Backward emitted protons with momentump>0.3 GeV/c in interactions of neutrino in the energy range 10–200 GeV with photoemulsion nuclei were investigated. Energy spectrum slope parameter of backward protons was measured to beT0=48.9±7.9 MeV. TheA-dependence power index of relative mean yield of backward protons was found to bea=0.68±0.12. A drop in the mean yield of backward protons at the four momentum squared over ∼15 (GeV/c)2 (the neutrino energy over ∼50 GeV) was observed.
NUCLEUS IS AVERAGE NUCLEI OF NUCLEAR EMULSION, <A> ABOUT 80.
NUCLEUS IS AVERAGE NUCLEI OF NUCLEAR EMULSION, <A> ABOUT 80.
NUCLEUS IS AVERAGE NUCLEI OF NUCLEAR EMULSION, <A> ABOUT 80.
Using the CELLO detector, we have measured cross sections for the processγγ→π+π− in the mass range 0.75–1.9 GeV/c2. A partial wave fit to the data indicates the presence of a sizeableS-wave amplitude with signs of resonant behaviour. Values for the γγ width of thef2(1270) are given, showing the model-dependence of this quantity. At higher dipion masses, the model of Brodsky and Lepage is found to give an order of magnitude description of the data.
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Meson production in proton, oxygen and sulphur interactions with uranium targets at 200 GeV/nucleon is studied. We measure the inclusive meson cross-section d σ/dPT2 and its evolution fromp+U to S+U. The cross-section fitted with an exponential gives an inverse slopePT0 of the order of 210 MeV/c. As a function of the neutral transverse energy,PT0 values show a slight rise followed by a plateau. The normalized difference (σ+−σ−)/σ− between positive and negative meson cross-sections is found to increase withET.
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NUCLEUS IS P, C, AL, CU.
NUCLEUS IS P, C, AL, CU.
NUCLEUS IS P, C, AL, CU.
We present a high-statistics, species-identified measurement of the W-to-Be per-nucleon cross-section ratio, RW/Be, for high-xt hadrons and high-τ h+h− pairs produced in p-A collisions at √s =38.8 GeV. The data extend to 0.62 in xt and 0.39 in √τ . For single hadrons, RW/Be peaks at pt≊5 GeV/c and decreases to ≊1 for mesons with pt>8 GeV/c. At fixed pt, RW/Be falls with √s . For symmetric pairs with √τ >0.28, RW/Be=0.84±0.02±0.07, suggesting a nuclear suppression of high-z fragmentation. RW/Be increases with pout, indicative of constituent multiple scattering.
No description provided.
We present an analysis of 800-GeV proton-induced Drell-Yan production data from isoscalar targets 2H and C, and from W, which has a large neutron excess. The ratio of cross sections per nucleon, R-σW/σIS, is sensitive to the difference between the d¯(x) and u¯(x) structure functions of the proton. We find that R is close to unity in the range 0.04≤x≤0.27, allowing upper limits to be set on the d¯-u¯ asymmetry. Additionally, the shape of the differential cross section m3 d2σ/dxF dm for 2H at xF≊0 shows no evidence of an asymmetric sea in the proton. We examine the implications of these data for various models of the violation of the Gottfried sum rule in deep-inelastic lepton scattering.
Upper limit at the 2sigma statistical error level. Mass of MU+ MU- in GeV.
The polarization of quasifree Λ hyperons produced by the (π+K+) reaction on C12 and on the deuteron was measured for the first time. The asymmetry of pions from weak decay of the Λ hyperon was used to determine the polarization. The polarization for the deuterium target was found to be consistent with that for the elementary n(π+,K+)Λ reaction. The polarization of the Λ produced by the quasifree process from C12 is consistent with that for the elementary reaction, which demonstrates that the spin characteristics of the elementary reaction are not modified by the nuclear medium.
No description provided.
This letter reports the full reconstruction of B mesons through the decay chain B±→J/ψ K±, J/ψ→μ+μ−, using data obtained at the Collider Detector at Fermilab in p¯p collisions at √s =1.8 TeV. This exclusive sample, the first observed at a hadron collider, is then used to measure the B-meson cross section, from which we extract the b-quark cross section. We obtain σ=2.8±0.9 (stat) ±1.1(syst) μb for B− mesons with PT>9.0 GeV/c and rapidity ‖y‖<1.0. We obtain σ=6.1±1.9(stat) ±2.4(syst) μb, for b quarks with transverse momentum PT>11.5 GeV/c and rapidity ‖y‖<1.0.
B-meson cross section.
B-quark cross section.
We present the first polarization measurements for pion absorption on a nucleus heavier than the deuteron. The polarization of protons resulting from π+ absorption in the He3 was measured at bombarding energies of 120 and 250 MeV. Protons from absorption in a quasideuteron were selected by applying kinematical constraints. A significant discrepancy was observed between the experimental results and theoretical predictions. At 120 MeV the measured polarizations for He3 are consistent with those of the deuteron. At 250 MeV the angular distribution of the polarization is significantly different than for the deuteron, showing sensitivity to the nuclear density, and thus may be sensitive to short range correlations between nucleons.
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