# COST Workshop on Higgs and Flavour Physics: Present and Future

Jan 14 – 17, 2019
IST, Lisboa, Portugal
Europe/Lisbon timezone

## Seesaw type I with Sizeable Deviations from 3x3 Unitarity

Jan 15, 2019, 6:10 PM
20m
Anfiteatro Abreu Faro (IST, Lisboa, Portugal)

### Anfiteatro Abreu Faro

#### IST, Lisboa, Portugal

Av Rovisco Pais 1049-001 Lisboa Portugal

Pedro Pereira

### Description

A minimal extension to the Standard Model with three positive chirality neutrinos is devised, under the Seesaw Type I framework. A novel parametrization is exploited, which enables to control all deviations from unitarity through a single $3 \times 3$ matrix, which is denoted by $X$, that also connects the mixing of the light and heavy neutrinos in the context of type I seesaw. This parametrization is adequate for a general and exact treatment, independent of the scale of the right handed neutrino mass term. Examples with sizeable deviations from unitarity and heavy neutrinos with not very large masses are presented. The problem of possibly large one-loop mass corrections to the light neutrino masses is taken into account.

### Presentation materials

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