2004/10/25 by Stephon Alexander, Jerome Martin, Jérôme Martin · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Amplitude #Anisotropy #Black Holes and Theoretical Physics #Cosmic microwave background #Cosmology and Gravitation Theories #Electron #Geophysics and Gravity Measurements #Gravitation #Gravitational wave #Inflation (cosmology) #Leptogenesis #Lepton #Mathematical physics #Physics #Planck #Quantum mechanics #Scalar (mathematics) #Theoretical physics #astro-ph #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.71.063526
published as Phys.Rev. D71 (2005) 063526 · 9 pages, 1 figure, RevTex
arxiv created 2004/10/25 · openalex publication_date 2005/03/24 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In this work we show that the gravitational Chern-Simons term, aside from being a key ingredient in inflationary baryogenesis, modifies superhorizon gravitational waves produced during inflation. We compute the super-Hubble gravitational power spectrum in the slow-roll approximation and show that its overall amplitude is modified while its spectral index remains unchanged (at leading order in the slow-roll parameters). Then, we calculate the correction to the tensor to scalar ratio, T/S. We find a correction of T/S which is dependent on N (more precisely quadratic in N), the parameter characterizing the amplitude of the Chern-Simons terms. In a stringy embedding of the leptogenesis mechanism, N is the ratio between the Planck scale and the fundamental string scale. Thus, in principle, we provide a direct probe of leptogenesis due to stringy dynamics in the cosmic microwave background. However, we demonstrate that the corresponding correction of T/S is in fact very small and not observable in the regime where our calculations are valid. To obtain a sizable effect, we argue that a nonlinear calculation is necessary.