Axion quality problem alleviated by nonminimal coupling to gravity

Bounds on the nonminimal coupling of the Higgs boson to gravity.

We derive the first bound on the value of the Higgs boson nonminimal coupling to the Ricci scalar. We show that the recent discovery of the Higgs boson at the Large Hadron Collider at CERN implies that the nonminimal coupling is smaller than 2.6×10(15).

Stationary BPS solutions to dilaton-axion gravity.

Stationary four-dimensional BPS solutions to gravity coupled bosonic theories admitting a three–dimensional sigma–model representation on coset spaces are interpreted as null geodesics of the target manifold equipped with a certain number of harmonic maps. For asymptotically flat (or Taub–NUT) space–times such geodesics can be directly parametrized in terms of charges saturating the Bogomol’nyi...

Inflation and quintessence with nonminimal coupling

The nonminimal coupling (NMC) of the scalar field to the Ricci curvature is unavoidable in many cosmological scenarios. Inflation and quintessence models based on nonminimally coupled scalar fields are studied, with particular attention to the balance between the scalar potential and the NMC term ξRφ2/2 in the action. NMC makes acceleration of the universe harder to achieve for the usual potent...

Solitons of axion-dilaton gravity.

We use soliton techniques of the two-dimensional reduced β-function equations to obtain non-trivial string backgrounds from flat space. These solutions are characterized by two integers (n,m) referring to the soliton numbers of the metric and axion-dilaton sectors respectively. We show that the NappiWitten universe associated with the SL(2) × SU(2)/SO(1, 1) × U(1) CFT coset arises as an (1, 1) ...

Palatini formulation of modified gravity with a nonminimal curvature-matter coupling