Birefringent gravitational waves and the consistency check of inflation
Abstract
In this work we show that the gravitational ChernSimons term, aside from being a key ingredient in inflationary baryogenesis, modifies superhorizon gravitational waves produced during inflation. We compute the superHubble gravitational power spectrum in the slowroll approximation and show that its overall amplitude is modified while its spectral index remains unchanged (at leading order in the slowroll 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 ChernSimons 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.
 Publication:

Physical Review D
 Pub Date:
 March 2005
 DOI:
 10.1103/PhysRevD.71.063526
 arXiv:
 arXiv:hepth/0410230
 Bibcode:
 2005PhRvD..71f3526A
 Keywords:

 98.80.Cq;
 98.70.Vc;
 Particletheory and fieldtheory models of the early Universe;
 Background radiations;
 Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 9 pages, 1 figure, RevTex