PT Journal
AU Aristizabal Sierra, D
   Degee, A
   Dorame, L
   Hirsch, M
TI Systematic classification of two-loop realizations of the Weinberg operator
SO Journal of High Energy Physics
JI J. High Energy Phys.
PY 2015
BP 040
EP 41pp
VL 03
IS 3
DI 10.1007/JHEP03(2015)040
LA English
DE Beyond Standard Model; Neutrino Physics
AB We systematically analyze the d = 5 Weinberg operator at 2-loop order. Using a diagrammatic approach, we identify two different interesting categories of neutrino mass models: (i) Genuine 2-loop models for which both, tree-level and 1-loop contributions, are guaranteed to be absent. And (ii) finite 2-loop diagrams, which correspond to the 1-loop generation of some particular vertex appearing in a given 1-loop neutrino mass model, thus being effectively 2-loop. From the large list of all possible 2-loop diagrams, the vast majority are infinite corrections to lower order neutrino mass models and only a moderately small number of diagrams fall into these two interesting classes. Moreover, all diagrams in class (i) are just variations of three basic diagrams, with examples discussed in the literature before. Similarly, we also show that class (ii) diagrams consists of only variations of these three plus two more basic diagrams. Finally, we show how our results can be consistently and readily used in order to construct two-loop neutrino mass models.
ER