Article

# Rapidity Dependence of Charged Antihadron to Hadron Ratios in A u + A u Collisions at s N N = 200 G e V

Niels Bohr Institute, Blegdamsvej 17, University of Copenhagen, Copenhagen 2100, Denmark.

Physical Review Letters (Impact Factor: 7.51). 04/2003; 90(10):102301. DOI: 10.1103/PhysRevLett.90.102301 Source: PubMed

**ABSTRACT**

We present ratios of the numbers of charged antihadrons to hadrons (pions, kaons, and protons) in Au+Au collisions at sqrt[s(NN)]=200 GeV as a function of rapidity in the range y=0-3. While the ratios at midrapidity are approaching unity, the K(-)/K(+) and p;/p ratios decrease significantly at forward rapidities. An interpretation of the results within the statistical model indicates a reduction of the baryon chemical potential from mu(B) approximately 130 MeV at y=3 to mu(B) approximately 25 MeV at y=0.

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**ABSTRACT:**Thesis (Ph. D. in Science)--University of Tsukuba, (A), no. 4906, 2009.3.25 On t.p. "[s]" is superscript Includes bibliographical references (p. 136-140) http://www.tulips.tsukuba.ac.jp/limedio/dlam/B28/B2862729/1.pdf - [Show abstract] [Hide abstract]

**ABSTRACT:**The single-freeze-out model of hadron production is used to describe the particle ratios and the transverse-momentum spectra from RHIC. The emphasis is put on the new measurements done at the highest beam energy of 200 GeV. An overall very good agreement is found between the data and the model predictions. The data for different centrality windows are analyzed separately. A simple scaling of the two expansion parameters of the model with the centrality is found. Interestingly, this scaling turns out to be equivalent to the scaling of hadron production with the number of wounded nucleons. Comment: results for the Omega baryons added - [Show abstract] [Hide abstract]

**ABSTRACT:**Production of resonances is considered in the framework of the single-freeze-out model of ultra-relativistic heavy ion collisions. The formalism involves the virial expansion, where the probability to form a resonance in a two-body channel is proportional to the derivative of the phase-shift with respect to the invariant mass. The thermal model incorporates longitudinal and transverse flow, as well as kinematic cuts of the STAR experiment at RHIC. We find that the shape of the pi+ pi- spectral line qualitatively reproduces the preliminary experimental data when the position of the rho peak is lowered. This confirms the need to include the medium effects in the description of the RHIC data. We also analyze the transverse-momentum spectra of rho, K*(892), and f_0(980), and find that the slopes agree with the observed values. Predictions are made for eta, eta', omega, phi, Lambda(1520), and Sigma(1385). Comment: minor modifications, a reference added

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