Do joint CMB and HST data support a scale invariant spectrum?

Benetti, Micol; Graef, Leila L.; Alcaniz, J. S.

doi:10.1088/1475-7516/2017/04/003

Cited by 43 publications

(44 citation statements)

References 54 publications

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“…We set the sum of neutrino masses as m ν = 0.06 eV and the pivot scale as k 0 = 0.05 Mpc −1 . We take the reasonable range of the number of e-folds, N e ∈ [50,60]. We modify the Cos-moMC code [77] to solve the Boltzmann equations and explore the cosmological parameter space.…”

Section: Models and Methodologymentioning

confidence: 99%

“…We take µ/M pl = 0.1 (solid lines) and µ/M pl = 0.01 (dashed lines), respectively. The values between small and big dots correspond to the number of e-folds of N e ∈ [50,60]. The gray line (η = 0) can distinguish between the convex potential (η > 0) and the concave potential (η < 0).…”

Section: The Prototype Modelmentioning

confidence: 99%

“…An important aspect that is worth mentioning concerns the tension between the direct H 0 measurement and the Planck observation. To avoid the extra effect of the tension on cosmological models, we consider the additional parameter N eff in the cosmological model because the addition of the parameter N eff is considered to be a good scheme to relieve the tension between the direct H 0 measurement and the Planck observation [23,24,[46][47][48][49][50]. In fact, in the literature it is shown that the tension could also be relieved to some extent by considering a dynamical dark energy [51][52][53][54][55] or light sterile neutrinos [47,48,[56][57][58][59][60][61][62][63].…”

Section: Introductionmentioning

confidence: 99%

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Constraints on brane inflation after Planck 2015: Impacts of the latest local measurement of the Hubble constant

Guo

Zhang

et al. 2018

Sci. China Phys. Mech. Astron.

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We investigate the observational constraints on three typical brane inflation models by considering the latest local measurement of the Hubble constant in the global fit. We also employ other observational data, including the Planck 2015 CMB data, the BICEP2/Keck Array B-mode data, and the baryon acoustic oscillations data, in our analysis. Previous studies have shown that the addition of the latest local H0 measurement favors a larger spectral index, and can exert a significant influence on the model selection of inflation. In this work, we investigate its impacts on the status of brane inflation models. We find that, when the direct H0 measurement is considered, the prototype model of brane inflation is still in good agreement with the current observational data within the 2σ level range. For the KKLMMT model, the consideration of the H0 measurement allows the range of the parameter β to be amplified to O(10 −2 ), which slightly alleviates the fine-tuning problem.For the IR DBI model, the addition of the H0 measurement does not provide a better fit. These results show that the consideration of the new H0 prior can exert a considerable influence on the brane inflation models. At last, we show that, when β 1.1, the equilateral non-Gaussianity in the IR DBI inflation model is compatible with the current CMB data at the 1σ level.

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Section: Models and Methodologymentioning

confidence: 99%

Section: The Prototype Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Constraints on brane inflation after Planck 2015: Impacts of the latest local measurement of the Hubble constant

Guo

Zhang

et al. 2018

Sci. China Phys. Mech. Astron.

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“…1, which illustrates how N eff varies with k UV for some particular values of n T . Unlike the constraints on n T from LIGO, 7 e.g., BBN imposes constraints on the quantity N eff , 6 Previous CMB data allowed even higher values of N eff and H 0 implying a stronger preference for models that predict an extra contribution to N eff (see, e.g., [34,35]). 7 Constraints from LIGO are more robust in the sense that they constrain directly n T instead of a quantity that can be degenerated to modifications on the neutrino sector.…”

Section: Resultsmentioning

confidence: 99%

Primordial gravitational waves and the H0 -tension problem

2019

Self Cite

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We analyze the H 0 -tension problem in the context of models of the early universe that predict a blue tilted spectrum of primordial gravitational waves (GWs), which is a positive value of the tensor tilt n T . By considering the GW's contribution, N GW eff , to the effective number of relativistic degrees of freedom, N eff , and assuming standard particle physics, we discuss the effects of N GW eff on the background expansion, especially the constraints on the Hubble parameter H 0 . We analyze three scenarios that take into account the contribution of N GW eff using recent data of cosmic microwave background, baryon acoustic oscillation, the latest measurement of the local expansion rate, along with the LIGO constraints on the tensor to scalar ratio, r, and the tensor index. For the models explored, we show that an additional contribution from the primordial GW's background to N eff does not solve but alleviates the current H 0 -tension problem.The contribution of N GW eff to the radiation content of the universe also affects the predictions of the primordial nucleosynthesis (BBN) [31,32].

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“…[46,47] for a more detailed discussion). The Bayesian evidence E is defined as the marginal likelihood for the model M i :…”

Section: Analysis Methodsmentioning

confidence: 99%

Constraining the break of spatial diffeomorphism invariance with Planck data

Graef

Benetti

Alcaniz

2017

J. Cosmol. Astropart. Phys.

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The current most accepted paradigm for the early universe cosmology, the inflationary scenario, shows a good agreement with the recent Cosmic Microwave Background (CMB) and polarization data. However, when the inflation consistency relation is relaxed, these observational data exclude a larger range of red tensor tilt values, prevailing the blue ones which are not predicted by the minimal inflationary models. Recently, it has been shown that the assumption of spatial diffeomorphism invariance breaking (SDB) in the context of an effective field theory of inflation leads to interesting observational consequences. Among them, the possibility of generating a blue tensor spectrum, which can recover the specific consistency relation of the String Gas Cosmology, for a certain choice of parameters. We use the most recent CMB data to constrain the SDB model and test its observational viability through a Bayesian analysis assuming as reference an extended ΛCDM+tensor perturbation model, which considers a power-law tensor spectrum parametrized in terms of the tensor-to-scalar ratio, r, and the tensor spectral index, nt. If the inflation consistency relation is imposed, r = −8nt, we obtain a strong evidence in favor of the reference model whereas if such relation is relaxed, a weak evidence in favor of the model with diffeomorphism breaking is found. We also use the same CMB data set to make an observational comparison between the SDB model, standard inflation and String Gas Cosmology.

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Do joint CMB and HST data support a scale invariant spectrum?

Cited by 43 publications

References 54 publications

Constraints on brane inflation after Planck 2015: Impacts of the latest local measurement of the Hubble constant

Constraints on brane inflation after Planck 2015: Impacts of the latest local measurement of the Hubble constant

Primordial gravitational waves and the H0 -tension problem

Constraining the break of spatial diffeomorphism invariance with Planck data

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