  In the Standard Model, scalar contributions to leptonic and semileptonic
decays are helicity suppressed. The hypothesis of additional physical
neutral/charged Higgses can enhance such scalar contributions and give
detectable effects especially in B physics.
  For the charged Higgs, experimental information on both Br(B -> D tau nu) and
Br(B -> tau nu) has already become available and in particular the B -> D tau
nu branching ratio measurements will be further improved in the coming years.
Hadronic uncertainties of scalar contributions in semileptonic decays are
already in much better shape than the ones plaguing the helicity suppressed
leptonic decays B -> tau nu. Combining existing experimental information form
the B factories, we explore which existing and future lattice estimates will be
useful to directly address new physics effects from measurements of
Br(B_{u,d,s} -> D_{u,d,s} tau nu), which can be performed also at hadron
colliders.
