Minimally flavored colored scalar in (B)over-bar → D(*)τ(ν)over-bar and the mass matrices constraints

The presence of a colored scalar that is a weak doublet with fractional electric charges of IQ = 2/3 and IQ = 5/3 with mass below 1 TeV can provide an explanation of the observed branching ratios in B -> D(*)n) decays. The required combination of scalar and tensor operators in the effective Hamiltonian for b -> c tau(nu) over bar is generated through the t-channel exchange. We focus on a scenario with a minimal set of Yukawa couplings that can address a semitauonic puzzle and show that its resolution puts a nontrivial bound on the product of the scalar couplings to tb and ay. We also derive additional constraints posed by Z -> b (b) over bar, muon magnetic moment, lepton flavor violating decays mu -> e gamma, tau -> mu gamma, tau -> e gamma, and tau electric dipole moment. The minimal set of Yukawa couplings is not only compatible with the mass generation in an SU(5) unification framework, a natural environment for colored scalars, but specifies all matter mixing parameters except for one angle in the up-type quark sector. We accordingly spell out predictions for the proton decay signatures through gauge boson exchange and show that p 70e+ is suppressed with respect to p -> K+nu and even p -> K(0)e(+) in some parts of available parameter space. Impact of the colored scalar embedding in 45-dimensional representation of SU(5) on low-energy phenomenology is also presented. Finally, we make predictions for rare top and charm decays where presence of this scalar can be tested independently.