Abstract
In the "Higgs basis" for a generic 2HDM, only one scalar doublet gets a nonzero vacuum expectation value and, under the criterion of minimal flavor violation, the other one is fixed to be either color-singlet or color-octet, which are named as the type-III and type-C models, respectively. In this paper, the charged-Higgs effects of these two models on $B_s^0-\bar{B}_s^0$ mixing are studied. Firstly, we perform a complete one-loop computation of the electro-weak corrections to the amplitudes of $B_s^0-\bar{B}_s^0$ mixing. Together with the up-to-date experimental measurements, a detailed phenomenological analysis is then performed in the cases of both real and complex Yukawa couplings of charged scalars to quarks. The spaces of model parameters allowed by the current experimental data on $B_s^0-\bar{B}_s^0$ mixing are obtained and the differences between type-III and type-C models are investigated, which is helpful to distinguish between these two models.
Highlights
One of the extensions of Standard Model (SM) scalar sector is the socalled two-Higgs-doublet model (2HDM) [11], in which a second scalar doublet is added to the SM field content
To avoid the experimental constraints on flavor-changing neutral-current (FCNC) transitions, which are forbidden at tree level in the SM due to the GIM mechanism [12], two different hypotheses, natural flavor conservation (NFC) [13] and minimal flavor violation (MFV) [14,15,16,17], have been proposed
In the “Higgs basis” [25], in which only one doublet gets a nonzero vacuum expectation value (VEV) and behaves as the SM one, the allowed SU (3)C ⊗ SU (2)L ⊗ U (1)Y representation of the second scalar doublet that couples to quarks via Yukawa interactions is fixed to be either (1, 2)1/2 or (8, 2)1/2 [26], which implies that the second scalar doublet can be either color-singlet or color-octet
Summary
One of the extensions of SM scalar sector is the socalled two-Higgs-doublet model (2HDM) [11], in which a second scalar doublet is added to the SM field content. In the “Higgs basis” [25], in which only one doublet gets a nonzero vacuum expectation value (VEV) and behaves as the SM one, the allowed SU (3)C ⊗ SU (2)L ⊗ U (1)Y representation of the second scalar doublet that couples to quarks via Yukawa interactions is fixed to be either (1, 2)1/2 or (8, 2)1/2 [26], which implies that the second scalar doublet can be either color-singlet or color-octet They are referred to as type-III and type-C models [27], respectively. Which are in good agreement with the recent SM predictions, MsSM = (17.3 ± 2.6) ps−1 and 0.021) ps−1 [31] There are another two interesting observables related to Bs0–Bs0 mixing, the flavor-specific CP asymmetry assl and the CP-violating phase φsccs, which are defined, respectively, by s assl. In this paper, we shall evaluate the effects of charged Higgs in type-III and type-C 2HDMs on Bs0–Bs0 mixing, and pursue possible differences between these two models. Explicit expressions for the loop functions appearing in Bs0–Bs0 mixing are collected in the appendix
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