In the standard model, the weak interaction is formulated with a purely vector-axial-vector (V-A) structure. Without restriction on the chirality of the neutrino, the most general limits on tensor currents from nuclear β decay are dominated by a single measurement of the β-ν¯ correlation in He6 β decay dating back over a half century. In the present work, the β-ν¯-α correlation in the β decay of Li8 and subsequent α-particle breakup of the Be8∗ daughter was measured. The results are consistent with a purely V-A interaction and in the case of couplings to right-handed neutrinos (CT=-CT′) limits the tensor fraction to |CT/CA|2<0.011 (95.5% C.L.). The measurement confirms the He6 result using a different nuclear system and employing modern ion-trapping techniques subject to different systematic uncertainties.
Publication Source (Journal or Book title)
Physical Review Letters
Sternberg, M., Segel, R., Scielzo, N., Savard, G., Clark, J., Bertone, P., Buchinger, F., Burkey, M., Caldwell, S., Chaudhuri, A., Crawford, J., Deibel, C., Greene, J., Gulick, S., Lascar, D., Levand, A., Li, G., Pérez Galván, A., Sharma, K., Van Schelt, J., Yee, R., & Zabransky, B. (2015). Limit on Tensor Currents from Li 8 β Decay. Physical Review Letters, 115 (18) https://doi.org/10.1103/PhysRevLett.115.182501