非束缚态初始状态：解决混沌模型与BICEP和Planck的冲突

201 浏览量更新于2024-09-02 收藏 285KB PDF 举报

本文主要探讨了在宇宙学的背景下，如何通过非束缚态(Davis初始状态)来解决BICEP2实验和Planck实验之间关于重力波信号的潜在冲突。BICEP2实验观测到了一个原始的重力波张量与标量比r的估计值，即r = 0.2-0.05 + 0.07。然而，这个结果与Planck实验的最新数据不完全吻合，后者倾向于更低的r值和不同的参数组合。为了解决这一矛盾，研究者提出了两种可能的途径。首先，他们考虑了一种理论模型，即存在一个较大的r值的张量态Tr的倾斜，Tr ≳ 0.57-0.27 + 0.29，这对应于nT（张量模式的标量分量）约为0.53，这与BICEP2的测量结果相匹配。同时，这需要标量功率谱的倾斜度dnS/dlnk接近Planck实验的最佳拟合值。第二种可能性涉及到标量谱指数dnS/dlnk出现负值，这会使得在Planck分析中的r上限从0.11提升到0.26，尽管这超出了简单慢摇模型的预测范围。文章的核心贡献在于提出非Bunch-Davies初始状态作为解释这一现象的手段。Bunch-Davies初始状态通常是在量子场论中假设的一种简化情况，但在宇宙早期的暴胀阶段，可能存在扰动，导致初始状态偏离标准。通过考虑这些非标准的初始条件，研究人员能够构建一个大场混沌模型（例如m2ϕ2模型），它不仅包含了BICEP2的蓝色倾斜特征，也能与Planck的结果相协调，特别是关于标量方程ns或ns的负运行部分。这篇论文深入研究了宇宙学中的非标准初始状态在理论模型中的应用，以及它如何帮助我们理解不同实验数据之间的差异，尤其是在重力波和标量波动的测量上。这对于理解早期宇宙的演化和粒子物理标准模型的扩展具有重要意义。通过这种方式，作者们展示了一个理论框架，使得BICEP2和Planck的观测结果可以在某种程度上得到统一。

Physics Letters B 737 (2014) 98–102

Contents lists available at ScienceDirect

Physics Letters B

www.elsevier.com/locate/physletb

Non-Bunch–Davis initial state reconciles chaotic models with BICEP

and Planck

Amjad Ashoorioon

a,∗

, Konstantinos Dimopoulos

, Mohammad M. Sheikh-Jabbari

b,c

Gary Shiu

d,e

Consortium for Fundamental Physics, Physics Department, Lancaster University, LA1 4YB, United Kingdom

School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran

Department of Physics, Kyung Hee University, Seoul 130-071, Republic of Korea

Department of Physics, University of Wisconsin, Madison, WI 53706, United States

Center for Fundamental Physics and Institute for Advanced Study, Hong Kong University of Science and Technology, Hong Kong

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

Article history:

Received

17 June 2014

Received

in revised form 5 August 2014

Accepted

16 August 2014

Available

online 19 August 2014

Editor: M.

Trodden

Keywords:

Chaotic

inﬂation

Excited

initial state

Planck

satellite data

BICEP

The BICEP2 experiment has announced a signal for primordial gravity waves with tensor-to-scalar ratio

r = 0.2

+0.07

−0.05

[1]. There are two ways to reconcile this result with the latest Planck experiment [2].

One is by assuming that there is a considerable tilt of r, T

, with a positive sign, T

= d ln r/d lnk 

0.57

+0.29

−0.27

corresponding to a blue tilt for the tensor modes of order n

 0.53

+0.29

−0.27

, assuming the Planck

experiment best-ﬁt value for tilt of scalar power spectrum n

. The other possibility is to assume that

there is a negative running in the scalar spectral index, dn

/d lnk −0.02 which pushes up the upper

bound on r from 0.11 up to 0.26 in the Planck analysis assuming the existence of a tensor spectrum.

