f(T,T)重力下的夸克星：TOLMAN-Oppenheimer-Volkoff方程与MIT袋模型研究

164 浏览量更新于2024-09-03 收藏 681KB PDF 举报

在本文中，作者探讨了在修正的f(T, T) - 重力框架下研究夸克星系统的过程。f(T, T) - 重力是一种扩展的引力理论，它考虑了曲率张量T的二次项，这在一般相对论中是传统的T (R) 引力的拓展。静态的球对称时空是研究的基础，利用四维贝辛格量构建了度量张量，这是理论物理中一个关键概念，它将几何与物质的度量联系起来。作者选取了一个线性f(T) 参数化形式，即f = αT(r) + βT(r) + ϕ，其中T(r) 是时空曲率张量的局部值，r 表示径向坐标。通过这样的设置，他们分析了线性能量动量张量迹线T的变化规律，这是理解物质分布和引力效应的重要途径。这种线性选择有助于简化计算并探索不同参数对模型行为的影响。论文着重讨论了f(T, T) - 重力对模型参数，特别是耦合参数的约束条件。这些约束对于理论的自洽性和可预测性至关重要，它们确保了模型在物理上的合理性。作者通过对这些参数的分析，揭示了它们如何影响夸克星的特性，如质量、半径以及内部密度分布。最后，文章引入了MIT袋模型，这是一个广泛用于描述强相互作用下夸克行为的模型，尤其在极端条件下，如夸克星内部。通过将MIT袋模型与f(T, T) - 重力相结合，作者得以计算出在这种新型引力理论下夸克星的质量半径关系以及质量中心的密度，从而提供了关于这些奇特天体可能存在的物理特性的新见解。总结来说，这篇研究论文深入探讨了f(T, T) - 重力理论在描述夸克星系统时的应用，通过理论推导和数值模拟，它为我们理解重力如何影响夸克星的内部结构和动力学行为提供了新的视角。这种工作模型不仅展示了理论物理学与实际天体观测之间的桥梁，也为未来探索量子引力或极端条件下的物理现象开辟了新的路径。

Eur. Phys. J. C (2017) 77:62

DOI 10.1140/epjc/s10052-017-4637-8

Regular Article - Theoretical Physics

Quark stars in f (T, T )-gravity

Mark Pace

1,2,a

, Jackson Levi Said

1,2,b

Department of Physics, University of Malta, Msida MSD 2080, Malta

Institute of Space Sciences and Astronomy, University of Malta, Msida MSD 2080, Malta

Received: 19 October 2016 / Accepted: 15 January 2017 / Published online: 31 January 2017

Abstract We derive a working model for the Tolman–

Oppenheimer–Volkoff equation for quark star systems within

the modiﬁed f (T , T )-gravity class of models. We consider

f (T, T )-gravity for a static spherically symmetric space-

time. In this instance the metric is built from a more funda-

mental tetrad vierbein from which the metric tensor can be

derived. We impose a linear f (T ) parameter, namely taking

f = αT (r) + βT (r) + ϕ and investigate the behaviour of a

linear energy-momentum tensor trace, T . We also outline the

restrictions which modiﬁed f (T, T )-gravity imposes upon

the coupling parameters. Finally we incorporate the MIT bag

model in order to derive the mass–radius and mass–central

density relations of the quark star within f (T, T )-gravity.

1 Introduction

In recent years it has been shown that the universe is accel-

erating in its expansion [1,2]. In order to explain this one

can introduce the concept of the cosmological constant [3,4].

Together with the inclusion of dark matter we get the CDM

model, which explains a whole host of phenomena within the

universe [5–7]. Another approach to explaining this acceler-

ation is to modify the gravitational theory itself with alterna-

tive theories of gravity an example of which is f (R)-gravity

[8–11].

f (T )-gravity uses a “teleparallel” equivalent of GR

(TEGR) [12] approach, in which, instead of the torsion-

less Levi-Civita connection, the Weitzenböck connection is

used, with the dynamical objects being four linearly inde-

pendent vierbein elements [13,14]. The Weitzenböck con-

nection is curvature-free and describes the torsion of a man-

ifold. In the current case we consider a pure tetrad [15],

meaning that the torsion tensor is formed by a multiple of

the tetrad and its ﬁrst derivative only. The Lagrangian den-

e-mail: mark.pace.10@um.edu.mt

e-mail: jackson.said@um.edu.mt

sity can be constructed from this torsion tensor under the

assumption of invariance under general coordinate transfor-

mations, global Lorentz transformations, and the parity oper-

ation [11,12,14,15]. Also the Lagrangian density is second

order in the torsion tensor [12,14]. Thus f (T )-gravity gener-

alises the above TEGR formalism, making the gravitational

Lagrangian a function of T [10–12].

Our study involves deriving a working model for the TOV

equation within a new modiﬁcation of f (T ) class grav-

ity, namely f (T, T )-gravity. There is no theoretical reason

against couplings between the gravitational sector and the

standard matter one [10]. f (T , T )-gravity takes inspiration

from f (R, T )-gravity [10,16] where instead of having the

Ricci scalar coupled with the trace of the energy-momentum

tensor T , one couples the torsion scalar T with the trace of

the matter energy-momentum tensor T [10,11,16].

Recently a modiﬁcation to this theory has been propose,

that of allowing for a general functional dependence on the

energy-momentum trace scalar, T

= T .

Our interest is in studying the behaviour of spherically

symmetric compact objects in this theory with a speciﬁc lin-

ear function being considered, namely f (T , T ) = αT (r) +

βT (r) + ϕ where α, β are arbitrary constants, and ϕ we take

as the cosmological constant. We consider the linear modiﬁ-

cation since it is the natural ﬁrst functional form to consider,

and the right place to start to understand how the trace of the

stress-energy tensor might effect f (T, T ) gravity. In partic-

ular, our focus is on quark stars in f (T , T ) gravity. Besides

the possibility of the existence of these exotic stars, this is

also a good place to study the behaviour of modiﬁed the-

ories of gravity in terms of constraints. Moreover, this also

opens the door to considerations of stiff matter in early phase

transitions [17].

The plan of this paper is as follows. In Sect. 2 we out-

line the theoretical background of the model. In Sect. 3 we

consider the rotated tetrad and use this to derive the TOV

equation in f (T , T )-gravity in Sect. 4. Section 5 will then

present the contrasting mass–radius relations derived using

123

下载后可阅读完整内容，剩余4页未读，立即下载

weixin_38646902

粉丝: 4
资源: 921

f(T,T)重力下的夸克星：TOLMAN-Oppenheimer-Volkoff方程与MIT袋模型研究

QCD和规则分析双夸克-双夸克-反夸克模型中的12±五夸克状态

QCD和规则分析双夸克-双夸克-反夸克模型中的32±五夸克态

f（R，T）重力下的各向异性夸克星

迈向全息夸克物质晶体

库仑分支上的强耦合N = 4超对称Yang-Mills等离子体。 一，热力学

江苏省东台市唐洋中学2012-2013学年高一物理下学期期末考试试题（无答案）新人教版

f(R,T)引力下各向异性夸克星特性分析： MIT袋模型与稳定性研究

三维超杨-米尔斯理论与可压缩夸克物质的重力对偶研究

简化Born-Infeld-f(T)理论中的畴壁膜研究

兰道极与全息重力理论的探索

最新资源

库仑分支上的强耦合N = 4超对称Yang-Mills等离子体。一，热力学