非微扰f(R)重力下的夸克星模型与质量半径关系研究

154 浏览量更新于2024-09-03 收藏 560KB PDF 举报

本文主要探讨了在非微扰f(R)重力理论框架下构建夸克星模型的非线性性质。f(R)引力理论是一种扩展的广义相对论，其中标量曲率R被看作是动力学变量，而非仅仅作为常数。文章关注的核心问题是研究如何在这样的理论背景下，通过考虑一个特定的模型，即f(R)= R + αR^2，来模拟真实的夸克星——一种由量子色动力学（QCD）预言的，可能存在于极端环境下的致密天体。作者Artyom V. Astashenok, Salvatore Capozziello, Sergei D. Odintsov等人，分别来自俄罗斯、意大利和西班牙的研究机构，他们研究了夸克星的内部结构，特别是质量和半径之间的关系。在f(R) = R + αR^2这样的模型中，他们发现需要对中心曲率R进行精细调整，以确保当距离中心趋于无穷大时，解决方案的曲率能够趋向于零，符合实际物理需求。这表明在非微扰的f(R)重力下，夸克星的形成和行为与标准的广义相对论有所不同。本文还提到了关键步骤，即将标量曲率R视为一个独立函数，这样可以为每个中心密度值找到对应的中心曲率值。这在计算上具有挑战性，因为它涉及到对非线性引力模型的精确求解。此外，文章可能还讨论了与传统引力理论（如爱因斯坦场方程）的比较，以及这种修正理论对宇宙学和天体物理学可能产生的影响，如星体演化、稳定性分析等。关键词方面，"Modified gravity"（修改引力）、"Quark stars"（夸克星）、"Nonperturbative models"（非微扰模型）和"f(R) gravity"（f(R)重力）都是核心概念，它们反映了研究的主要焦点和理论基础。这篇Open Access的文章在2015年的《物理学快报B》期刊上发表，提供了关于在f(R)理论中理解夸克星复杂行为的新见解。这篇文章深入探讨了在f(R)重力下，如何通过非微扰方法构建并解决夸克星模型的问题，强调了中心曲率对模型参数的敏感性和理论预测的特殊性。这不仅有助于深化我们对极端环境下的天体物理现象的理解，也为研究广义相对论的修正提供了实验验证的可能途径。

Physics Letters B 742 (2015) 160–166

Contents lists available at ScienceDirect

Physics Letters B

www.elsevier.com/locate/physletb

Nonperturbative models of quark stars in f (R) gravity

Artyom V. Astashenok

, Salvatore Capozziello

b,c,d,∗

, Sergei D. Odintsov

e,f

I. Kant Baltic Federal University, Institute of Physics and Technology, Nevskogo st. 14, 236041 Kaliningrad, Russia

Dipartimento di Fisica, Università di Napoli “Federico II”, Italy

INFN Sez. di Napoli, Compl. Univ. di Monte S. Angelo, Ed. G., Via Cinthia, 9, I-80126 Napoli, Italy

Gran Sasso Science Institute (INFN), Viale F. Crispi, 7, I-67100 L’Aquila, Italy

Instituciò Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain

Institut de Ciencies de l’Espai (IEEC-CSIC), Campus UAB, Facultat de Ciencies, Torre C5-Par-2a pl, E-08193 Bellaterra, Barcelona, Spain

a r t i c l e i n f o a b s t r a c t

Article history:

Received

17 December 2014

Received

in revised form 20 January 2015

Accepted

21 January 2015

Available

online 23 January 2015

Editor:

J. Hisano

Keywords:

Modiﬁed

gravity

Compact

stars

Quark

stars

Quark star models with realistic equation of state in nonperturbative f (R) gravity are considered. The

mass-radius relation for f (R) = R + αR

model is obtained. Considering scalar curvature R as an

independent function, one can ﬁnd out, for each value of central density, the unique value of central

curvature for which one has solutions with the required asymptotic R → 0for r →∞. In other words,

one needs a ﬁne-tuning for R to achieve quark stars in f (R) gravity. We consider also the analogue

description in corresponding scalar-tensor gravity. The ﬁne-tuning on R is equivalent to the ﬁne-tuning

on the scalar ﬁeld φ in this description. For distant observers, the gravitational mass of the star

increases with increasing α (α > 0) but the interpretation of this fact depends on frame where we work.

Considering directly f (R) gravity, one can say that increasing of mass occurs by the “gravitational sphere”

outside the star with some “effective mass”. On the other hand, in conformal scalar-tensor theory, we

also have a dilaton sphere (or “disphere”) outside the star but its contribution to gravitational mass for

distant observer is negligible. We show that it is possible to discriminate modiﬁed theories of gravity

from General Relativity due to the gravitational redshift of the thermal spectrum emerging from the

surface of the star.

(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP

1. Introduction

The accelerated expansion of the Universe remains one of the

puzzles of modern cosmology. Initially discovered by observations

of distant standard candles [1–3], this acceleration is conﬁrmed by

several other observations such as microwave background radiation

(CMBR) anisotropies [4], cosmic shear through gravitational weak

lensing surveys [5] and data on Lyman alpha forest absorption

lines [6]. Analysis of these observations shows that the required

cosmological dynamics cannot be obtained by models where the

universe contains only standard matter and radiation or, in some

sense, canonical scalar ﬁelds.

One

possible solution of this puzzle is that General Relativity

should be modiﬁed. It is possible to obtain accelerated expansion

in modiﬁed gravity without assuming dark energy as a new mate-

rial

ﬁeld [7–15].

Corresponding author.

E-mail

address: capozziello@na.infn.it (S. Capozziello).

Another explanation considers the existence of a non-standard

cosmic ﬂuid with negative pressure consisting about 70% of the

universe energy, which is not clustered in large scale structure.

However, the nature of this dark energy ﬂuid is unclear. According

to the simplest hypothesis, the dark energy is nothing else but the

Einstein Cosmological Constant. Despite some questions at funda-

mental

level (for example the cosmological constant problem and

problems with ﬁne tuning [16]), the ΛCDM model [17], based on

dark matter and cosmological Λ term, gives, in principle, a good

agreement

with observational data at present epoch.

has been shown that modiﬁed gravity also could give ad-

equate

description of cosmological observations [17–20]. One can

conclude therefore that cosmological observations only cannot wit-

ness

in favor to modiﬁed gravity or ΛCDM model. We need new

probes and testbeds at completely different scales.

Speciﬁcally,

any theory of modiﬁed gravity should be tested at

astrophysical level also. One can hope that strong ﬁeld regimes of

relativistic stars could discriminate between General Relativity and

its possible extensions [21]. For example, some models of f (R)

gravity can be rejected since they do not allow the existence of

http://dx.doi.org/10.1016/j.physletb.2015.01.030

0370-2693/

SCOAP

下载后可阅读完整内容，剩余6页未读，立即下载

weixin_38740596

粉丝: 3
资源: 986

非微扰f(R)重力下的夸克星模型与质量半径关系研究

重力场模型_matlab重力场_matlab重力模型_重力数据_重力场_重力场模型_

地球重力场模型

f（R）重力下的高维非均匀完美流体坍塌

重力波对重构f（R）重力模型的约束

利用动力学系统分析对f（R）重力下的宇宙学模型进行稳定性分析

f（R，T）重力下标量场模型的宇宙学分析。

超重力下近二次混沌膨胀模型中张量与标量比r≳0.1的下界

f（R，T）重力下满足Karmarker条件的真实恒星各向异性模型

GRACE.rar_GRACE 重力_grace_重力_重力场_重力场模型

非最小耦合度量f（R）重力下各向异性源的复杂度因子

最新资源