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Constraints on Metastable Dark Energy Decaying into Dark Matter 可迁移暗能量衰变为暗物质的制约因素
IF 2.9 4区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2024-09-18 DOI: 10.3390/universe10090371
Jônathas S. T. de Souza, Gustavo S. Vicente, Leila L. Graef
We revisit the proposal that an energy transfer from dark energy into dark matter can be described in field theory by a first order phase transition. We analyze a metastable dark energy model proposed in the literature, using updated constraints on the decay time of a metastable dark energy from recent data. The results of our analysis show no prospects for potentially observable signals that could distinguish this scenario from the ΛCDM. We analyze, for the first time, the process of bubble nucleation in this model, showing that such model would not drive a complete transition to a dark matter dominated phase even in a distant future. Nevertheless, the model is not excluded by the latest data and we confirm that the mass of the dark matter particle that would result from such a process corresponds to the mass of an axion-like particle, which is currently one of the best motivated dark matter candidates. We argue that extensions to this model, possibly with additional couplings, still deserve further attention as it could provide an interesting and viable description for an interacting dark sector scenario based in a single scalar field.
我们重新审视了暗能量向暗物质的能量转移可以在场论中用一阶相变来描述的提议。我们分析了文献中提出的一种可陨落暗能量模型,并使用了最新数据对可陨落暗能量衰变时间的最新约束。我们的分析结果表明,没有潜在的可观测信号可以把这种情况与ΛCDM区分开来。我们首次分析了这一模型中的气泡成核过程,结果表明,即使在遥远的未来,这种模型也不会完全过渡到暗物质主导的阶段。尽管如此,最新的数据并没有排除这一模型,而且我们证实,这一过程所产生的暗物质粒子的质量与类轴子粒子的质量相对应,而类轴子粒子是目前动机最好的暗物质候选粒子之一。我们认为,该模型的扩展(可能还有额外的耦合)仍然值得进一步关注,因为它可以为基于单一标量场的相互作用暗部门情景提供有趣而可行的描述。
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引用次数: 0
Quantum Field Theory of Black Hole Perturbations with Backreaction: I General Framework 具有反作用的黑洞扰动量子场论:I 总体框架
IF 2.9 4区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2024-09-18 DOI: 10.3390/universe10090372
Thomas Thiemann
In a seminal work, Hawking showed that natural states for free quantum matter fields on classical spacetimes that solve the spherically symmetric vacuum Einstein equations are KMS states of non-vanishing temperature. Although Hawking’s calculation does not include the backreaction of matter on geometry, it is more than plausible that the corresponding Hawking radiation leads to black hole evaporation which is, in principle, observable. Obviously, an improvement of Hawking’s calculation including backreaction is a problem of quantum gravity. Since no commonly accepted quantum field theory of general relativity is available yet, it has been difficult to reliably derive the backreaction effect. An obvious approach is to use the black hole perturbation theory of a Schwarzschild black hole of fixed mass and to quantize those perturbations. However, it is not clear how to reconcile perturbation theory with gauge invariance beyond linear perturbations. In recent work, we proposed a new approach to this problem that applies when the physical situation has an approximate symmetry, such as homogeneity (cosmology), spherical symmetry (Schwarzschild), or axial symmetry (Kerr). The idea, which is surprisingly feasible, is to first construct the non-perturbative physical (reduced) Hamiltonian of the reduced phase space of fully gauge invariant observables and only then apply perturbation theory directly in terms of observables. The task to construct observables is then disentangled from perturbation theory, thus allowing to unambiguously develop perturbation theory to arbitrary orders. In this first paper of the series we outline and showcase this approach for spherical symmetry and second order in the perturbations for Einstein–Klein–Gordon–Maxwell theory. Details and generalizations to other matter and symmetry and higher orders will appear in subsequent companion papers.
