Strangeness production in a statistical effective model of hadronization (original) (raw)

Strange quark production in an effective statistical model

Nuclear Physics A, 2003

An effective model with constituent quarks as fundamental degrees of freedom is used to predict the relative strangeness production pattern in both high energy elementary and heavy ion collisions. The basic picture is that of the statistical hadronization model, with hadronizing color-singlet clusters assumed to be at full chemical equilibrium at constituent quark level. Thus, by assuming that at least the ratio between strange and non-strange constituent quarks survives in the final hadrons, the apparent undersaturation of strange particle phase space observed in the data can be accounted for. In this framework, the enhancement of relative strangeness production in heavy ion collisions in comparison with elementary collisions is mainly owing to the excess of initial non-strange matter over antimatter and the so-called canonical suppression, namely the constraint of exact color and flavor conservation over small volumes.

Strangeness Production in a Constituent Quark Model

Quark-Gluon Plasma and Heavy Ion Collisions - Proceedings of a Meeting Held in the Framework of the Activities of GISELDA, the Italian Working Group on Strong Interactions, 2002

We develop a model to calculate strangeness production in both elementary and heavy ion collisions, within the framework of a statistical approach to hadronisation. Calculations are based on the canonical partition function of the thermal Nambu-Jona-Lasinio model with exact conservation of flavor and color. It turns out that the growth of strange quarks production in heavy ion collisions is due to the initial excess of non-strange matter over antimatter, whereas a suppression occurs for elementary collisions, owing to the constraint of exact quantum charges conservation over small volumes.

Strangeness production in hadronic models and recombination models

Journal of Physics G-nuclear and Particle Physics, 2010

We present recent results on the production, spectra and elliptic flow of strange particles in dynamic simulations employing hadronic degrees of freedom and from recombination models. The main focus will be on the Ultra-relativistic Molecular Dynamics (UrQMD) Boltzmann approach to relativistic heavy ion collisions and a hybrid approach with intermediate hydrodynamic evolution based on UrQMD (available for download as UrQMD v3.3). Compared to the standard binary collision approach, an enhancement of the strange particle particle yields is found in the hybrid approach due to the assumption of local equilibration. The production origins of the Phi-meson in the hybrid approach are studied in further detail. We also present results on the transverse momentum spectra of baryon to meson ratios of strange particles. Due to the approximate energy independent scaling of this ratio as a function of p_T we argue, that a maximum in these spectra may not be a unique sign for quark coalescence but can be understood in terms of flow and fragmentation.

Modeling the strangeness content of hadronic matter

Physical Review C, 2002

The strangeness content of hadronic matter is studied in a string-flip model that reproduces various aspects of the QCD-inspired phenomenology, such as quark clustering at low density and color deconfinement at high density, while avoiding long range van der Waals forces. Hadronic matter is modeled in terms of its quark constituents by taking into account its internal flavor (u,d,s) and color (red, blue, green) degrees of freedom. Variational Monte-Carlo simulations in three spatial dimensions are performed for the groundstate energy of the system. The onset of the transition to strange matter is found to be influenced by weak, yet not negligible, clustering correlations. The phase diagram of the system displays an interesting structure containing both continuous and discontinuous phase transitions. Strange matter is found to be absolutely stable in the model. 24.85.+p, 26.60.+c

Strangeness enhancement and energy dependence in heavy ion collisions

The European Physical Journal C - Particles and Fields, 2002

The canonical statistical model analysis of strange and multistrange hadron production in central A-A relative to p-p/p-A collisions is presented over the energy range from √ s = 8.73 GeV up to √ s = 130 GeV. It is shown that the relative enhancement of strange particle yields from p-p/p-A to A-A collisions substantially increases with decreasing collision energy. It is largest at √ s = 8.7 GeV, where the enhancement of Ω, Ξ and Λ is of the order of 100, 20 and 3, respectively. In terms of the model these results are due to the canonical suppression of particle thermal phase space at lower energies, which increases with the strangeness content of the particle and with decreasing size of the collision fireball. The comparison of the model with existing data on energy dependence of the kaon/pion ratio is also discussed.

Hadronization effects on the baryon-strangeness correlation in quark combination models

2015

The baryon-strangeness correlation in the hadronization of the quark matter is studied within the quark combination mechanism. We calculate the correlation coefficient C BS = −3 BS − B S / S 2 − S 2 of initial hadrons produced from the deconfined free quark system with C (q) BS = 1. The competition of the production of baryons against that of mesons is the key dynamics that is most relevant to the change of baryon-strangeness correlation during system hadronization. Results of quark combination under the Poisson statistics agree with the statistical model predictions for a hadron resonance gas at vanishing chemical potential but differ from those at relatively large chemical potentials. Results beyond Poisson statistics are also obtained and are compared with calculations of Lattice QCD in the phase boundary, giving the best agreement at temperature T = 163 MeV. We predict the dependence of the C BS of hadron system on the baryon chemical potential and strangeness. These predictions are expected to be tested by the future Lattice QCD calculations at non-zero chemical potentials and/or by the Beam Energy Scan experiment of STAR Collaboration at RHIC. PACS numbers: 25.75.Gz, 25.75.Nq

Canonical description of strangeness conservation and particle production

Zeitschrift für Physik C Particles and Fields, 1991

We study the production of particles in terms of a statistical formalism requiring strangeness to be exactly conserved while baryon number is treated grand canonically using a chemical potential. A complete treatment is presented for the case where the overall strangeness of the gas is zero and particles having strangeness up to _+ 3 are present. As an illustration we have applied the above formalism to the description of particle production in proton-proton, proton-nucleus and nucleusnucleus collisions. In particular the K/~ ratio shows a strong dependence on the interaction volume of the system while, in contrast, the ratio A/A is almost independent of the volume. These results are in qualitative agreement with experimental data.

Open and Hidden Strangeness Production in Nucleon-Nucleon Collisions

International Journal of Modern Physics E, 2009

Strange meson production reactions are expected to provide information on the manifestation of quantum chromodynamics in the non-perturbative regime of energies larger than that of the low energy pion physics. The K meson contains a strange quark (s) or antiquark [Formula: see text] while the η meson has hidden strangeness as it contains some component of the [Formula: see text] pair. In this lecture we present an overview of describing the production of K and η mesons in nucleon-nucleon collisions within an effective Lagrangian model (ELM) where meson production proceeds via excitation, propagation and subsequent decay of intermediate baryonic resonant states. Specific examples are discussed where proper understanding of the data is still lacking.

Prospects for strangeness production in p – p collisions at LHC

Journal of Physics G: Nuclear and Particle Physics, 2010

Prospects for strangeness production in p−p collisions at the Large Hadron Collider (LHC) are discussed within the statistical model. Firstly, the system size and the energy dependence of the model parameters are extracted from existing data and extrapolated to LHC energy. Particular attention is paid to demonstrate that the chemical decoupling temperature is independent of the system size. In the energy regime investigated so far, strangeness production in p − p interactions is strongly influenced by the canonical suppression effects. At LHC energies, this influence might be reduced. Particle ratios with particular sensitivity to canonical effects are indicated. Secondly, the relation between the strangeness production and the charged-particle multiplicity in p − p interactions is investigated. In this context the multiplicity dependence studied at Tevatron is of particular interest. There, the trend in relative strangeness production known from centrality dependent heavy-ion collisions is not seen in multiplicity selected p − p interactions. However, the conclusion from the Tevatron measurements is based on rather limited data samples with low statistics and number of observables. We argue, that there is an absolute need at LHC to measure strangeness production in events with different multiplicities to possibly disentangle relations and differences between particle production in p − p and heavy-ion collisions.