  We perform an analysis of the K* polarization states in the exclusive B meson
decay B0->K*0(-> K- pi+)l+ l- (l=e, mu, tau) in the low dilepton mass region,
where the final vector meson has a large energy. Working in the transversity
basis, we study various observables that involve the K* spin amplitudes Aperp,
Apar, A0 by exploiting the heavy-to-light form factor relations in the heavy
quark and large-E_K* limit. We find that at leading order in 1/m_b and alpha_s
the form-factor dependence of the asymmetries that involve transversely
polarized K* completely drops out. At next-to-leading logarithmic order,
including factorizable and non-factorizable corrections, the theoretical errors
for the transverse asymmetries turn out to be small in the standard model (SM).
Integrating over the lower part of the dimuon mass region, and varying the
theoretical input parameters, the SM predicts A_T^(1)=0.9986+/- 0.0002 and
A_T^(2)=-0.043+/- 0.003. In addition, the longitudinal and transverse
polarization fractions are found to be (69+/-3)% and (31+/-3)% respectively, so
that Gamma_L/Gamma_T = 2.23+/-0.31. Beyond the SM, we focus on new physics that
mainly gives sizable contributions to the coefficients C_7^eff' of the
electromagnetic dipole operators. Taking into account experimental data on rare
B decays, we find large effects of new physics in the transverse asymmetries.
Furthermore, we show that a measurement of longitudinal and transverse
polarization fractions will provide complementary information on physics beyond
the SM.
