The electroweak interaction in the Standard Model (SM) is described by a pure vector-axial-vector structure, though any Lorentz-invariant component could contribute. In this work, we present the most precise measurement of tensor currents in the low-energy regime by examining the $\beta$-$\bar{ \nu}$ correlation of trapped $^{ 8}$Li ions with the Beta-decay Paul Trap. We find $a_{ \beta\nu} = -0.3325 \pm 0.0013_{ stat} \pm 0.0019_{ syst}$ at $1\sigma$ for the case of coupling to right-handed neutrinos $(C_T=-C_T')$, which is consistent with the SM prediction.
Categories: nucl-ex hep-ph nucl-th