arXiv subjects

Yong-Tao Lu

Publications and source records attributed to Yong-Tao Lu.

7 recordsLinked to original sources

arXiv2026

Complex scalar field thick branes: stability of linear perturbation and evolution of scalar Kaluza-Klein modes coupled with gravity

We investigate the stability and localization properties of Minkowski, de Sitter (dS), and anti-de Sitter (AdS) thick branes generated by a complex scalar field $Φ$. The scalar self-interaction potential contains a temperature parameter $a$. As $a$ approaches its critical value, the imaginary part of $Φ$ becomes double-kinked and the energy density splits into two peaks, indicating the formation of two sub-branes. The analysis of linear scalar, vector, and tensor perturbations shows no signs of instability in the scalar and vector sectors, while the factorization of the tensor perturbation equation excludes tachyonic tensor modes. The graviton zero mode is localized on the Minkowski and dS branes but is not normalizable on the AdS brane. We further study a real test scalar field $Ψ$ with a coupling function $F(R)$ between its kinetic term and the spacetime curvature. The scalar zero mode can always be localized on the Minkowski and dS branes, with a continuous gapless spectrum of scalar Kaluza--Klein (KK) modes. Massive scalar resonances emerge near the critical value of $a$ for suitable values of $β$. Increasing $β$ produces more resonances and prolongs the lifetimes of the lower resonances, while their time evolution exhibits the characteristic decay of metastable modes. For the AdS brane, the scalar zero mode is also localized, whereas the divergent effective potential at the boundaries traps the massive scalar KK modes as bound states, yielding a discrete mass spectrum.

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arXiv2026

Reduction of the six-dimensional $q$-form fields to the four-dimensional fields by coupling with gravity

In this paper, we investigate the localization of various $q$-form fields on a codimension-two brane. In particular, the $0$-form scalar field, the $1$-form $U(1)$ gauge vector field, and the $2$-form Kalb-Ramond field are considered with gravitational coupling, where a coupling function $F(R)$ is introduced into the six-dimensional actions of these fields. The function $F(R)$ depends on the scalar curvature of the bulk. Within this framework, we find that the massless modes of different $q$-form fields can be localized on the thick brane for positive values of the coupling parameters $t_1$ and $t_2$. For the massive modes, the different $q$-form fields exhibit similar localization properties determined by the coupling parameter $t_2$. When $0 v^2/24$, the effective potentials associated with the Kaluza-Klein modes of these $q$-form fields form infinitely deep potential wells, so that all massive modes can be localized on the brane. Moreover, the tachyonic massive modes can always be excluded for different $q$-form fields.

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arXiv2025

Localization of $q$-form field on squared curvature gravity domain wall brane coupling with gravity and background scalar

Unlike the duality in four-dimensional spacetime, where the $q-$form fields corresponds to the scalar fields or the vector fields, in higher dimensional spacetime, they denote new types of particles. In this paper, we investigate the localization of the KK modes of the $q$-form fields in a five dimensional brane world. We introduce the coupling between the $q-$form fields and both the gravity and the background scalar field. This consideration enables the localization of the $q$-form fields on the five-dimensional RS-2 thick brane, leading to the derivation of zero modes, Schrödinger-like equations, and a four-dimensional effective action. We suggest a new function $F(R,φ)$ to stand for the coupling of the $q$-form field with gravity and background scalar fields. Our analysis highlights the significance of the parameters $\text C_2$ and $\displaystyle t$ in the localization processes.

