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Tuesday, August 19, 2014

AGRAVITY (Adimensional Gravity).

This new and ambitious theory propose a general principle that leads to a renormalizable and predictive theory of quan- tum gravity where all scales are generated dynamically, where a small weak scale coexists with the Planck scale, where inflation is a natural phenomenon. The price to pay is a ghost- like anti-graviton state.
It could be an alternative to SUSY theory because it seems this theory failed since no single experimental hint provide by LHC data till now.
The agravity general principle is: "Nature does not possess any scale".
Some observations vaguely indicates that Nature "prefers" adimensional terms.
Thus, the fundamental theory of Nature does not posses any mass or length scale and thereby only contains "renormalizable" interactions - i.e. interactions with dimensionless couplings.
We explore the possibility that the fundamental theory of nature does not contain any scale. This implies a renormalizable quantum gravity theory where the graviton kinetic term has 4 derivatives, and can be reinterpreted as gravity minus an anti-graviton. We compute the super-Planckian RGE of adimensional gravity coupled to a generic matter sector. The Planck scale and a flat space can arise dynamically at quantum level provided that a quartic scalar coupling and its β function vanish at the Planck scale. This is how the Higgs boson behaves for Mh ≈ 125 GeV and Mt ≈ 171 GeV. Within agravity, inflation is a generic phe- nomenon: the slow-roll parameters are given by the β-functions of the theory, and are small if couplings are perturbative. The predictions ns ≈ 0.967 and r ≈ 0.13 arise if the inflaton is identified with the Higgs of gravity. Furthermore, quadratically divergent corrections to the Higgs mass vanish: a small weak scale is natural and can be generated by agravity quantum corrections.In conclusion, we proposed that the fundamental theory contains no dimensionful parameter. Adimensional gravity (agravity for short) is renormalizable because gravitons have a kinetic term with 4 derivatives and two adimensional coupling constants f0 and f2.The theory predicts physics above the Planck scale. We computed the RGE of a generic agravity theory. We found that quantum corrections can dynamically generate the Planck scale as the vacuum expectation value of a scalar s, that acts as the Higgs of gravity. The cosmological constant can be tuned to zero. This happens when a running quartic coupling and its β function both vanish around the Planck scale. The quartic coupling of the Higgs in the SM can run in such a way.
The graviton splits into the usual massless graviton, into a massive spin 2 anti-graviton, and into a scalar. The spin 2 state is a ghost, to be quantised as a state with positive kinetic energy but negative norm.The lack of dimensional parameters implies successful quasi-flat inflationary potentials at super-Planckian vacuum expectation values: the slow-roll parameters are the β functions of the theory. Identifying the inflaton with the Higgs of gravity leads to predictions ns ≈ 0.967 for the spectral index and r ≈ 0.13 for the tensor/scalar amplitude ratio.
The Higgs of gravity can also be identified with the Higgs of the Higgs: if f0,f2 ∼ 10−8 are small enough, gravitational loops generate the observed weak scale. In this context, a weak scale much smaller than the Planck scale is natural: all small parameters receive small quantum corrections. In particular, quadratic divergences must vanish in view of the lack of any fundamental dimensionful parameter, circumventing the usual hierarchy problem.

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