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, [1] 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 WR 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 1010 GeV, which is in the range suggested by the non-supersymmetric SO(10) Grand Unified Theory with an intermediate left-right symmetry scale. Although WR 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 − LSM ≠ 0. A key aspect of this setup is that SU(2)R sphalerons are never in equilibrium, and the primordial B − LSM 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., ηB ≃ 0.3Pζ and ΩDM ≃ 5ΩB. 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.

Axion anomalies

“…In this paper, motivated by theories of the early Universe containing axion fields with classical vacuum expectation values interacting with fermions [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], we revisit anomalous Ward identities due to axion or pseudoscalar interactions.…”

The Standard Model Quiver in de Sitter String Compactifications

“…5.2. Furthermore, our realisation of the left-right symmetric model could provide a golden opportunity to study all the interesting properties of the left-right symmetric models within concrete string models, providing a UV completion for these interesting phenomenological models (see [123][124][125] for recent discussions). Having explicit low-energy string models, there are plenty of flavour questions that may need to be studied before claiming to have a fully realistic model.…”

New physics from the polarised light of the cosmic microwave background

“…The SM weak interaction acts on left-handed fermions. Recently, Maleknejad embedded the above SU(2) field in the right-handed sector of weak interaction in the so-called leftright symmetric extension of SM 240,241 . Her model has a rich phenomenology not only for the primordial GW from inflation but also for dark matter and the origin of matter-anti matter asymmetry.…”