Towards a realistic solution of the cosmological constant fine-tuning problem by Higgs inflation

TL;DR

This paper proposes that Higgs inflation with a variable cosmological constant during inflation can resolve the fine-tuning problem of the cosmological constant, predicting observable inflationary parameters.

Contribution

It introduces a novel approach combining Higgs inflation with a variable cosmological constant to address the cosmological constant fine-tuning issue.

Findings

Predicts a tensor-to-scalar ratio r ≈ 0.20

Forecasts a spectral index n_s ≈ 0.96 with a large running n'_s ≈ -0.028

Achieves a sufficient number of e-folds N ≈ 40

Abstract

Why the cosmological constant $\Lambda$ observed today is so much smaller than the Planck scale or why the universe is accelerating at present? This is so-called the cosmological constant fine-tuning problem. In this paper, we find that this problem is solved with the help of Higgs inflation by simply assuming a variable cosmological "constant" during the inflation epoch. In the meanwhile, it could predict a large tensor-to-scalar ratio $r\approx 0.20$ and a large running of spectral index $n'_s \approx -0.028$ with a red-tilt spectrum $n_s \approx 0.96$, as well as a big enough number of e-folds $N\approx 40$ that required to solve the problems in the Big Bang cosmology with the help of $\Lambda$.