The photon structure function F 2 γ has been measured at average Q 2 values of 73 and 390 GeV 2 using data collected by the AMY detector at the TRISTAN e + e − collider. F 2 γ is observed to be increasing as ln Q 2 . The x -dependence of F 2 γ , where x is the momentum fraction carried by the parton inside the photon, is also measured. The measurements are compared with several parton density models.
No description provided.
No description provided.
Errors contain both statistics and systematics.
Single particle distributions of π ± , K ± , p , p and d near mid-rapidity from 450 GeV/c p A and 200 GeV/c per nucleon SA collisions are presented. Inverse slope parameters are extracted from the transverse mass spectra, and examined for indications of collective phenomena. Proton and antiproton yields are determined for different projectile-target combinations. First results from 160 GeV/c per nucleon PbPb collisions are presented.
No description provided.
PRELIMINARY DATA FOR CENTRAL EVENTS.
We have used 19 pb**-1 of data collected with the Collider Detector at Fermilab to search for new particles decaying to dijets. We exclude at 95% confidence level models containing the following new particles: axigluons with mass between 200 and 870 GeV, excited quarks with mass between 80 and 570 GeV, and color octet technirhos with mass between 320 and 480 GeV.
Here UNSPEC refers to axigluons, excited quarks, colour octet technirhos, ngauge bosons (W' and Z') and diquarks (D and Dc). M is the mass of the new particle (axigluon, q*, ...). Measurements are given to the 95% confidence limit.
J ψ and ψ′ production cross sections are studied for several proton induced reactions and in SU collisions, in the NA38 experiment, by measuring the resonances' decays in the muon pair channel. Whereas in p-A interactions the ψ ′/ J / ψ ratio remains constantin going from p-p and p-d collisions to p-W and p-U, with a mean value of 1.76% ± 0.04%, in the SU data it exhibits half of this value and decreases as centrality of the collision increases. Also studied are the differences between the γ π 0 ratio yields correlated with the J ψ mass range and other dimuon masses; no significant effect is seen.
DATA IN THE COLLINS-SOPPER FRAME, OF -0.5<COS(THETA)<0.5.
DATA IN THE COLLINS-SOPPER FRAME, OF -0.5<COS(THETA)<0.5.
No description provided.
We have carried out inclusive measurements of $\Lambda(\overline{\Lambda})$ production in two-photon processes at TRISTAN. The mean $\sqrt{s}$ was 58 GeV and the integrated luminosity was 265 pb$~{-1}$. Inclusive $\Lambda (\overline{\Lambda})$ samples were obtained under such conditions as no-electron, anti-electron, and remnant-jet tags. The data were compared with theoretical calculations. The measured cross sections are two-times larger than the leading-order theoretical predictions, suggesting the necessity of next-to-leading-order Monte-Carlo generator.
No-tag data.
Anti-electron tag data.
Remnant-jet tag with VDM subtraction data.
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CENTRAL EVENTS: 10% OF SIG(GEOM).
Antiproton production cross-sections have been measured for p+C, C+C, C+Cu and C+Pb collisions at 3.65 GeV/nucleon.\(\bar p\) laboratory momentum and angle are 0.8 GeV/c and 24°. The target mass dependence parameter is found to be 0.43±0.1. A strong increase in antiproton yield is observed from p+C, d+C to C+C collisions. Projectile mass parameter is 1.2±0.2 for d+C to C+C. The construction and calibration of APAKI, an annihilation detector for\(\bar p\) identification, are also described.
No description provided.
The multiplicity distributions and the correlations of different types of slow particles produced in 200A GeV oxygen-induced interactions with emulsion nuclei are presented. The experimental distributions are studied within the framework of the generalized Andersson-Otterlund-Stenlund (AOS) model for nucleus-nucleus interactions. The generalized (AOS) model fails to describe the present experimental data. Also a systematic comparison using the calculations of VENUS model is made. The grey-particles multiplicity is successfully reproduced by the theoretical multistring model VENUS, while the model is inadequate for explaining the distribution of black particles.
No description provided.
We confirm the existence of the two I G ( J PC ) = 0 + (0 ++ ) resonances f 0 (1370) and f 0 (1500) reported by us in earlier analyses. The analysis presented here couples the final states π 0 π 0 π 0 , π 0 π 0 η and π 0 ηη of p p annihilation at rest. It is based on a 3 × 3 K -matrix. We find masses and widths of M = (1390±30) MeV, Γ = (380±80) MeV; and M = (1500±10) MeV, Γ = (154 ± 30) MeV, respectively. The product branching ratios for the production and decay into π 0 π 0 and ηη of the f 0 (1500) are (1.27 ± 0.33) · 10 −3 and (0.60 ± 0.17) · 10 −3 , respectively.
No description provided.
The annihilation p p → Φγ has been investigated with the Crystal Barrel detector at LEAR for antiprotons stopped in liquid hydrogen. The observed branching ratio BR ( p p → Φγ = (1.7 ± 0.4) · 10 −5 is almost two orders of magnitude higher than expected from the OZI-rule. As a by-product, the branching ratios BR ( p p → K L K S ) = (9.0 ± 0.6) · 10 −4 and BR ( p p → Φπ 0 ) = (5.5 ± 0.7) · 10 −4 have been measured.
No description provided.
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