Limits on Lorentz Violation from Synchrotron and Inverse Compton Sources

Abstract

We derive new bounds on Lorentz violations in the electron sector from existing data on high-energy astrophysical sources. Synchrotron and inverse Compton data give precisely complementary constraints. The best bound on a specific combination of electron Lorentzviolating coefficients is at the 6 × 10 −20 level, and independent bounds are available for all the Lorentz-violating c coefficients at the 2 × 10 −14 level or better. This represents an improvement in some bounds by fourteen orders of magnitude.1 baltschu@indiana.eduThe possibility that Lorentz invariance may not be exact in nature has been a subject of great interest since the discovery that Lorentz symmetry could be broken spontaneously in string theory [1]. Any observed deviations from Lorentz invariance would be powerful clues about the nature of Planck-scale physics. There has been a great deal of work probing the physics of Lorentz violation, both experimental and theoretical. Sensitive tests of Lorentz symmetry have included studies of matter-antimatter asymmetries for trapped charged particles [2,3,4,5] and bound state systems [6,7], determinations of muon properties [8,9], analyses of the behavior of spin-polarized matter [10,11], frequency standard comparisons [12,13,14,15], Michelson-Morley experiments with cryogenic resonators [16,17], Doppler effect measurements [18,19], measurements of neutral meson oscillations [20,21,22,23], polarization measurements on the light from distant galaxies [24,25,26], and others.On the theoretical side, a Lorentz-and CPT-violating effective field theory, the standard model extension (SME) has been developed in detail [27,28]. Basic issues regarding this theory, including stability and causality [29] and one-loop renormalizability [30] have been addressed. The SME contains coefficients that parameterize possible Lorentz violations. Many of these coefficients are tightly constrained by the various experiments, but many others are not.In this paper, we shall provide some further bounds on an important but relatively poorly constrained sector of the SME. By analyzing data from high-energy astrophysical sources, we can get strong new constraints, the best of which is at the 6 × 10 −20 level. We shall use data on both synchrotron and inverse Compton (IC) emissions; it turns out that these two types of radiation give complementary bounds.Synchrotron radiation has previously been used to bound nonrenormalizable Lorentzviolating parameters [31,32]. The Crab nebula shows evidence of synchrotron emission from electrons with Lorentz factors of γ = (1 − v 2 ) −1/2 ∼ 3 × 10 9 . The presence of electrons with velocities this large can be used to constrain models with deformed dispersion relations. For a nonrenormalizable Lorentz-violating coefficient with a particular sign, the data show that the coefficient must be at least seven orders of magnitude smaller than O(E/M P ) Planck-level suppression. We shall use a similar technique, but concentrating on the more important renormalizable Lorentz-violating operators. We...

Tests of Relativity by Complementary Rotating Michelson-Morley Experiments

“…We determine 14 limits on Lorentz violation parameters of the standard model extension. Compared to the best previous limits that do not use assumptions on the vanishing of Lorentz violation in one sector [8,11,12,21], they are improved by factors between ∼ 3 − 50. Thus, we also confirm the isotropy of the velocity of light without using such assumptions.…”

Spin dependent masses and symmetry

“…The experimental consequences depend on the surviving symmetry group and have been subject to numerous studies, see Refs. [6,7,8,9,10,11,12].…”

Lorentz violation andαdecay

“…Sensitive searches for Lorentz violation have included studies of matter-antimatter asymmetries for trapped charged particles [13,14,15] and bound state systems [16,17], determinations of muon properties [18,19], analyses of the behavior of spin-polarized matter [20,21], frequency standard comparisons [22,23,24,25], Michelson-Morley experiments with cryogenic resonators [26,27,28], Doppler effect measurements [29,30], measurements of neutral mesons [31,32,33,34,35,36], polarization measurements on the light from distant galaxies [37,38,39,40], high-energy astrophysical tests [41,42,43,44] and others. The results of these experiments set bounds on various SME coefficients.…”