Tests of Lorentz andCPTsymmetry with hadrons and nuclei

Abstract

We explore the breaking of Lorentz and CPT invariance in strong interactions at low energy in the framework of chiral perturbation theory. Starting from the set of Lorentz-violating operators of mass-dimension five with quark and gluon fields, we construct the effective chiral Lagrangian with hadronic and electromagnetic interactions induced by these operators. We develop the power-counting scheme and discuss loop diagrams and the one-pionexchange nucleon-nucleon potential. The effective chiral Lagrangian is the basis for calculations of low-energy observables with hadronic degrees of freedom. As examples, we consider clock-comparison experiments with nuclei and spin-precession experiments with nucleons in storage rings. We derive strict limits on the dimensionfive tensors that quantify Lorentz and CPT violation.

Testing Lorentz Symmetry Using Chiral Perturbation Theory

“…Subleading effects of C and H on atomic energy levels, as well as their effect on spin-precession, can be found in Ref. 5.…”

“…However, despite the lack of kinetic nucleon terms, the D coefficient does contribute to one-pion exchange between nucleons. 5 In future work it might therefore be possible to improve the bounds on D by considering the LV nucleon-nucleon (NN) potential. Studies of the NN potential and its applications to deuterons and other light nuclei have been performed successfully in the context of chiral EFT with discrete-symmetry violations other than CPTV (see Ref.…”

“…In Ref. 5, we calculated the contribution of D to the electromagnetic form factor of the nucleon, through pion loops. Experimental effects of this are suppressed with a factor of 10 −15 with respect to effects of C and H, due to small electromagnetic fields.…”

“…5 we constructed the effective lagrangian in the SO(4) formalism of χPT. The form of the effective operators is severely constrained by the transformation properties of the operators in Eq.…”

Meson-baryon scattering to one-loop order in heavy baryon chiral perturbation theory

“…Although relativistic approaches (such as infrared regularization [5] and the extended on-mass-shell scheme [6,7]) have made substantial progress in many aspects [8,9,10,11,12,13], HBχPT is still a reasonable and powerful tool for the study of meson-baryon scattering processes. Dark matter interactions with mesons or nucleons [14,15] and the breaking of Lorentz and CPT symmetry [16] can also be investigated in HBχPT.…”