Forward-backward asymmetry in [Formula Presented]

We study the forward-backward asymmetries in the decays of [Formula Presented] [Formula Presented] and μ) in the presence of scalar or tensor terms. We find that with the scalar [tensor] type interaction the asymmetry can be up to [Formula Presented] [Formula Presented] and arbitrarily large for the electron and muon modes, respectively, without conflict with the experimental data. We also discuss the cases in the minimal supersymmetric standard model where the scalar terms can be induced. In particular, we show that the asymmetry in [Formula Presented] can be as large as [Formula Presented] in the large [Formula Presented] limit, which can be tested in future experiments such as the CKM experiment at Fermilab.