Higgs boson mass bounds in the presence of a very heavy fourth quark generation

Abstract

Abstract:We study the effect of a potential fourth quark generation on the upper and lower Higgs boson mass bounds. This investigation is based on the numerical evaluation of a chirally invariant lattice Higgs-Yukawa model emulating the same Higgs-fermion coupling structure as in the Higgs sector of the electroweak Standard Model. In particular, the considered model obeys a Ginsparg-Wilson version of the underlying SU(2) L × U(1) Y symmetry, being a global symmetry here due to the neglection of gauge fields in this model. We present our results on the modification of the upper and lower Higgs boson mass bounds induced by the presence of a hypothetical very heavy fourth quark doublet. Finally, we compare these findings to the standard scenario of three fermion generations.

Study of the Higgs-Yukawa Theory at the Strong-Yukawa Regime

“…Such a scenario is clearly of nonperturbative nature and motivates the use of lattice field theory as a first-principle and nonperturbative tool for this research avenue. Lattice investigations at small and moderate values of the bare Yukawa coupling showed [5] that the lower Higgs boson mass bound is strongly affected by the presence of a heavy 4th fermion generation when compared to results using a physical value of the top quark mass [6,7]. Still, in these simulations no signs of bound states were observed, as expected.…”

“…The bare scalar quartic couplingλ is fixed to infinity, which results in the largest possible Higgs mass [5,6,7]. We already accumulated data with reasonable statistics for the volumes 8 3 × 16, 12 3 × 24 and 16 3 × 32.…”

Higgs mass bounds from renormalization flow for a Higgs–top–bottom model

“…The same line of argument can in fact be used to put strong constraints on the existence of a fourth generation of flavor in the light of the Higgs boson mass measurement [45][46][47][48][49]. These results have also been substantiated by conventional analytical methods [50].…”

Constraining the Higgs boson mass: a non-perturbative lattice study

“…2, where in the left graph, the situation for a SM top quark mass is shown. The right graph shows, at a fixed value of the cut-off of 1.5TeV, the mass dependence of the lower and upper Higgs boson mass bounds as a function of the fermion mass, see also [22]. It can be clearly seen that while the upper bound is relatively unaffected when using a heavy fermion mass, the lower bound increases substantially.…”