From weak interaction to gravity (original) (raw)
Related papers
A spinor theory of gravity and the cosmological framework
Journal of Cosmology and Astroparticle Physics, 2007
Recently we have presented a new formulation of the theory of gravity based on an implementation of the Einstein equivalence principle distinct from general relativity. The kinetic part of the theory---that describes how matter is affected by the modified geometry due to the gravitational field---is the same as in general relativity. However, we do not consider the metric as an
Physical Review D, 2004
We investigate a possible unified theory of all interactions which is based only on fundamental spinor fields. The vielbein and metric arise as composite objects. The effective quantum gravitational theory can lead to a modification of Einstein's equations due to the lack of local Lorentz-symmetry. We explore the generalized gravity with global instead of local Lorentz symmetry in first order of a systematic derivative expansion. At this level diffeomorphisms and global Lorentz symmetry allow for two new invariants in the gravitational effective action. The one which arises in the one loop approximation to spinor gravity is consistent with all present tests of general relativity and cosmology. This shows that local Lorentz symmetry is tested only very partially by present observations. In contrast, the second possible new coupling is severely restricted by present solar system observations.
Dynamical gravitational coupling as a modified theory of general relativity
A modified theory of general relativity is proposed, where the gravita-tional constant is replaced by a dynamical variable in space-time. The dynamics of the gravitational coupling is described by a family of parametrized null geodesics, implying that the gravitational coupling at a space-time point is determined by solving transport equations along all null geodesics through this point. General relativity with dynamical gravitational coupling (DGC) is introduced. We motivate DGC from general considerations and explain how it arises in the context of causal fermion systems. The underlying physical idea is that the gravi-tational coupling is determined by microscopic structures on the Planck scale which propagate with the speed of light. In order to clarify the mathematical structure, we analyze the conformal behavior and prove local existence and uniqueness of the time evolution. The differences to Einstein's theory are worked out in the examples of the Friedmann-Robertson-Walker model and the spherically symmetric collapse of a shell of matter. Potential implications for the problem of dark matter and for inflation are discussed. It is shown that the effects in the solar system are too small for being observable in present-day experiments.
Physics Letters B, 2003
A unified description of all interactions could be based on a higher-dimensional theory involving only spinor fields. The metric arises as a composite object and the gravitational field equations contain torsion-corrections as compared to Einstein gravity. Lorentz symmetry in spinor space is only global, implying new goldstone-boson-like gravitational particles beyond the graviton. However, the Schwarzschild and Friedman solutions are unaffected at one loop order. Our generalized gravity seems compatible with all present observations.
Universally Coupled Massive Gravity, I
2006
Einstein’s equations are derived from a linear theory in flat spacetime using free field gauge invariance and universal coupling. The gravitational potential can be either covariant or contravariant and of almost any density weight. These results are adapted to yield universally coupled massive variants of Einstein’s equations, yielding two one-parameter families of distinct theories with spin 2 and spin 0. The Freund-Maheshwari-Schonberg theory is thus not the unique universally coupled massive generalization of Einstein’s theory, though it is privileged in some respects. The theories derived are a subset of those found by V. I. Ogievetsky and I. V. Polubarinov by other means. The question of positive energy remains open, but might be addressed by numerical relativists in the context of spherical symmetry. A few remarks are made on the issue of causality with two observable metrics and the possible need for gauge freedom. Some criticisms by Padmanabhan of field derivations of Einst...
Physical Review D, 1999
In this work we propose an extended formulation for the interaction between neutrinos and gravitational fields. It is based on the parametrized post-Newtonian aproach, and includes a violation of the universality of the gravitational interaction which is non diagonal in the weak flavor space. We find new effects that are not considered in the standard scenario for violation of the equivalence principle. They are of the same order as the effects produced by the Newtonian potential, but they are highly directional dependent and could provide a very clean test of that violation. Phenomenological consequences are briefly discussed.
Gravitationally Generated Interactions
2012
Starting from a 5D-Riemannian manifold, we show that a reduction mechanism to 4D-spacetimes reproduces Extended Theories of Gravity (ETGs) that are direct generalizations of Einstein's gravity. In this context, the gravitational degrees of freedom can be dealt under the standard of spacetime deformations. Besides, such deformations can be related to the mass spectra of particles. The intrinsic non-linearity of ETGs gives an energy-dependent running coupling, while torsion gives rise to interactions among spinors displaying the structure of the weak forces among fermions. We discuss how this scheme is compatible with the known observational evidence and suggest that eventual discrepancies could be detected in experiments, as ATLAS and CMS, today running at LHC (CERN). We finally discuss the consequences of the present approach in view of unification of physical interactions.
The Coupling of Gravity to Spin and Electromagnetism
Modern Physics Letters A, 1999
The coupled Einstein-Dirac-Maxwell equations are considered for a static, spherically symmetric system of two fermions in a singlet spinor state. Stable soliton-like solutions are shown to exist, and we discuss the regularizing effect of gravity from a Feynman diagram point of view.
Weak Interaction and Cosmology
arXiv: General Physics, 2008
In this paper we examine the connection among the themes: the cosmological constant, the weak interaction and the neutrino mass. Our main propose is to review and modify the ideas first proposed by Hayakawa [ Prog. Theor. Phys.Suppl.,532(1965).], in the light of the new-fashioned features of contemporary physics. Assuming the pressure of a Fermi gas of neutrinos should be balanced by its gravitational attraction, we evaluate the mass of the background neutrino and its number.The neutrino mass here evaluated is compatible with the known value for the cosmological constant (or dark energy).Taking in account the role played by the weak forces experimented by the neutrinos, we also determined a value for the electroweak mixing angle. For sake of comparison, an alternative evaluation of the neutrino mass is also done.
2020
In this work, using differential forms, an alternative approach to matter coupling in Minimal Massive 3D Gravity (MMG) is presented. In the first part, we consider the minimal coupling of matter Lagrangian assuming that matter Lagrangian 3-form depends on the metric co-frame fields and some matter fields but not on the connections. We construct additional source 2-form to obtain a consistent matter-coupled MMG theory. We see that additional source 2-form involves terms that are quadratic in stress-energy 2-forms. In addition, we derive consistency relation in the language of differential forms. Next, we consider minimal coupling of Dirac Lagrangian where for this case massive spinor-matter Lagrangian depends on both metric co-frames and connection fields. To get a consistent spinor-matter coupled MMG field equation, we obtain additional source 2-form as well. It is shown that with spinor coupling, source 2-form involves terms which are quadratic in covariant derivatives of spinor fi...