Strangeness Enhancement in Heavy Ion Collisions - Evidence for Quark-Gluon-Matter ?

Abstract

The centrality dependence of (multi-)strange hadron abundances is studied for Pb(158 AGeV)Pb reactions and compared to p(158 GeV)Pb collisions. The microscopic transport model UrQMD is used for this analysis. The predicted Lambda/pi-, Xi-/pi- and Omega-/pi- ratios are enhanced due to rescattering in central Pb-Pb collisions as compared to peripheral Pb-Pb or p-Pb collisions. A reduction of the constituent quark masses to the current quark masses m_s \sim 230 MeV, m_q \sim 10 MeV, as motivated by chiral symmetry restoration, enhances the hyperon yields to the experimentally observed high values. Similar results are obtained by an ad hoc overall increase of the color electric field strength (effective string tension of kappa=3 GeV/fm). The enhancement depends strongly on the kinematical cuts. The maximum enhancement is predicted around midrapidity. For Lambda's, strangeness suppression is predicted at projectile/target rapidity. For Omega's, the predicted enhancement can be as large as one order of magnitude. Comparisons of Pb-Pb data to proton induced asymmetric (p-A) collisions are hampered due to the predicted strong asymmetry in the various rapidity distributions of the different (strange) particle species. In p-Pb collisions, strangeness is locally (in rapidity) not conserved. The present comparison to the data of the WA97 and NA49 collaborations clearly supports the suggestion that conventional (free) hadronic scenarios are unable to describe the observed high (anti-)hyperon yields in central collisions. The doubling of the strangeness to nonstrange suppression factor, gamma_s \approx 0.65, might be interpreted as a signal of a phase of nearly massless particles.

arXiv commentpublished version, discussion on strange mesons and new table added, extended discussion on strange baryon yields. Latex, 20 pages, including 5 eps-figures

References in corpus (8)

• Microscopic Models for Ultrarelativistic Heavy Ion Collisions
• Signatures of Quark-Gluon-Plasma formation in high energy heavy-ion collisions: A critical review
• Chiral Lagrangian for strange hadronic matter
• The parton to hadron phase transition observed in Pb+Pb collisions at 158 GeV per nucleon
• Equation of State, Spectra and Composition of Hot and Dense Infinite Hadronic Matter in a Microscopic Transport Model
• Hadronic Particle Production in Nucleus-Nucleus Collisions
• Strange Particles from Dense Hadronic Matter
• Strangeness in ultrarelativistic nucleus-nucleus collisions

Cited by in corpus (58)

• Fully integrated transport approach to heavy ion reactions with an intermediate hydrodynamic stage
• Strangeness dynamics and transverse pressure in relativistic nucleus-nucleus collisions
• Strange Resonance Production: Probing Chemical and Thermal Freeze-out in Relativistic Heavy Ion Collisions
• Hadronic observables from SIS to SPS energies - anything strange with strangeness ?
• K/pi Fluctuations at Relativistic Energies
• Near-threshold production of the multi-strange ${\Xi }^{-}$ hyperon
• Evidence for nonhadronic degrees of freedom in the transverse mass spectra of kaons from relativistic nucleus-nucleus collisions?
• Strange hadron production in heavy ion collisions from SPS to RHIC
• Charged particle (pseudo-)rapidity distributions in proton+anti-proton/proton+proton and Pb+Pb/Au+Au collisions from SPS to LHC energies from UrQMD
• Multistrange baryon production in relativistic heavy ion collisions
• Probing hadronization and freeze-out with multiple strange hadrons and strange resonances
• Equation of state of resonance-rich matter in the central cell in heavy-ion collisions at $\sqrt{s}$=200 AGeV
• Effects of Strong Color Fields on Baryon Dynamics
• In-medium pseudoscalar $D/B$ mesons and charmonium decay width
• Baryon-antibaryon annihilation and reproduction in relativistic heavy-ion collisions
• Enhanced Strange Particle Yields - Signal of a Phase of Massless Particles ?
• Transient field fluctuations effects in d+Au and Au+Au collisions at \sqrt{s_nn} = 200 GeV
• Transverse Dynamics at RHIC
• Nucleus-nucleus collisions at high baryon densities
• Enhanced antiproton production in Pb(160 AGeV)+Pb reactions: evidence for quark gluon matter?
• Is Anomalous Production of Omega and anti-Omega Evidence for Disoriented Chiral Condensates?
• Baryon stopping and strange baryon/antibaryon production at SPS energies
• Analysis of pseudoscalar and scalar $D$ mesons and charmonium decay width in hot magnetized asymmetric nuclear matter
• Strong Color Field Baryonic Remnants in Nucleus-Nucleus Collisions at 200A GeV
• Rapidity distribution of protons from the potential version of UrQMD model and the traditional coalescence afterburner
• Strangeness dynamics in relativistic nucleus-nucleus collision
• Strangeness Report
• Strangeness Production in Microscopic Transport Models
• Strangeness enhancement from strong color fields at RHIC
• Global observables and secondary interactions in central Au+Au reactions at $\sqrt{s}=200$ AGeV
• Vacuum creation of quarks at the time scale of QGP thermalization and strangeness enhancement in heavy-ion collisions
• Pion freeze-out as seen through HBT correlations in heavy ion collisions from FAIR/AGS to RHIC energies
• QGP Theory: Status and Perspectives
• Heavy vector and axial-vector $D$ mesons in hot magnetized asymmetric nuclear matter
• A Microscopic Picture of Strangeness Production at the SPS
• Multi-strange baryon production in Au+Au collisions near threshold
• Xi production at AGS energies
• Resonances and fluctuations of strange particle in 200 GeV Au-Au collisions
• Production and rescattering of strange baryons at SPS energies in a transport model with hadron potentials
• Effects of nuclear absorption on the antiLambda/antiproton ratio in relativistic heavy ion collisions
• Microscopic study of strange hadron productions at the LHC with$\sqrt{s_{NN}}$=2.76 TeV
• System-size dependence of the pion freeze-out volume as a potential signature for the phase transition to a Quark Gluon Plasma
• Fluctuations of identified particle yields using the ν dyn variable at energies available at the BNL Relativistic Heavy Ion Collider
• An explanation of the elliptic flow difference between proton and anti-proton from the UrQMD model with hadron potentials
• Dynamics of particle production in Pb--Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV using PYTHIA8 Angantyr model
• News on Strangeness at Ultrarelativistic Energies - Review of Microscopic Models
• Phi-Meson Production at RHIC, Strong Color Fields and Intrinsic Transverse Momenta
• Resonances and fluctuations at SPS and RHIC
• Strangeness Production at RHIC in the Perturbative Regim
• Enhancement of $\varphi$ mesons in Pb+Pb collisions at 158A GeV/c
• Anomalous Production of Omega and AntiOmega is Evidence for the Formation of Disoriented Chiral Condensates?
• Energy and system size dependence of strongly intensive fluctuation measures in heavy-ion collisions at FAIR energies
• The freeze-out properties of hyperons in a microscopic transport model
• SQM 2006: Theory Summary and Perspectives
• Strange behavior of rapidity dependent strangeness enhancement of particles containing and not containing leading quarks
• Current Status of Quark Gluon Plasma Signals
• Possible Evidence of Disoriented Chiral Condensates from the Anomaly in Omega and AntiOmega Abundances at the SPS
• Study of diffusion coefficients of identified particles at energies available at BNL Relativistic Heavy Ion Collider