The effect of isospin-violating, charge-symmetry-breaking (CSB) terms in the np interaction has been observed at TRIUMF by measuring the difference in the zero-crossing angles of the neutron and proton analyzing powers, An and Ap, at a neutron energy of 477 MeV. The scattering asymmetries were measured with a neutron beam incident on a polarizable proton target. To reduce systematic errors, interleaved measurements of An and Ap were made using the same beam and target (apart from their respective polarization states). Neutrons and protons were detected in coincidence in the center-of-mass angle range from 59°–80°. The difference in zero-crossing angles was 0.340°±0.162° (±0.058°), which yields ΔA≡An-Ap=0.0047±0.0022 (±0.0008) using dA/dθc.m.=−0.01382 deg−1. The second errors represent systematic effects. This result is in good agreement with recent theoretical calculations which include CSB effects due to the np mass difference in π, ρ, and 2π exchange, electromagnetic coupling of the neutron anomalous magnetic moment to the proton current, ρ-ω-meson mixing, and short- and medium-range effects of the up- and down-quark mass difference.
No description provided.
We have carried out high-statistics measurements of inclusive π0 and γ-ray spectra from p¯p annihilation at rest. From the monochromatic peaks in the π0 spectra, we derive the yield (or its upper limit) of the reaction p¯p→π0M for M=φ, η’, ω, ρ0, η, and π0. The same quantity was independently obtained from the γ-ray spectra, which included some π0’s that were mistaken as single γ rays due to the limited granularity of the γ detector. Taking the monochromatic peaks in the γ-ray spectra as being due to prompt γ rays, we also derive the upper limit for p¯p→γM.
No description provided.
No description provided.
We report new results on a precision measurement of the ratio R=σLσT and the structure function F2 for deep-inelastic electron-nucleon scattering in the kinematic range 0.2≤x≤0.5 and 1≤Q2≤10 (GeV/c)2. Our results show, for the first time, a clear falloff of R with increasing Q2. Our R and F2 results are in good agreement with QCD predictions only when corrections for target-mass effects are included.
2.6 pct rad length target.
2.6 pct rad length target.
2.6 pct rad length target.
Values of the spin-rotation parameter, β, are measured in the reaction π + p → K + Σ + at incident pion momenta of 1.69 and 1.88 GeV/ c .
No description provided.
No description provided.
Using the CHARM detector 36 000 deep inelastic neutral-current reactions of neutrinos (and 2000 of antineutrinos) from the 160 GeV narrow-band beam were recorded. The differential cross section d σ d x in the Bjorken scaling variable x was computed by unfolding the effects of limited acceptance and of resolution of the detector as well as the ambiguity of the energy of the incoming neutrinos (produced by π- or K-decay). Combining the results from the neutrino and antineutrino data, the structure functions F 2 and xF 3 and the antiquark momentum distribution measured via the NC coupling were determined. The distributions are in agreement with the corresponding CC distibutions. Comparisons with deep inelastic muon scattering confirm the universality of nuclear structure functions as probed by the weak and the electromagnetic currents.
SEE THE PAPER FOR THE PRECISE DEFNS OF F(+), F(-).
We report the first observation of an orbitally excited baryon, the Λ(1520), in quark and gluon fragmentation. The production rate is found to be (1.15±0.21±0.16)×10 −2 and (0.80±0.17 −0.13 +0.10 )×10 −2 Λ (1520) hyperons per event in direct ϒ decays and in the continuum, respectively. In contrast to the observed situation for ground state baryons, the production of the Λ(1520) in direct ϒ decays shows little or no enhancement with respect to continuum production.
Full X range uses extrapolation from fit to dsig/dz distribution.
No description provided.
UPSI(1S) DECAYS.
A search for multihadronic events produced with two energetic leptons has been performed at PETRA using 130 pb −1 accumulated by the CELLO detector at 35 GeV ⩽ √ s ⩽46.8 GeV. Three μ + μ − , eleven e + e − and three eμ events were observed. The mesured yields an dthe event characteristics are in good agreement with the expectation for the α 4 QED processes e + e − → ℓ + ℓ − q q and from semileptonic decays of pairs of heavy quarks.
No description provided.
The final states K S 0 K S 0 π + π − and K S 0 K ∓ π 0 π ± , produced in two-photon reactions, have been studied using the ARGUS detector at the e + e − storage ring DORIS II at DESY. The reaction γγ→ K ∗+ K ∗− has been observed for the first time. Its cross section is about eight times larger than that for γγ→ K ∗0 K ∗0 , but it has a similar W γγ dependence.
No description provided.
Topological cross section.
Topological cross section.
None
PION SPECTRA HAVE BEEN FITTED BY: E*D(SIG)/D3(P)=CONST(Q=1)* EXP(-SLOPE(Q=1)*EKIN)+CONST(Q=2)*EXP(-SLOPE(Q=2)*EKIN).
We report on a high precision measurement of ϕ-meson production in continuum events and in direct decays of the Υ(1S)- and Υ(2S)-mesons. The ratio of the total production rate of ϕ-mesons in direct Υ(1S)- and Υ(2S)-decays over that in continuum events is 1.32±0.08±0.09 and 1.07±0.13±0.11 respectively. This is compatible with the corresponding ratio obtained for lighter mesons, but is appreciably smaller than the relative baryon production rate.
PHI meson cross section on the continuum.
Differential particle density for PHI mesons in decays of upsilon(1S) and upsilon(2S).
No description provided.
Forum