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Determination of N* amplitudes from associated strangeness production in p+p collisions
Mü,nzer, R.,Fabbietti, L.,Epple, E.,Lu, S.,Klose, P.,Hauenstein, F.,Herrmann, N.,Grzonka, D.,Leifels, Y.,Maggiora, M.,Pleiner, D.,Ramstein, B.,Ritman, J.,Roderburg, E.,Salabura, P.,Sarantsev, A.,B North-Holland Pub. Co 2018 Physics letters. Section B Vol.785 No.-
<P><B>Abstract</B></P> <P>We present the first determination of the energy-dependent amplitudes of N<SUP>⁎</SUP> resonances extracted from their decay in KΛ pairs in p+p → <SUP> pK + </SUP> Λ reactions. A combined Partial Wave Analysis of seven data samples with exclusively reconstructed p+p → <SUP> pK + </SUP> Λ events measured by the COSY-TOF, DISTO, FOPI and HADES Collaborations in fixed target experiments at kinetic energies between 2.14 to 3.5 GeV is used to determine the amplitude of the resonant and non-resonant contributions into the associated strangeness final state. The contribution of seven N<SUP>⁎</SUP> resonances with masses between 1650 MeV/c<SUP>2</SUP> and 1900 MeV/c<SUP>2</SUP> for an excess energy between 0 and 600 MeV has been considered. The Σ–p cusp and final state interactions for the p–Λ channel are also included as coherent contributions in the PWA. The N<SUP>⁎</SUP> contribution is found to be dominant with respect to the phase space emission of the pK Λ + final state at all energies demonstrating the important role played by both N<SUP>⁎</SUP> and interference effects in hadron–hadron collisions.</P>
Strange meson production in Al+Al collisions at 1.9 A GeV
Gasik, P.,Piasecki, K.,Herrmann, N.,Leifels, Y.,Matulewicz, T.,Andronic, A.,Averbeck, R.,Barret, V.,Basrak, Z.,Bastid, N.,Benabderrahmane, M. L.,Berger, M.,Buehler, P.,Cargnelli, M.,Č,aplar, R.,C Springer 2016 European Physical Journal A Vol.52 No.6
<P>The production of K+, K- and phi(1020) mesons is studied in Al+Al collisions at a beam energy of 1.9 A GeV which is close to or below the production threshold in NN reactions. Inverse slopes, anisotropy parameters, and total emission yields of K-+/- mesons are obtained. A comparison of the ratio of kinetic energy distributions of K- and K+ mesons to the HSD transport model calculations suggests that the inclusion of the in-medium modifications of kaon properties is necessary to reproduce the ratio. The inverse slope and total yield of phi mesons are deduced. The contribution to K- production from phi meson decays is found to be [17 +/- 3(stat)(-7)(+2) (syst)]%. The results are in line with the previous K-+/- and phi data obtained for different colliding systems at similar incident beam energies.</P>
Measurement of the In-MediumK0Inclusive Cross Section inπ−-Induced Reactions at1.15 GeV/c
Benabderrahmane, M. L.,Herrmann, N.,Wiś,niewski, K.,Kecskemeti, J.,Andronic, A.,Barret, V.,Basrak, Z.,Bastid, N.,Buehler, P.,Cargnelli, M.,Č,aplar, R.,Cordier, E.,Deppner, I.,Crochet, P.,Dup American Physical Society 2009 Physical Review Letters Vol.102 No.18
<P>The K0 meson production by pi(-) mesons of 1.15 GeV/c momentum on C, Al, Cu, Sn, and Pb nuclear targets was measured with the FOPI spectrometer at the Schwer-Ionen-Synchrotron accelerator of GSI. Inclusive production cross sections and the momentum distributions of K0 mesons are compared to scaled elementary production cross sections and to predictions of theoretical models describing the in-medium production of kaons. The data represent a new reference for those models, which are widely used for interpretation of the strangeness production in heavy-ion collisions. The presented results demonstrate the sensitivity of the kaon production to the reaction amplitudes inside nuclei and point to the existence of a repulsive KN potential of 20+/-5 MeV at normal nuclear matter density.</P>
Centrality dependence of subthresholdϕmeson production in Ni + Ni collisions at1.9AGeV
Piasecki, K.,Tymiń,ski, Z.,Herrmann, N.,Averbeck, R.,Andronic, A.,Barret, V.,Basrak, Z.,Bastid, N.,Benabderrahmane, M. L.,Berger, M.,Buehler, P.,Cargnelli, M.,Č,aplar, R.,Cordier, E.,Crochet American Physical Society 2016 Physical Review C Vol.94 No.1
<P>We analyzed the phi meson production in central Ni + Ni collisions at a beam kinetic energy of 1.93A GeV with the FOPI spectrometer and found a production probability per event of [8.6 +/- 1.6(stat) +/- 1.5(syst)] x 10(-4). This new data point allows us for the first time to inspect the centrality dependence of subthreshold phi meson production in heavy-ion collisions. The rise of phi meson multiplicity per event with mean number of participants can be parametrized by a power function with exponent alpha = 1.8 +/- 0.6. The ratio of phi to K- production yields seems not to depend, within the experimental uncertainties, on the collision centrality, and the average of measured values was found to be 0.36 +/- 0.05.</P>