization. The data are compared with measurements at lower energies, with deep inclastic lepton nucleon data and with predictions of quark-parton models. The models underestimate Λ production in the central c.m. region, a feature also seen in recent heavy-ion data. This failure can be cured in JETSET 6.3 by adjustment of the di-quark break-up probability.
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The inclusive production of neutral kaons is studied inK+p and π+p interactions at 250 GeV/c. Total and semi-inclusive cross sections and average kaon multiplicities are presented and compared with the data at lower energies. The longitudinal and transverse momentum distributions and their energy dependence are analyzed. The results are interpreted in the framework of recent parton models.
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The inclusive production cross sections of the strange vector mesons K*0, K*0bar, and phi have been measured in interactions of 920 GeV protons with C, Ti, and W targets with the HERA-B detector at the HERA storage ring. Differential cross sections as a function of rapidity and transverse momentum have been measured in the central rapidity region and for transverse momenta up to pT=3.5 GeV/c. The atomic number dependence is parametrised as sigma(pA) = sigma(pN)*A**alpha, where sigma(pN) is the proton-nucleon cross section. Within the phase space accessible, alpha(K*0) = 0.86+/-0.03, alpha(K*0bar) = 0.87+/-0.03, and alpha(phi) = 0.96+/-0.02. The total proton-nucleon cross sections, determined by extrapolating the differential measurements to full phase space, are sigma(pN->K*0) = 5.06+/-0.54 mb, sigma(pN->K*0bar) = 4.02+/-0.45 mb, and sigma(pN->phi) = 1.17+/-0.11 mb. The Cronin effect is observed for the first time for vector mesons containing strange quarks/ compared to the measurements of Cronin et al. for K+- mesons, the measured values of alpha for phi mesons coincide with those of K- mesons for all transverse momenta, while the enhancement for K*0 / K*0bar mesons is smaller.
Measured rapidity distribution for K*0 production in the accessible phase space.
Measured rapidity distribution for K*BAR0 production in the accessible phase space.
Measured rapidity distribution for PHI production in the accessible phase space.
The production of $J/\psi$ mesons accompanied by open charm, and of pairs of open charm hadrons are observed in pp collisions at a centre-of-mass energy of 7 TeV using an integrated luminosity of $355pb^{-1}$ collected with the LHCb detector. Model independent measurements of absolute cross-sections are given together with ratios to the measured $J/\psi$ and open charm cross-sections. The properties of these events are studied and compared to theoretical predictions.
Normalized differential cross-section $d\ln\sigma(pp\rightarrow J/\psi D^0 X)/dp_T(J/\psi)$ for $2<y(J/\psi)<4$, $p_T(J/\psi)<12$ GeV/$c$, $2<y(D^0)<4$, $3<p_T(D^0)<12$ GeV/$c$ region.
Normalized differential cross-section $d\ln\sigma(pp\rightarrow J/\psi D^+ X)/dp_T(J/\psi)$ for $2<y(J/\psi)<4$, $p_T(J/\psi)<12$ GeV/$c$, $2<y(D^+)<4$, $3<p_T(D^+)<12$ GeV/$c$ region.
Normalized differential cross-section $d\ln\sigma(pp\rightarrow J/\psi D_s^+ X)/dp_T(J/\psi)$ for $2<y(J/\psi)<4$, $p_T(J/\psi)<12$ GeV/$c$, $2<y(D_s^+)<4$, $3<p_T(D_s^+)<12$ GeV/$c$ region.
An analysis of the production of the Λ baryon in the hadronic decays of the Z 0 is presented, based on about 993K multihadronic events collected by the DELPHI detector at LEP during 1991 and 1992. The differencial cross section of the Λ and the correlations between Λ and Λ produced in the same event are compared to current models, based both on string fragmentation and on cluster decay. The predictions of the string fragmentation model are found to give satisfactory agreements with the data, clearly better than those of the cluster model.
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Combined LAMBDA and LAMBDABAR multiplicity.
Errors contain systematic uncertainties.
Measurements of the inclusive cross-sections forK0 and Λ production in hadronic decays of the Z are presented together with measurements of two-particle correlations within pairs of Λ andK0. The results are compared with predictions from the hadronization models Jetset, based on string fragmentation, and Herwig, based on cluster decays. TheK0 spectrum is found to be harder than predicted by both models, while the Λ spectrum is softer than predicted. The correlation measurements are all reproduced well by Jetset, while Herwig misses some of the qualitative features and overestimates the size of the\(\Lambda \bar \Lambda \) correlation. Finally, the possibility of Bose-Einstein correlation in theKS0KS0 system is discussed.
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