K + fragmentation and prompt kaon production inK + p collisions at 70 GeV/c

Zeitschrift für Physik C Particles and Fields - We present data on inclusive production ofK + andK 0 mesons in a 70 GeV/cK + p experiment performed in BEBC filled withH 2. Cross sections and...     

π 0 andη meson production inπ + p andK + p collisions at 250 GeV/c

We report on a study of inclusiveπ ⁰ and η meson production inπ ⁺ p andK ⁺ p interactions at 250 GeV/c beam momentum. The Feynman-x spectrum ofπ ⁰ is very similar in shape and normalization to that of negatively charged particles produced in the same experiment. The results are compared with data at other energies and with FRITIOF model predictions. This model overestimates the η cross section by a factor of 2.5. It reproduces theπ ⁰ cross section correctly, but predicts a too hardπ ⁰ x distribution.     

Inclusive production of charged pions in p+p collisions at 158 GeV/c beam momentum

New results on the production of charged pions in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. Pions are identified by energy loss measurement in a large TPC tracking system which covers a major fraction of the production phase space. Inclusive invariant cross sections are given on a grid of nearly 300 bins per charge over intervals from 0 to 2 GeV/c in transverse momentum and from 0 to 0.85 in Feynman x. The results are compared to existing data in overlapping energy ranges. Arrival of the final proofs: 8 December 2005     

Hadron production inpBe interactions at 14.6 GeV/c

Invariant cross sections for the production of ^±,K ^±,p, andd inpBe interactions at 14.6 GeV/c are well reproduced by calculations carried out in the framework of the Rossendorf collision model.Communicated by: F. Lenz     

Azimuthal anisotropy and correlations at large transverse momenta in p + p and Au + Au collisions at square root sNN=200 GeV

Results on high transverse momentum charged particle emission with respect to the reaction plane are presented for Au + Au collisions at square root s(NN)=200 GeV. Two- and four-particle correlations results are presented as well as a comparison of azimuthal correlations in Au + Au collisions to those in p + p at the same energy. The elliptic anisotropy v(2) is found to reach its maximum at p(t) approximately 3 GeV/c, then decrease slowly and remain significant up to p(t) approximately 7-10 GeV/c. Stronger suppression is found in the back-to-back high-p(t) particle correlations for particles emitted out of plane compared to those emitted in plane. The centrality dependence of v(2) at intermediate p(t) is compared to simple models based on jet quenching.     

Analysis of the 8° proton spectrum fromd+p collisions at 9 GeV/c

The 8° proton spectrum from d+p collisions at 9 GeV/c is described on the basis of the impulse approximation. We apply the Paris deuteron wave function and take the various inelastic channels into account. This approach is compared to results from light-cone dynamics. The two variants lead to contradictory conclusions concerning the origin of the high-momentum tail of the spectrum.     

Squeezed back-to-back correlations of K~+K~- in d+Au collisions at sNN~(1/2)=200 GeV and Au+Au collisions at sNN~(1/2)=62.4 GeV

We investigate the squeezed back-to-back correlations(BBC) of K~+K~-, caused by the mass modification of particles in the dense medium formed in d + Au collisions at sNN~(1/2)= 200 GeV and Au + Au collisions at sNN~(1/2)= 62.4 GeV. Considering that some kaons may not be affected by the medium, we further study the BBC functions of K~+K~-when parts of all kaons have a mass-shift. Our results indicate that the BBC functions of K~+K~-can be observed when only ～10% of all kaons have a mass-shift in d + Au collisions at sNN~(1/2) = 200 GeV and the peripheral collisions of Au + Au at sNN~(1/2)= 62.4 GeV. Since the BBC function is caused by the mass-shift due to the interactions between the particle and the medium, the successful detection of the BBC function indirectly marks that the dense medium has formed in these collision systems. We suggest the experimental measurement of the BBC function of K~+K~- in d + Au collisions at sNN~(1/2) = 200 GeV and peripheral collisions of Au + Au at sNN~(1/2) = 62.4 GeV.     

Analysis of the O° proton spectrum fromd+p collisions at 9 GeV/c

The O° proton spectrum from d+p collisions at 9 GeV/c is described using the impulse approximation and a conventional deuteron wave function without six-quark admixture. It turnes out that the phase space constraints of the various inelastic channels strongly influence the high-momentum part of the spectrum and are decisive for the correct reproduction of the spectrum.     

Strange baryon resonance production in sqrt s NN=200 GeV p+p and Au+Au collisions

We report the measurements of Sigma(1385) and Lambda(1520) production in p+p and Au+Au collisions at sqrt[s{NN}]=200 GeV from the STAR Collaboration. The yields and the p(T) spectra are presented and discussed in terms of chemical and thermal freeze-out conditions and compared to model predictions. Thermal and microscopic models do not adequately describe the yields of all the resonances produced in central Au+Au collisions. Our results indicate that there may be a time span between chemical and thermal freeze-out during which elastic hadronic interactions occur.     

Bose-Einstein correlations inK + p and π+ p at 250 GeV/c

Two-pion correlations are studied for pions of like charge inK ⁺ p andπ ⁺ p collisions at 250 GeV/c. An enhanced production is observed at small momentum difference and is attributed to Bose-Einstein interference between identical particles. A systematic study is presented on the influence of parametrization and reference sample. Interpreted in terms of the Kopylov-Podgoretskii parametrization a size of the emitting regionr _K ≈1.4 fm is found. The Lorentz invariant parametrization of Goldhaber givesr _G ≈0.8 fm. With fixed parametrization, similarity is found for hadronhadron,e ⁺ e ^? and lepton-hadron collisions. No multiplicity or angular dependence is found at our energy.     

Forward neutral pion production in p + p and d + Au collisions at square root sNN=200 GeV

Measurements of the production of forward pi0 mesons from p + p and d + Au collisions at square root sNN=200 GeV are reported. The p + p yield generally agrees with next-to-leading order perturbative QCD calculations. The d + Au yield per binary collision is suppressed as eta increases, decreasing to approximately 30% of the p + p yield at eta =4.00, well below shadowing expectations. Exploratory measurements of azimuthal correlations of the forward pi0 with charged hadrons at eta approximately 0 show a recoil peak in p + p that is suppressed in d + Au at low pion energy. These observations are qualitatively consistent with a saturation picture of the low-x gluon structure of heavy nuclei.     

Rho0 production and possible modification in Au+Au and p+p collisions at square root [sNN] = 200 GeV

We report results on rho(770)(0)-->pi(+)pi(-) production at midrapidity in p+p and peripheral Au+Au collisions at sqrt[s(NN)]=200 GeV. This is the first direct measurement of rho(770)(0)-->pi(+)pi(-) in heavy-ion collisions. The measured rho(0) peak in the invariant mass distribution is shifted by approximately 40 MeV/c(2) in minimum bias p+p interactions and approximately 70 MeV/c(2) in peripheral Au+Au collisions. The rho(0) mass shift is dependent on transverse momentum and multiplicity. The modification of the rho(0) meson mass, width, and shape due to phase space and dynamical effects are discussed.