Chiral Anomaly in SU(2)${}_R$-Axion Inflation and the New Prediction for Particle Cosmology

Abstract

Upon embedding the axion-inflation in the minimal left-right symmetric gauge extension of the SM with gauge group SU (2) L × SU (2) R × U (1) B−L , [arXiv:2012.11516] proposed a new particle physics model for inflation. In this work, we present a more detailed analysis. As a compelling consequence, this setup provides a new mechanism for simultaneous baryogenesis and right-handed neutrino creation by the chiral anomaly of W R in inflation. The lightest right-handed neutrino is the dark matter candidate. This setup has two unknown fundamental scales, i.e., the scale of inflation and left-right symmetry breaking SU (2) R × U (1) B−L → U (1) Y . Sufficient matter creation demands the left-right symmetry breaking scale happens shortly after the end of inflation. Interestingly, it prefers left-right symmetry breaking scales above 10 10 GeV , which is in the range suggested by the non-supersymmetric SO(10) Grand Unified Theory with an intermediate left-right symmetry scale. Although W R gauge field generates equal amounts of right-handed baryons and leptons in inflation, i.e. B − L = 0, in the Standard Model sub-sector B − L SM = 0. A key aspect of this setup is that SU (2) R sphalerons are never in equilibrium, and the primordial B − L SM is conserved by the Standard Model interactions. This setup yields a deep connection between CP violation in physics of inflation and matter creation (visible and dark); hence it can naturally explain the observed coincidences among cosmological parameters, i.e., η B 0.3P ζ and Ω DM 5Ω B . The new mechanism does not rely on the largeness of the unconstrained CP-violating phases in the neutrino sector nor fine-tuned masses for the heaviest right-handed neutrinos. The SU (2) R -axion inflation comes with a cosmological smoking gun; chiral, non-Gaussian, and blue-tilted gravitational wave background, which can be probed by future CMB missions and laser interferometer detectors.

The Inflated Chern-Simons Number in Spectator Chromo-Natural Inflation

“…One would be to investigate models with a more general potential U (χ) rather than a simple cosine potential. Axion monodromy [38,39] could allow for an effectively non-periodic potential, an idea that has been invoked, but not thoroughly explored, in the CNI context [40][41][42]. Structurally, these models have a similar challenge in explaining the origin of the large coupling of axions to gauge fields, but the details are different enough that the constraints discussed here should be re-evaluated.…”

“…We do not consider this case here, sticking with the cosine potential studied in most of the CNI and S-CNI literature. However, more general monodromy potentials have been invoked in similar contexts [40][41][42], and could be an interesting target for further study.…”

Gravitational waves from spectator Gauge-flation

“…Furthermore, inflationary models with non-Abelian gauge fields can have interesting consequences for baryogenesis and dark matter production [31][32][33][34], leading to correlated observables.…”

“…( 9) -( 12) and find that, indeed, it is possible to satisfy the conditions of Eqs. ( 29) and (34). Notice that Q(N ) evolves mildly with N and stays almost constant.…”

The isotropic attractor solution of axion-SU(2) inflation: Universal isotropization in Bianchi type-I geometry

“…In particular, they produce particles during inflation, such as charged Higgs via the Schwinger effect [16] and charged fermions by both the Schwinger effect [17][18][19] and chiral anomaly [20,21]. As all the Sakharov conditions [22] are satisfied during inflation [23][24][25][26], it provides a natural setting for generating the matter-anti matter asymmetry [20,21]. Another consequence of the Schwinger effect [15] is the sourced primordial gravitational waves.…”