The cross section for the reaction $ e p \to e^{\prime} p \pi^{+} \pi^{-}$ was measured in the resonance region for 1.4$<$W$<$2.1 GeV and 0.5$
Measured cross section DSIG/DM(PI+PI-) for the W range 1400 to 1425GeV.
Measured cross section DSIG/DM(PI+PI-) for the W range 1425 to 1450GeV.
Measured cross section DSIG/DM(PI+PI-) for the W range 1450 to 1475GeV.
The differential cross section, $d\sigma/dt$ for $\omega$ meson exclusive photoproduction on the proton above the resonance region ($2.6
Differential cross section in the energy region 3.20 to 3.38 GeV.
Differential cross section in the energy region 3.38 to 3.56 GeV.
Differential cross section in the energy region 3.56 to 3.74 GeV.
We have measured the mean charged particle multiplicities separately for bbbar, ccbar and light quark (uubar, ddbar, ssbar) initiated events produced in e+e- annihilations at LEP. The data were recorded with the OPAL detector at eleven different energies above Z0 peak, corresponding to the full statistics collected at LPE1.5 and LEP2. The difference in mean charged and particle multiplicities for bbbar and light quark events, delta_bl, measured over this energy range is consistent with an energy independent behaviour, as predicted by QCD, but is inconsistent with the prediction of a more phenomenological approach which assumes that the multiplicity accompanying the decay of a heavy quark is independent of the quark mass itself. Our results, which can be combined into the single measurement delta_bl = 3.44+-0.40(stat)+-0.89(syst) at a luminosity weighted average centre-of mass energy of 195 GeV, are also consistent with an energy independent behaviour as extrapolated from lower energy data.
Corrected mean charged particle multiplicities for the different quark quarkbar initiated events.
The inclusive cross section for J/ψ production times the branching ratio B(J/ψ→μ+μ−) has been measured in the forward pseudorapidity region: B×dσ[p¯+p→J/ψ(pT>10GeV/c,2.1<|η|<2.6)+X]/dη=192±9(stat)±29(syst)pb. The results are based on 74.1±5.2pb−1 of data collected by the CDF Collaboration at the Fermilab Tevatron Collider. The measurements extend earlier measurements of the D0 Collaboration to higher pTJ/ψ. In the kinematic range where the experiments partially overlap, these data are in good agreement with previous measurements.
The integrated cross section for J/PSI --> MU+ MU- decay.
Cross section as a function of PT. Statistical errors only.
Using data collected by the HERA-B experiment, we have measured the fraction of J\psi's produced via radiative chi_c decays in interactions of 920 GeV protons with carbon and titanium targets. We obtained R_{\chi_c} = 0.32 \pm 0.06_{stat} \pm 0.04_{sys} for the fraction of J\psi from chi_c decays averaged over proton-carbon and proton-titanium collisions. This result is in agreement with previous measurements and is compared with theoretical predictions.
Ratio of CHIC to J/PSI production cross section in P C interactions for the E+ E- and MU+ MU- channels separately.
Ratio of CHI/C to J/PSI production cross section in P TI interactions for the E+ E- and MU+ MU- channels separately.
Averaged ratio of CHIC to J/PSI production cross section in P C and P Ti interactions.
Values of the ratios in the mid-rapidity yields of anti-Lambda/Lambda = 0.71 +/- 0.01(stat.) +/- 0.04(sys.), anti-Xi+/Xi- = 0.83 +/- 0.04(stat.) +/- 0.05 (sys.), anti-Omega+/Omega- = 0.95 +/- 0.15(stat) +/- 0.05(sys.) and K+/K- 1.092 +/- 0.023(combined) were obtained in central sqrt(s_NN) = 130 GeV Au+Au collisions using the STAR detector. The ratios indicate that a fraction of the net-baryon number from the initial system is present in the excess of hyperons over anti-hyperons at mid-rapidity. The trend in the progression of the baryon ratios, with increasing strange quark content, is similar to that observed in heavy-ion collisions at lower energies. The value of these ratios may be related to the charged kaon ratio in the framework of simple quark-counting and thermal models.
