The Higgs boson discovery at the LHC with a mass of approximately 126 GeV
suggests, that the electroweak vacuum of the standard model may be metastable
at very high energies. However, any new physics beyond the standard model can
change this picture. We want to address this important question within a
lattice Higgs-Yukawa model as the limit of the standard model (SM). In this
framework we will probe the effect of a higher dimensional operator for which
we take a (ϕ†ϕ)3-term. Such a term could easily originate as
a remnant of physics beyond the SM at very large scales.
As a first step we investigate the phase diagram of the model including such
a (ϕ†ϕ)3 operator. Exploratory results suggest the existence
of regions in parameter space where first order transitions turn to second
order ones, indicating the existence of a tri-critical line. We will explore
the phase structure and the consequences for the stability of the SM, both
analytically by investigating the constraint effective potential in lattice
perturbation theory, and by studying the system non-perturbatively using
lattice simulations.Comment: 7 pages, 6 figures; Proceedings of the 31st International Symposium
on Lattice Field Theory - LATTICE 201