Naslov
Spin alignment measurements of the K*0(892) and phi (1020) vector mesons in heavy ion collisions at root S-NN=200 GeV

Autori
Abelev, B.I. ; ... ; Planinić, Mirko ; ... ; Poljak, Nikola ; et al. (the STAR Collaboration)

Izvornik
Physical Review C (0556-2813) 77 (2008), 6; 061902-1

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
mid-rapidity with transverse momenta

Sažetak
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.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

Napomena
Art. no. 061902.

POVEZANOST RADA