Universal gapless Dirac cone and tunable topological states in 
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Hu, Yong; Xu, Lixuan; Shi, Mengzhu; Luo, Aiyun; Peng, Shuting; Wang, Z. Y.; Ying, Jianjun; Wu, Tao; Liu, Z. K.; Zhang, C. F.; Chen, Y. L.; Xu, Gang; Chen, X.-H.; He, Junfeng

doi:10.1103/physrevb.101.161113

Cited by 69 publications

(44 citation statements)

References 52 publications

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“…We now also present the results for the CMB power spectra for both models and we compare our predictions with those of several other codes. As we show in Appendix B, our implementation of the effective fluid approach in the CLASS code [73], while much simpler, also gives results in excellent agreement with other codes, such as EFTCAMB [66], MGCAMB [60], FRCAMB [63], CLASS EOS FR [74]. In all cases, we took extreme care in order to match the various cosmological parameters between the codes and we explicitly tested that in the As described in the text, the DE perturbations reach a plateau and then flatten out for both models, as expected from the fact that the DE effective sound speed given by Eq.…”

Section: Cmb Power Spectrummentioning

confidence: 59%

“…An Effective Field Theory (EFT) approach [65] to DE and MG models was pursued in Ref. [66] where authors had into account a fairly general theory with unbroken symmetries and implemented it in a code called EFT-CAMB 5 (i.e., a modified version of CAMB). Although this approach does not use any quasi-static approximation and evolves the full dynamics of perturbations on linear scales, the mapping of specific models into an EFT formalism might be cumbersome.…”

Section: Introductionmentioning

confidence: 99%

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Unraveling the effective fluid approach for f(R) models in the subhorizon approximation

2019

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We provide explicit formulas for the effective fluid approach of f (R) theories, such as the Hu & Sawicki and the designer models. Using the latter and simple modifications to the CLASS code, which we call EFCLASS, in conjunction with very accurate analytic approximations for the background evolution, we obtain competitive results in a much simpler and less error-prone approach. We also derive the initial conditions in matter domination and we find they differ from those already found in the literature for a constant w model. A clear example is the designer model that behaves as ΛCDM in the background, but has nonetheless dark energy perturbations. We then use the aforementioned models to derive constraints from the latest cosmological data, including supernovae, BAO, CMB, H(z) and growth-rate data, and find they are statistically consistent to the ΛCDM model. Finally, we show that the viscosity parameter c 2 vis in realistic models is not constant as commonly assumed, but rather evolves significantly over several orders of magnitude, something which could affect forecasts of upcoming surveys.

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Section: Cmb Power Spectrummentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Unraveling the effective fluid approach for f(R) models in the subhorizon approximation

2019

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“…Different versions of the linear EFT-DE approach has been implemented in numerical codes able to obtain predictions based on linear perturbation theory. Publicly available implementations exist in EFTCAMB [188], hi class [189] and COOP [190], with the first two based on the CAMB and CLASS Boltzmann codes [191,192]. In addition, the CLASS-Gal code (integrated into CLASS) can be used to compute relativistic corrections to cosmological observables [193].…”

Section: Effective Theory Of Dark Energymentioning

confidence: 99%

Dark Energy in Light of Multi-Messenger Gravitational-Wave Astronomy

Ezquiaga

Zumalacárregui

2018

Front. Astron. Space Sci.

207

202

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Gravitational waves (GWs) provide a new tool to probe the nature of dark energy (DE) and the fundamental properties of gravity. We review the different ways in which GWs can be used to test gravity and models for late-time cosmic acceleration. Lagrangian-based gravitational theories beyond general relativity (GR) are classified into those breaking fundamental assumptions, containing additional fields and massive graviton(s). In addition to Lagrangian based theories we present the effective theory of DE and the µ-Σ parametrization as general descriptions of cosmological gravity. Multi-messenger GW detections can be used to measure the cosmological expansion (standard sirens), providing an independent test of the DE equation of state and measuring the Hubble parameter. Several key tests of gravity involve the cosmological propagation of GWs, including anomalous GW speed, massive graviton excitations, Lorentz violating dispersion relation, modified GW luminosity distance and additional polarizations, which may also induce GW oscillations. We summarize present constraints and their impact on DE models, including those arising from the binary neutron star merger GW170817. Upgrades of LIGO-Virgo detectors to design sensitivity and the next generation facilities such as LISA or Einstein Telescope will significantly improve these constraints in the next two decades.

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“…The basic framework is a code that integrates the perturbed Einstein field equations, the coupled set of matter (and other fluid like) conservation equations and the Boltzman equations for radiation and neutrinos. The main, general purpose, Einstein-Boltzman solvers are EFTCAMB (Hu et al 2013) and MGCAMB (Hojiati et al 2011) and ISITGR (Dossett et al 2011) (derived from CAMB (Lewis et al 1999)) and HiCLASS ) derived from CLASS although over a dozen more specific Einstein-Boltzman solvers have been written. Most of these codes have been cross calibrated and agree at the sub-percent level ).…”

Section: General Theories Of Gravity On Cosmological Scalesmentioning

confidence: 99%

Cosmological Tests of Gravity

Ferreira

2019

Annu. Rev. Astron. Astrophys.

171

125

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Cosmological observations are beginning to reach a level of precision that allows us to test some of the most fundamental assumptions in our working model of the Universe. One such as assumption is that gravity is governed by the General Theory of Relativity. In this review we discuss how one might go about extending General Relativity and how such extensions can be described in a unified way on large scales. This allows us to describe the phenomenology of modified gravity in the growth and morphology of the large scale structure of the Universe. On smaller scales we explore the physics of gravitational screening and how it might manifest itself in galaxies, clusters and, more generally, in the cosmic web. We then analyse the current constraints from large scale structure and conclude by discussing the future prospects of the field in light of the plethora of surveys currently being planned.The key results are: www.annualreviews.org • Cosmological Gravity 7

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Universal gapless Dirac cone and tunable topological states in (MnBi2Te4)m(

Cited by 69 publications

References 52 publications

Unraveling the effective fluid approach for f(R) models in the subhorizon approximation

Unraveling the effective fluid approach for f(R) models in the subhorizon approximation

Dark Energy in Light of Multi-Messenger Gravitational-Wave Astronomy

Cosmological Tests of Gravity

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