Upper and lower bounds of the lightest CP-even Higgs boson in the two-Higgs-doublet model

S. Kanemura; T. Kasai; Y. Okada

doi:10.1016/S0370-2693(99)01351-9

paper

Upper and lower bounds of the lightest CP-even Higgs boson in the two-Higgs-doublet model

arXiv:hep-ph/9911312 · doi:10.1016/S0370-2693(99)01351-9

Abstract

By imposing validity of the perturbation and stability of vacuum up to an energy scale $I^$ ( $\leq 1 0^{19}$ GeV), we evaluate mass bounds of the lightest CP-even Higgs-boson mass ( $m_{h}$ ) in the two-Higgs-doublet model (2HDM) with a softly-broken discrete symmetry. The most general bounds are obtained as a function of $I^$ vering all the free parameters under the experimental constraint from the $r h o$ parameter and the b \to s Î³ $r es u l t s . W e f in d t ha t, w hi l e t h e u pp er b o u n d i s a l m os tt h es am e a s in t h e S M, t h e l o w er b o u n d i ss i g ni f i c an tl y r e d u ce d . I n t h e d eco u pl in g r e g im e w h er e t h e m o d e l b e ha v es l ik e t h e S M a tl o w e n er g y, t h e l o w er b o u n d i s g i v e n, f or e x am pl e, b y ab o u t 100 G e V f or$ Î= 10^{19} $G e V an d$ m_t = 175 $G e V, w hi c hi ss ma l l er b y ab o u t 40 G e V t han t h ecor r es p o n d in g l o w er b o u n d in t h e S M . I n g e n er a l c a se, t h e$ m_h $i s n o l o n g er b o u n d e df r o mb e l o w b y t h eseco n d i t i o n s . I f w eco n s i d er t h ee x p er im e n t a l$ b \to s Î³ $co n s t r ain t, s ma l l$ m_h$ are excluded in Model II of the 2HDM.

Talk given by S. Kanemura at the 2nd ECFA/DESY LCWS in Obernai, France (16-19. October 1999), 7 pages including 3 figures