Inclusive production of the Δ (1232) resonance has been measured in 280 GeV/ c muon-proton interactions. The production of the Δ ++ as a function of the variables χ BJ , W , Q 2 , χ F and p T 2 is investigated. The average Δ ++ multiplicity is found to be smaller, by a factor of 6.2 ± 1.2, than the average multiplicity of protons. An upper limit for Δ 0 production is obtained. The net hadronic charge distribution for events with a Δ ++ is presented. The results are compared to the predictions of the Lund and Fire string models.
No description provided.
No description provided.
We have measured the differential and total cross sections ofD meson production in 200 GeV π−-beryllium interactions, using a sample of 48 fully reconstructed and nearly background-freeD mesons in the decay channelsK∓π±,K∓π±π± andK∓π∓π±π±. A single electron trigger has been used to select events containing a pair of charmed particles. A vertex telescope of 6 silison microstrip detectors allowed the reconstruction of tracks of charged secondaries and the reconstruction of primary and decay vertices with high precision. The ratio of branching fractions for\(\mathop {D^0 }\limits^{( - )}\to K^ \mp\pi ^ \pm\) to\(\mathop {D^0 }\limits^{( - )}\to K^ \mp\pi ^ \mp\pi ^ \pm\pi ^ \pm\), and an upper limit for\(D^0- \bar D^0 \) mixing are presented.
'leading' D-mesons, i.e. D-mesons, containing quarks, from PI- beam. Also AD0-mesons from. D*- decays.
'non-leading' D-mesons.
No description provided.
A study ofW± andZ0 properties has been performed using the UA2 detector at the\(\bar pp\) collider. The data correspond to a total integrated luminosity of 142 nb−1 at\(\sqrt s \)=546 GeV, and of 310 nb−1 at\(\sqrt s \)=630 GeV. The experimental results are compared with the predictions of the Standard Model of the unified electroweak theory.
No description provided.
No description provided.
No description provided.
The relative yields of kaons and protons compared with the yield of pions at highpT and polar angles θ away from 90° (in the range from 10° to 45°) are presented forpp, dd, and αα interactions at a centre-of-mass energy\(\sqrt {s_{NN} }= 31\) GeV per nucleon-nucleon collision. The measured particle ratios depend on the atomic mass numberA of the beam particles and on θ. TheA dependence of the ratios becomes stronger for largerpT and is more pronounced at smaller polar angles.
ERRORS ARE PURELY STATISTICAL.
ERRORS ARE PURELY STATISTICAL.
ERRORS ARE PURELY STATISTICAL.
This paper describes measurements of the semileptonic weak-neutral-current reactions νpμ→νpμ and ν¯pμ→ν¯pμ which yield the absolute differential cross sections dσ(νpμ)dQ2 and dσ(ν¯pμ)dQ2. The weak-neutral-current parameter, sin2θW, is determined to be sin2θW=0.220±0.016(stat.)(syst.)−0.031+0.023.
No description provided.
No description provided.
No description provided.
We have measured the inclusive branching ratio for B→φX to be 0.023±0.006±0.005. The momentum distribution of the φ mesons is compared with that expected from the cascade decays B→F→φ and B→D→φ. .AE
DATA SAMPLE CONSISTED OF 30.4 1/PB. DATA TAKEN ON THE PEAK OF THE UPSI(10575).
CONTINUUM DATA SAMPLE CONSISTED OF 12.8 1/PB. ENERGY JUST BELOW THE UPSI(10575).
69970 B BBAR EVENTS.
This Letter reports a search for the production by e+e− annihilation of a single photon accompanied by particles that interact only weakly in matter. The search was performed at the SLAC e+e− storage ring PEP (√s =29 GeV) with a new detector, ASP. No unexpected signal was observed. The limit Nν<14 (90% C.L.) is placed on the number of light neutrino species, and the mass of scalar electrons predicted by theories of supersymmetry is constrained to mẽ>51 GeV/c2 (90% C.L.) for mγ̃=0 and degenerate ẽ mass states.
No description provided.
The production of φ-meson pairs has been observed in 400-GeV/c proton-nucleon interactions at the Fermilab multiparticle spectrometer in the inclusive reaction pN→φφ+X, where each φ decays to a K+K− pair. A fast (200 nsec) high-level processor was used to selectively trigger on events containing two pairs of oppositely charged kaons having low invariant masses. The experimental apparatus and trigger processor are described. The cross section for φφ production and an upper limit for ηc production are presented.
No description provided.
The UA2 experiment, running at the CERN SPS\(\bar pp\) Collider, has performed a study of events containing three hard jets in the final state. The angular distributions of the three jets show evidence for gluon bremsstrahlung, in good agreement with a QCD model to leading order in the strong coupling constant αs. The yield of three-jet events relative to that of two-jet events provides a measure of the strong coupling constant: ;3K3/K2=0.23±0.01±0.04, whereK2 andK3 represent the contributions arising from higher order corrections in α3 to the two- and three-jet exclusive cross-sections. A detailed discussion of the systematic and theoretical uncertainties is given.
No description provided.
We present density-matrix elements and single-spin correlations for the reaction p↑p→pπ+n at 3, 4, 6, and 11.75 GeV/c, using both longitudinal and transverse beam polarizations. For small momentum transfers, the spin correlations are mainly due to off-shell π+p elastic scattering, while for larger t there are large polarization effects associated with the production dynamics for p↑p→Δ++n. Comparison of longitudinal and transverse polarization correlations suggests that the Δ++-production spin effects are due mainly to unnatural-parity exchanges. We present a model-dependent amplitude analysis, and extract the energy dependence of the natural- and unnatural-parity-exchange contributions.
Unpolarized cross sections.
Unpolarized cross sections.
Unpolarized cross sections.
Forum