Blue running of the primordial tensor spectrum

Abstract

We examine the possibility of positive spectral index of the power spectrum of the primordial tensor perturbation produced during inflation in the light of the detection of the B-mode polarization by the BICEP2 collaboration. We find a blue tilt is in general possible when the slow-roll parameter decays rapidly. We present two known examples in which a positive spectral index for the tensor power spectrum can be obtained. We also briefly discuss other consistency tests for further studies on inflationary dynamics.

arXiv comment(v1) 6 pages; (v2) 7 pages, more discussions and changes including the title, to appear in Journal of Cosmology and Astroparticle Physics

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Cited by in corpus (13)

• Features and New Physical Scales in Primordial Observables: Theory and Observation
• Blue Tensor Spectrum from Particle Production during Inflation
• Blue-tilted Tensor Spectrum and Thermal History of the Universe
• Generalised tensor fluctuations and inflation
• Nonsingular bouncing cosmologies in light of BICEP2
• Implications of the NANOGrav result on primordial gravitational waves in nonstandard cosmologies
• Primordial black holes as a novel probe of primordial gravitational waves
• Probing The Early Universe Cosmology With NANOGrav: Possibilities and Limitations
• Inflation and Alternatives with Blue Tensor Spectra
• Null energy condition violation during inflation and pulsar timing array observations
• Scalar suppression on large scales in open inflation
• Ambiguity in running spectral index with an extra light field during inflation
• Climbing over the potential barrier during inflation via null energy condition violation