Parity nonconservation in 19F nuclei

Elsener, K.; Grüebler, W.; König, V.; Schmelzbach, P.A.; Ulbricht, J.; Vuaridel, B.; Singy, D.; Forstner, Ch.; Zhang, W.Z.

doi:10.1016/0375-9474(87)90411-8

Cited by 18 publications

(7 citation statements)

References 17 publications

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“…Alternatively, one could consider a new attempt on A γ ( 19 F), one of two cases where axial charge β decay is available as a nuclear matrix element calibration. One important aspect of this experiment is the success in controlling systematic errors: The analysis of [51] found that systematic errors were negligible, contributing to the overall uncertainty at a level that would have allowed a 10% measurement, had the statistics been available. Thus a repetition of this experiment with a factor of 20 increase in counting could reach the target 10% uncertainty.…”

Section: Testing the Lo Theorymentioning

confidence: 99%

A New Paradigm for Hadronic Parity Nonconservation and Its Experimental Implications

Gardner

Haxton

Holstein

2017

Annu. Rev. Nucl. Part. Sci.

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For decades the primary experimental goal in studies of hadronic parity nonconservation (PNC) has been the isolation of the isovector weak nucleon-nucleon interaction, expected to be dominated by long-range pion exchange and enhanced by the neutral current. In mesonexchange descriptions this interaction together with an isoscalar interaction generated by ρ and ω exchange dominate most observables. Consequently these two amplitudes have been used to compare and check the consistency of the field's experiments. Yet to date, despite sensitive searches like that performed with 18 F, no evidence for isovector hadronic PNC has been found. Here we argue, based on recent large-N c treatments and new global analyses, that the emphasis on isovector hadronic PNC was misplaced. Large-N c provides an alternative and theoretically better motivated simplification of effective field theories (EFTs) of hadronic PNC, separating the five low-energy constants (LECs) into two of leading order (LO), and three others that are N 2 LO. This scheme pivots the isospin coordinates we have traditionally used, placing one dominant axis in the isoscalar plane, and a second along the isotensor direction. We show that this large-N c LEC hierarchy accurately describes all existing data on hadronic PNC. In particular, the null result found in 18 F reflects its dependence on an N 2 LO observable. We discuss opportunities to further test the predicted large-N c hierarchy of LECs, illustrating the kind of analyses experimentalists can use to better constrain the LO theory and to determine the size of N 2 LO corrections. This formalism -combined with a new wave of experiments that will be performed at the SNS cold neutron beam line and the recent demonstration that lattice QCD can now be applied to PNC NN scattering -could lead to rapid progress in the next five years. We discuss the impact of anticipated new results, including NPDGamma and a lattice QCD calculation of isotensor PNC. We also describe future experiments that can yield more precise values of the LO LECs and help isolate the N 2 LO ∼ 10% corrections.

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Section: Testing the Lo Theorymentioning

confidence: 99%

A New Paradigm for Hadronic Parity Nonconservation and Its Experimental Implications

Gardner

Haxton

Holstein

2017

Annu. Rev. Nucl. Part. Sci.

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“…It would be clearly very interesting to take into account also PVTC measurements in medium-mass and heavy-systems. In particular, it is worth to mention that there exist fairly accurate measurements of the gamma angular asymmetry in 19 F gamma decay and the gamma circular polarization in 18 F gamma decay [242][243][244]. The mixing induced by the PVTC interaction in the matrix elements can be calibrated by the corresponding analog β decays of Ne isotopes [242].…”

Section: Discussionmentioning

confidence: 99%

Parity- and Time-Reversal-Violating Nuclear Forces

et al. 2020

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“…, which need to be fixed by measurement. Several measurements from NN system to heavy nuclei were carried out but only some place constraints on HWI [11], which include p+p [12][13][14][15][16][17], p+ 4 He [18,19], P γ ( 18 F) [20][21][22][23], and A γ ( 19 F) [24][25][26]. In heavy nuclei measurements, an asymmetry enhancement is observed but the theory calculations are complicated [5,27].…”

Section: Ppns 2018mentioning

confidence: 99%

Neutron spin rotation measurements

et al. 2019

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The neutron spin rotation (NSR) collaboration used parity-violating spin rotation of transversely polarized neutrons transmitted through a 0.5 m liquid helium target to constrain weak coupling constants between nucleons. While consistent with theoretical expectation, the upper limit set by this measurement on the rotation angle is limited by statistical uncertainties. The NSR collaboration is preparing a new measurement to improve this statistically-limited result by about an order of magnitude. In addition to using the new high-flux NG-C beam at the NIST Center for Neutron Research, the apparatus was upgraded to take advantage of the larger-area and more divergent NG-C beam. Significant improvements are also being made to the cryogenic design. Details of these improvements and readiness of the upgraded apparatus are presented. We also comment on how recent theoretical work combining effective field theory techniques with the 1/Nc expansion of QCD along with previous NN weak measurements can be used to make a prediction for dϕ/dz in 4He. An experiment using the same apparatus with a room-temperature target was carried out at LANSCE to place limits on parity-conserving rotations from possible fifth-force interactions to complement previous studies. We sought this interaction using a slow neutron polarimeter that passed transversely polarized slow neutrons by unpolarized slabs of material arranged so that this interaction would tilt the plane of polarization and develop a component along the neutron momentum. The results of this measurement and its impact on the neutron-matter coupling gA2 from such an interaction are presented. The NSR collaboration is also preparing a new measurement that uses an upgraded version of the room-temperature target to be run on the NG-C beamline; and it is expected to constrain gA2 by at least two additional orders of magnitude for λc between 1 cm and 1 μm.

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Parity nonconservation in 19F nuclei

Cited by 18 publications

References 17 publications

A New Paradigm for Hadronic Parity Nonconservation and Its Experimental Implications

A New Paradigm for Hadronic Parity Nonconservation and Its Experimental Implications

Parity- and Time-Reversal-Violating Nuclear Forces

Neutron spin rotation measurements

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