Tests ofCPTand Lorentz symmetry from muon anomalous magnetic dipole moment

Abstract

We derive the relativistic factor for splitting of the g-factors of a fermion and its anti-fermion partner, which is important for placing constraints on dimension-5, CP T -odd and Lorentz-invarianceviolating interactions from experiments performed in a cyclotron. From existing data, we extract limits (1σ) on the coupling strengths of the temporal component, f 0 , of a background field (including the field amplitude), which is responsible for such g-factor splitting, with an electron, proton, and muon: |f 0 e | < 2.3 × 10 −12 µB, |f 0 p | < 4 × 10 −9 µB, and |f 0 µ | < 8 × 10 −11 µB, respectively, in the laboratory frame. From existing data, we also extract limits on the coupling strengths of the spatial components, d⊥ , of related dimension-5 interactions of a background field with an electron, proton, neutron, and muon: |d ⊥ e | 10 −9 µB, |d ⊥ p | 10 −9 µB, |d ⊥ n | 10 −10 µB, and |d ⊥ µ | 10 −9 µB, respectively, in the laboratory frame.

A parts-per-billion measurement of the antiproton magnetic moment

“…28 . Furthermore, our measurement enables us to derive new limits on a possible magnetic moment splitting for protons/antiprotons f p 0 , which has been discussed in a recent analysis of CPT-odd physics based on dimension-five interactions 11 . Using 95% confidence limit on the g-factor difference of the value presented here, we obtain:…”

ConstrainingCPT-even and Lorentz-violating nonminimal couplings with the electron magnetic and electric dipole moments

“…The relation of these LV terms with anomalous magnetic moment (MDM) were considered in Ref. [5], which developed an analysis involving the splitting of the g factors of a fermion and antifermion to constrain some of them. These CP T -odd terms constitute nonminimal couplings between fermions and photons.…”

Laboratory tests of Lorentz andCPTsymmetry with muons

“…The effects of minimal-SME coefficients on the behavior of muons [9] have been studied at impressive sensitivities in the laboratory via muonium hyperfine spectroscopy [10] and via measurements of the anomalous magnetic moments of the muon and antimuon [11,12]. The latter have also been used to place limits on nonminimal interaction terms with d ¼ 5 [13], while minimal-SME interactions have been studied in the context of muon decay [14]. A few constraints from astrophysical processes have been obtained as well, both for minimal-SME coefficients [15] and for isotropic nonminimal operators with d ¼ 5, 6 [16,17].…”