Vacuum stability, perturbativity, EWPD and Higgs-to-diphoton rate in type II seesaw models

Abstract

We study constraints from perturbativity and vacuum stability as well as the EWPD in the type II seesaw model. As a result, we can put stringent limits on the Higgs triplet couplings depending on the cut-off scale. The EWPD tightly constrain the Higgs triplet mass splitting to be smaller than about 40 GeV. Analyzing the Higgs-to-diphoton rate in the allowed parameter region, we show how much it can deviate from the Standard Model prediction for specific parameter points.

Revisiting the high-scale validity of the type II seesaw model with novel LHC signature

“…The strongest bound comes from the T-parameter which imposes strict limit on the mass splitting between the doubly and singly charged scalars, ΔM ≡ jm H AEAE − m H AE j which should be ≲50 GeV [9,24] assuming a light SM Higgs boson of mass m h ¼ 125 GeV and top quark mass M t ¼ 173 GeV. In our study, we do not explicitly analyze the T-parameter constraints but rather impose this restrictive bound of 50 GeV between the two charged scalar masses.…”

“…However, the total width will mainly be modified by the loop-induced decay modes h → γγ where the nonstandard singly and doubly charged scalar may contribute significantly. Some detailed studies have already been performed in this respect [9,11,15,27,[56][57][58]. Here we will refrain ourselves from giving an elaborate description except a comment on the parameter space and for the collider study, our choice of benchmark points remain within the 2σ limit of the current experimental bound of the Higgs to diphoton signal strength [59].…”

“…Therefore, NP models that extends the SM scalar sector can easily serve the purpose. In view of this, the triplet scalar extension, alias, the type II seesaw model has already been proven a well-deserved NP candidate to ameliorate the vacuum stability problem [9][10][11][12][13]. In order to seek an absolutely stable vacuum in the type II seesaw regime, one must also maintain the perturbative unitarity of all the new couplings introduced lately.…”

“…The search strategy could thus be restrictive as the extra theoretical constraints have put stringent bound on the non standard scalar mass splitting. The splitting between the singly and doubly charged scalar masses is also tuned by the one-loop T-parameter constraint at the EW scale [9,24]. It is therefore expected that the allowed parameter region in the highscale valid space will be more contrived.…”

TeV scale universal seesaw, vacuum stability and heavy Higgs

“…However another direction of physics which may be suggested by this and one that has received great deal of attention in recent months, is that this "near criticality" of the Higgs coupling is a signal of nearby new physics that would stabilize this vacuum. Many extensions of the standard model by enlarging the Higgs and/or the gauge sector have been proposed as a way to eliminate the deeper high scale minimum of the potential [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28].…”