3 research outputs found
Can the string scale be related to the cosmic baryon asymmetry?
In a previous work, a mechanism was presented by which baryon asymmetry can
be generated during inflation from elliptically polarized gravitons.
Nonetheless, the mechanism only generated a realistic baryon asymmetry under
special circumstances which requires an enhancement of the lepton number from
an unspecified GUT. In this note we provide a stringy embedding of this
mechanism through the Green-Schwarz mechanism, demonstrating that if the
model-independent axion is the source of the gravitational waves responsible
for the lepton asymmetry, one can observationally constrain the string scale
and coupling.Comment: 12 Pages, typo corrected in the tex
Leptogenesis from Gravity Waves in Models of Inflation
We present a new mechanism for creating the observed cosmic matter-antimatter
asymmetry which satisfies all three Sakharov conditions from one common thread,
gravitational waves. We generate lepton number through the gravitational
anomaly in the lepton number current. The source term comes from elliptically
polarizated gravity waves that are produced during inflation if the inflaton
field contains a CP-odd component. In simple inflationary scenarios, the
generated matter asymmetry is very small. We describe some special conditions
in which our mechanism can give a matter asymmetry of realistic size.Comment: 4 pages, RevTeX4.1 format; an error in computations correcte
Completing Natural Inflation
If the inflaton is a pseudo-scalar axion, the axion shift symmetry can
protect the flatness of its potential from too large radiative corrections.
This possibility, known as natural inflation, requires an axion scale which is
greater than the (reduced) Planck scale. It is unclear whether such a high
value is compatible with an effective field theoretical description, and if the
global axionic symmetry survives quantum gravity effects. We propose a
mechanism which provides an effective large axion scale, although the original
one is sub-Planckian. The mechanism is based on the presence of two axions,
with a potential provided by two anomalous gauge groups. The effective large
axion scale is due to an almost exact symmetry between the couplings of the
axions to the anomalous groups. We also comment on a possible implementation in
heterotic string theory.Comment: 9 pages, 1 figur