We report a study of single photon production in e + e − collisions at s =58 GeV with the TOPAZ detector at TRISTAN. From data corresponding to an integrated luminosity of 213 pb −1 , 5 single photon candidates remained after event selection, which can be compared with the expected 3.1 ν ν γ and 2.8 background events. These results exclude the selectron mass below 47.2 GeV at the 90% confidence level, if e ̃ L and e ̃ R are mass-degenerate and the photino is massless. When combined with results from other experiments, this limit improves to 75.0 GeV.
No description provided.
The depolarization parameter Donon of the p dash p → n dash n charge exchange reaction has been measured for the first time at the CERN Low Energy Antiproton Ring (LEAR) at two antiproton momenta, 546 and 875 MeV/ c . The transverse polarization of the recoil neutron was analyzed using a large-acceptance neutron polarimeter made up of two parallel plastic scintillator planes. D 0 n 0 n is usually less than 0.35 which suggests that the spin-spin amplitudes dominate in the scattering matrix. Results are compared with the predictions of various N dash N potential models. The agreement is in general satisfactory.
No description provided.
No description provided.
We have conducted a search for bound states of a negative pion and a number of neutrons (pineuts) using the E814 spectrometer. A beam of Si28 at a momentum of 14.6A GeV/c was used to bombard targets of Al, Cu, Sn, and Pb. We describe our experimental technique, present measured upper limits for pineut production, and discuss the significance of our results.
AUTHORS NAMED CHARGED- BY PINEUT. Here ALL means the total number of interactions.
We have investigated the fragmentation of 3.65 GeV/nucleon O16, Mg24, and S32 projectiles on C, Al, Cu, Ag, and Pb targets using solid state nuclear track detectors. Track counting was performed by an automatic measuring system. Total charge changing and the partial cross sections for the production of fragments with charges 9≤Z≤15 for S32 projectiles and of charge 6≤Z≤11 for Mg24 were determined. Comparison with theoretical models and other experimental data is made.
No description provided.
The vector analyzing power iT11 and the composite observable τ22=T22+T20/ √6 were measured at 10 incident pion energies between 100 and 294 MeV, in an angular range between 50° and 120°. Two different techniques were applied, the detection of the pion with a magnet spectrometer, and the πd coincidence method with scintillation counters. In the case of the first technique also two different target materials were used. Consistency among all data was obtained. The experimental data are compared to Faddeev calculations from one of us (H.G.). The discrepancies between theory and experiment are discussed, and an outlook for further research is given.
Vector analyzing power iT11 and composite observale TAU22 = T22 + T20/sqrt(6). LiDeut target.
Vector analyzing power iT11 and composite observale TAU22 = T22 + T20/sqrt(6). LiDeut target.
Vector analyzing power iT11 and composite observale TAU22 = T22 + T20/sqrt(6). LiDeut target.
The polarization transfer κ 0 and the tensor analyzing power T 20 for the 1 H d p)d reaction have been measured up to an internal momentum of k = 0.58 GeV/c. Comparison of the same observables obtained in recent studies for 1 H d p)d reaction, as a function of k , show different behavior. However the data from these two reactions are almost identical when compared in T 20 versus κ 0 correlation plots. We discuss similarities and differences observed in the two reactions.
The authors use the Infinite Momentum Frame variable K= M( proton) * sqrt(1/(4*a*(1-a)) - 1), where a = (E(proton)+P_long(proton))/(E(deut)+P(deut)).
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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No description provided.
The abundances of light nuclei probe the later stages of the evolution of a system formed in a relativistic heavy-ion collision. After the system has cooled and expanded, nucleons in close proximity and moving with small relative momenta coalesce to form nuclei. Light nuclei production enables the study of several topics, including the mechanism of composite particle production, freeze-out temperature, size of the interaction region, and entropy of the system. NA44 is the only relativistic heavy-ion experiment to have both deuteron and antideuteron results in both pA and AA collisions and the first CERN experiment to study the physics topics addressed by d and d production.
PRELIMINARY DATA.
The measurement of different reactions of p d annihilation at rest in a gaseous target has been performed using the OBELIX spectrometer at LEAR (CERN). A strong deviation from the OZI-rule prediction was found from the measurement of the ratio R = φπ ωπ in two regions of proton momenta, P < 200 MeV/ c and P > 400 MeV/ c : R( φπ − ωπ − ) = (133 ± 26) × 10 −3 and (113 ± 30) × 10 −3 , respectively. These values are about 30 times greater than the theoretical prediction. For the first time the excitation of the †-resonance was observed among the final-state products of p d annihilation. The existence of a broad enhancement in the 4π invariant mass at m ≈ 1480 MeV, seen in previous experiments, was confirmed. A ≈ 100 MeV downward shift of the bump position, when the proton momentum increased up to P > 400 MeV/ c , was also observed, while the positions of ω, ϱ and f 2 (1270) did not change with the proton momentum. The following branching ratios were measured: BR( p d → π − φ p ) = (6.62 ± 0.49) × 10 −4 , for P < 200 MeV/ c ; BR( p d → π − φ p ) = (0.95 ± 0.22) × 10 −4 , for P > 400 MeV/ c ; BR( p d → π − ω p ) = (49.7 ± 8.9) × 10 −4 , for P < 200 MeV/ c ; BR( p d → π − ω p ) = (8.38 ± 1.09) × 10 −4 , for P > 400 MeV/ c ; BR( p d → 2π − π + p ) = (150 ± 6) × 10 −4 , for P < 200 MeV/ c ; BR( p d → 2π − π + p ) = (16.6 ± 0.9) × 10 −4 , for P > 400 MeV/ c ; BR( p d → 3π − 2π + p ) = (326 ± 12) × 10 −4 , for P < 200 MeV/ c ; BR( p d → 3π − 2π + p ) = (44 ± 7) × 10 −4 , for P > 400 MeV/ c ; BR( p d → Λ K + π − ) = (0.96 ± 0.19) × 10 −4 , for P > 400 MeV/ c ; BR( p d → Λ K + π − π 0 ) = (3.5 ± 0.8) × 10 −4 , for P > 400 MeV/ c ; BR( p p → 2π − 2π + ) = (540 ± 20) × 10 −4 ; BR( p p → 3π − 3π + ) = (251 ± 21) × 10 −4 .
No description provided.
No description provided.
No description provided.
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