Simple slow-roll models fail to provide such large values for T

or negative runnings in n

[1]. In this

note we show that a non-Bunch–Davies initial state for perturbations can provide a match between large

ﬁeld chaotic models (like m

) with the latest Planck result [3] and BICEP2 results by accommodating

either the blue tilt of r or the negative large running of n

(http://creativecommons.org/licenses/by/3.0/). Funded by SCOAP

Early Universe cosmology has become a very active area of re-

in the last decade or so, as there is a wealth of precise

cosmic microwave background (CMB) measurements pouring in. In

particular, since last year two major collaborations Planck [2] and

BICEP [1] have announced their results. The CMB measurements

analyzed with other cosmological data favor the simple CDM

model for late time cosmology and inﬂationary paradigm for early

stages of Universe evolution. According to the Planck Collabora-

tion data

[2] the power spectrum of CMB temperature ﬂuctuations

(or as it is known, the power spectrum of curvature perturbations)

is measured to be about 2.195 × 10

−9

. The spectrum is almost

ﬂat, with a few-percent tilt toward larger scales (i.e., red spectrum)

and is almost Gaussian.

Planck

took cosmologists by surprise as it not only did not

observe non-Gaussianity, which could have been used to consid-

erably

constrain inﬂationary models, but also put a strong upper

bound on the amplitude of primordial gravity waves during inﬂa-

tion.

These gravity waves are tensor mode ﬂuctuations which are

produced during inﬂation. The power spectrum of gravity waves

Corresponding author.

is usually reported through the tensor-to-scalar ratio r = P

which Planck reported to be bounded at 2σ level as r < 0.12, as-

suming

no running in the scalar spectral index, n

. This bound

corresponds to the pivot scale k

∗

= 0.002 Mpc

−1

, 

∗

 28. The tilt

in the power spectrum of curvature perturbations is customarily

denoted by n

−1, n

−1 ≡ d ln P

/d ln k, where k is inverse of the

scale. Planck constrained n

− 1 =−0.0397 ± 0.0146 at 2σ level.

Of course the upper bound on r

0.002

could be increased, if there is

running in the scalar spectral index. The Planck Collaboration lim-

its

the running of scalar spectral index, dn

/d ln k =−0.021 ±0.011

the presence of the tensor modes. Then the upper bound on r

the Planck pivot scale, k

∗

= 0.002 Mpc

−1

, becomes weaker,

r < 0.26. Planck’s measurement of n

and its running dn

/d ln k

disfavored

many single ﬁeld models, especially those with convex

potential [2].

CMB

besides having one-in-10

part temperature ﬂuctua-

tions

is partially polarized and the parity odd polarization, the

B-mode, is usually attributed to primordial gravity waves, tensor

modes [4]. BICEP2 Collaboration has recently announced observa-

tion

of B-mode polarization [1]. BICEP results took cosmologists

http://dx.doi.org/10.1016/j.physletb.2014.08.038

0370-2693/

SCOAP

下载后可阅读完整内容，剩余4页未读，立即下载

weixin_38661466

粉丝: 7
资源: 930

非束缚态初始状态：解决混沌模型与BICEP和Planck的冲突

从PLANCK和BICEP2的分数阶混沌膨胀

根据BICEP2的动态混沌膨胀

复合通胀面临BICEP2和PLANCK

azure-bicep：各种Bicep文件

BICEP2发现希格斯混沌膨胀和原始B型极化

BICEP2，Planck和WMAP的宇宙学参数的约束

bicep-types-az：ARM资源的Bicep类型定义

bicep-policy-examples:@jesseloudon使用Bicep的Azure策略示例

根据Planck 2015和BICEP2结果，Randall–Sundrum II模型中的中等中间通胀：总耗散系数

新希格斯通货膨胀的自单位化以及与Planck和BICEP2数据的兼容性

最新资源