Recent experimental results for the ratios of the branching fractions of the decays
B ! D() and B ! D() came as a surprise and lead to a discussion of possibility
of testing New Physics beyond the Standard Model through these modes. We show that
these decay channels can provide us with good constraints on New Physics and several
New Physics cases are favored by the present experimental data. In order to discriminate
various New Physics scenarios, we examine the q2 distributions and estimate the sensitivity
of this potential measurement at the SuperKEKB/Belle II experiment.