1,048 research outputs found
Relating production and masses of the vector and P-wave mesons for light and heavy flavours al LEP
No full textThe production rates of primary vector and P-wave mesons in Z hadronic decays are analysed. The mass dependence of production rates for the bottom, charm, strange charm and three families of the light-flavour mesons is found to be very similar, allowing to relate the relative production rates for mesons with different flavours and, possibly, their masses. The strange axial mesons K_1(1273) and K_1(1402) might be assigned to the 1^+(1/2) and 1^+(3/2) levels degenerate with the 0^+(1/2) and 2^+(3/2) levels of the K^*_0(1430) and K^*_2(1430), respectively, if the observed K^*_0(1430) mass is replaced by its ``bare'' q\bar{q} mass corresponding to the K-matrix pole and close to the K_1(1273) mass. Then the 0^+(1/2) and 1^+(1/2) levels are below the 1^+(3/2) and 2^+(3/2) levels for the strange, charm and bottom mesons
Comparing fragmentation of strange quark in decays and p reactions
No full textThe ratios of the production rates K*(892)/K, phi/K, rho^0/pi, omega/pi, Delta^{++}/p, Sigma+(1385)/Lambda, Xi^-/Lambda and their x_p dependences obtained from results of the LEP and SLD experiments in Z hadronic decays are analysed. The corresponding ratios for promptly produced mesons are estimated at x_p -> 1. A comparison of the LEP results with those from the Mirabelle and BEBC K+p experiments at 32 and 70 GeV/c shows striking similarity in fragmentation of the strange valence quark of the incident K+ and strange quarks produced in Z decays. The JETSET model describes the LEP, Mirabelle and BEBC results. The model of Pei is consistent with the data for mesons, but presumably underestimates the fractions of primary octet baryons. The quark combinatorics model of Anisovich et al.is incompatible with the data
Do strange quarks in Z decays and kaon valence s-bar quark in Kp reactions fragment differently?
No full textScaling in energy dependence of relative particle production rates and properties of the distributions in annihilations
No full textWith the production rates, , of the K/sup 0/, K/sup +/, p and Lambda and average charged particle multiplicities, , recently measured at LEP1.5-LEP2, scaling of the relative particle production rates / is seen in a broad center of mass energy range from square root s=29-35 to 183 Ge V. The quantity xi /sub 0///sup 1/2 /, where xi /sub 0/ is the position of the maximum of the xi =-In(2p/ square root s) distribution and p is the particle momentum, also scales from 14 to 183 GeV. It is shown that the Gaussian shape of the xi distribution is a simple consequence of longitudinal phase space. The slope parameter in the logarithmic increase of xi /sub 0/ with the center of mass energy must be smaller than 1, as observed experimentally, but this does not necessarily imply a manifestation of coherence. (14 refs)
Hyperfine splitting in light-flavour hadron production at LEP
No full textThe production rates of light-flavour hadrons at LEP~1 are set by their masses, spins, strangeness suppression, and strongly influenced by the spin-spin interactions of their quarks. Similarities in production of pseudoscalar mesons and octet baryons, vector mesons and decuplet baryons are observed and explained by the relative spin configurations of their quarks. Similarity in production of tensor mesons and is also seen. The vector-to-pseudoscalar meson and decuplet-to-octet baryon suppressions are the same and explained by the hyperfine mass splitting. The strangeness suppression factor, , is the same for mesons and baryons. It is related to the difference in the constituent quark masses, , where , at the temperature, ~MeV/. No evidence for additional suppression of strange baryons is observed. The LEP~1 data are compared with hadronic reactions and heavy nuclear collisions
Relative Production of Vector and Pseudoscalar States for Light- and Heavy-Flavour Mesons
No full textThe production ratios for strange, charm and beauty mesons evaluated from the ratio, measured at LEP for primary produced and , agree with the results of LEP and lower energy experiments
Inclusive neutral kaon production in 70 GeV/c Kp interactions
No full textThe inclusive production of neutral kaons in 70 GeV/c K/sup +/p interactions is studied with the CERN BEBC bubble chamber. The (semi-) inclusive cross sections are interpreted in terms of the various strangeness channels leading to neutral kaon production. The invariant inclusive cross section for kaon production is studied as a function of p/sub t//sup 2/ and the Feynman variable x. The latter distributions are considered both 'raw' and corrected for the presence of K/sup 0/'s resulting from K* decay. They are compared with the prediction expected from the Regge-Mueller formalism, the recombination model and fragmentation models. (24 refs)
Slow proton and Delta /sup ++/ production in K/sup +/p interactions at 70 GeV/c
No full textThe inclusive inelastic processes K/sup +/p to pX/sup +/ and K/sup +/p to Delta /sup ++/X/sup 0/ are studied in an incident momentum of 70 Ge V/C. The data comes from the Big European Bubble Chamber BEBC filled with hydrogen, exposed to an rf separated K/sup +/ beam at the CERN SPS accelerator. The inclusive cross section is measured for protons with laboratory momentum p/sub LAB/<or approximately=1.2 GeV/c. Comparisons are made with other K/sup +/p data and with pp data at 69 GeV/c. Evidence is found for Pomeron exchange at the beam vertex both for slow proton and Delta /sup ++/-production as well as for absorptive pion exchange at the (p, Delta /sup ++/) vertex. (11 refs)
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