Invariant mass distributions for $\Lambda$ and Anti-$\Lambda$
Invariant mass distributions for $\Xi$ and Anti-$\Xi$
Invariant mass distributions for $\Omega$ and Anti-$\Omega$
We report the results of a new measurement of spin structure functions of the deuteron in the region of moderate momentum transfer ($Q^2$ = 0.27 -- 1.3 (GeV/c)$^2$) and final hadronic state mass in the nucleon resonance region ($W$ = 1.08 -- 2.0 GeV). We scattered a 2.5 GeV polarized continuous electron beam at Jefferson Lab off a dynamically polarized cryogenic solid state target ($^{15}$ND$_3$) and detected the scattered electrons with the CEBAF Large Acceptance Spectrometer (CLAS). From our data, we extract the longitudinal double spin asymmetry $A_{||}$ and the spin structure function $g_1^d$. Our data are generally in reasonable agreement with existing data from SLAC where they overlap, and they represent a substantial improvement in statistical precision. We compare our results with expectations for resonance asymmetries and extrapolated deep inelastic scaling results. Finally, we evaluate the first moment of the structure function $g_1^d$ and study its approach to both the deep inelastic limit at large $Q^2$ and to the Gerasimov-Drell-Hearn sum rule at the real photon limit ($Q^2 \to 0$). We find that the first moment varies rapidly in the $Q^2$ range of our experiment and crosses zero at $Q^2$ between 0.5 and 0.8 (GeV/c)$^2$, indicating the importance of the $\Delta$ resonance at these momentum transfers.
The measured virtual photon asymmetry (A1D+ETA*A2D) for the Q** region 0.27to 0.39 GeV**2.
The measured virtual photon asymmetry (A1D+ETA*A2D) for the Q** region 0.39to 0.65 GeV**2.
The measured virtual photon asymmetry (A1D+ETA*A2D) for the Q** region 0.65to 1.3 GeV**2.
Inclusive differential cross sections $d\sigma_{pA}/dx_F$ and $d\sigma_{pA}/dp_t^2$ for the production of \kzeros, \lambdazero, and \antilambda particles are measured at HERA in proton-induced reactions on C, Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to $\sqrt {s} = 41.6$ GeV in the proton-nucleon system. The ratios of differential cross sections \rklpa and \rllpa are measured to be $6.2\pm 0.5$ and $0.66\pm 0.07$, respectively, for \xf $\approx-0.06$. No significant dependence upon the target material is observed. Within errors, the slopes of the transverse momentum distributions $d\sigma_{pA}/dp_t^2$ also show no significant dependence upon the target material. The dependence of the extrapolated total cross sections $\sigma_{pA}$ on the atomic mass $A$ of the target material is discussed, and the deduced cross sections per nucleon $\sigma_{pN}$ are compared with results obtained at other energies.
Inclusive differential cross section DSIG/DXL for K0S production in the XL interval -0.12 to 0.0 plus the total cross section after extrapolation to the full XL range.
Inclusive differential cross section DSIG/DXL for LAMBDA production in the XL interval -0.12 to 0.0 plus the total cross section after extrapolation to thefull XL range.
Inclusive differential cross section DSIG/DXL for LAMBDABAR production in the XL interval -0.12 to 0.0 plus the total cross section after extrapolation to the full XL range.
We measured the inclusive electron-proton cross section in the nucleon resonance region (W < 2.5 GeV) at momentum transfers Q**2 below 4.5 (GeV/c)**2 with the CLAS detector. The large acceptance of CLAS allowed for the first time the measurement of the cross section in a large, contiguous two-dimensional range of Q**2 and x, making it possible to perform an integration of the data at fixed Q**2 over the whole significant x-interval. From these data we extracted the structure function F2 and, by including other world data, we studied the Q**2 evolution of its moments, Mn(Q**2), in order to estimate higher twist contributions. The small statistical and systematic uncertainties of the CLAS data allow a precise extraction of the higher twists and demand significant improvements in theoretical predictions for a meaningful comparison with new experimental results.
No description provided.
No description provided.
No description provided.
Charmonium production in p – A collisions is a unique tool for the study of the interaction of bound c c states in nuclear matter. It can provide details on the basic features of the resonance formation mechanism and, in particular, on its non-perturbative aspects. In this Letter, we present an experimental study of charmonia and Drell–Yan production in proton–nucleus collisions at 450 GeV/ c . The results are analyzed in the framework of the Glauber model and lead to the values of the nuclear absorption cross-section σ abs pA for J / ψ and ψ ′. Then, we compare the J / ψ absorption in proton–nucleus and sulphur–uranium interactions, using NA38 data. We obtain that, for the J / ψ , σ abs pA and σ abs SU are compatible, showing that no sizeable additional suppression mechanism is present in S–U collisions, and confirming that the anomalous J / ψ suppression only sets in for Pb–Pb interactions.
The J/PSI production cross section times the branching ratio to MU+ MU- pernucleon-nucleon collision for the differential nuclear targets.
The PSI(3685) production cross section times the branching ratio to MU+ MU-per nucleon-nucleon collision for the differential nuclear targets.
The Drell Yan cross section, divided by the mass number A, and multiplied by the isospin correction factors in the mass interval 2.9 to 4.5 GeV.
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