We explore the warm inflation scenario theoretical predictions looking at two different dissipative regimes for several representative primordial potentials. As it is well known, warm inflation is ...able to decrease the tensor-to-scalar ratio value, rehabilitating several primordial potentials ruled out in the cold inflation context by the recent cosmic microwave background data. Here we show that warm inflation is also able to produce a running of the running βs positive and within the Planck data limits. This is very remarkable since the standard cold inflation model is unable to justify the current indication of a positive constraint on βs. We achieve a parametrization for the primordial power spectrum able to take into account higher order effects as the running of the spectral index and the running of the running, and we perform statistical analysis using the most up-to-date Planck data to constrain the dissipative effects. We find that the warm inflation can explain the current observables with a good statistical significance, even for those potentials ruled out in the simplest cold inflation scenario.
A
bstract
In this work, we revisit the non-minimally coupled Higgs Inflation scenario and investigate its observational viability in light of the current Cosmic Microwave Background, Baryon Acoustic ...Oscillation and type Ia Supernovae data. We explore the effects of the Coleman-Weinberg approximation to the Higgs potential in the primordial universe, connecting the predictions for the Lagrangian parameters at inflationary scales to the electroweak observables through Renormalization Group methods at two-loop order. Initially, we find that electroweak scale measurements may be dissonant to the limits obtained from the cosmological data sets used in the analysis. Specifically, an ≈ 8
σ
-discrepancy between the inflationary parameters and the value of the Monte Carlo reconstructed top quark mass is found. However, considering the most recent results obtained by the CMS Collaboration from differential cross-section measurements of the top quark production a good agreement is obtained.
The uncertainty on measurements, given by the Heisenberg principle, is a quantum concept usually not taken into account in General Relativity. From a cosmological point of view, several authors ...wonder how such a principle can be reconciled with the Big Bang singularity, but, generally, not whether it may affect the reliability of cosmological measurements. In this letter, we express the Compton mass as a function of the cosmological redshift. The cosmological application of the indetermination principle unveils the differences of the Hubble-Lemaître constant value,
H
0
, as measured from the Cepheids estimates and from the Cosmic Microwave Background radiation constraints. In conclusion, the
H
0
tension could be related to the effect of indetermination derived in comparing a kinematic with a dynamic measurement.
Different astrophysical methods can be combined to detect possible deviations from General Relativity. In this work, we consider a class of
f
(
R
) gravity models selected by the existence of Noether ...symmetries. In this framework, it is possible to determine a set of static and spherically symmetric black hole solutions, encompassing small departures from the Schwarzschild geometry. In particular, when gravity is the only dominating interaction, we exploit the ray-tracing technique to reconstruct the image of a black hole, the epicyclic frequencies, and the black hole shadow profile. Moreover, when matter dynamics is also affected by an electromagnetic radiation force, we take into account the general relativistic Poynting–Robertson effect. In light of the obtained results, the proposed strategy results to be robust and efficient: on the one hand, it allows to investigate gravity from strong to weak field regimes; on the other hand, it is capable of detecting small departures from General Relativity, depending on the current observational sensitivity.
The Heisenberg Limit at Cosmological Scales Spallicci, Alessandro D. A. M.; Benetti, Micol; Capozziello, Salvatore
Foundations of physics,
02/2022, Volume:
52, Issue:
1
Journal Article
Peer reviewed
Open access
For an observation time equal to the universe age, the Heisenberg principle fixes the value of the smallest measurable mass at
m
H
=
1.35
×
10
-
69
kg and prevents to probe the masslessness for any ...particle using a balance. The corresponding reduced Compton length to
m
H
is
, and represents the length limit beyond which masslessness cannot be proved using a metre ruler. In turns,
is equated to the luminosity distance
d
H
which corresponds to a red shift
z
H
. When using the Concordance-Model parameters, we get
d
H
=
8.4
Gpc and
z
H
=
1.3
. Remarkably,
d
H
falls quite short to the radius of the
observable
universe. According to this result, tensions in cosmological parameters could be nothing else but due to comparing data inside and beyond
z
H
. Finally, in terms of quantum quantities, the expansion constant
H
0
reveals to be one order of magnitude above the smallest measurable energy, divided by the Planck constant.
We revise the cosmological bounds on Hořava gravity, taking into account the stringent constraint on the speed of propagation of gravitational waves from GW170817 and GRB170817A. In light of this, we ...also investigate the degeneracy between massive neutrinos and Hořava gravity. We show that a luminal propagation of gravitational waves suppresses the large-scale cosmic microwave background (CMB) radiation temperature anisotropies, and the presence of massive neutrinos increases this effect. On the contrary, large neutrinos mass can compensate the modifications induced by Hořava gravity in the lensing, matter, and primordial B-mode power spectra. Another degeneracy is found, at a theoretical level, between the tensor-to-scalar ratio r and massive neutrinos, as well as with the model's parameters. We analyze these effects using CMB, supernovae type Ia (SNIa), galaxy clustering, and weak gravitational lensing measurements, and we show how such degeneracies are removed. We find that the model's parameters are constrained to be very close to their general relativity limits, and we get a 2 orders of magnitude improved upper bound, with respect to the big bang nucleosynthesis constraint, on the deviation of the effective gravitational constant from the Newtonian one. The deviance information criterion suggests that in Hořava gravity, Σmν > 0 is favored when CMB data only are considered, while the joint analysis of all datasets prefers zero neutrinos mass.
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