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.
Differential cross sections for jet photoproduction in the reaction ep --> e jet X have been measured with the ZEUS detector at HERA using 82.2 pb^-1 of integrated luminosity. Inclusive jet cross sections are presented as a function of the jet transverse energy, E_T^jet, for jets with E_T^jet > 17 GeV and pseudorapidity -1 < eta^jet < 2.5, in the gamma-p centre-of-mass-energy range 142 < W_gamma-p < 293 GeV. Scaled jet invariant cross sections are presented as a function of the dimensionless variable x_T = 2 E_T^jet/W_gamma-p for
Measured inclusive jet cross section.
Measured scaled jet invariant cross section in two W intervals.
Ratio of the measured scaled jet invariant cross section in the two W intervals.
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.
Kinematically complete measurements of the $pp\to pp\pi^{0}$ reaction were performed for beam energies in the range $292 - 298 $MeV. By detecting both protons in coincidence with the large acceptance COSY-TOF spectrometer set up at an external beam line of the proton synchrotron COSY-Julich, total and differential cross sections and energy distributions were obtained. A strong enhancement is observed in the Dalitz plots resulting from the final state interaction between the outgoing proton pair: the data are well reproduced by Monte Carlo simulations with standard parameters for scattering length $a_0$=-7.83 fm and effective range $r_0$=2.8 fm. The total cross sections exceed the ones measured recently in internal target experiments at IUCF and CELSIUS by roughly 50%. Arguments are presented which link this discrepancy with the effect of the final state interaction pushing yield into the very small-angle region and the near-impossibility of an internal target experiment to cover just this range.
Total P P --> P P PI0 cross section.
Transverse mass spectra of protons emitted in Au+Au collisions at beam energies of 6, 8, and 10.8 GeV/nucleon have been measured as a function of collision centrality over a rapidity range 0.5
The inverse slope, mean transverse mass and rapidity density values for centrality 0 to 5 PCT for 6 GeV/nucleon collisions. Statistical errors only.
The inverse slope, mean transverse mass and rapidity density values for centrality 5 to 12 PCT for 6 GeV/nucleon collisions. Statistical errors only.
The inverse slope, mean transverse mass and rapidity density values for centrality 12 to 23 PCT for 6 GeV/nucleon collisions. Statistical errors only.
We have measured the differential cross section for the gamma n --> pi- p and gamma p --> pi+ n reactions at center of mass angle of 90 degree in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at photon energies greater than 3.3 GeV exhibit a global scaling behavior for both pi- and pi+ photoproduction, consistent with the constituent counting rule and the existing pi+ photoproduction data. Possible oscillations around the scaling value are suggested by these new data The data show enhancement in the scaled cross section at a center-of-mass energy near 2.2 GeV. The cross section ratio of exclusive pi- to pi+ photoproduction at high energy is consistent with the prediction based on one-hard-gluon-exchange diagrams.
Differential cross section at THETA(CM) = 90 degrees.
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.
Inclusive phi-meson production in neutral current deep inelastic e+p scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 45 pb^{-1}. The phi mesons were studied in the range 10
The total PHI meson cross section, corrected for acceptance (45%) in the given kinematical region.
Differential PHI meson cross section as a function of its transverse momentum.
Differential PHI meson cross section as a function of its pseudorapidity.
Inclusive event-shape variables have been measured in the current region of the Breit frame for neutral current deep inelastic ep scattering using an integrated luminosity of 45.0 pb^-1 collected with the ZEUS detector at HERA. The variables studied included thrust, jet broadening and invariant jet mass. The kinematic range covered was 10 < Q^2 < 20,480 GeV^2 and 6.10^-4 < x < 0.6, where Q^2 is the virtuality of the exchanged boson and x is the Bjorken variable. The Q dependence of the shape variables has been used in conjunction with NLO perturbative calculations and the Dokshitzer-Webber non-perturbative corrections (`power corrections') to investigate the validity of this approach.
Mean value of the event shape variables 1-THRUST(C=T) in different Q**2 and X bins.
Mean value of the event shape variables B(C=T) in different Q**2 and X bins.
Mean value of the event shape variables RHO**2 in different Q**2 and X bins.
Inclusive charged hadron production, e+e- -> e+e- h+- X, is studied using 414 pb-1 of data collected at LEP with the L3 detector at centre-of-mass energies between 189 and 202 GeV. Single particle inclusive differential cross sections are measured as a function of the particle transverse momentum, pt, and pseudo-rapidity, eta. For p_t < 1.5 GeV, the data are well described by an exponential, typical of soft hadronic processes. For higher pt, the onset of perturbative QCD processes is observed. The pi+- production cross section for pt > 5 GeV is much higher than the NLO QCD predictions.
Transverse momentum distribution for inclusive charged hadron production.
Transverse momentum distributions for charged pion and charged kaon production separately.
Transverse momentum distributions for charged pion production with different W (effective mass of the GAMMA GAMMA system) cuts.
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