Determining the leading-order contact term in neutrinoless double $\mathbf{\beta }$ decay

Vincenzo Cirigliano, Wouter Dekens, Jordy de Vries +2

We present a method to determine the leading-order (LO) contact term contributing to the $nn\to pp{e}^{-}{e}^{-}$ amplitude through the exchange of light Majorana neutrinos. Our approach…