# Propagating speed of primordial gravitational waves

@article{Giar2020PropagatingSO, title={Propagating speed of primordial gravitational waves}, author={William Giar{\'e} and Fabrizio Renzi}, journal={Physical Review D}, year={2020}, volume={102} }

Primordial Gravitational Waves, i.e. a background of metric perturbations sourced by the quantum inflationary fluctuations, if measured, could both provide a substantial evidence for primordial inflation and shed light on physics at extremely high energy scales. In this work we focus on their propagating speed. Using an effective field theory approach we introduce a time-dependent propagating speed $c_{\rm T}(t)$ showing that also small deviations from the General Relativity (GR) prediction $c_…

## 11 Citations

### Intermittent NEC violations during inflation and primordial gravitational waves

- Physics
- 2020

Primordial null energy condition (NEC) violation would imprint a blue-tilted spectrum on gravitational wave background (GWB). However, its implications on the GWB might be far richer than expected.…

### Implications of the NANOGrav pulsar timing results for inflation

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The NANOGrav pulsar timing array experiment recently reported evidence for a stochastic common-spectrum process affecting pulsar timing residuals in its 12.5-year dataset, which might be interpreted…

### Generating enhanced parity-violating gravitational waves during inflation with violation of the null energy condition

- PhysicsPhysical Review D
- 2023

A violation of the null energy condition (NEC) during inflation in a single-field inflation model will naturally enhance the amplitude of the parity violation effect (defined by $\Delta\chi$) of…

### Generating enhanced parity-violating gravitational waves during inﬂation with violation of NEC

- Physics
- 2022

: A violation of the null energy condition (NEC) during inﬂation in a single ﬁeld inﬂation model will naturally enhance the amplitude of the parity violation eﬀect (deﬁned by ∆ χ ) of inﬂationary…

### Effects of a Geometrically Realized Early Dark Energy Era on the Spectrum of Primordial Gravitational Waves

- PhysicsSymmetry
- 2022

In this work, we investigate the effects of a geometrically generated early dark energy era on the energy spectrum of the primordial gravitational waves. The early dark energy era, which we choose to…

### Spectrum of Primordial Gravitational Waves in Modified Gravities: A Short Overview

- Physics, GeologySymmetry
- 2022

In this work, we shall exhaustively study the effects of modified gravity on the energy spectrum of the primordial gravitational waves background. S. Weinberg has also produced significant works…

### Generating enhanced primordial GWs during inflation with intermittent violation of NEC and diminishment of GW propagating speed

- PhysicsJournal of High Energy Physics
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We investigate both the null energy condition (NEC) violating scenario and the cT-diminishing scenario for generating enhanced power spectrum of primordial gravitational waves (GWs) during inflation,…

### CFTs blueshift tensor fluctuations universally

- PhysicsJournal of Cosmology and Astroparticle Physics
- 2022

The strong constraints of conformal symmetry cause any nearly-conformal sector to blueshift tensor fluctuations in cosmology. Hidden sectors with approximate conformal symmetry, which may be quite…

### Intermittent null energy condition violations during inflation and primordial gravitational waves

- Physics
- 2021

Primordial null energy condition (NEC) violation would imprint a blue-tilted spectrum on gravitational wave background (GWB). However, its implications on the GWB might be far richer than expected.…

### Higher-curvature corrections and tensor modes

- Mathematics
- 2021

Higher-curvature corrections to the effective gravitational action may leave signatures in the spectrum of primordial tensor perturbations if the inflationary energy scale is sufficiently high. In…

## References

SHOWING 1-10 OF 160 REFERENCES

### Measuring the speed of cosmological gravitational waves.

- Physics
- 2015

In general relativity gravitational waves propagate at the speed of light, however in alternative theories of gravity that might not be the case. We study the effects of a modified speed of gravity,…

### Prospects for direct detection of primordial gravitational waves

- Physics
- 2006

We study the primordial gravitational wave background produced in models of single-field inflation. Using the inflationary flow approach, we investigate the amplitude of gravitational wave spectrum,…

### Gravitational waves and the scale of inflation

- Physics
- 2015

We revisit alternative mechanisms of gravitational wave production during inflation and argue that they generically emit a non-negligible amount of scalar fluctuations. We find the scalar power is…

### Speed of gravity

- PhysicsPhysical Review D
- 2020

Within the standard effective field theory of General Relativity, we show that the speed of gravitational waves deviates, ever so slightly, from luminality on cosmological and other spontaneously…

### Scale-dependent gravitational waves from a rolling axion

- Physics
- 2015

We consider a model in which a pseudo-scalar field σ rolls for some e-folds during inflation, sourcing one helicity of a gauge field. These fields are only gravitationally coupled to the inflaton,…

### WMAP-normalized inflationary model predictions and the search for primordial gravitational waves with direct detection experiments

- Physics
- 2006

In addition to density perturbations, inflationary models of the early Universe generally predict a stochastic background of gravitational waves or tensor fluctuations. By making use of the…

### Cosmological backgrounds of gravitational waves

- PhysicsClassical and Quantum Gravity
- 2018

Gravitational waves (GWs) have a great potential to probe cosmology. We review early universe sources that can lead to cosmological backgrounds of GWs. We begin by presenting proper definitions of…

### Rolling axions during inflation: perturbativity and signatures

- Physics
- 2016

The motion of a pseudo-scalar field X during inflation naturally induces a significant amplification of the gauge fields to which it is coupled. The amplified gauge fields can source characteristic…

### Propagating speed of primordial gravitational waves and inflation

- Physics
- 2016

We show that if the propagating speed of gravitational waves (GWs) gradually diminishes during inflation, the power spectrum of primordial GWs will be strongly blue, while that of the primordial…

### Forecasts on the speed of gravitational waves at high z

- PhysicsJournal of Cosmology and Astroparticle Physics
- 2020

The observation of GW170817 binary neutron star (BNS) merger event has imposed strong bounds on the speed of gravitational waves (GWs) locally, inferring that the speed of GWs propagation is equal to…