Narrow states observable through the emission of monoenergetic charged pions have been searched for in p p annihilation at rest in a gaseous hydrogen target where annihilation from atomic angular momentum L = 1 states dominates. No structure is observed. The 5σ upper limit for the production of narrow states in the mass range 1100–1670 MeV is 2 × 10 −3 of all annihilations.
X means a narrow state.
We have measured the process e+e−→μ+μ− at √s =29 GeV using the High Resolution Spectrometer at SLAC PEP. The forward-backward charge asymmetry is Aμμ=-(4.9±1.5±0.5)% based on 5057 events. A subsample of 3488 μ+μ− events in the angular range ‖cosθ‖<0.55 gives a cross-section ratio of Rμμ=0.990±0.017±0.030. The resulting couplings of the weak neutral current are gaegaμ=0.208±0.064± 0.021 and gvegvμ=0.027 ±0.051±0.089. The QED cutoff parameters are Λ+>170 GeV and Λ−>146 GeV at 95% C.L.
Corrected for acceptance and O(alpha**3) QED radiation. Numerical values taken from SUGANO-ANL-HEP-CP-84-90.
Forward-backward asymmetry based on fit to angular distribution. Result is given combined with earlier data from BENDER et al.
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We have studied the production of prompt muons in hadronic events from e+e− annihilation at a center-of-mass energy of 29 GeV with the PEP4-TPC (Time Projection Chamber) detector. The muon p and pt distributions are well described by a combination of bottom- and charm-quark decays, with fitted semimuonic branching fractions of (15.2±1.9±1.2)% and (6.9±1.1±1.1)%, respectively. The muon spectra imply hard fragmentation functions for both b and c quarks, with 〈z(b quark)〉=0.80±0.05±0.05 and 〈z(c quark)〉=0.60±0.06±0.04. We derive neutral-current axial-vector couplings of a(b quark)=-0.9±1.1±0.3 and a(c quark)=1.5±1.5±0.5 from the forward-backward asymmetries.
PT is the transverse momentum of the muon relative to the event thrust axis.
PT is the transverse momentum of the MUON relative to the event thrust axis. At this table MUON is from JET and its PT < 1 GeV/c.
PT is the transverse momentum of the MUON relative to the event thrust axis. At this table MUON is from JET and its PT > 1 GeV/c.
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We present a measurement of the polarization and decay asymmetry parameters of the Ξ − inclusively produced in the forward direction in K − p interactions at 5 GeV/ c . The Ξ − decay parameters have been determined to be α Ξ = −0.405 ± 0.029 and Φ Ξ = 14.7° ± 16.0° from a sample of 20 865 events. A linear rise of the Ξ − polarization has been seen with respect to the transverse momentum of the Ξ − , reaching a maximum of 49 ± 4% at P ⊥ ∼ 0.50 GeV/ c . The value of α Ξ is consistent with the world average prior to 1975, but below the value measured by two recent experiments.
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Differential cross sections of proton Compton scattering have been measured in the angular range between 50° and 130° at incident photon energies from 900 MeV to 1150 MeV. A sharp dip in the angular distribution found by a Bonn group at 110° in the photon energy region around 900 MeV is not observed in the present measurement. A new dip-bump structure is found at photon energies above 1050 MeV, which is similar to that for pion-nucleon scattering.
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The p̄p annihilation cross section has been measured with good resolution (∼2 MeV rms) in the mass range 1900–1960 MeV. No narrow structures are seen, the 90% confidence level upper limit being 8–12 mb‐MeV for the integrated area of a resonance in this mass range. However, we do not rule out a very narrow bump‐dip structure seen in an earlier experiment in the 1935–1941 MeV mass interval. The data also do not support the existence of a broad structure previously reported at 1937 MeV.
Fit of form A + B/D gives A = 8.5 +- 2.5mb and B = 40.7 +- 1.3mb in the mass range 1900 to 1960 MeV.
The angular distributions of the analyzing power for the pp → dπ + reaction have been measured at seven energies T p = 1.2, 1.4, 1.6, 1.7, 1.8, 2.0 and 2.3 GeV. The data show a strong energy dependence with a structure centered at √ s π d = 2.66 GeV. Possible interpretations are presented in the frame of the OPE model and involving the question of the excitation of a dibaryon resonance.
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