Gauge coupling unification in a classically scale invariant model

Haba, Naoyuki; Ishida, Hiroyuki; Takahashi, Ryo; Yamaguchi, Yuya

doi:10.1007/jhep02(2016)058

Cited by 15 publications

(8 citation statements)

References 79 publications

(82 reference statements)

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“…(35) proportional to 2 × 2N cỹ 3 since each of the ψ 1 and ψ 2 contribute as in the SM, and (iii) the top-quark contribution in Σ h which yields 2N c y 2 tỹ as in the second term in Eq. (35). Adding these three contributions then gives the first part of βỹ in Eq.…”

Section: Discussionmentioning

confidence: 99%

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Higgs vacuum stability with vectorlike fermions

Gopalakrishna

Velusamy

2019

Phys. Rev. D

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We present the effects of vector-like fermions (VLF) on the stability of the Higgs electroweak vacuum, using the renormalization group improved Higgs effective potential. We review the calculation of the one-loop beta-functions of the standard model couplings paying particular attention to the fermion contributions. From this, we derive the VLF contributions to the betafunctions. We also include the significant two-loop contributions to the beta-functions. Using these beta-functions, we determine the scale at which the effective Higgs quartic-coupling becomes zero and goes negative, signaling vacuum instability. We find that for certain VLF masses and Yukawa couplings, the Higgs quartic stays positive for field values all the way up to the Planck scale, implying that the meta-stable vacuum of the standard model can be rendered absolutely stable if VLFs are present with certain parameters. For other values of VLF parameters, the Higgs vacuum is metastable as in the standard model. For cases where the vacuum is metastable, we compute the probability of quantum tunneling from the false electroweak vacuum into a deeper true vacuum in our Hubble volume by numerically solving for the bounce configuration in Euclidean space-time and computing the bounce action for it. We compare our numerical solution with the analytical approximation for the bounce action commonly used in the literature, and comment on when the latter may be used. * shri@imsc.res.in † arunprasath@imsc.res.in arXiv:1812.11303v3 [hep-ph] 13 Jul 2019Denoting the field value as h ≡ µ and denoting λ eff (µ) as just λ(µ), it can be shown (see for example Ref. [41]) that λ(µ) obeys a renormalization group equation (RGE) of the formThe RGE is interpreted now as an evolution with field value h = µ, and the β-function β λ is the usual β-function for the coupling λ, governed by the RGE. The λ(µ) obtained by integrating the RGE has the leading logs of the form log n (µ/M ) resummed. β λ is shown as a function of λ itself, and also of the other couplings that contribute significantly, which, in the SM, are the top Yukawa coupling y t and the SU (3), SU (2), U (1) gauge couplings g a = {g 3 , g 2 , g 1 }. All these couplings also evolve with µ via analogous RGE equations with their corresponding β-functions β yt , β ga . We neglect the contributions of the other SM couplings to the β-functions as they contribute insignificantly. From Eq.(3) we see that for h m h , the instability is signalled by the Higgs quartic effective coupling λ(µ) becoming negative.As we show explicitly later, β λ obtains a negative contribution from y t , while it obtains a positive contribution from λ(µ) itself and from gauge couplings. Thus, the top quark has the important effect of decreasing λ(µ), and for y t as large as in the SM, for the observed m h , it drives λ(µ) negative at higher energies, signaling vacuum instability. The effect of fermions coupled to the Higgs is generally to destabilize the electroweak vacuum, although in this work we show that this statement is not so definit...

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Section: Discussionmentioning

confidence: 99%

“…[31,32], a combination of these in Ref. [33,34,35], models of inflation in Refs. [36,37], and effective models in Refs.…”

Section: Introductionmentioning

confidence: 99%

Higgs vacuum stability with vectorlike fermions

Gopalakrishna

Velusamy

2019

Phys. Rev. D

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“…Therefore, it is obvious that, with growing λ, the fermionic contributions always destabilize the system even more. 7 Other extensions of the Higgs sector by one SU(2) L scalar representation turn out to be unstable as well, as for example the conformal inert doublet model [24]. 8 Having excluded those simplest theories, we find the minimal model, which leads to correct radiative breaking of electroweak symmetry and is RG stable, among the extensions of the Higgs sector by two scalars.…”

Section: Jhep07(2017)113mentioning

confidence: 91%

“…In this system a light Higgs boson can be realized without fine-tuning. In addition, the theory contains a pseudo-Goldstone boson (PGB) with its mass being strongly suppressed with respect to the vacuum expectation value of the new 7 The different treatment of the wave function renormalization leads to deviations with respect to the results of [2]. 8 In order to check this, we have performed a fully consistent analysis as presented in section 2.2.2.…”

Section: Jhep07(2017)113mentioning

confidence: 99%

Minimal conformal extensions of the Higgs sector

Helmboldt

Humbert

Lindner

et al. 2017

J. High Energ. Phys.

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In this work we find the minimal extension of the Standard Model's Higgs sector which can lead to a light Higgs boson via radiative symmetry breaking and is consistent with the phenomenological requirements for a low-energy realization of a conformal theory. The model which turns out to be stable under renormalization group translations is an extension of the Standard Model by two scalar fields, one of which acquires a finite vacuum expectation value and therefore mixes into the physical Higgs. We find that the minimal model predicts a sizable amount of mixing which makes it testable at a collider. In addition to the physical Higgs, the theory's scalar spectrum contains one light and one heavy boson. The heavy scalar's properties render it a potential dark matter candidate.

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“…Due to these observaa e-mail: valdir@fisica.ufpb.br b e-mail: crisnfer@msn.com c e-mail: elton.apj@gmail.com tions with supernovae it has been concluded that the universe nowadays is expanding rapidly. One idea to explain this acceleration is that the universe is dominated by dark energy that seems to be more abundant than the usual energy [1,2].…”

Section: Introductionmentioning

confidence: 99%

Some results on a black hole with a global monopole in Poincaré gravity

2018

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The aim of this work is to study the thermodynamics and spin current of a system corresponding to a black hole containing a global monopole in the context of Poincaré gravity theory which is an extension of general relativity, in the sense that the intrinsic angular momentum of matter is also a source of gravitational interaction. Thus, in this work we find the solution corresponding to the spacetime under consideration by taking into account that the action which describes this system contains terms corresponding to the curvature and torsion. The metric obtained is a function of mass, solid angle deficit and the coupling constants of the quadratic terms of the curvature and torsion. In this model, the stability of the system is studied through the analysis of the Hawking temperature and the specific heat. In this context it was also studied the critical temperatures of the system considering positive or negative cosmological constant. In the vicinity of the black hole with a global monopole, where there is a logarithmic correction due to the relationship between the torsion and curvature fields, some analysis were done. We also study the AdS/dS limit where the black hole is analyzed from the topological point of view. Although the effect of spin current density at low energies is negligible, in the vicinity of strong gravitational fields it can generate an appreciable effect due to spin gravity coupling.

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Gauge coupling unification in a classically scale invariant model

Cited by 15 publications

References 79 publications

Higgs vacuum stability with vectorlike fermions

Higgs vacuum stability with vectorlike fermions

Minimal conformal extensions of the Higgs sector

Some results on a black hole with a global monopole in Poincaré gravity

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