Eur. Phys. J. C (2016) 76: 258
https://doi.org/10.1140/epjc/s10052-016-4076-y

Regular Article - Theoretical Physics

in the 2HDM: an exercise in EFT

¹ IPNL, CNRS/IN2P3, 4 rue E. Fermi, 69622, Villeurbanne Cedex, France
² Université Lyon 1, Villeurbanne, France
³ Université de Lyon, 69622, Lyon, France

^* e-mail: s.davidson@ipnl.in2p3.fr

Received: 23 January 2016
Accepted: 8 April 2016
Published online: 6 May 2016

Abstract

The 2 Higgs Doublet Model of type III has renormalisable Lepton Flavour-Violating couplings, and its one- and two-loop (“Barr–Zee”) contributions to are known. In the decoupling limit, where the mass scale M of the second doublet is much greater than the electroweak scale, the model can be parametrised with an Effective Field Theory (EFT) containing dimension-six operators. The terms of the exact calculation are reproduced in the EFT, provided that the four-fermion operator basis below the weak scale is enlarged with respect to the SU(2)-invariant Buchmuller–Wyler list. It is found that the dominant two-loop “Barr–Zee” contributions arise mostly in two-loop matching and running, and that dimension-eight operators might be numerically relevant.