This paper presents measurements of \k\ and \lam\ production in neutral current, deep inelastic scattering of 26.7 GeV electrons and 820 GeV protons in the kinematic range $ 10 < Q~{2} < 640 $ GeV$~2$, $0.0003 < x < 0.01$, and $y > 0.04$. Average multiplicities for \k\ and \lam\ production are determined for transverse momenta \ \ptr\ $> 0.5 $ GeV and pseudorapidities $\left| \eta \right| < 1.3$. The multiplicities favour a stronger strange to light quark suppression in the fragmentation chain than found in $e~+ e~-$ experiments. The production properties of \k's in events with and without a large rapidity gap with respect to the proton direction are compared. The ratio of neutral \k's to charged particles per event in the measured kinematic range is, within the present statistics, the same in both samples.
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Differential cross sections for a W boson produced in association with jets are measured in a data sample of proton-proton collisions at a center-of-mass energy of 8 TeV recorded with the CMS detector and corresponding to an integrated luminosity of 19.6 inverse femtobarns. The W bosons are identified through their decay mode W to mu nu. The cross sections are reported as functions of jet multiplicity, transverse momenta, and the scalar sum of jet transverse momenta (HT) for different jet multiplicities. Distributions of the angular correlations between the jets and the muon are examined, as well as the average number of jets as a function of HT and as a function of angular variables. The measured differential cross sections are compared with tree-level and higher-order recent event generators, as well as next-to-leading-order and next-to-next-to-leading-order theoretical predictions. The agreement of the generators with the measurements builds confidence in their use for the simulation of W+jets background processes in searches for new physics at the LHC.
The cross section measurement as a function of the exclusive jet multiplicity, for jet multiplicities of up to 7.
The cross section measurement as a function of the exclusive jet multiplicity, for jet multiplicities of up to 7.
The cross section measurement as a function of the inclusive jet multiplicity, for jet multiplicities of up to 7.
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The production of K s 0 , Λ and Λ is measured in π + p interactions at 32 GeV/ c . The total inclusive cross sections are found to be 2.07±0.14, 1.00±0.10 and 0.14±0.04 mb, respectively. The energy dependence of total inclusive cross sections and inclusive distributions is discussed and a comparison is made with p, p , K + and K − induced reactions. We find that the factorization hypothesis is satisfied for the inclusive reactions π + p→ Λ X and K + p→ Λ X. Multi-strange-particle production is similar in π + p and K + p interactions at 32 GeV/ c . There is evidence for beam fragmentation in Λ production. The hierarchy of Λ inclusive cross sections in p , K + , π + and K − induced reactions at 32 GeV/ c is qualitatively explained by a quark recombination model. The cross sections for inclusive K ∗ + (892) and Σ + (1385) production in 32 GeV/ c π + p interactions are 1.07±0.57 mb and 0.19±0.08 mb, respectively.
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New experimental results are presented on inclusive production properties of\(\bar \Sigma ^{ *+ } \)(1385) and\(\bar \Sigma ^{ *+ } \)(1385) inK+p interactions at 32 GeV/c. The analysis is based on significantly larger statistics than previously available. A comparison is also made of invariantx-distributions ofK0/\(\bar K^0 \),\(\bar \Lambda \) and\(\bar \Xi ^ +\) and of\(\bar \Sigma ^{ *\pm } \)(1385) andK*+(892). These spectra exhibit regularities expected from the quark-recombination picture when it is assumed that the strange mesons and antibaryons are produced off the strange\(\bar s\)-valence-quark in the incidentK+ meson. Transverse momentum distributions are also presented forK*+(892) and\(\bar \Sigma ^{ *\pm } \)(1385) and found to be very similar. The results on strange antibaryon average multiplicities disagree strongly with a recent version of the additive quark model.
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The production properties ofKs0,\(\bar \Lambda\) andK+p interactions at 32 GeV/c are investigated using the final statistics of the experiment. We present total and semi-inclusive cross sections and aver-age multiplicities. Estimates are given of the diffractive dissociation contributions to total and differential cross sections. Thex-,pT−, and transverse mass dependence of inclusive and semi-inclusive distributions is discussed as well as properties of “prompt”Ks0's. The ratio of “prompt”K890+ (K8900) to “prompt”K0 cross sections is measured to be 1.03±0.12 (0.98±0.17). From a comparison of\(\bar \Lambda\) production inK±p interactions at 32 GeV/c, we estimate a strange sea-quark suppression of 0.26 ±0.02. The double differential cross sections ofKs0's is studied as a function of Feynman-x andpT2, and a Triple-Regge fit performed. The data are compared in detail to versions of the Lund-model for low-pT hadronic collisions.
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Inclusive production of Δ ++ (1232) with >| t p, Δ ++>|<0.6 (GeV/ c ) 2 is studied in 32 GeV/ c K + p interactions. A systematic comparison with the reaction K + p→pX for >| t p,p>| < 0.6 (GeV/ c ) 2 is made. The production properties of the Δ ++ (1232), of associated π + , π − and K 0 production and of the recoiling system X 0 are investigated in detail. The polarization of the Δ ++ and the energy dependence of the total K + π − cross sections, determined by a Chew-Low extrapolation, are presented and discussed.
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