Speaker
Description
Ulrich Schmidt on behalf of the aSPECT collaboration
The aSPECT collaboration published in 2020 the most precise value on the electron-antineutrino correlation coefficient $a=-0.10407(82)$ of neutron $\beta$-decay. The value of this correlation coefficient $a$ is directly linked to the $\lambda$ parameter of the Weak Interaction of the Standard Model. The value for $\lambda$ obtained in this way is in tension with the most precise determination of $\lambda$ via the measurement of the neutron spin verus electron momentum correlation $A$, measured by Perkeo III. Meanwhile we revised some systematic errors and reanalysed our data including parameters from physics beyond the Standard Model like the Fierz interference term $b$. We will present the status of our reanalysis and discuss out result in the context of today most precise result on $b$ from neutron $\beta$-decay published by the Perkeo III collaboration.
