Testing time reversal invariance in exclusive semileptonic B meson decays

We demonstrate that polarization measurements in exclusive semileptonic B decays are powerful tools for unraveling non-standard model sources of T-violation. Measurements of the transverse polarization of the τ lepton in the B → Dτν and B → D∗τν decays probe separately effective scalar and pseudoscalar CP-violating four-Fermi interactions, whereas the D∗ polarization in the B → D∗lν (l = e, μ) decay is sensitive to an effective right-handed quark current interaction. Two T-odd polarization structures exist involving the D∗ polarization and they can be isolated and studied separately. An estimate of these T-odd effects is also given in the context of supersymmetric theories.