在一项开创性的工作中,霍金证明了经典时空中的自由量子物质场的自然态,解决了球对称真空爱因斯坦方程,是温度不等的KMS态。虽然霍金的计算不包括物质对几何的反作用,但相应的霍金辐射导致黑洞蒸发是完全有可能的,而黑洞蒸发原则上是可以观测到的。显然,要改进霍金的计算并将反作用包括在内,是一个量子引力问题。由于目前还没有公认的广义相对论量子场论,因此很难可靠地推导出反作用效应。一个显而易见的方法是使用质量固定的施瓦兹柴尔德黑洞的黑洞扰动理论,并将这些扰动量子化。然而,除了线性扰动之外,如何协调扰动理论与轨距不变性并不清楚。在最近的研究中,我们提出了一种解决这个问题的新方法,它适用于具有近似对称性的物理情形,如均质性(宇宙学)、球对称性(施瓦兹柴尔德)或轴对称性(克尔)。这个想法出人意料地可行,即首先构建完全量规不变观测变量的还原相空间的非微扰物理(还原)哈密顿,然后才根据观测变量直接应用微扰理论。这样,构建观测值的任务就与扰动理论分开了,从而可以明确地将扰动理论发展到任意阶。在本系列的第一篇论文中,我们概述并展示了针对球对称和爱因斯坦-克莱因-戈登-麦克斯韦理论二阶扰动的这一方法。对其他物质、对称性和更高阶的详细介绍和概括将出现在后续的配套论文中。
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引用次数: 0
Bayesian Knowledge Infusion for Studying Historical Sunspot Numbers 贝叶斯知识注入法研究历史太阳黑子数量
IF 2.9 4区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2024-09-14 DOI: 10.3390/universe10090370
Wenxin Jiang, Haisheng Ji
A scientific method that proposes a value Y to estimate a target value ρ is often subject to some level of uncertainty. In the Bayesian framework, the level of uncertainty can be measured by the width of the 68% interval, which is the range of the middle 68% of the ranked ρ values sampled from the posterior distribution p(ρ|Y). This paper considers Bayesian knowledge infusion (BKI) to reduce the uncertainty of the posterior distribution p(ρ|Y) based on additional knowledge that an event A happens. BKI is achieved by using a conditional prior distribution p(ρ|A) in the Bayes theorem, assuming that given the true ρ, its error-contaminated value Y is independent of event A. We use two examples to illustrate how to study whether or not it is possible to reduce uncertainty from 14C reconstruction (Y) of the annual sunspot number (SSN) (ρ) by infusing additional information (A) using BKI. Information (A) that SSN is from a year that has a Far Eastern record of naked eye sunspots is found to be not so effective in reducing the uncertainty. In contrast, information that SSN is from a year at a cycle minimum is found to be very effective, producing much narrower 68% intervals. The resulting Bayesian point estimates of SSN (the posterior medians of ρ) are cross-validated and tested on a subset of telescopically observed SSNs that were unused in the process of Bayes computation.
提出一个值 Y 来估计目标值 ρ 的科学方法通常会受到一定程度的不确定性影响。在贝叶斯框架中,不确定性水平可以用 68% 区间的宽度来衡量,68% 区间是从后验分布 p(ρ|Y) 中采样的排序 ρ 值的中间 68% 的范围。本文认为贝叶斯知识注入(BKI)可以根据事件 A 发生的额外知识来减少后验分布 p(ρ|Y) 的不确定性。BKI 是通过贝叶斯定理中的条件先验分布 p(ρ|A)来实现的,假设给定真实的 ρ,其误差污染值 Y 与事件 A 无关。我们用两个例子来说明如何研究是否有可能通过使用 BKI 注入额外信息 (A) 来减少年度太阳黑子数 (SSN) (ρ)的 14C 重建 (Y) 的不确定性。发现 SSN 来自有远东肉眼太阳黑子记录的年份这一信息(A)在减少不确定性方面并不那么有效。相比之下,SSN 来自周期最小值年份的信息则非常有效,产生的 68% 间隔要小得多。贝叶斯计算过程中未使用的望远镜观测到的 SSN 子集对得出的 SSN 贝叶斯点估计值(ρ 的后验中值)进行了交叉验证和测试。
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引用次数: 0
Predicting Solar Cycles with a Parametric Time Series Model 用参数时间序列模型预测太阳周期
IF 2.9 4区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2024-09-11 DOI: 10.3390/universe10090364
Kristof Petrovay
The objective of this paper is to reproduce and predict the series of solar cycle amplitudes using a simple time-series model that takes into account the variable time scale of the Gleissberg oscillation and the absence of clear evidence for odd–even alternation prior to Solar Cycle 9 (SC9). It is demonstrated that the Gleissberg oscillation can be quite satisfactorily modelled as a sinusoidal variation of constant amplitude with a period increasing linearly with time. Subtracting this model from the actual cycle amplitudes, a clear even–odd alternating pattern is discerned in the time series of the residuals since SC9. For this period of time, the mean value of the residuals for odd-numbered cycles is shown to exceed the value for even-numbered cycles by more than 4σ, providing the clearest evidence yet for a persistent odd–even–odd alternation in cycle amplitudes. Random deviations from these means are less than half the standard deviation of the raw cycle amplitude time series for the same period, which allows the use of these regularities for solar cycle prediction with substantially better confidence than the simple climatological average. Predicted cycle amplitudes are found to be robust against the addition or omission of some data points from the input set, and the method correctly hindcasts SC23 and SC24. The potential physical background of the regularities is also discussed. Our predictions for the amplitudes of SC25, SC26, and SC27 are 155.8±20.7, 96.9±25.1 and 140.8±20.7, respectively. This suggests that the amplitude of SC26 will be even lower than that of SC24, making it the weakest cycle since the Dalton Minimum.
