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.
Muon pair production is studied in p - W and S U collisions at 200 GeV per nucleon, as a function of transverse momentum P Tμμ . The inclusive ϱ + ω and Φ differential cross-sections dσ dP T are measured in the dimuon decay channel, for P T ≥ 0.6 GeV/c, in the central rapidity region, 3.0≤ y ≤ 4.0. Assuming the power law A-dependence σ = σ 0 ( A beam · A target ) α , the study of the integrated cross-sections for p - W and S U collisions leads to α ϱ + ω = 1.00±0.02±0.07 and α Φ = 1.23±0.03±0.05, showing clear evidence of Φ enhancement in S U interactions as compared to p - W collisions.
Statistical errors only.
Statistical errors only.
Statistical errors only.
None
THE RATIO SIG(RHO0)/SIG(OMEGA) IS FREE PARAMETER.
THE RATIO SIG(RHO0)/SIG(OMEGA)=1. AND FIXED.
No description provided.
We report the measurements of the inclusive μ-pair production by 150-GeV protons and π+ mesons on beryllium. Absolute cross sections as well as the Feynman-x and PT dependence are presented in the mass region between 0.211 and 3.5 GeV/c2. Upper limits are also given for the inclusive production of η and ρ′(1600) mesons.
DATA OBTAINED FROM FIGURE BY A.A. LEBEDEV.
DATA OBTAINED FROM FIGURE BY A.A. LEBEDEV.
No description provided.
Results of the experimental study of inclusive φ meson production off berillium nuclei by 70 GeV/ c protons in the beam fragmentation region x > 0.41 are presented. Fitting of the measured differential cross sections to the forms d σ d x ∼ (1 − x) n x and d σ d p 2 t ∼ exp (−bp 2 t ) gives the parameters n = 6.0 ± 1.7 and b = (2.4 ± 0.7) (GeV/ c ) −2 . In the framework of a quark-parton model the measured φ meson x -distribution suggests that in the region of x > 0.41 nearly 90% of the φ mesons are produced via a strange sea quark fusion. The ratio of the OZI-forbidden and OZI-allowed transition coupling constants has been found to be ten times smaller than the same ratio calculated from the partial decay widths. The total inclusive cross section is estimated to be σ (pN → φ X) = (0.7 ± 0.2) × 10 −27 cm 2 .
No description provided.
No description provided.
No description provided.
We use low mass dimuons (0.35 < M μμ ⩽ 2 GeV/ c 2 ) to analyse the production at high transverse momentum ( P T ⩾ 2 GeV/ c ) of the resonances ϱ, ω, π. We have studied the variation of the cross section with the type of incident particle (π, K, p) at 150, 200, 280 GeV/ c and the nuclear effects by comparison of platinum and hydrogen targets. There is no significant difference between the slopes of the transverse momentum distributions with those observed at lower P T (0 < P T < 2 GeV/ c ), meanwhile x F -distributions show a leading effect in the production of gf by kaons at these relatively high transverse momenta.
No description provided.
No description provided.
No description provided.
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