Unitarity bounds in the Higgs model including triplet fields with custodial symmetry

Abstract

We study bounds on Higgs boson masses from perturbative unitarity in the Georgi-Machacek model, whose Higgs sector is composed of a scalar isospin doublet, a real and a complex isospin triplet fields. This model can be compatible with the electroweak precision data without fine tuning because of the imposed global SU (2) R symmetry in the Higgs potential, by which the electroweak rho parameter is unity at the tree level. All possible two-body elastic-scattering channels are taken into account to evaluate the S-wave amplitude matrix, and then the condition of perturbative unitarity is imposed on the eigenvalues to obtain constraint on the Higgs parameters. Masses of all scalar bosons turn out to be bounded from above, some of which receive more strict upper bounds as compared to that in the standard model (712 GeV). In particular, the upper bound of the lightest scalar boson, whatever it would be, is about 270 GeV.

Demise of CKM and its aftermath

“…Review of all quenched results prior to 2003 is marked as Becirevic [34]. Unquenched 2 flavors calculations are shown in green including RBC 2004 [35]; JLQCD 2008 [17] and ETMC 2009 [36,37] [38] with domain wall and ALV [14] using mixed action. Also RBC-UKQCD 2010 [19] using domain-wall quarks and SBW [16] using staggered.…”

“…• Regarding calculations ofB K [11] on the lattice, it is useful to note that in the past 3 years a dramatic reduction in errors has been achieved and by now a number of independent calculations with errors < ∼ 5% and with consistent central values have been obtained using N f = 2 + 1 [12][13][14][15][16] as well as N f = 2 [17] dynamical simulations (see Ref. [18] for a review).…”

Charged Higgs boson searches in the Georgi-Machacek model at the LHC

“…In Fig. 1, we show the region allowed simultaneously by the electroweak vacuum stability and the perturbative unitarity bounds on the scalar quartic couplings [19,29]. For illustration purpose, we have shown the allowed region in the v t -m 3 plane and in the m 3 -m 5 plane.…”

Implications of the discovery of a Higgs triplet on electroweak right-handed neutrinos

“…Bounds from unitarity [10] are incorporated through the following relations: plane due to unitarity. It amounts to require the heavier of the two to be less than (700 − 550) GeV when the lighter is in the range of (0 − 300) GeV.…”