Marek Lewicki

Higher-order scalar interactions and SM vacuum stability

A bstractInvestigation of the structure of the Standard Model effective potential at very large field strengths opens a window towards new phenomena and can reveal properties of the UV completion of the SM. The map of the lifetimes of the vacua of the SM enhanced by nonrenormalizable scalar couplings has been compiled to show how new interactions modify stability of the electroweak vacuum. Whereas it is possible to stabilize the SM by adding Planck scale suppressed interactions and taking into account running of the new couplings, the generic effect is shortening the lifetime and hence further destabilisation of the SM electroweak vacuum. These findings have been illustrated with phase diagrams of modified SM-like models. It has been demonstrated that stabilisation can be achieved by lowering the suppression scale of higher order operators while picking up such combinations of new couplings, which do not deepen the new minima of the potential. Our results show the dependence of the lifetime of the electroweak minimum on the magnitude of the new couplings, including cases with very small couplings (which means very large effective suppression scale) and couplings vastly different in magnitude (which corresponds to two different suppression scales).

Upper bounds on sparticle masses from muon g − 2 and the Higgs mass and the complementarity of future colliders

A bstractSupersymmetric (SUSY) explanation of the discrepancy between the measurement of (g − 2)μ and its SM prediction puts strong upper bounds on the chargino and smuon masses. At the same time, lower experimental limits on the chargino and smuon masses, combined with the Higgs mass measurement, lead to an upper bound on the stop masses. The current LHC limits on the chargino and smuon masses (for not too compressed spectrum) set the upper bound on the stop masses of about 10 TeV. The discovery potential of the future lepton and hadron colliders should lead to the discovery of SUSY if it is responsible for the explanation of the (g − 2)μ anomaly. This conclusion follows from the fact that the upper bound on the stop masses decreases with the increase of the lower experimental limit on the chargino and smuon masses.

Gauge fixing and renormalization scale independence of tunneling rate in Abelian Higgs model and in the standard model

We explicitly show perturbative gauge fixing independence of the tunneling rate to a stable radiatively induced vacuum in the Abelian Higgs model. We work with a class of

The impact of non-minimally coupled gravity on vacuum stability

{R}_{ensuremath{xi}}

Inflation and dark energy from the Brans-Dicke theory

gauges in the presence of both dimensionless and dimensionful gauge fixing parameters. We show that Nielsen identities survive the inclusion of higher order operators and compute the tunnelling rate to the vacua modified by the nonrenormalizable operators in a gauge invariant manner. We also discuss implications of this method for the complete Standard Model.

Multi-phase induced inflation in theories with non-minimal coupling to gravity

A bstractWe consider vacuum decay in the presence of a non-minimal coupling to gravity. We extend the usual thin-wall solution to include the non-minimal coupling. We also perform a full numerical study and discuss the validity of the new thin-wall approximation. Implications of a large cosmological constant, whose influence on the geometry boosts the tunneling rate, are discussed. Our results show that the influence of the non-minimal coupling differs significantly between the cases of Minkowski and de Sitter backgrounds. In the latter the decay probability quickly decreases when the coupling grows and in fact the vacuum can be made absolutely stable simply due to introduction of the non-minimal coupling. In the case of Minkowski background the effect is much weaker and the decay rate even increases for small values of the non-minimal coupling.

Domain walls and gravitational waves in the Standard Model

We consider the Brans-Dicke theory motivated by the

Fine-tuning in GGM and the 126 GeV Higgs particle

f(R) = R + alpha R^n - beta R^{2-n}

Implications of extreme flatness in a general

model to obtain a stable minimum of the Einstein frame scalar potential of the Brans-Dicke field. As a result we have obtained an inflationary scalar potential with non-zero value of residual vacuum energy, which may be a source of Dark Energy. In addition we discuss the probability of quantum tunnelling from the minimum of the potential. Our results can be easily consistent with PLANCK or BICEP2 data for appropriate choices of the value of

f(R)

n