On the reactions p + p -> p + Lambda + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds

The cross sections for the reactions of the strange production p + p -> p + Lambda + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds of the final states p Lambda K^+ and p Sigma^0 K^+ are calculated in the effective Lagrangian approach. Our approach is based on the dominant contribution of the one-pion exchange and strong interaction of the colliding protons in the initial state. The theoretical values of the cross sections agree reasonably well with the experimental data. The polarization properties of the Lambda and Sigma^0 hyperons are discussed.Comment: 15 pages, 1 Postscript figure, Latex, to appear in Eur. Phys. J

Initial-state nuclear effects in proton-nucleus collisions

Two important initial-state nuclear effects in hadron-nucleus collisions are considered. The ratios of inclusive differential cross sections for Drell-Yan dimuon production are calculated. The calculated results are compared to the E866 data. It is shown that consideration of multiple soft rescatterings of incident quarks in nuclei and initial-state quark energy loss effects allow to get a good agreement between the calculated results and the experimental data.Comment: 6 pages, 6 figure

Tvorba hadrona u fazi kvark-gluon plazme ultrarelativističih sudara teških iona

We describe the quark gluon plasma (QGP) as a thermalized quark–gluon system, the thermalized QGP phase of QCD. The hadronization of the thermalized QGP phase is given in a way resembling a coalescence model with correlated quarks and antiquarks. The input parameters of the approach are the spatial volumes of the hadronization. We introduce three dimensionless parameters, CM, CB and CB¯ , related to the spatial volumes of the production of low-lying mesons (M), baryons (B) and antibaryons (B). We show that at the temperature ¯ T = 175MeV our predictions for the ratios of multiplicities agree well with the presently available set of hadron ratios measured for various experiments given by the NA44, NA49, NA50 and WA97 Collaborations on Pb+Pb collisions at 158 GeV/nucleon, the NA35 Collaboration on S+S collisions and the NA38 Collaboration on O+U and S+U collisions at 200 GeV/nucleon.Opisujemo kvark-gluon plazmu (QGP) kao ravnotežni sustav kvarkova i gluona, tj. termaliziranu QGP fazu kvantne kromodinamike. Hadronizacija ravnotežne QGP faze opisuje se slično modelu skupljanja s koreliranim kvarkovima i antikvarkovima. Ulazni parametri ovog pristupa su prostorni volumeni hadronizacije. Uvodimo tri bezdimenzijska parametra, CM, CB i CB¯ , vezanih s prostornim volumenima tvorbe lakih mezona (M), bariona (B) i antibariona (B). Pokazujemo da su na temperaturi ¯ T = 175MeV naša predviđanja za omjere višestrukosti u skladu s poznatim skupom omjera hadrona određenim mjerenjima Pb + Pb sudara u eksperimentima NA44, NA49, NA50 i WA97 na 158 GeV/nukleon, NA35 suradnje za S + S sudare i NA38 suradnje za O + U i S + U sudare na 200 GeV/nukleon

Tvorba hadrona u fazi kvark-gluon plazme ultrarelativističih sudara teških iona

We describe the quark gluon plasma (QGP) as a thermalized quark–gluon system, the thermalized QGP phase of QCD. The hadronization of the thermalized QGP phase is given in a way resembling a coalescence model with correlated quarks and antiquarks. The input parameters of the approach are the spatial volumes of the hadronization. We introduce three dimensionless parameters, CM, CB and CB¯ , related to the spatial volumes of the production of low-lying mesons (M), baryons (B) and antibaryons (B). We show that at the temperature ¯ T = 175MeV our predictions for the ratios of multiplicities agree well with the presently available set of hadron ratios measured for various experiments given by the NA44, NA49, NA50 and WA97 Collaborations on Pb+Pb collisions at 158 GeV/nucleon, the NA35 Collaboration on S+S collisions and the NA38 Collaboration on O+U and S+U collisions at 200 GeV/nucleon.Opisujemo kvark-gluon plazmu (QGP) kao ravnotežni sustav kvarkova i gluona, tj. termaliziranu QGP fazu kvantne kromodinamike. Hadronizacija ravnotežne QGP faze opisuje se slično modelu skupljanja s koreliranim kvarkovima i antikvarkovima. Ulazni parametri ovog pristupa su prostorni volumeni hadronizacije. Uvodimo tri bezdimenzijska parametra, CM, CB i CB¯ , vezanih s prostornim volumenima tvorbe lakih mezona (M), bariona (B) i antibariona (B). Pokazujemo da su na temperaturi ¯ T = 175MeV naša predviđanja za omjere višestrukosti u skladu s poznatim skupom omjera hadrona određenim mjerenjima Pb + Pb sudara u eksperimentima NA44, NA49, NA50 i WA97 na 158 GeV/nukleon, NA35 suradnje za S + S sudare i NA38 suradnje za O + U i S + U sudare na 200 GeV/nukleon

On polarization of strange baryons in reactions p + p -> p + Lambda^0 + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds

Polarization properties of strange baryons produced in pp reactions, p + p -> p + Lambda^0 + K^+ and p + p -> p + Sigma^0 + K^$, near thresholds of the final states (p Lambda^0 K^+) and (p Sigma^0 K^+) are analysed relative to polarizations of colliding protons. The cross sections for pp reactions are calculated within the effective Lagrangian approach accounting for strong pp rescattering in the initial state of colliding protons with a dominant contribution of the one-pion exchange and strong final-state interaction of daughter hadrons (Eur. Phys. J. A 9, 425 (2000)).Comment: 11 pages, latex, no figure

Higher-order ratios of baryon number cumulants

The relevance of higher order cumulants of net baryon number fluctuations for the analysis of freeze-out and critical conditions in heavy-ion collisions at LHC and RHIC is addressed. The sign structure of the higher order cumulants in the vicinity of the chiral crossover temperature might be a sensitive probe and may allow to elucidate their relation to the QCD phase transition. We calculate ratios of generalized quark-number susceptibilities to high orders in three flavor QCD-like models and investigate their sign structure close to the chiral crossover line.Comment: presented at the International Conference "Critical Point and Onset of Deconfinement - CPOD 2011", Wuhan, November 7-11, 2011; version to appear in Cent. Eur. J. Phy