B physics is sensitive to the effects of Higgs bosons in the
Minimal Supersymmetric Standard Model, if
the parameter $\tan\beta$ is large. I briefly summarise the role
of $B\to \mu^+\mu^-$ and $\BTNp$ in the hunt for new Higgs effects
and present new results on the decay $\BDTN$:
Using the analyticity properties of form factors one can predict the
ratio $R\equiv\mathcal{B}(\BDTN)/\mathcal{B}(\BDLN)$, $\ell=e,\mu$,
with small hadronic uncertainties. In the Standard Model one
finds $R= 0.31 \pm 0.02$, ${\cal B} (B^- \to D^0 \tau^-
\bar{\nu}_{\tau}) = (0.71\pm 0.09)\% $ and ${\cal B} (\bar{B}^0 \to
D^+ \tau^- \bar{\nu}_{\tau})= (0.66\pm 0.08)\% $, if the vector form
factor of the Heavy Flavor Averaging Group is used. $\BDTN$ is
competitive with $\BTNp$ in the search for effects of charged Higgs
bosons. Especially sensitive to the latter is the differential
distribution in the decay chain $\bar{B}\to
D\bar{\nu}_{\tau}\tau^-[\to\pi^-\nu_{\tau}]$.
