Yuri Bonder

Lorentz violation in the gravity sector: The t puzzle

Lorentz violation is a candidate quantum-gravity signal, and the Standard-Model Extension (SME) is a widely used parametrization of such a violation. In the gravitational SME sector, there is an elusive coefficient for which no effects have been found. This is known as the

Lorentz violation in a uniform newtonian gravitational field

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Quantum gravity phenomenology without Lorentz invariance violation: a detailed proposal

puzzle and, to date, it has no compelling explanation. This paper analyzes whether there is a fundamental explanation for the

A first-principles model of birefringent porous silicon

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Testing the equivalence principle with unstable particles

puzzle. To tackle this question, several approaches are followed. Mainly, redefinitions of the dynamical fields are studied, showing that other SME coefficients can be moved to nongravitational sectors. It is also found that the gravity SME sector can be consistently treated \`a la Palatini, and that, in the presence of spacetime boundaries, it is possible to correct its action to get the desired equations of motion. Moreover, through a reformulation as a Lanczos-type tensor, some problematic features of the

Can gravity account for the emergence of classicality

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Experimental search for a Lorentz invariant spacetime granularity: Possibilities and bounds

term, which should arise at the phenomenological level, are revealed. The most important conclusion of the paper is that there is no evidence of a fundamental explanation for the

Unambiguous Quantum Gravity Phenomenology Respecting Lorentz Symmetry

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OPERATIONAL GEOMETRY ON DE SITTER SPACETIME

puzzle, suggesting that it may be linked to the approximations taken at the phenomenological level.

Space-time variation of the electron-to-proton mass ratio in a Weyl model

Lorentz invariance is one of the fundamental principles of physics, and, as such, it must be experimentally tested. The purpose of this work is to obtain, within the Standard-Model Extension, the dynamics of a Lorentz-violating spinor in a uniform newtonian gravitational field. This is achieved by treating the spinor as a test particle and introducing the gravitational field through a uniformly accelerated observer. The nonrelativistic hamiltonian is obtained and some experimental consequences are discussed. One unexpected outcome of this work is that the gravitational field helps disentangling bounds on coefficients for Lorentz violation.