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arXiv2025

Localization mechanism of the Kalb-Ramond field on brane with codimension-two

The $2$-form Kalb-Ramond (KR) field, together with the metric tensor and dilaton, arises as one of the massless excitation mode of a closed string. Subsequently, this field plays an important role in both string theory and field theory. In this paper, we investigate the localization of the KR field on the brane with codimension-2. A general Kaluza-Klein (KK) decomposition is adopted, wherein the six-dimensional KR field is expanded into one four-dimensional (4D) KR field, two 4D vector fields, and one 4D scalar field. Then, for the case of the extra dimensions $\mathcal{R}_1\times\mathcal{R}_1$, only the 4D scalar field can be localized on the brane. In contrast, for the case of extra dimensions $\mathcal{R}_1\times\mathcal{S}_1$, one 4D vector field and the 4D scalar field can be localized on the brane at the same time. In both cases, the mass of the 4D scalar field remains zero. Next, we examine the localization of the KR field within a specific six-dimensional brane model with extra dimensions $\mathcal{R}_1\times\mathcal{S}_1$. By introducing the background scalar coupling, we show that the 4D KR field, along with the other three 4D fields, can be localized on the brane under the condition of the coupling parameter $t>v^2/12$. Additionally in this case, for both the 4D KR field and the one 4D vector field which acquires its mass from the non-compact extra dimension, the resonant KK modes could exist near the origin of this extra dimension.

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arXiv2025

Pure geometric $f(R)$ branes

In this paper, we investigate pure geometric $f(R)$ cosmology branes embedded in five-dimensional spacetime. The form of $f(R)$ is chosen as a polynomial. The Five-dimensional scalar curvature $R$ is assumed to be constant. Based on the value of the four-dimensional cosmological constant $λ_4$, the branes can be classified into Minkowski, de Sitter, and de anti-de Sitter cases. Solutions for each case can be calculated. These solutions are stable against linear tensor perturbations in all cases. In the Minkowski brane case, the zero mode of gravity can be localized on the brane. In the de Sitter brane case, the zero mode and one massive Kaluza-Klein mode can be localized on the brane. In the anti-de Sitter brane case, all massive Kaluza-Klein modes can be localized on the brane. The results of the analysis of tensor fluctuations are the same in both the Einstein frame and the Jordan frame.

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arXiv2025

Localization mechanism of $q-$form field on the brane-world by coupling with gravity

It is known that the scalar fields can be trapped on branes of different types, and the $U(1)$ gauge vector fields can be localized on the thick de Sitter brane, or the thick Minkowski brane via coupling with gravity. The Kalb-Ramond fields can be localized on the Minkowski brane and the thick de-Sitter brane, with certain couplings. In this paper, with considering a coupling mechanism between the kinetic term of the $q-$form fields and the background spacetime, we investigate the localization of Kaluza-Klein modes for the $q-$form fields in $D-$dimensional spacetime. Concrete $q-$form fields are discussed within five-dimensional brane models with typical spacetime geometries: Minkowski, de Sitter, and Anti-de Sitter. In the Minkowski brane case, the zero modes of various $q-$form fields can be localized on the brane. In the de Sitter brane case, the zero mode of the $U(1)$ gauge vector fields can be localized on the brane. Lastly in the Anti-de Sitter brane case, the zero mode of the Kalb-Ramond fields can be localized on the brane. For the massive Kaluza-Klein modes of these $q-$form fields, they could be localized or quasi-localized on the brane of different types. Besides, subtle and detailed behaviors of the Kaluza-Klein modes for $q-$form fields are observed: the zero modes could be localized on both sides of the brane, and the massive modes could be localized or quasi-localized at the brane position.

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arXiv2024

Localization of scalar field on the brane-world by coupling with gravity

In this paper, we consider a coupling mechanism between the kinetic term and the gravity, in which a coupling function $F(R)$ is introduced into the kinetic term of the five-dimensional scalar field. Based on this scenario, we investigate the localization of scalar fields in three specific braneworld models: the Minkowski brane, the de Sitter brane, and the Anti-de Sitter brane. The brane models considered here are regular with no singularity for scalar curvature. For the Minkowshi brane case, the zero mode can always be localized on the brane, and the massive modes can be localized or quasi-localized on the brane. For the dS$_4$ brane case, two forms of factor $F(R)$ is considered. The zero mode can always be localized, and the massive modes could be quasi-localized on the brane. Besides, with the second coupling factor, the scalar zero mode could be localized on the both sides of the origin of extra dimension, while the massive modes could be quasi-localized on the origin. Lastly, for the AdS$_4$ brane case, the localization of the scalar zero mode requires the consideration of a coupling potential $V(Φ,φ)$, while the massive modes can still be localized on the brane with an infinite number.

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