https://doi.org/10.1140/epjc/s10052-018-6281-3
Regular Article - Theoretical Physics
One-loop effective LFV 
vertex from heavy neutrinos within the mass insertion approximation
1
Departamento de Física Teórica and Instituto de Física Teórica, IFT-UAM/CSIC, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
2
Laboratoire de Physique Théorique, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405, Orsay, France
3
IFLP, CONICET - Dpto. de Física, Universidad Nacional de La Plata, C.C. 67, 1900, La Plata, Argentina
* e-mail: roberto.morales@fisica.unlp.edu.ar
Received:
13
July
2018
Accepted:
22
September
2018
Published online:
10
October
2018
In this paper we study the effective lepton flavor violating vertex of an electroweak Z gauge boson and two charged leptons with different flavor, 
and 
, that is generated to one-loop in low scale seesaw models with right handed neutrinos whose masses are heavier than the electroweak scale. We first compute the form factor describing this vertex by using the mass insertion approximation, where the flavor non-diagonal entries of the neutrino Yukawa coupling matrix are the unique origin, to one-loop level, of lepton flavor changing processes with charged leptons in the external legs. Then, by considering the proper large right handed neutrino mass expansion of the form factor, we derive a formula for the 
effective vertex which is very simple and useful for fast phenomenological estimates. In the last part of this work we focus on the phenomenological applications of this vertex for simple and accurate estimates of the 
decay rates. Concretely, this vertex will allow us to conclude easily on the maximum allowed decay rates by present data in the inverse seesaw model. The found rates are promising, at the reach of future lepton colliders.
© The Author(s), 2018
