Scale symmetry, the Higgs and the Cosmos

We study gravity coupled to scalar and fermion fields in the Einstein-Cartan framework. We discuss the most general form of the action that contains terms of mass dimension not bigger than four, leaving out only contributions quadratic in curvature. By resolving the theory explicitly for torsion, we arrive at an equivalent metric theory containing additional six-dimensional operators. This lays the groundwork for cosmological studies of the theory. We also perform the same analysis for a no-scale scenario in which the Planck mass is eliminated at the cost of adding an extra scalar degree of freedom. Finally, we outline phenomenological implications of the resulting theories, in particular to inflation and dark matter production.

Section: Jhep10(2020)177mentioning

confidence: 91%

Section: Einstein-cartan Gravity and Global Scale Symmetrymentioning

confidence: 99%

Section: Jhep10(2020)177mentioning

confidence: 99%

Section: Jhep10(2020)177mentioning

confidence: 99%

See 2 more Smart Citations

Einstein-Cartan gravity, matter, and scale-invariant generalization

Shaposhnikov

Shkerin

Timiryasov

et al. 2020

“…One possible interesting solution is that the vacuum can be stabilised by the inclusion of a non-minimal coupling of the Higgs field to gravity [53][54][55][56][57][58][59][60][61][62][63][64][65][66] (for a review within Higgs inflation see refs. [67,68]), well motivated by quantum corrections of the SM in curved backgrounds [69].…”

Section: Introductionmentioning

confidence: 99%

Neutrino masses, vacuum stability and quantum gravity prediction for the mass of the top quark

Domènech

Goodsell

Wetterich

2021

A general prediction from asymptotically safe quantum gravity is the approximate vanishing of all quartic scalar couplings at the UV fixed point beyond the Planck scale. A vanishing Higgs doublet quartic coupling near the Planck scale translates into a prediction for the ratio between the mass of the Higgs boson MH and the top quark Mt. If only the standard model particles contribute to the running of couplings below the Planck mass, the observed MH∼ 125 GeV results in the prediction for the top quark mass Mt∼ 171 GeV, in agreement with recent measurements. In this work, we study how the asymptotic safety prediction for the top quark mass is affected by possible physics at an intermediate scale. We investigate the effect of an SU(2) triplet scalar and right-handed neutrinos, needed to explain the tiny mass of left-handed neutrinos. For pure seesaw II, with no or very heavy right handed neutrinos, the top mass can increase to Mt ∼ 172.5 GeV for a triplet mass of M∆ ∼ 108GeV. Right handed neutrino masses at an intermediate scale increase the uncertainty of the predictions of Mt due to unknown Yukawa couplings of the right-handed neutrinos and a cubic interaction in the scalar potential. For an appropriate range of Yukawa couplings there is no longer an issue of vacuum stability.

Scale invariant Einstein-Cartan gravity and flat space conformal symmetry

Karananas,

Shaposhnikov,

Zell

2023

We find the conditions under which scale-invariant Einstein-Cartan gravity with scalar matter fields leads to an approximate conformal invariance of the flat space particle theory up to energies of the order of the Planck mass. In the minimal setup, these models, in addition to the fields of the Standard Model and the graviton, contain only one extra particle — a massless dilaton. Theories of this type can pave the way for a self-completion all the way up the Planck scale and lead to rather universal inflationary predictions, close to those of the simplest Higgs-inflation scenario in the metric theory of gravity.