Results are presented from a study of the annihilation interaction p―p→K+K−π+π− at 8.3 GeV/c based on data from an experiment performed with the large-aperture solenoid spectrometer (LASS) at the Stanford Linear Accelerator Center. A measurement of the reaction cross section is made, and contributions to the final state from the φ, f0A20, K*(890), K*(1430), and ρ0 resonances are studied.
No description provided.
No description provided.
We report the final results of a search for narrow structures in the p¯p total cross section between 395 and 740 MeV/c with a rms mass resolution of 1.5 MeV around the S-resonance region. A reanalysis of the data significantly improved the statistical accuracy. No evidence is found for narrow structures and a 90%-confidence-level upper limit of 24 mb MeV is set at around 500 MeV/c for the integrated cross section of a Breit-Wigner-type resonance of width ≲4 MeV.
No description provided.
We have measured 〈p⊥〉 as a function of multiplicity for the reaction proton (antiproton) on proton, neon, argon, and xenon. For all reactions, 〈p⊥〉 is independent of multiplicity. We observed that the pion-emission volume is the same for both hydrogen and xenon targets and has a radius about 1.5 fm. Our analysis shows no indication of a deconfinement phase transition in nuclear matter.
No description provided.
η′η pair production in the charge exchange reaction π−p→η′ηn has been observed and studied in a search for glueballs with the 38 GeV/c pion beam of the 70 GeV IHEP accelerator. The γ-rays from the decay η′η→4γ were detected with the hodoscope spectrometer GAMS-2000. The η′η events in the mass range from threshold up to 1.8 GeV are decays of the scalar G(1590)-meson which has been already observed in its ηη decay mode. The measured ratio of the partial widths of the G→η′η and the G → ηη decay channels is 2.7±0.8 in agreement with the value expected for glueballs.
No description provided.
We have studied antiproton elastic scattering on Al, Cu, and Pb for two incident momenta: 514 and 633 MeV/c. The angular region covered extends from the forward Coulomb region to approximately 30 deg. The differential cross sections were analyzed using a nonrelativistic optical potential of the Woods-Saxon form, with the imaginary shape taken from electron scattering data. We obtained fits for the strengths of the real and imaginary parts of the potential, (V0, W0), of (51, 116) MeV for Al, (12, 71) MeV for Cu, and (12, 278) MeV for Pb.
No description provided.
The electroweak production asymmetry and the decay fragmentation function for e + e − → c c have been measured at s = 29 GeV using charged D ∗ production over the full kinematic range. The data were taken at PEP using the High Resolution Spectrometer. The measured asymmetry is −0.12 ± 0.08. The total production cross section in units of the point cross section corrected for initial state radiation is R D ∗ = 2.7 ± 0.9 .
ASSUMES SIG(D*+) = SIG(D*0). (EXPT. MEASURES D*+ PRODUCTION ONLY). R VALUE CORRECTED FOR INITIAL STATE RADIATION.
No description provided.
We have observed inclusive production of D0 and D+ mesons, and their charge conjugates, in e+e− annihilation at 29 GeV on the basis of a data sample of 106 pb−1. These signals correspond to R values of R(D0+D―0)=1.8±0.5 and R(D++D−)=1.2±0.4. Taking the D+ and D0 data together, we measure a charge asymmetry of A=−0.08±0.12 for charmed quarks. A comparison of R(D+D―) with R(D*+D―*) obtained via the process D*+→D0π+ gives a DD* ratio of 1.0−0.2+0.3, indicating that direct D* production dominates over direct D production.
No description provided.
EXTRAPOLATED TO ALL Z.
No description provided.
Distributions of the Bjorken scaling variables x and y, and the structure function F+(x), are presented both for neutral-current and for charged-current νμ interactions. The data were obtained by use of the Fermilab 15-ft neon bubble chamber exposed to a narrow-band νμ beam. Results are based on 151 neutral-current and 683 charged-current events. An important feature of the neutral-current analysis is the event-by-event reconstruction of the outgoing neutrino.
No description provided.
DATA REQUESTED FROM C.BALTAY ON 20/9/91.
DATA REQUESTED FROM C.BALTAY ON 20/9/91.
New data are presented on the charged multiplicity distribution for non single-diffractive events produced in pp̄ interactions at a CM energy s = 540 GeV . The distribution in the full pseudorapidity range is compared with data from the ISR. Using the scaling variable z = n 〈n〉 a change of shape is observed. The effect is manifested as an increase from 2% to 6% in the proportion of high multiplicity ( z > 2) events. For the central pseudorapidity range, | η | ⪅ 1.5, scaling is approximately valid up to s = 540 GeV .
THE SCALING VARIABLE Z IS N/MEAN(N). THE ERRORS ARE HIGHLY CORRELATED AND ARE BASED ON THE SQUARE ROOT OF THE NUMBER OF EVENTS IN THE BIN. IN THE CASE OF MULTIPLICITIES 2,4, AND 6, ADDITIONAL SYSTEMATIC ERRORS HAVE BEEN INCLUDED. ABOVE MULTIPLICITY 96 BINS HAVE BEEN COMBINED - THE VALUE IN THE TABLE IS THE AVERAGE OVER THE RANGE - NOT THE SUM. NOTE ALSO THAT IN FIG. 1 THE "Y-VALUE" IS MULTIPLIED BY THE MEAN MULTIPLICITY (29.1).
CHARGED MULTIPLICITY (NON-CORRECTED) FOR EVENTS WHICH HAVE AT LEAST ONE TRACK WITH ABS(ETARAP) <1.5.
CHARGED MULTIPLICITY (NON CORRECTED) FOR EVENTS WHICH HAVE AT LEAST ONE TRACK WITH ABS(ETARAP) <1.3.
The interference structure function xG 3 ( x ) has been measured for the first time scattering positive and negative muons of opposite helicity off a carbon target. The x dependence observed for Q 2 between 40 and 180 (GeV/c 2 ) is in good agreement with predictions of the quark-parton model. The measured ratio 2( a u Q u + a d Q d )/( Q u 2 + Q d 2 = 1.87 ± 0.25 (stat.) ± 0.24 (syst.) is consistent with the hypothesis of fractional quark charges and determines the sign of Q u − Q d to be positive.
No description provided.
No description provided.
No description provided.
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