scholarly journals Measuring chiral gravitational waves in Chern-Simons gravity with CMB bispectra

2019 ◽  
Vol 2019 (01) ◽  
pp. 050-050 ◽  
Author(s):  
Nicola Bartolo ◽  
Giorgio Orlando ◽  
Maresuke Shiraishi
Keyword(s):  
Gravitational Waves ◽  
Chern Simons

scholarly journals Inflationary birefringence and baryogenesis

2016 ◽  
Vol 25 (11) ◽  
pp. 1640013 ◽  
Author(s):  
Stephon Alexander
Keyword(s):  
Gravitational Waves ◽  
Lepton Number ◽  
Gauge Fields ◽  
Lepton Asymmetry ◽  
Complex Phase ◽  
Inflaton Field ◽  
Model Based ◽  
Cross Correlations ◽  
Chern Simons

A decade ago, the first leptogenesis model based on inflation was proposed, where the complex phase of the inflaton field carries lepton number [S. H. S. Alexander, M. E. Peskin and M. M. Sheikh-Jabbari, Phys. Rev. Lett. 96 (2006) 081301, arXiv:hep-th/0403069 ]. If the inflaton field is an axion, it can couple to gravitational waves and gauge fields via Chern–Simons invariants. Due to these couplings, birefringent gravitational and gauge primordial perturbations are created during inflation to generate a lepton asymmetry, establishing a possible connection between nonvanishing TB-parity-violating polarization cross-correlations and leptogenesis. We also discuss the prospect for a subset of these models which can directly source circular (V-mode) polarization in the CMB.

scholarly journals Gravitational waves propagation in nondynamical Chern–Simons gravity

2017 ◽  
Vol 26 (13) ◽  
pp. 1750148
Author(s):  
A. Martín-Ruiz ◽  
L. F. Urrutia
Keyword(s):  
Surface Layer ◽  
Domain Wall ◽  
Gravitational Waves ◽  
Electromagnetic Waves ◽  
Condensed Matter ◽  
Additional Contribution ◽  
Reflection And Transmission ◽  
First Derivative ◽  
Waves Propagation ◽  
Chern Simons

We investigate the propagation of gravitational waves in linearized Chern–Simons (CS) modified gravity by considering two nondynamical models for the coupling field [Formula: see text]: (i) a domain wall and (ii) a surface layer of [Formula: see text], motivated by their relevance in condensed matter physics. We demonstrate that the metric and its first derivative become discontinuous for a domain wall of [Formula: see text], and we determine the boundary conditions by realizing that the additional contribution to the wave equation corresponds to one of the self-adjoint extensions of the D'Alembert operator. Nevertheless, such discontinuous metric satisfies the area matching conditions introduced by Barrett. On the other hand, the propagation through a surface layer of [Formula: see text] behaves similarly to the propagation of electromagnetic waves in CS extended electrodynamics. In both cases, we calculate the corresponding reflection and transmission amplitudes. As a consequence of the distributional character of the additional terms in the equations that describe wave propagation, the results obtained for the domain wall are not reproduced when the thickness of the surface layer goes to zero, as one could naively expect.

scholarly journals Propagation of gravitational waves in Chern-Simons axion Einstein gravity

2019 ◽  
Vol 100 (8) ◽  
Author(s):  
Shin’ichi Nojiri ◽  
S. D. Odintsov ◽  
V. K. Oikonomou ◽  
Arkady A. Popov
Keyword(s):  
Gravitational Waves ◽  
Einstein Gravity ◽  
Chern Simons

scholarly journals Resonant gravitational waves in dynamical Chern–Simons–axion gravity

2020 ◽  
Vol 38 (4) ◽  
pp. 045010
Author(s):  
Tomohiro Fujita ◽  
Ippei Obata ◽  
Takahiro Tanaka ◽  
Kei Yamada
Keyword(s):  
Gravitational Waves ◽  
Chern Simons

scholarly journals Gravitational waves from extreme mass-ratio inspirals in dynamical Chern-Simons gravity

2011 ◽  
Vol 83 (10) ◽  
Author(s):  
Paolo Pani ◽  
Vitor Cardoso ◽  
Leonardo Gualtieri
Keyword(s):  
Gravitational Waves ◽  
Mass Ratio ◽  
Chern Simons

scholarly journals Gravitational Waves in Axion Dark Matter

Universe ◽  
2020 ◽  
Vol 6 (7) ◽  
pp. 89 ◽  
Author(s):  
Chong-Sun Chu ◽  
Jiro Soda ◽  
Daiske Yoshida
Keyword(s):  
Dark Matter ◽  
Gravitational Waves ◽  
Parametric Amplification ◽  
Coupling Constant ◽  
Speed Of Light ◽  
Coherent Oscillation ◽  
Axion Field ◽  
Specific Frequency ◽  
Chern Simons

Axion dark matter is interesting as it allows a natural coupling to the gravitational Chern–Simons term. In the presence of an axion background, the gravitational Chern–Simons term produces parity violating effects in the gravitational sector, in particular on the propagation of gravitational waves. Previously, it has been shown that the coherent oscillation of the axion field leads to a parametric amplification of gravitational waves with a specific frequency. In this paper, we focus on the parity violating effects of the Chern–Simons coupling and show the occurrence of gravitational birefringence. We also find deviation from the speed of light of the velocity of the gravitational waves. We give constraints on the axion-Chern–Simons coupling constant and the abundance of axion dark matter from the observation of GW170817 and GRB170817A.

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