Spin alignment measurements of the K*0(892) and ϕ(1020) vector mesons in heavy ion collisions at √sNN=200 GeV

Abelev, B. I. and Planinić, Mirko and Poljak, Nikola and Zuo, J. X. (STAR Collaboration) (2008) Spin alignment measurements of the K*0(892) and ϕ(1020) vector mesons in heavy ion collisions at √sNN=200 GeV. Physical Review C, 77 (6). pp. 61902-7. ISSN 0556-2813

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Abstract

We present the first spin alignment measurements for the K*0(892) and ϕ(1020) vector mesons produced at midrapidity with transverse momenta up to 5 GeV/c at √sNN=200 GeV at RHIC. The diagonal spin-density matrix elements with respect to the reaction plane in Au+Au collisions are ρ00=0.32±0.04 (stat) ± 0.09 (syst) for the K*0 (0.8<p_T<5.0 GeV/c) and ρ_00=0.34±0.02 (stat) ± 0.03 (syst) for the ϕ (0.4<pT<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 ϕ in Au+Au collisions were also measured with respect to the particle's production plane. The ϕ result, ρ_00=0.41±0.02 (stat) ± 0.04 (syst), is consistent with that in p+p collisions, ρ_00=0.39±0.03 (stat) ± 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.

Item Type: Article
Keywords: mid-rapidity with transverse momenta
Date: June 2008
Subjects: NATURAL SCIENCES > Physics
Additional Information: Copyright (2008) by the American Physical Society.
Divisions: Faculty of Science > Department of Physics
Project code: 119-0982887-1006
Publisher: American Physical Society
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 10 Jun 2014 12:53
Last Modified: 10 Jun 2014 12:53
URI: http://digre.pmf.unizg.hr/id/eprint/2342

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