Inclusive γ and π0 production inK − p interactions at 32 GeV/c

The inclusive production of γ's and π^p0's inK ^? p-interactions at 32 GeV/c is studied. About 30.000 γ's coming from a Mirabelle bubble chamber experiment with a sensitivity of 6.5 ev/μb have been used for the analysis. Inclusive and topological cross sections of γ's are measured. The γ invariant differential distributions and their scaling properties are investigated. The inclusive cross section of π^p0-production is determined and the π^p0 invariant differential distributions are evaluated and compared to those of π^p±.     

Cross-section measurements of single pion production in charged current neutrino and antineutrino interactions

All six exclusive single pion production processes from neutrino and antineutrino charged current interactions are studied in the energy range between 3 and 30 GeV. Using a quark model for single pion production from Rein and Sehgal we fitted the aximal mass parameter from total cross sections and compare the results with values from other experiments and the world-averages.     

The axial-vector strength in the proton-rich argon isotopes

The proton-rich isotopes³²Ar-³⁵Ar represent the first sequence for which the superallowed Gamow-Teller strength is known out toZ? N=4. The results are compared with two sets of predictions from large shell-model calculations, which give systematically different quenching factors, on the average 0.54 and 0.89. Possible reasons for this are discussed. A comparison is also made with the Gamow-Teller strength of proton-rich isotopes of neighbouring elements.     

Dynamics of antiproton cooling in a positron plasma during antihydrogen formation

We demonstrate cooling of 10⁴ antiprotons in a dense, cold plasma of 10⁸ positrons, confined in a nested cylindrical Penning trap at about 15 K. The time evolution of the cooling process has been studied in detail, and several distinct types of behavior identified. We propose explanations for these observations and discuss the consequences for antihydrogen production. We contrast these results with observations of interactions between antiprotons and “hot” positrons at about 3000 K, where antihydrogen production is strongly suppressed.     

Non-perturbative renormalisation and improvement of the local vector current for quenched and unquenched Wilson fermions

By considering the local vector current between nucleon states and imposing charge conservation, we determine its renormalisation constant and quark mass improvement coefficient for Symanzik O(a) improved Wilson fermions. The computation is first performed for quenched fermions (and for completeness also with unimproved fermions) and compared against known results. The two-flavour unquenched case is then considered.     

A search for high energy neutrinos from SN 1987A,the Carb,Hercules X-1, and Cygnus X-3 with the Fréjus detector

With the Fréjus detector we studied four astrophysical point-like sources by using \(v_e (\bar v_e )\) and \(v_\mu (\bar v_\mu )\) interactions in the detector and \(v_\mu (\bar v_\mu )\) interactions in the surrounding rock. No excess of events was found. Therefore upper limits of neutrino fluxes and source luminositics are quoted. These limits confirm results from other experiments. In addition new limits are presented for spectral indices above 3.     

A study of the centrally producedK *0 K^{*0} \bar K^{*0} final state in the reactionpp→p f (K + K -π+π-)p s at 300 GeV/c

The reactionpp→p _f (K ⁺ K ^-π⁺π^-)p _s , where theK ⁺ K ^? π⁺π^- system is centrally produced, has been studied at 300 GeV/c. TheK ^*0 \(K^{*0} \bar K^{*0} \) final state has been observed and the cross sections for its central production are found to be the same at 300 and 85 GeV/c. TheK ^*0 \(K^{*0} \bar K^{*0} \) final state appears to be produced as a non-resonant threshold enhancement.     

Inclusive meson resonance production inK + p interactions at 250 GeV/c

A detailed analysis of the inclusive production of the vector mesonsφ,K ^*+,0(892) \(\bar K*^0 (892),\rho ^{ + ,0} ,\omega \) and the tensor mesonsK ₂ ^*0 )(1430) andf ₂(1270) inK ⁺ p interactions at 250 GeV/c is presented The data are compared with results at lower energies and with various quark-parton models. The production ofρ ⁰,K ^*0(892) and \(\bar K*^0 (892)\) increases at the same rate as a function ofs, is concentrated in the central region and is not reproduced by the models. Production of the tensor mesonsf ₂(1270) andK ₂ ^*0 (1340) is suppressed relative toρ ⁰ andK ^*0(892) by a factor of about 3.