Atomic Parity Nonconservation and Nuclear Anapole Moments

Abstract

Anapole moments are parity-odd, time-reversal-even moments of the E1 projection of the electromagnetic current. Although it was recognized, soon after the discovery of parity violation in the weak interaction, that elementary particles and composite systems like nuclei must have anapole moments, it proved difficult to isolate this weak radiative correction. The first successful measurement, an extraction of the nuclear anapole moment of 133 Cs from the hyperfine dependence of the atomic parity violation, was obtained only recently. An important anapole moment bound in Tl also exists. We discuss these measurements and their significance as tests of the hadronic weak interaction, focusing on the mechanisms that operate within the nucleus to generate the anapole moment. The atomic results place new constraints on weak meson-nucleon couplings, ones we compare to existing bounds from a variety of p − p and nuclear tests of parity nonconservation.

Parity-violating asymmetry in the reactions 6Li $(n,\alpha)$ 3H and 10B $(n,\alpha)^{7}$ Li* $\rightarrow$ 7Li $+$ $\gamma$

“…The objective of decades-long studies was to measure the weak meson-nucleon coupling constant; thus, one would link the meson-exchange mechanism with underlying physics. The field is overviewed in [4][5][6]. The observation of parity violation in proton-proton scattering is a manifestation of the charged weak current [7,8]; the isoscalar couplings h 0 ρ , h 0 ω agree with the DDH "best values".…”

Just a Taste: Lectures on Flavor Physics

“…Look up references on 'atomic parity violation.' See, for example, [92,93] for reviews. The main point is that part of the Z coupling is axial, which means its coupling is proportional to a fermion's helicity.…”

Preliminary studies for anapole moment measurements in rubidium and francium

“…8 in Ref. [21] that shows the constraints obtained from different experiments. This figure complements the one that appears in the review of Behr and Gwinner [1] as it adds the rubidium numbers to the constraints obtained from the anapole moment measurement in Cs considering only the experimental uncertainty [3,27] and the calculations for Fr.…”