Primordial Black Holes and Gravitational Waves in Multi-Axion-Chern-Simons Inflation. (arXiv:2206.07963v2 [hep-th] UPDATED)
<a href="http://arxiv.org/find/hep-th/1/au:+Mavromatos_N/0/1/0/all/0/1">Nick E. Mavromatos</a>, <a href="http://arxiv.org/find/hep-th/1/au:+Spanos_V/0/1/0/all/0/1">Vassilis C. Spanos</a>, <a href="http://arxiv.org/find/hep-th/1/au:+Stamou_I/0/1/0/all/0/1">Ioanna D. Stamou</a>
We study aspects of inflation and the possibility of enhanced production of
primordial black holes (PBHs) and gravitational waves (GWs) in a
string-inspired model of two axion fields coupled to Chern-Simons gravity,
which results in a running-vacuum-model inflation. Fluctuations of the scale
invariant spectrum, consistent with the cosmological data, are provided in this
model by world-sheet (non-perturbative) instanton terms of the axion field
arising from string compactification. As a result of such modulations, there is
an enhanced production of PBHs and GWs in such cosmologies, which may lead to
observable in principle patterns in the profile of GWs during the radiation
era. Moreover, we demonstrate that the PBHs may provide a significant amount of
Dark Matter in this Universe. For comparison, we also discuss a two-stage
inflation cosmological model of conventional string-inspired axion monodromy,
involving again two axion fields. The resulting modifications imprinted on the
GWs spectra between these two classes of models are distinct, and can, in
principle, be distinguished by future interferometers.
We study aspects of inflation and the possibility of enhanced production of
primordial black holes (PBHs) and gravitational waves (GWs) in a
string-inspired model of two axion fields coupled to Chern-Simons gravity,
which results in a running-vacuum-model inflation. Fluctuations of the scale
invariant spectrum, consistent with the cosmological data, are provided in this
model by world-sheet (non-perturbative) instanton terms of the axion field
arising from string compactification. As a result of such modulations, there is
an enhanced production of PBHs and GWs in such cosmologies, which may lead to
observable in principle patterns in the profile of GWs during the radiation
era. Moreover, we demonstrate that the PBHs may provide a significant amount of
Dark Matter in this Universe. For comparison, we also discuss a two-stage
inflation cosmological model of conventional string-inspired axion monodromy,
involving again two axion fields. The resulting modifications imprinted on the
GWs spectra between these two classes of models are distinct, and can, in
principle, be distinguished by future interferometers.
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