Model dependence of the cosmological upper bound on the Higgs-boson mass

166

167

The discovery of the Higgs boson by the LHC experiments ATLAS and CMS has marked a milestone for particle physics. Yet, there are still many open questions that cannot be answered within the Standard Model (SM). For example, the generation of the observed matter-antimatter asymmetry in the universe through baryogenesis can only be explained qualitatively in the SM. A simple extension of the SM compatible with the current theoretical and experimental constraints is given by the 2-Higgs-Doublet Model (2HDM) where a second Higgs doublet is added to the Higgs sector. We investigate the possibility of a strong first order electroweak phase transition in the CP-conserving 2HDM type I and type II where either of the CP-even Higgs bosons is identified with the SM-like Higgs boson. The renormalisation that we apply on the loop-corrected Higgs potential allows us to efficiently scan the 2HDM parameter space and simultaneously take into account all relevant theoretical and up-to-date experimental constraints. The 2HDM parameter regions found to be compatible with the applied constraints and a strong electroweak phase transition are analysed systematically. Our results show that there is a strong interplay between the requirement of a strong phase transition and collider phenomenology with testable implications for searches at the LHC.

Section: Jhep02(2017)121mentioning

confidence: 99%

Strong first order electroweak phase transition in the CP-conserving 2HDM revisited

Basler

Krause

Mühlleitner

et al. 2017

166

167

“…Once the temperature drops below the critical one T < T c , bubbles of true vacuum (φ c = 0) start to nucleate where the rate is suppressed as Γ ∼ exp (−E sph /T ). The sphaleron decoupling condition indicates that the rate of baryon number violation must be much smaller than the the Hubble parameter [8,9,43,44] and therefore, the…”

Section: Sphaleron Decoupling Conditionmentioning

confidence: 99%

Sphalerons and the electroweak phase transition in models with higher scalar representations

Ahriche

Chowdhury

Nasri

2014

In this work we investigate the sphaleron solution in a SU(2) × U(1) X gauge theory, which also encompasses the Standard Model, with higher scalar representation(s) (J (i) , X (i) ). We show that the field profiles describing the sphaleron in higher scalar multiplet, have similar trends like the doublet case with respect to the radial distance. We compute the sphaleron energy and find that it scales linearly with the vacuum expectation value of the scalar field and its slope depends on the representation. We also investigate the effect of U(1) gauge field and find that it is small for the physical value of the mixing angle, θ W and resembles the case for the doublet. For higher representations, we show that the criterion for strong first order phase transition, v c /T c > η, is relaxed with respect to the doublet case, i.e. η < 1.

“…Conventionally, the amount of BAU is calculated via the following relation, 5) where N f is the number of flavors in the model. The sphaleron rate, Γ sph , is defined as Γ sph = K(α W T ) 4 in the symmetric phase.…”

Section: Jhep11(2016)065mentioning

confidence: 99%

“…If the phase transition is strongly first order, the baryon violating processes are out of equilibrium in the bubble walls and a net baryon number can be generated during the phase transition. Phase transition is strong enough when [38][39][40],…”

Section: The Cp Violating Vacuummentioning

confidence: 99%

“…The baryon asymmetry of the universe (BAU) could be generated during the electroweak phase transition, as disused in numerous studies, e.g. [1][2][3][4][5][6][7][8][9][10][11][12][13], trying to identify the source of this asymmetry. According to the Sakharov conditions [14], in order to generate the BAU it is required to have, first, the violation of the baryon number, second, the violation of C and CP symmetries and third, the existence of a non equilibrium processes, see also the reference.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Baryogenesis of the universe in cSMCS model plus iso-doublet vector quark

Darvishi

2016

CP violation of the SM is insufficient to explain the baryon asymmetry in the universe and therefore an additional source of CP violation is needed. Here the extension of the SM by a neutral complex scalar singlet with a nonzero vacuum expectation value (cSMCS) plus a heavy vector quark pair is considered. This model offers the spontaneous CP violation and proper description in the baryogenesis, it leads strong enough first-order electro-weak phase transition to suppress the baryon-violating sphaleron process.