本文的目的是利用一个简单的时间序列模型来重现和预测太阳周期振幅序列,该模型考虑到了格来斯伯格振荡的时间尺度可变,以及在太阳周期 9(SC9)之前缺乏奇偶交替的明确证据。研究表明,格来斯伯格振荡可以非常令人满意地模拟为振幅恒定、周期随时间线性增加的正弦变化。从实际周期振幅中减去这个模型,可以在 SC9 后的残差时间序列中发现明显的偶数-多 数交替模式。在这段时间内,奇数周期的残差平均值比偶数周期的残差平均值高出 4σ 以上,这为周期振幅持续存在奇偶偶交替提供了最清晰的证据。这些平均值的随机偏差小于同期原始周期振幅时间序列标准偏差的一半,这使得利用这些规律性进行太阳周期预测的可信度大大高于简单的气候学平均值。预测的周期振幅对从输入集中添加或省略某些数据点具有鲁棒性,而且该方法能正确后报 SC23 和 SC24。我们还讨论了这些规律性的潜在物理背景。我们对 SC25、SC26 和 SC27 振幅的预测分别为 155.8±20.7、96.9±25.1 和 140.8±20.7。这表明,SC26的振幅将比SC24的振幅更低,成为道尔顿极小期以来最弱的周期。
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引用次数: 0
Comparing Analytic and Numerical Studies of Tensor Perturbations in Loop Quantum Cosmology 环路量子宇宙学中张量扰动的分析研究与数值研究的比较
IF 2.9 4区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2024-09-11 DOI: 10.3390/universe10090365
Guillermo A. Mena Marugán, Antonio Vicente-Becerril, Jesús Yébana Carrilero
We investigate the implications of different quantization approaches in Loop Quantum Cosmology for the primordial power spectrum of tensor modes. Specifically, we consider the hybrid and dressed metric approaches to derive the effective mass that governs the evolution of the tensor modes. Our study comprehensively examines the two resulting effective masses and how to estimate them in order to obtain approximated analytic solutions to the tensor perturbation equations. Since Loop Quantum Cosmology incorporates preinflationary effects in the dynamics of the perturbations, we do not have at our disposal a standard choice of privileged vacuum, like the Bunch–Davies state in quasi-de Sitter inflation. We then select the vacuum state by a recently proposed criterion which removes unwanted oscillations in the power spectrum and guarantees an asymptotic diagonalization of the Hamiltonian in the ultraviolet. This vacuum is usually called the NO-AHD (from the initials of Non-Oscillating with Asymptotic Hamiltonian Diagonalization) vacuum. Consequently, we compute the power spectrum by using our analytic approximations and by introducing a suitable numerical procedure, adopting in both cases an NO-AHD vacuum. With this information, we compare the different spectra obtained from the hybrid and the dressed metric approaches, as well as from the analytic and numerical procedures. In particular, this proves the remarkable accuracy of our approximations.
