Rapidity-dependent spectra from a single-freeze-out model of relativistic heavy-ion collisions

Abstract

An extension of the single-freeze-out model with thermal and geometric parameters dependent on the spatial rapidity, ${\alpha }_{\parallel }$, is used to describe the rapidity and transverse-momentum spectra of pions, kaons, protons, and antiprotons measured at RHIC at $\sqrt{s_{NN}}=200\mathrm{GeV}$ by the BRAHMS collaboration. {\tt THERMINATOR} is used to perform the necessary simulation, which includes all resonance decays. The result of the fit to the rapidity spectra in the range of the BRAHMS data is the expected growth of the baryon and strange chemical potentials with the magnitude of ${\alpha }_{\parallel }$, while the freeze-out temperature is kept fixed. The value of the baryon chemical potential at ${\alpha }_{\parallel }\sim 3$, which is the relevant region for particles detected at the BRAHMS forward rapidity $y\sim 3$, is about $200\mathrm{GeV}$, {\em i.e.} lies in the range of the values obtained for the highest SPS energy. The chosen geometry of the fireball has a decreasing transverse size as the magnitude of ${\alpha }_{\parallel }$ is increased, which also corresponds to decreasing transverse flow. This feature is verified by reproducing the transverse momentum spectra of pions and kaons at various rapidities. The strange chemical potential obtained from the fit to the $K^{+}/K^{-}$ ratio is such that the local strangeness density in the fireball is compatible with zero. The resulting rapidity spectra of net protons are described qualitatively in the model. As a result of the study, the knowledge of the ``topography'' of the fireball is achieved, making other calculations possible. As an example, we give predictions for the rapidity spectra of hyperons.

11 pages, 9 figures, better quality figures supplied

References in corpus (5)

• Space-time evolution of bulk QCD matter
• Therminator: Thermal heavy-Ion generator
• Status of Chemical Freeze-Out
• Femtoscopy in hydro-inspired models with resonances
• The centrality dependence of transverse energy and charged particle multiplicity at RHIC: Statistical model analysis

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• Equilibrium Statistical-Thermal Models in High-Energy Physics
• Rapid hydrodynamic expansion in relativistic heavy-ion collisions
• Soft heavy-ion physics from hydrodynamics with statistical hadronization - predictions for the Large Hadron Collider
• Particlization of an interacting hadron resonance gas with global conservation laws for event-by-event fluctuations in heavy-ion collisions
• Exteneded Longitudinal Scaling and the Thermal Model
• Splitting of proton-antiproton directed flow in relativistic heavy-ion collisions
• Rapidity scan with multistage hydrodynamic and statistical thermal models
• Rapidity-dependent chemical potentials in a statistical approach
• The effect of flow on Hadronic Spectra in an Excluded-Volume Model