The problem with false vacuum Higgs inflation

Abstract

We investigate the possibility of using the only known fundamental scalar, the Higgs, as an inflaton with minimal coupling to gravity. The peculiar appearance of a plateau or a false vacuum in the renormalised effective scalar potential suggests that the Higgs might drive inflation. For the case of a false vacuum we use an additional singlet scalar field, motivated by the strong CP problem, and its coupling to the Higgs to lift the barrier allowing for a graceful exit from inflation by mimicking hybrid inflation. We find that this scenario is incompatible with current measurements of the Higgs mass and the QCD coupling constant and conclude that the Higgs can only be the inflaton in more complicated scenarios. * malcolm.fairbairn@kcl.ac.uk † philipp.grothaus@kcl.ac.uk ‡ robert.hogan@kcl.ac.uk 1 This requirement is to fit the perturbations for N = 60 e-folds before the end of inflation. This model is also in tension with Planck's n S − r plane constraints [1], where n S is the spectral index and r is the tensor-to-scalar ratio 1 arXiv:1403.7483v1 [hep-ph]

Higgs mass and gravity waves in standard model false vacuum inflation

“…Similar conclusions have been recently found by [15] in the case of inflation from the Higgs false vacuum with an additional scalar weakly coupled to the Higgs, in standard gravity. Of course such conclusion can be changed if extra ingredients are added to the standard model.…”

“…3 that a large value of £ allows for the potential to fit CMB observations, also for larger mH, compatible 'Note also that such a conclusion is in agreement with [21], which also concludes that the height of the potential is too high with the present values of mH and m,. For instance Fig.…”

“…For instance Fig. 4 of such paper shows that only very low mH or very high as (more than 3 sigma from the present measured values) would lead to accept able values of r. Note also that [21] performs the analysis of the number of efolds, ns and r, only for the hybrid type of model introduced in [3], while in the present paper we focus on the scalar-tensor type of model introduced in [1], with the LHC measurements. However let us comment that this is based only on a tree level analysis and when having a value of the extra coupling constant | larger than 0( 1) we have to be careful about the regime of validity of the theory, similarly to the models proposed in [25], due to the fact that a new cutoff scale appears, MP//£.…”

“…Such bounds could be also be evaded by modifying the shape of the potential in a model-dependent way. For instance a possibility would be to introduce direct couplings of the Higgs with the extra scalar as in [30], which would change the potential either at tree level or in the RGE, or perhaps to allow a faster change of the barrier in hybrid models during inflation (see [15]). …”

Higgs inflation with singlet scalar dark matter and right-handed neutrino in light of BICEP2

“…h end is given as the slow roll conditions (ǫ, |η| ≪ 1) are broken. It is known that the SM Higgs potential can have a plateau by taking a fine-tuned small top mass of M t = 171.0789 (171.0578) GeV for m H = 125.6 (125) GeV [24,28,33]. By using this plateau, the authors of Ref.…”