我们研究了环路量子宇宙学中不同量子化方法对张量模式原始功率谱的影响。具体来说,我们考虑了混合公因子和着色公因子方法,以推导出支配张量模式演化的有效质量。我们的研究全面考察了由此得出的两种有效质量,以及如何估算它们,以获得张量扰动方程的近似解析解。由于环路量子宇宙学在扰动动力学中加入了预膨胀效应,我们无法像准德西特膨胀中的邦奇-戴维斯态那样选择标准的特权真空。于是,我们通过最近提出的一种标准来选择真空状态,这种标准可以消除功率谱中不必要的振荡,并保证哈密顿在紫外的渐近对角化。这种真空通常被称为 NO-AHD(源自 "非振荡与渐近哈密顿对角化 "的首字母)真空。因此,我们在两种情况下都采用 NO-AHD 真空,通过使用我们的分析近似和引入合适的数值程序来计算功率谱。有了这些信息,我们就可以比较从混合方法和着色度量方法,以及从分析程序和数值程序得到的不同频谱。这尤其证明了我们的近似方法的显著准确性。
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引用次数: 0
Dark Atoms of Nuclear Interacting Dark Matter 核相互作用暗物质的暗原子
IF 2.9 4区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2024-09-11 DOI: 10.3390/universe10090368
Vitaly A. Beylin, Timur E. Bikbaev, Maxim Yu. Khlopov, Andrey G. Mayorov, Danila O. Sopin
The lack of positive evidence for Weakly Interacting Massive Particles (WIMPs) as well as the lack of discovery of supersymmetric (SUSY) particles at the LHC may appeal to a non-supersymmetric solution for the Standard Model problem of the Higgs boson mass divergence, the origin of the electroweak energy scale and the physical nature of the cosmological dark matter in the approach of composite Higgs boson. If the Higgs boson consists of charged constituents, their binding can lead to stable particles with electroweak charges. Such particles can take part in sphaleron transitions in the early Universe, which balance their excess with baryon asymmetry. Constraints on exotic charged species leave only stable particles with charge −2n possible, which can bind with n nuclei of primordial helium in neutral dark atoms. The predicted ratio of densities of dark atoms and baryonic matter determines the condition for dark atoms to dominate in the cosmological dark matter. To satisfy this condition of the dark-atom nature of the observed dark matter, the mass of new stable −2n charged particles should be within reach of the LHC for their searches. We discuss the possibilities of dark-atom binding in multi-atom systems and present state-of-the-art quantum mechanical descriptions of dark-atom interactions with nuclei. Annual modulations in such interactions with nuclei of underground detectors can explain the positive results of DAMA/NaI and DAMA/LIBRA experiments and the negative results of the underground WIMP searches.
由于缺乏弱相互作用大质量粒子(WIMPs)的正面证据,也没有在大型强子对撞机上发现超对称(SUSY)粒子,因此可能需要用一种非超对称的方法来解决希格斯玻色子质量发散的标准模型问题、电弱能量尺度的起源以及复合希格斯玻色子的宇宙学暗物质的物理本质。如果希格斯玻色子由带电成分组成,它们之间的结合会产生具有电弱电荷的稳定粒子。这些粒子可以参与早期宇宙中的闪烁跃迁(sphaleron transition),从而用重子不对称来平衡它们的过剩。由于对奇异带电物种的限制,只有电荷为-2n的稳定粒子才有可能与中性暗原子中的n个原始氦核结合。暗原子和重子物质密度的预测比例决定了暗原子在宇宙学暗物质中占主导地位的条件。为了满足观测到的暗物质的暗原子性质这一条件,新的稳定-2n带电粒子的质量应该在大型强子对撞机的搜索范围之内。我们讨论了多原子系统中暗原子结合的可能性,并介绍了暗原子与原子核相互作用的最新量子力学描述。这种与地下探测器原子核相互作用的年调制可以解释 DAMA/NaI 和 DAMA/LIBRA 实验的积极结果和地下 WIMP 搜寻的消极结果。
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引用次数: 0
The Operational Meaning of Total Energy of Isolated Systems in General Relativity 广义相对论中孤立系统总能量的操作意义
IF 2.9 4区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2024-09-11 DOI: 10.3390/universe10090367
Abhay Ashtekar, Simone Speziale
We present thought experiments to measure the Arnowitt–Deser–Misner EADM and Bondi–Sachs energy EBS of isolated systems in general relativity. The expression of EBS used in the protocol is likely to have other applications. In particular, it is well-suited to be promoted to an operator in non-perturbative loop quantum gravity.
我们介绍了测量广义相对论中孤立系统的阿诺维特-德瑟-米斯纳能量 EADM 和邦迪-萨克斯能量 EBS 的思想实验。协议中使用的 EBS 表达式可能还有其他应用。特别是,它非常适合提升为非微扰环量子引力中的算子。
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引用次数: 0
Initial State in Quantum Cosmology and the Proper Mass of the Universe 量子宇宙学中的初始状态与宇宙的适当质量
IF 2.9 4区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2024-09-11 DOI: 10.3390/universe10090366
Natalia Gorobey, Alexander Lukyanenko, Alexander V. Goltsev
In the Euclidean form of the theory of gravity, where there is no dedicated time parameter, a generalized canonical form of the principle of least action is proposed. On its basis, the quantum principle of least action is formulated, in which the “dynamics” of the universe in the Origin is described by the eigenvector of the action operator—the wave functional on the space of 4D Riemannian geometries and configurations of matter fields in some compact region of 4D space. The corresponding eigenvalue of the action operator determines the initial state for the world history of the universe outside this region, where the metric signature is Lorentzian and, thus, the time parameter exists. The boundary of the Origin region is determined by the condition that the rate of change of the determinant of the 3D metric tensor is zero on it. The size of the Origin is interpreted as a reciprocal temperature of the universe in the initial state. It has been suggested that in the initial state, the universe contains a certain distribution of its own mass, which is not directly related to the fields of matter.
