The angular distribution for the reaction n+p→d+γ has been measured at neutron energies of 475, 560, 625, and 750 MeV. Results based on 31 000 events at nine scattering angles are reported and compared with existing data for the inverse reaction, γ+d→n+p. The angular distributions are found to agree, as predicted by time-reversal invariance.
No description provided.
The strong coupling alpha_s(M_Z^2) has been measured using hadronic decays of Z^0 bosons collected by the SLD experiment at SLAC. The data were compared with QCD predictions both at fixed order, O(alpha_s^2), and including resummed analytic formulae based on the next-to-leading logarithm approximation. In this comprehensive analysis we studied event shapes, jet rates, particle correlations, and angular energy flow, and checked the consistency between alpha_s(M_Z^2) values extracted from these different measures. Combining all results we obtain alpha_s(M_Z^2) = 0.1200 \pm 0.0025(exp.) \pm 0.0078(theor.), where the dominant uncertainty is from uncalculated higher order contributions.
Final average value of alpha_s. The second (DSYS) error is from the uncertainty on the theoretical part of the calculation.
TAU is 1-THRUST.
RHO is the normalized heavy jet mass MH**2/EVIS**2.
The parity-violating asymmetries between a longitudinally-polarized electron beam and an unpolarized deuterium target have been measured recently. The measurement covered two kinematic points in the deep inelastic scattering region and five in the nucleon resonance region. We provide here details of the experimental setup, data analysis, and results on all asymmetry measurements including parity-violating electron asymmetries and those of inclusive pion production and beam-normal asymmetries. The parity-violating deep-inelastic asymmetries were used to extract the electron-quark weak effective couplings, and the resonance asymmetries provided the first evidence for quark-hadron duality in electroweak observables. These electron asymmetries and their interpretation were published earlier, but are presented here in more detail.
Asymmetry results on $\vec e-^2$H parity-violating scattering from the PVDIS experiment at JLab.
Asymmetry results on $\vec e-^2$H parity-violating scattering from the PVDIS experiment at JLab, for RES I settings.
Asymmetry results on $\vec e-^2$H parity-violating scattering from the PVDIS experiment at JLab, for RES II settings.
Precise measurements of the spin structure functions of the proton $g_1^p(x,Q^2)$ and deuteron $g_1^d(x,Q^2)$ are presented over the kinematic range $0.0041 \leq x \leq 0.9$ and $0.18 $ GeV$^2$ $\leq Q^2 \leq 20$ GeV$^2$. The data were collected at the HERMES experiment at DESY, in deep-inelastic scattering of 27.6 GeV longitudinally polarized positrons off longitudinally polarized hydrogen and deuterium gas targets internal to the HERA storage ring. The neutron spin structure function $g_1^n$ is extracted by combining proton and deuteron data. The integrals of $g_1^{p,d}$ at $Q^2=5$ GeV$^2$ are evaluated over the measured $x$ range. Neglecting any possible contribution to the $g_1^d$ integral from the region $x \leq 0.021$, a value of $0.330 \pm 0.011\mathrm{(theo.)}\pm0.025\mathrm{(exp.)}\pm 0.028$(evol.) is obtained for the flavor-singlet axial charge $a_0$ in a leading-twist NNLO analysis.
Integrals of G1 for P, DEUT and N targets.. The second DSYS systematic error is due to the uncertainty in the parameterizations (R, F2, A2, Azz, omegaD).. The third DSYS systematic error is due to the uncertainty in evolving to a common Q**2.
Integrals of G1 for the Non-Singlet contributions.. The second DSYS systematic error is due to the uncertainty in the parameterizations (R, F2, A2, Azz, omegaD).. The third DSYS systematic error is due to the uncertainty in evolving to a common Q**2. Axis error includes +- 5.2/5.2 contribution.
Integrals of G1 over different X ranges for P target at various Q*2 values. The second DSYS systematic error is due to the uncertainty in the parameterizations (R, F2, A2, Azz, omegaD).. The third DSYS systematic error is due to the uncertainty in evolving to a common Q**2. Axis error includes +- 5.2/5.2 contribution.
Data are presented on inclusiveKs0 and Λ production inK+ and π+ collisions with Al and Au nuclei at 250 GeV/c. Results are given on total inclusive cross sections and theA dependence, as well as on distributions in Feynman-xF, rapidityy and transverse momentum. Ratios ofKS0 and of Λ to π+ production are presented. The data are compared with predictions of the quark-parton model FRITIOF.
