Interference effects for the top quark decays $t\to b+W^{+}/H^{+}(\to {\tau }^{+}{\nu }_{\tau })$

Abstract

Applying the narrow-width approximation (NWA), we first review the NLO QCD predictions for the total decay rate of top quark considering two unstable intermediate particles: the $W^{+}$-boson in the standard model (SM) of particle physics and the charged Higgs boson $H^{+}$ in the generic type-I and II two-Higgs-doublet models, i.e. $t\to b+W^{+}/H^{+}(\to {\tau }^{+}{\nu }_{\tau })$. We then estimate the errors arised from this approximation at leading-order perturbation theory. Finally, we shall investigate the interference effects in the factorization of production and decay parts of intermediate particles. We will show that for nearly mass-degenerate states ($m_{H^{+}}\approx m_{W^{+}}$), the correction due to the interference effect is considerable.

Comments: 10 pages, 10 figures, 51 References. Accepted by Physical Review D. arXiv admin note: text overlap with arXiv:1806.02546; text overlap with arXiv:1411.4652, arXiv:0911.3027 by other authors