https://doi.org/10.1140/epjc/s10052-014-2860-0
Regular Article - Theoretical Physics
Different approaches to calculate the 
decay width
Joint Institute for Nuclear Research, Dubna, Russia
* e-mail: gevs@jinr.ru
Received:
12
March
2014
Accepted:
9
April
2014
Published online:
20
May
2014
The rare 
decay, currently under analysis by the NA62 Collaboration, is considered. We have followed two theoretical approaches to calculate the differential decay width—in the kaon rest frame, where we use Cabibbo–Maksymowicz variables, and in the center-of-mass system of the lepton pair. The latter essentially simplifies the computations. A comparison between the two approaches has been performed. We have also found the dependencies of the differential decay rate as a function of the virtual photon and dipion system masses.
© SIF and Springer-Verlag Berlin Heidelberg, 2014
