2023/06/07 by Alexander, Stephon, Creque-Sarbinowski, Cyril, Gilmer, Humberto +1
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2306.04671
We introduce a new method that allows for the Higgs to be the inflaton. That is, we let the Higgs be a pseudo-Nambu-Goldstone (pNG) boson of a global coset symmetry G/H that spontaneously breaks at an energy scale ∼ 4πf and give it a suitable SU(2) ⊂ G Chern-Simons interaction, with β the dimensionless Chern-Simons coupling strength and f an SU(2) decay constant. As a result, slow-roll inflation occurs via SU(2)-induced friction down a steep sinusoidal potential. In order to obey electroweak SU(2)\rm L× U(1)Y symmetry, the lowest-order Chern-Simons interaction is required to be quadratic in the Higgs with coupling strength ∝ β2/f2. Higher-order interaction terms keep the full Lagrangian nearly invariant under the approximate pNG shift symmetry. Employing the simplest symmetry coset SU(5)/SO(5), N e-folds of inflation occur when N ≈ 60 (g/0.64)2[β/(3× 106)]8/3[f/(5× 1011 \rm GeV)]2/3, with g the weak isospin gauge coupling constant. Small values of the decay constant, f \lesssim 5 × 1011 \rm GeV, which are needed to address the Higgs hierarchy problem, are ruled out by electric dipole measurements and so successfully explaining inflation requires large β. We discuss possible methods to achieve such large couplings and other alternative Higgs inflation scenarios outside the standard modified-gravity framework.