Flavor conservation in two-Higgs-doublet models

In extensions of the Standard Model with two Higgs doublets, flavor-changing Yukawa couplings of the neutral scalars may be present at tree level. In this work, we consider the most general scenario in which those flavor-changing couplings are absent. We revise the conditions that the Yukawa coupling matrices must obey for such general flavour conservation (gFC) and study the one-loop renormalization group evolution of such conditions in both the quark and lepton sectors. We show that gFC in the leptonic sector is one-loop stable under the renormalization group evolution, and in the quark sector, we present some new Cabibbo-like solution also one-loop stable under renormalization group evolution. At a phenomenological level, we obtain the regions for the different gFC parameters that are allowed by the existing experimental constraints related to the 125 GeV Higgs.

Figure 1

$\overline{q}q\to \mathrm{h}$ process.

Figure 2

h-mediated contribution to $d_e$ at one loop.

Figure 3

$|n_f|$ vs $c_{\beta \alpha }$ for the different fermions $f$; darker to lighter regions correspond to 68%, 95%, and 99% C.L.

Figure 4

Allowed regions at 99% C.L. for pseudoscalar vs scalar couplings for the different fermions $f$ with ${\mathcal{L}}_{\mathrm{h}\overline{f}f}=-\frac{\mathrm{h}}{v}\overline{f}({\overline{a}}_f+i{\overline{b}}_f{\gamma }_5)f$.

Figure 5

Effect of including $q\overline{q}\to \mathrm{h}$ production in ggF in analyses of Higgs signal strengths; darker to lighter regions correspond to 68%, 95%, and 99% C.L.

Figure 6

$t_{\beta }$ vs $c_{\beta \alpha }$; darker to lighter regions correspond to 68%, 95%, and 99% C.L.

Figure 7

${\overline{a}}_u/m_u$ vs $c_{\beta \alpha }$; darker to lighter regions correspond to 68%, 95%, and 99% C.L.

Figure 8

${\overline{a}}_d/m_d$ vs $c_{\beta \alpha }$; darker to lighter regions correspond to 68%, 95%, and 99% C.L.

Figure 9

${\overline{a}}_{\ell }/m_{\ell }$ vs $c_{\beta \alpha }$; darker to lighter regions correspond to 68%, 95%, and 99% C.L.

Figure 10

Aligned; darker to lighter regions correspond to 68%, 95%, and 99% C.L.