Differential cross sections and polarisations in the reaction π + p→K + Σ + have been measured using the Rutherford Multiparticle Spectrometer at NIMROD. Data are presented at 26 momentum points at approximately 50 MeV/ c intervals in the range 1.282 to 2.473 GeV/ c with an order of magnitude more events than previous experiments. Legendre polynomial expansion coefficients have also been determined.
ERRORS HAVE SYSTEMATIC AND STATISTICAL ERRORS FOLDED IN QUADRATURE. TYPICAL STATISTICAL ERRORS ARE 2 PCT OR LESS.
No description provided.
No description provided.
Differential cross sections fore+e−→e+e−, τ+, τ- measured with the CELLO detector at\(\left\langle {\sqrt s } \right\rangle= 34.2GeV\) have been analyzed for electroweak contributions. Vector and axial vector coupling constants were obtained in a simultaneous fit to the three differential cross sections assuming a universal weak interaction for the charged leptons. The results,v2=−0.12±0.33 anda2=1.22±0.47, are in good agreement with predictions from the standardSU(2)×U(1) model for\(\sin ^2 \theta _w= 0.228\). Combining this result with neutrino-electron scattering data gives a unique axial vector dominated solution for the leptonic weak couplings. Assuming the validity of the standard model, a value of\(\sin ^2 \theta _w= 0.21_{ - 0.09}^{ + 0.14}\) is obtained for the electroweak mixing angle. Additional vector currents are not observed (C<0.031 is obtained at the 95% C.L.).
No description provided.
Combined MU and TAU asymmetry. See PL 114B(1982)282 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1234> RED = 1234 </a>) and ZP C14(1982)283 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1245> RED = 1245 </a>) for individual asymmetry measurements.
We present an analysis ofρ0ρ0 production by two photons in theρ0ρ0 invariant mass range from 1.2 to 2.0 GeV. From a study of the angular correlations in the process γγ→ρ0ρ0→π−π+π− we exclude a dominant contribution fromJP=0− or 2− states. The data indicate sizeable contributions fromJP=0+ for four pion massesM4π<1.7 GeV and fromJP=2+ forM4π>1.7 GeV. The data are also well described by a model with isotropic production and uncorrelated isotropic decay of theρ0,s. The cross section stays high below the nominalρ0ρ0 threshold, i.e.M4π<1.5 GeV. The matrix element forρ0ρ0 production is found to decrease steeply with increasingM4π. Upper limits for the couplings of the ι(1440) and Θ(1640) to γγ andρ0ρ0 are given:Γ(ι→γγ)·B(ι→ρ0ρ0)<1.0 keV andΓ(Θ→γγ)
ASSUMING ISOTROPIC RHO0 RHO0 PRODUCTION AND ISOTROPIC RHO DECAY.
CROSS SECTIONS FOR DIFFERENT SPIN-PARITY CONTRIBUTIONS.
The electroproduction of π0-mesons on protons has been measured with electrons of 1.7 and 2.1 GeV energy in the region of the nucleon resonances at\(W = \sqrt {(q + p)^2 }= 1,400 - 2,000MeV\) at rather low values of |q2|=|(e−e′)2|=0.01–0.1 GeV2 but at high values of the nucleon recoil |t|=|(p−p′)2|≈0.6–2.2 GeV2 corresponding to\(\Theta _\pi ^{cm}\approx 145^ \circ- 180^ \circ\). Up toW≈1,650 MeV the cross section for π0-production with virtual photons of |q2|≈0.03 GeV2 is only slightly smaller than that with real photons. ForW≳1,700 MeV the cross section at |q2|≈0.03 GeV2 is on average a factor of 2 smaller than that atq2=0 but only slightly higher than that at |q2|≈0.3–1 GeV2.
INCLUDING RADIATIVE CORRECTIONS.
INCLUDING RADIATIVE CORRECTIONS.
INCLUDING RADIATIVE CORRECTIONS.
We report on a measurement of the process e + e − →e + e − + hadrons, where one of the scattered electrons is detected at large angles, with an average Q 2 of 23 GeV. The results are analysed in terms of the photon structure function F 2 and are compared with QCD predictions.
Data read off graph.
Data read off graph.
Data read off graph.
Differential three-jet cross sections have been measured in e + e − -annihilation at an average CM energy of 33.8 GeV and were compared to first- and second-order predictions of QCD and of a QED-like abelian vector theory. QCD provides a good description of the observed distributions. The inclusion of second-order effects reduced the observed quark-gluon coupling strength by about 20% to α S = 0.16 ± 0.015 (stat.) ± 0.03 (syst.). The abelian vector theory is found to be incompatible with the data.
FIRST ORDER QCD.
SECOND ORDER QCD.
We have measured transverse momentum spectra up to 10 GeV/ c for charged particles produced centrally in proton-antiproton collisions at 540 GeV in the centre of mass at the CERN collider. Our results are compared with data at ISR energies and with the predictions of a QCD model. The charged particle spectrum shows a clear dependence on charged track multiplicity.
No description provided.
No description provided.
Measurements of charged particle multiplicity distributions in the central rapidity region in p-p and p-α, and α-α collisions are reported. They are better fitted to the “wounded nucleon” than to the “gluon string” model. The average transverse momenta, for all three reactions, are identical (and almost independent of multiplicity) up to very high multiplicities.
THE FIRST PP DATA IS AT 44 GEV, THE SECOND AT 63 GEV.
No description provided.
The rationR=σ(e+e−→hadrons)/σ(e+e−→ µ+ µ−) was measured with the LENA detector at DORIS in a scan between 7.40 and 7.48 GeV and between 8.67 and 9.43 GeV center of mass energies. Corrected for QED radiative effects,R is found to be constant with an average value ofR=3.37 ±0.06stat±0.23syst. No narrow resonances withΓee(Γhad/Γtot)⊗0.30 keV (95% C.L.) and no steps have been observed. Based on this value ofR, revised values for υ(1S) resonance parameters are presented.
No description provided.
No description provided.
NUMERICAL VALUES GIVEN IN APPENDIX IN PREPRINT. STATISTICAL ERRORS ONLY.
In a high statistics (180 events/μb) bubble chamber study of the reaction fx K − p → K 0 π − p at 8.25 GeV c , we observe a K 0 π − state at 2088±20 MeV with a width 170 +100 −50 MeV, produced with a cross section of 3.6±1.2 μ b. In addition we observe this state in the channels K ∗ (890)ππ , ϱ K π , ω K π with a combined cross section of 7.1±2.6 μ b, and possibly K ∗ (890)πππ .
No description provided.
No description provided.