在引力理论的欧几里得形式中,没有专门的时间参数,因此提出了最小作用原理的广义规范形式。在此基础上,提出了量子最小作用原理,其中宇宙在起源中的 "动力学 "是由作用算子的特征向量描述的--作用算子是 4 维黎曼几何空间上的波函数和 4 维空间某个紧凑区域中物质场的配置。作用算子的相应特征值决定了该区域外宇宙世界历史的初始状态,在该区域内,度量特征是洛伦兹的,因此存在时间参数。原点区域的边界由三维度量张量的行列式变化率为零这一条件决定。起源区域的大小被解释为初始状态下宇宙的倒数温度。有人认为,在初始状态下,宇宙自身包含一定的质量分布,这与物质场没有直接关系。
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引用次数: 0
On the Propagation of Gravitational Waves in the Weyl Invariant Theory of Gravity 论韦尔引力不变理论中引力波的传播
IF 2.9 4区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2024-09-09 DOI: 10.3390/universe10090361
Mauro Duarte, Fabio Dahia, Carlos Romero
We revisit Weyl’s unified field theory, which arose in 1918, shortly after general relativity was discovered. As is well known, in order to extend the program of the geometrization of physics started by Einstein to include the electromagnetic field, H. Weyl developed a new geometry which constitutes a kind of generalization of Riemannian geometry. In this paper, our aim is to discuss Weyl’s proposal anew and examine its consistency and completeness as a physical theory. We propose new directions and possible conceptual changes in the original work. Among these, we investigate with some detail the propagation of gravitational waves, and the new features arising in this recent modified gravity theory, in which the presence of a massive vector field appears somewhat unexpectedly. We also speculate whether the results could be examined in the context of primordial gravitational waves.
我们重温韦尔的统一场论,它产生于 1918 年,即广义相对论被发现后不久。众所周知,为了将爱因斯坦开始的物理学几何化计划扩展到电磁场,H. 魏尔发展了一种新的几何,它构成了黎曼几何的一种广义化。在本文中,我们的目的是重新讨论韦尔的提议,并研究其作为物理理论的一致性和完整性。我们提出了新的方向,并可能对原著的概念进行修改。其中,我们详细研究了引力波的传播,以及最近修正的引力理论中出现的新特征,其中大质量矢量场的出现有些出人意料。我们还推测这些结果是否可以在原始引力波的背景下进行检验。
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引用次数: 0
From de Sitter to de Sitter: A Thermal Approach to Running Vacuum Cosmology and the Non-Canonical Scalar Field Description 从德西特到德西特运行真空宇宙学和非正则标量场描述的热学方法
IF 2.9 4区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS Pub Date : 2024-09-09 DOI: 10.3390/universe10090362
Pedro Eleuterio Mendonça Almeida, Rose Clivia Santos, Jose Ademir Sales Lima
The entire classical cosmological history between two extreme de Sitter vacuum solutions is discussed based on Einstein’s equations and non-equilibrium thermodynamics. The initial non-singular de Sitter state is characterised by a very high energy scale, which is equal or smaller than the reduced Planck mass. It is structurally unstable, and all of the continuous created matter, energy, and entropy of the material component comes from the irreversible flow powered by the primeval vacuum energy density. The analytical expression describing the running vacuum is obtained from the thermal approach. It opens a new perspective to solve the old puzzles and current observational challenges plaguing the cosmic concordance model driven by a rigid vacuum. Such a scenario is also modelled through a non-canonical scalar field. It is demonstrated that the resulting scalar field model is shown to be a step-by-step a faithful analytical representation of the thermal running vacuum cosmology.
根据爱因斯坦方程和非平衡热力学,讨论了两个极端德西特真空解之间的整个经典宇宙学历史。初始非星状德西特态的特点是能量尺度非常高,等于或小于还原普朗克质量。它在结构上是不稳定的,所有连续产生的物质、能量和物质成分的熵都来自原始真空能量密度驱动的不可逆流动。描述运行真空的分析表达式来自热学方法。它为解决困扰由刚性真空驱动的宇宙和谐模型的旧难题和当前的观测挑战打开了一个新视角。这种情况也通过非经典标量场来模拟。研究表明,由此产生的标量场模型是热运行真空宇宙学的逐步忠实分析表征。
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引用次数: 0
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Universe
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