Abstract
In this paper we show that the Germani-Kehagias model of Higgs inflation (or New Higgs Inflation), where the Higgs boson is kinetically non-minimally coupled to the Einstein tensor is in perfect compatibility with the latest Planck and BICEP2 data. Moreover, we show that the tension between the Planck and BICEP2 data can be relieved within the New Higgs inflation scenario by a negative running of the spectral index. Regarding the unitarity of the model, we argue that it is unitary throughout the evolution of the Universe. Weak couplings in the Higgs-Higgs and Higgs-graviton sectors are provided by a large background dependent cut-off scale during inflation. In the same regime, the W and Z gauge bosons acquire a very large mass, thus decouple. On the other hand, if they are also non-minimally coupled to the Higgs boson, their effective masses can be enormously reduced. In this case, the W and Z bosons are no longer decoupled. After inflation, the New Higgs model is well approximated by a quartic Galileon with a renormalizable potential. We argue that this can unitarily create the right conditions for inflation to eventually start.
Highlights
Gauge bosons Wμa with generator τ a and the U (1)Y gauge boson Bμ
We show that the tension between the Planck and BICEP2 data can be relieved within the New Higgs inflation scenario by a negative running of the spectral index
One obvious possibility is to allow for a running of the scalar spectral index. Other explanations of this tension are possible, such as a better measure of the optic depth, it is intriguing to see that the New Higgs inflationary model can provide a non-trivial negative running of the spectral index relaxing the tension between Planck and BICEP2
Summary
We shall consider a generic inflationary Lagrangian of gravity and a scalar field kinetically coupled to gravity in the following form:. Varying the Lagrangian (2.2) with respect to the lapse N , we find the Hamiltonian constraint equation. Varying the Lagrangian (2.2) with respect to φ(t), we find the background equation of motion for φ as. Varying the Lagrangian (2.2) with respect to a(t) and combining with (2.5), we get another useful background relation. Varying the Lagrangian (2.2) with respect to the shift Nj, we find the momentum constraint equation. Note that in the limit 3H2 M 2 (conventional general relativity limit), c2s 1 and in the other limit 3H2 M 2 (gravitationally enhanced friction limit), c2s 1 − 8 /3 These limits have no impact on the amplitude of curvature perturbation, they do on its spectral index and change theoretical predictions.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
