Editing Beta decay (section)

===Gamow–Teller transitions===
A '''Gamow–Teller transition''' is a beta decay in which the spins of the emitted electron (positron) and anti-neutrino (neutrino) couple to total spin <math>S=1</math>, leading to an angular momentum change <math>\Delta J=0,\pm 1</math> between the initial and final states of the nucleus (assuming an allowed transition).
In this case, the nuclear part of the operator is given by
<math display="block"> \mathcal{O}_{GT}=G_{A}\sum_{a} \hat{\sigma}_{a}\hat{\tau}_{a\pm} </math>
with <math>G_{A}</math> the weak axial-vector coupling constant, and <math>\sigma</math> the [[Pauli matrices|spin Pauli matrices]], which can produce a spin-flip in the decaying nucleon.