Speaker
Description
The distribution of particles is highly anisotropic in the initial stage of a heavy-ion collision. We demonstrate that this anisotropy induces a sizable effect on the spin alignment of vector mesons. We study two different production mechanisms for ϕ and K∗0 mesons, on one hand the coalescence of quarks and on the other that of pseudoscalar mesons. In the quark-coalescence picture where ϕ and K^{∗0} are produced via a bare vector coupling to quarks, a negative δρ{00} of order 10^−3 is observed. In contrast, when ϕ and K∗0 are produced via quark coalescence with a vertex with spin-orbit coupling, or when they are produced via pseudoscalar-meson coalescence, a positive δρ{00} emerges. In all cases, the magnitude of the spin alignment is directly proportional to the degree of anisotropy. The sign difference between the cases provides a possibility to clarify the production mechanism for vector mesons.
