Experimental Test of Parity Conservation in Beta Decay

Wu, Chenye; Ambler, E.; Hoppes, D.D.; Hayward, R.W.; Hudson, R. P.

doi:10.1103/physrev.105.1413

Cited by 1,899 publications

(1,031 citation statements)

References 2 publications

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“…It has been over half a century since Lee and Yang first suggested the possibility of parity non-conservation in the weak interaction [45], which was confirmed expermentially shortly thereafter by Wu et al [46][47][48][49][50]. Modern day experimental [51][52][53][54][55][56][57][58][59][60] and theoretical [61][62][63][64][65] studies have given attention to parity violating two-nucleon processes, where the strong interactions are most precisely understood.…”

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confidence: 99%

Relativistic, model-independent, multichannel 2→2 transition amplitudes in a finite volume

2016

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We derive formalism for determining 2 + J → 2 infinite-volume transition amplitudes from finitevolume matrix elements. Specifically, we present a relativistic, model-independent relation between finite-volume matrix elements of external currents and the physically observable infinite-volume matrix elements involving two-particle asymptotic states. The result presented holds for states composed of two scalar bosons. These can be identical or non-identical and, in the latter case, can be either degenerate or non-degenerate. We further accommodate any number of strongly-coupled two-scalar channels. This formalism will, for example, allow future lattice QCD calculations of the ρ-meson form factor, in which the unstable nature of the ρ is rigorously accommodated.

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confidence: 99%

Relativistic, model-independent, multichannel 2→2 transition amplitudes in a finite volume

2016

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“…It is an ideal system for studying parity violating β-decay of spin-polarized protons. Parity violation was first suggested by Lee and Yang [16], and subsequently discovered in 1957 by Wu et al [17], in the beta decay of polarized 60 Co. Today, parity violation is encompassed by the standard model (V-A) interaction between leptons and quarks. Nonetheless, the nature of these helicity couplings is derived from empirical measurements and the standard model offers no fundamental understanding of the origin of these symmetries and how they become broken at the energy scales probed by modern experiments.…”

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confidence: 99%

Trapping radioactiveRb82in an optical dipole trap and evidence of spontaneous spin polarization

et al. 2007

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Optical trapping of selected species of radioactive atoms has great potential in precision measurements for testing fundamental physics such as EDM, PNC and parity violating β-decay asymmetry correlation coefficients. We report trapping of 10 4 radioactive 82 Rb atoms (t 1/2 = 75 s) with a trap lifetime of ∼55 seconds in an optical dipole trap. Transfer efficiency from the magneto-optical trap was ∼14%. We further report the evidence of spontaneous spin polarization of the atoms in optical dipole trap loading. This advancement is an important step towards a new generation of precision J − β correlations measurements with polarized 82 Rb atoms.Recent advancements in atom trapping have resulted in exciting breakthroughs in atomic, molecular and optical physics, with the realization of diverse phenomena such as Bose-Einstein condensation [1,2,3,4], FermiDegenerate gases [5] and fermion superfluidity [6], as well as ultracold plasmas [7,8] and atomic clocks.The technique of trapping ultracold atoms also has great potential for precision measurements because it can provide an ideal sample in a well controlled environment. There are several attempts and ongoing efforts in β-recoil measurements on 38m K (t 1/2 = 0.9 s) [9] and 21 Na (t 1/2 = 21 s) [10] in a magneto-optical trap (MOT), β-spin correlation of 82 Rb in a time-orbiting potential(TOP) trap [11], Fr PNC [12,13] and Ra EDM [14,15]. Yet no group has demonstrated the trapping of short lived radioisotopes in an optical dipole trap, largely due to small number of atoms in the primary MOT and poor transfer efficiency from the MOT to the dipole trap.Radioactive atoms confined in a far-off-resonance dipole trap (FORT) have many intrinsic advantages for fundamental symmetry experiments, providing a highly polarized, point-like sample with minimal perturbation from the environment which can be well characterized. It is an ideal system for studying parity violating β-decay of spin-polarized protons. Parity violation was first suggested by Lee and Yang [16], and subsequently discovered in 1957 by Wu et al. [17], in the beta decay of polarized 60 Co. Today, parity violation is encompassed by the standard model (V-A) interaction between leptons and quarks. Nonetheless, the nature of these helicity couplings is derived from empirical measurements and the standard model offers no fundamental understanding of the origin of these symmetries and how they become broken at the energy scales probed by modern experiments. Low energy physics experiments that exploit nuclear beta decay continue to offer a means to probe the fundamental origin of parity violation and, more generally, the helicity structure of the weak interaction [18]. With advantages * Electronic address: xxz@lanl.gov

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“…In this work we report on the first calculation directly from QCD of the leading-order momentum-independent parity violating coupling between pions and nucleons, h 1 πN N , using n f = 2 + 1 lattice QCD calculations on configurations with a pion mass of m π ∼ 389 MeV. Parity violating interactions have been known since the late 1950s [1][2][3], and their discovery radically changed perceptions of the role of fundamental symmetries in particle physics. While these interactions can be studied in flavor-changing decays, the effects of the PV neutralcurrent in such decays are tiny as the tree-level coupling between quarks and the Z boson are flavor diagonal and radiative corrections are suppressed by the GIM mechanism [4,5].…”

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confidence: 99%

Lattice QCD calculation of nuclear parity violation

Wasem

2012

Phys. Rev. C

117

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We present the first lattice QCD calculation of the leading-order momentum-independent parity violating coupling between pions and nucleons, h 1 πNN . The calculation performs measurements on dynamical anisotropic clover gauge configurations, with a spatial extent of L ∼ 2.5 fm, a spatial lattice spacing of as ∼ 0.123 fm, and a pion mass of mπ ∼ 389 MeV. While this first calculation does not include non-perturbative renormalization of the bare parity-violating operators, a chiral extrapolation to the physical pion mass, or contributions from disconnected (quark-loop) diagrams, these are expected to result in systematic errors within the quoted statistical error. We find a contribution from the 'connected' diagrams of h 1,con πNN = (1.099 ± 0.505 +0.058 −0.064 ) × 10 −7 , consistent with current experimental bounds and previous model-dependent theoretical predictions.

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Experimental Test of Parity Conservation in Beta Decay

Cited by 1,899 publications

References 2 publications

Relativistic, model-independent, multichannel 2→2 transition amplitudes in a finite volume

Relativistic, model-independent, multichannel 2→2 transition amplitudes in a finite volume

Trapping radioactiveRb82in an optical dipole trap and evidence of spontaneous spin polarization

Lattice QCD calculation of nuclear parity violation

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