Double monodromy inflation: Gravitational wave factory for CMBS4, LiteBIRD, and LISA
Abstract
We consider a short rollercoaster cosmology based on two stages of monodromy inflation separated by a stage of matter domination, generated after the early inflaton falls out of slow roll. If the first stage is controlled by a flat potential, V ∼ϕ^{p} with p <1 and lasts N ∼30  40 e folds, the scalar and tensor perturbations at the largest scales will fit the CMB perfectly, and produce relic gravity waves with 0.02 ≲r ≲0.06 , which can be tested by LiteBIRD and CMBS4 experiments. If in addition the first inflaton is strongly coupled to a hidden sector U (1 ), there will be an enhanced production of vector fluctuations near the end of the first stage of inflation. These modes convert rapidly to tensors during the short epoch of matter domination, and then get pushed to superhorizon scales by the second stage of inflation, lasting another 2030 e folds. This band of gravity waves is chiral, arrives today with wavelengths in the range of 10^{8} km , and with amplitudes greatly enhanced compared to the long wavelength CMB modes by vector sources. It is therefore accessible to LISA. Thus our model presents a rare early universe theory predicting several simultaneous signals testable by a broad range of gravity wave searches in the very near future.
 Publication:

Physical Review D
 Pub Date:
 October 2021
 DOI:
 10.1103/PhysRevD.104.L081302
 arXiv:
 arXiv:2101.05861
 Bibcode:
 2021PhRvD.104h1302D
 Keywords:

 High Energy Physics  Theory;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology
 EPrint:
 13 pages, 4 figures. v2: Minor changes, references added, accepted in PRD