Charm multiplicity and the branching ratios of inclusive charmlessbquark decays in the general two-Higgs-doublet models

Abstract

In the framework of general two-Higgs-doublet models, we calculate the branching ratios of various inclusive charmless b decays by using the low-energy effective Hamiltonian including next-to-leading order QCD corrections, and examine the current status and the new physics effects on the determination of the charm multiplicity ${n}_{c}$ and semileptonic branching ratio ${B}_{\mathrm{SL}}.$ Within the considered parameter space, the enhancement to the ratio $\mathrm{BR}(\stackrel{\ensuremath{\rightarrow}}{b}sg)$ due to the charged-Higgs penguin diagrams can be as large as a factor of 8 (3) in the model III (II), while the ratio $\mathrm{BR}(\stackrel{\ensuremath{\rightarrow}}{b}\mathrm{no}$ charm) can be increased from the standard model prediction of 2.49 to $4.91%$ $(2.99%)$ in model III (II). Consequently, the value of ${B}_{\mathrm{SL}}$ and ${n}_{c}$ can be decreased simultaneously in model III. The central value of ${B}_{\mathrm{SL}}$ will be lowered slightly by about $0.003,$ but the ratio ${n}_{c}$ can be reduced significantly from the theoretical prediction of ${n}_{c}=1.28\ifmmode\pm\else\textpm\fi{}0.05$ in the SM to ${n}_{c}=1.23\ifmmode\pm\else\textpm\fi{}0.05,$ $1.18\ifmmode\pm\else\textpm\fi{}0.05$ for ${m}_{{H}^{+}}=200,$ 100 GeV, respectively. We find that the predicted ${n}_{c}$ and the measured ${n}_{c}$ now agree within roughly one standard deviation after taking into account the effects of gluonic charged Higgs penguin diagrams in model III with a relatively light charged Higgs boson.