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 $\mathrm{BR}\left(\overrightarrow{b}sg\right)$ 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 $\mathrm{BR}(\overrightarrow{b}\mathrm{no}$ charm) can be increased from the standard model prediction of 2.49 to $4.91\%$ $\mathrm{}(2.99\%)\mathrm{}$ 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 $n_c=1.28\mathrm{}\pm 0.05$ in the SM to $n_c=1.23\mathrm{}\pm 0.05,$ $1.18\pm 0.05$ 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.

• Received 13 March 2000

DOI:https://doi.org/10.1103/PhysRevD.62.094008