No description provided.
No description provided.
No description provided.
An analysis of the reaction K−p→K−pπ+π− at 2.0-GeVc incident momentum is presented. The total cross section for the reaction is 627±20 μb, based on 4519 events. The reaction is dominated by resonance production through several channels which overlap kinematically but do not appear to interferesubstantially. A maximum-likelihood procedure was used to determine the production fractions, which for the major channels are 0.44±0.02 for N*++(1236), 0.145±0.02 for Y*0(1520), 0.10±0.03 for N*+(1688), and 0.20±0.02 for simultaneous K¯*0N*0. Evidence is presented for the production of Y*+(1765) and its decay into Y*0(1520) as well as for production of Y*+(1660) with decay into K−pπ+. A four-standard-deviation enhancement is present at a K−π+ invariant mass of 690 MeV. Angular correlation data are presented for the N*++K−π−, Y*0π+π−, and K¯*0N*0 reaction channels. However, the difficulty of separating the various channels prevents a detailed study of the reaction dynamics.
No description provided.
We report on the interactions of an incident 200 GeV / c beam composed of 33% protons, 16% kaons, and 48% pions on targets of silver and gold mounted in the Fermilab 30″ bubble chamber. Within our limited statistics, we find the total cross sections and average multiplicities to agree with previously published data. We find the KNO scaling distribution curve to be broader for heavy nuclei than for hydrogen. We present the first data for V 0 production on gold and silver. We also present, for the first time, evidence for a positive charge excess among the sample of relativistic tracks from interactions on gold and silver. We observe a trend where the positive charge excess increases with target atomic number and with increasing charged particle multiplicity. We find the charge excess to exist among the sample of particles having greater than 2 GeV / c momentum and to persist in the sample with momentum greater than 4 GeV / c .
SIG REFERS PRODUCTION OF 2 OR MORE CHARGED PARTICLES EXCLUDING ELASTICS BUT INCLUDING COHERENT PRODUCTION. MULT REFERS TO RELATIVISTIC SECONDARIES (BETA > 0.7).
NO CORRECTION FOR GAMMA CONVERSIONS IN THE TARGET IN THIS TABLE BUT DIFFERENCE DOES NOT NEED CORRECTION.
No description provided.
Neutral and charged two-pion production in p+d→ 3 He+2 π reactions has been studied at CELSIUS at a proton beam energy of 477 MeV. The total cross section for double pion production is 0.22±0.03 μ b. The ratio of the cross sections for the production of charged pion pairs with isospin T =1 and T =0 was determined to be σ ( π + π − ; T =1)/ σ ( π + π − ; T =0)=1.4±0.4.
(I=1, I=0) stands for isospin of PI+ PI- system.
The d( α , 6 Li ∗ 3.56 ) π 0 reaction has been studied at E c.m. =1.2 and 1.9 MeV above threshold with an alpha-particle beam incident on a deuterium cluster-jet target in CELSIUS. Complete differential cross sections were measured at both energies, integrated to σ =228±6+70 nb and 141±12+42 nb respectively. Observed large anisotropies are discussed in relation to the cluster structure of the 6 Li ∗ halo.
The excited LI6* level has E=3.56 mev (at the highest beam energy the second T=1 state in LI6 at 5.37 mev is possible to populate).
We report measurements of the asymmetry A_parallel for inclusive hadron production on longitudinally polarized proton and deuteron targets by circularly polarized photons. The photons were produced via internal and external bremsstrahlung from an electron beam of 48.35 GeV. Asymmetries for both positive and negative signed hadrons, and a subset of identified pions, were measured in the momentum range 10<P<30 GeV at 2.75 and 5.5 degrees. Small non-zero asymmetries are observed for the proton, while the deuteron results are consistent with zero. Recent calculations do not describe the data well.
The asymmetry for polarized photoproduction of inclusive hadrons from a polarized proton target. The errors are statistical only.
The asymmetry for polarized photoproduction of inclusive identified pions from a polarized proton target. The errors are statistical only.
The asymmetry for polarized photoproduction of inclusive hadrons from a polarized deuteron target. The errors are statistical only.
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