Sphalerons on orbifolds

Ahriche, Amine

doi:10.1140/epjc/s10052-010-1234-5

“…The previous considerations motivate us to calculate the sphaleron barrier in nonstandard realizations of the Higgs vacuum, in order to look for possible deviations with respect to the SM value coming from a modified potential and/or derivative terms. Sphaleron configurations have been calculated not only for the Standard Model [40,41] (with a resulting energy barrier of the order of 9 TeV for the observed value of the Higgs mass), but also in a number of extensions of the Standard Model involving an elementary Higgs and other scalars [42][43][44][45][46][47][48][49][50][51][52]. In many of these models, the deviations from the SM behaviour arise mainly due to the existence of additional scalars with electroweak charges, all of them acquiring nontrivial profiles in the sphaleron configuration.…”

Section: Introductionmentioning

confidence: 99%

Sphalerons in composite and nonstandard Higgs models

Spannowsky¹,

Tamarit²

2017

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. After the discovery of the Higgs boson and the rather precise measurement of all electroweak boson's masses the local structure of the electroweak symmetry breaking potential is already quite well established. However, despite being a key ingredient to a fundamental understanding of the underlying mechanism of electroweak symmetry breaking, the global structure of the electroweak potential remains entirely unknown. The existence of sphalerons, unstable solutions of the classical action of motion that are interpolating between topologically distinct vacua, is a direct consequence of the Standard Model's SUð2Þ L gauge group. Nevertheless, the sphaleron energy depends on the shape of the Higgs potential away from the minimum and can therefore be a litmus test for its global structure. Focusing on two scenarios, the minimal composite Higgs model SOð5Þ=SOð4Þ or an elementary Higgs with a deformed electroweak potential, we calculate the change of the sphaleron energy compared to the Standard Model prediction. We find that the sphaleron energy would have to be measured to Oð10Þ% accuracy to exclude sizeable global deviations from the Standard Model Higgs potential. We further find that because of the periodicity of the scalar potential in composite Higgs models a second sphaleron branch with larger energy arises.

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“…. We summarize most generally that the triggers for the EWPT process are either particles outside the SM or manually added quantities [48][49][50][51][52][53][54][56][57][58][59][60][61]. A commonplace negative solution is that the EWPT's strength satisfies the decoupling condition at a few hundred GeV scale with the mass of Higgs boson must be less than 125 GeV [3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…This is known as the decoupling condition of sphaleron. In the SM, this condition is often expressed as v c /T c > 1 by using an approximation E sph (T ) ≈ [v(T )/v]E sph (T = 0) [47][48][49]72]; however, in beyond SM models this approximation should be again considered with caution.…”

Section: Introductionmentioning

confidence: 99%

“…Sphaleron has also been calculated in various frameworks. We see there are two main directions: the first is to investigate the phenomena of sphaleron in models [47][48][49][72][73][74][75][76][77][78][79][80][81], the second is to investigate by simulation and numerical methods [8,82]. We found that there are two basic ways to calculate the sphaleron energy [83].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Baryogenesis and gravitational waves in the Zee–Babu model

Phong

¹

,

Thao

²

,

Long

³

2022

Eur. Phys. J. C

2

0

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To explain the matter-antimatter asymmetry in the Zee–Babu (ZB) model, the sphaleron process in the baryogenesis scenario is calculated. It always satisfies the de-coupling condition and the strength of phase transition (S) is always greater than 1 in the presence of triggers other than that in the Standard Model, which are singly ($$h^{\pm }$$ h ± ) and doubly ($$k^{\pm \pm }$$ k ± ± ) charged scalar bosons. Sphaleron energies are in the range of 5-10 TeV, in calculation with bubble profiles containing free parameters and assuming nuclear bubbles of $$h^{\pm }$$ h ± and $$k^{\pm \pm }$$ k ± ± are very small. We tested the scaling law of sphaleron again with an average error of $$10\%$$ 10 % . When the temperature is close to the critical one ($$T_c$$ T c ), the density of nuclear bubble is produced very large and decreases as the temperature decreases. The key parameter is $$\alpha $$ α which results in the gravitational wave density parameter ($$\Omega h^2$$ Ω h 2 ) in the range of $$10^{-14}$$ 10 - 14 to $$10^{-12}$$ 10 - 12 when $$\beta /H^*=22.5$$ β / H ∗ = 22.5 , this is not enough to detect gravitational waves from electroweak phase transition (EWPT) according to the present LISA data but may be detected in the future. As the larger strength of phase transition is, the more $$\alpha $$ α increases (this increase is almost linear with S), the larger the gravitational wave density parameter is. Also in the context of considering the generation of gravitational waves, in the ZB model we calculated $$\alpha \sim \text {a few} \times 10^{-2}\ll 1$$ α ∼ a few × 10 - 2 ≪ 1 , so rigorously conclude that the EWPT is not strong even though $$S>1$$ S > 1 . We also suggest that, for a model with a lot of extra scalar particles and particles which play a role in mass generation, the stronger the EWPT process and the larger $$\Omega h^2$$ Ω h 2 can be.

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“…the energy of the sphaleron [7]. Such baryon number violation induced by the sphaleron is one of the essential ingredients of Electroweak Baryogenesis [8][9][10][11][12][13] and therefore it has been extensively studied not only in the SM [14][15][16][17][18][19][20][21][22][23][24] and but also in extended SM variants such as, SM with a singlet [25,26], two Higgs doublet model [27], Minimal Supersymmetric Standard Model [28], the next-to-Minimal Supersymmetric Standard Model [29] and 5-dimensional model [30].…”

Section: Introductionmentioning

confidence: 99%

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

Ahriche

¹

,

Chowdhury

²

,

Nasri

³

2014

J. High Energ. Phys.

Self Cite

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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.

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Sphalerons on orbifolds

Cited by 5 publications

References 33 publications

Sphalerons in composite and nonstandard Higgs models

Sphalerons in composite and nonstandard Higgs models

Baryogenesis and gravitational waves in the Zee–Babu model

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

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