Spin alignment of vector mesons produced in multihadronic Z0 decays

DELPHI results on the spin density matrix analysis of the ρ0, K*0(892) and phi produced in Z0 hadronic decays at LEP are discussed. There is no spin alignment of the K*0(892) and phi in the region xp ≤ 0.3 (xp = p/Pbeam). In the fragmentation region, the evidence is presented for noticeable spin alignment of the ρ0, K*0(892) and phi, with the diagonal matrix element ρ00 increasing with xp. The off-diagonal matrix element ρ1-1 is consistent with zero in all cases. These results are compared with those obtained by OPAL for the K*0(892) and phi