Spin alignment measurements of the K*0(892) and phi (1020) vector mesons in heavy ion collisions at root S-NN=200 GeV (CROSBI ID 151511)
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Podaci o odgovornosti
Abelev, B.I. ; ... ; Planinić, Mirko ; ... ; Poljak, Nikola ; et al. (the STAR Collaboration)
engleski
Spin alignment measurements of the K*0(892) and phi (1020) vector mesons in heavy ion collisions at root S-NN=200 GeV
We present the first spin alignment measurements for the $K^{; ; *0}; ; (892)$ and $\phi(1020)$ vector mesons produced at mid-rapidity with transverse momenta up to 5 GeV/c at $\sqrt{; ; s_{; ; NN}; ; }; ; $ = 200 GeV at RHIC. The diagonal spin density matrix elements with respect to the reaction plane in Au+Au collisions are $\rho_{; ; 00}; ; $ = 0.32 $\pm$ 0.04 (stat) $\pm$ 0.09 (syst) for the $K^{; ; *0}; ; $ ($0.8<p_T<5.0$ GeV/c) and $\rho_{; ; 00}; ; $ = 0.34 $\pm$ 0.02 (stat) $\pm$ 0.03 (syst) for the $\phi$ ($0.4<p_T<5.0$ GeV/c), and are constant with transverse momentum and collision centrality. The data are consistent with the unpolarized expectation of 1/3 and thus no evidence is found for the transfer of the orbital angular momentum of the colliding system to the vector meson spins. Spin alignments for $K^{; ; *0}; ; $ and $\phi$ in Au+Au collisions were also measured with respect to the particle's production plane. The $\phi$ result, $\rho_{; ; 00}; ; $ = 0.41 $\pm$ 0.02 (stat) $\pm$ 0.04 (syst), is consistent with that in p+p collisions, $\rho_{; ; 00}; ; $ = 0.39 $\pm$ 0.03 (stat) $\pm$ 0.06 (syst), also measured in this work. The measurements thus constrain the possible size of polarization phenomena in the production dynamics of vector mesons.
mid-rapidity with transverse momenta
Art. no. 061902.
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Podaci o izdanju
77 (6)
2008.
061902-1-061902-7
objavljeno
0556-2813
10.1103/PhysRevC.77.061902