In this paper, we study the braneworld models with non-standard kinetic term of Dirac–Born–Infeld (DBI) type in two case which are (I) in usual gravity and (II) in f(T) gravity. In each of these cases, we examine gravity localization on branes and show that both models are stable and capable of gravity localizing in a similar manner to the standard case of braneworld models. In addition, we investigate the problem of fermion localization in both models and by considering the Yukawa coupling as a function of the warp factor, we show that the massless zero mode of fermion fields are localized on both types of the the branes. Meanwhile, the effect of parameters in both models is addressed on the zero mode and massive mode of graviton and fermion and the effective potentials. Finally, we study the gauge hierarchy problem in both models and we show that by choosing the appropriate parameters, both models are able to solve the gauge hierarchy problem between the Tev scale and the Planck scale.

Iran

Esmaeil Mazani

Ali Tofighi

Masoumeh Sorkhi

Fermion and graviton in Dirac–Born–Infeld braneworld models

In this paper, the electroweak phase transition, the gravitational waves and the dark matter issues are investigated in two scalar singlet extension of the standard model. The detectability of the gravitational wave signals are discussed by comparing the results with the sensitivity curves of $$\mathbf {eLISA}$$ <math><mi>eLISA</mi></math> , $$\mathbf {ALIA}$$ <math><mi>ALIA</mi></math> , $$\mathbf {DECIGO}$$ <math><mi>DECIGO</mi></math>  and $$\mathbf {BBO}$$ <math><mi>BBO</mi></math>  detectors. It is shown that the results support the recent reports on the dark matter relic density by $$\mathbf {Planck}$$ <math><mi>Planck</mi></math>  $$\mathbf {2018}$$ <math><mn>2018</mn></math>  collaboration and the direct detection experiment by $$\mathbf {XENON1T} \mathbf {2018}$$ <math><mrow><mrow><mi>XENON</mi><mn>1</mn><mi>T</mi></mrow><mn>2018</mn></mrow></math>  collaboration.

Vahid Shajiee

Electroweak phase transition, gravitational waves and dark matter in two scalar singlet extension of the standard model

We consider an extension of the Standard Model (SM) with additional gauge singlets which exhibits a strong first-order phase transition. Due to this first-order phase transition in the early universe gravitational waves are produced. We estimate the contributions such as the sound wave, the bubble wall collision, and the plasma turbulence to the stochastic gravitational wave background, and we find that the strength at the peak frequency is large enough to be detected at future gravitational interferometers such as eLISA. Deviations in the various Higgs boson self-couplings are also evaluated.

Mina Saeedhosseini

Strong Electroweak Phase Transition in a Model with Extended Scalar Sector

We study fermion localization and resonances on a special type of brane-world model supporting brane splitting. In such models one can construct multiwall branes which cause considerable simplification in the field equations. We use a polynomial superpotential to construct this brane. The suitable Yukawa coupling between the background scalar field and the localized fermion is determined. The massive fermion resonance spectrum is obtained. The number of resonances is increased for higher values of Yukawa coupling.

Ali Farokhtabar

Localization of Massive and Massless Fermions on Two-Field Branes

We present an exact treatment of the modulus stabilization condition with the general boundary conditions of the bulk scalar field in the Randall-Sundrum model. We find analytical expressions for the value of the modulus and the mass of the radion.