Searching for Tensor Currents in the Weak Interaction Using Lithium-8 $\beta$ Decay

Nuclear physics remains a powerful tool to search for unobserved phenomena by probing the limits of the Standard Model. The electroweak interaction is well-predicted by a pure vector-axial vector structure. However, high-precision measurements of the beta-neutrino correlation coefficient, a$_{\beta\nu}$ in beta decay have long been used as a test for New Physics because of the term's sensitivity to tensor and scalar currents. The beta decay of $^8$Li is an ideal reaction for probing a$_{\beta\nu}$ due to its high Q-value and delayed alpha emission of the daughter nucleus. By measuring the kinematics of stopped $^8$Li ions in a Paul Trap surrounded with silicon strip detectors backed with plastic scintillators and comparing to simulation, we can set a limit on tensor contributions from a$_{\beta\nu}$. This work represents the analysis of a high-statistics $^8$Li dataset obtained in 2016 to extract a value of a$_{\beta\nu}$. The results indicated a value of $a_{\beta\nu}=-0.3346 \pm -0.0011_{stat} \pm 0.0024_{sys}$ at 1$\sigma$ uncertainty, which is consistent with the Standard Model and is the most stringent tensor current limit yet achieved in the low energy regime.