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Flavor constraints on two-Higgs-doublet models with general diagonal Yukawa couplings

Abstract : We consider constraints from flavor physics on two-Higgs-doublet models (2HDM) with general, flavor-diagonal, Yukawa couplings. Analyzing the charged Higgs contribution to different observables, we find that $b\to s\gamma$ transitions and $\Delta M_{B_d}$ restrict the coupling $\lambda_{tt}$ of the top quark (corresponding to $\cot\beta$ in models with a $Z_2$ symmetry) to $|\lambda_{tt}|<1$ for $m_{H^+}\lesssim 500$ GeV. Stringent constraints from $B$ meson decays are obtained also on the other third generation couplings $\lambda_{bb}$ and $\lambda_{\tau\tau}$, but with stronger dependence on $m_{H^+}$. For the second generation, we obtain constraints on combinations of $\lambda_{ss}$, $\lambda_{cc}$, and $\lambda_{\mu\mu}$ from leptonic $K$ and $D_s$ decays. The limits on the general couplings are translated to the common 2HDM types I -- IV with a $Z_2$ symmetry, and presented on the $(m_{H^+},\tan\beta)$ plane. The flavor constraints are most excluding in the type II model which lacks a decoupling limit in $\tan\beta$. We obtain a lower limit $m_{H^+}\gtrsim 300$ GeV in models of type II and III, while no lower bound on $m_{H^+}$ is found for types I and IV.
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Contributor : Jeanine Pellet <>
Submitted on : Monday, November 30, 2009 - 4:59:02 PM
Last modification on : Tuesday, April 20, 2021 - 12:00:10 PM

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Farvah Mahmoudi, Oscar Stål. Flavor constraints on two-Higgs-doublet models with general diagonal Yukawa couplings. Physical Review D, American Physical Society, 2010, 81, pp.035016. ⟨10.1103/PhysRevD.81.035016⟩. ⟨in2p3-00437499⟩



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