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Register a new userTests of Lorentz symmetry using antihydrogen
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Authors
Neil Russell
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Signals of CPT and Lorentz violation are possible in the context of spectroscopy using hydrogen and antihydrogen. We apply the Standard-Model Extension, a broad framework for Lorentz breaking in physics, to various transitions in the hydrogen and antihydrogen spectra. The results show an unsuppressed effect in the transition between the upper two hyperfine sublevels of the ground state of these systems. We also discuss related tests in Penning traps, and recent work on Lorentz violation in curved spacetime.
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This article reports on the Fourth Meeting on Lorentz and CPT Symmetry, CPT 07, held in August 2007 in Bloomington, Indiana, USA. The focus is on recent tests of Lorentz symmetry using atomic and optical physics. Results presented at the meeting include improved bounds on Lorentz violation in the photon sector, and the first bounds on several coefficients in the gravity sector.
Interferometric gyroscope systems are being developed with the goal of measuring general-relativistic effects including frame-dragging effects. Such devices are also capable of performing searches for Lorentz violation. We summarize efforts that relate gyroscope measurements to coefficients for Lorentz violation in the gravity sector of the Standard-Model Extension.
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-pion-exchange 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 dimension-five tensors that quantify Lorentz and CPT violation.
Various approaches to physics beyond the Standard Model can lead to small violations of CPT invariance. Since CPT symmetry can be measured with ultrahigh precision, CPT tests offer an interesting phenomenological avenue to search for underlying physics. We discuss this reasoning in more detail, comment on the connection between CPT and Lorentz invariance, and review how CPT breaking would affect the (anti)hydrogen spectrum.
We consider the low-energy effects of a selected set of Lorentz- and CPT-violating quark and gluon operators by deriving the corresponding chiral effective lagrangian. Using this effective lagrangian, low-energy hadronic observables can be calculated. We apply this to magnetometer experiments and derive the best bounds on some of the Lorentz-violating coefficients. We point out that progress can be made by studying the nucleon-nucleon potential, and by considering storage-ring experiments for deuterons and other light nuclei.
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