# Strong thermal leptogenesis and the absolute neutrino mass scale

## Abstract

We show that successful strong thermal leptogenesis, where the final asymmetry is independent of the initial conditions and in particular a large pre-existing asymmetry is efficiently washed-out, favours values of the lightest neutrino mass m{sub 1}∼>10 meV for normal ordering (NO) and m{sub 1}∼>3 meV for inverted ordering (IO) for models with orthogonal matrix entries respecting |Ω{sub ij}{sup 2}|∼<2. We show analytically why lower values of m{sub 1} require a higher level of fine tuning in the seesaw formula and/or in the flavoured decay parameters (in the electronic for NO, in the muonic for IO). We also show how this constraint exists thanks to the measured values of the neutrino mixing angles and could be tightened by a future determination of the Dirac phase. Our analysis also allows us to place a more stringent constraint for a specific model or class of models, such as SO(10)-inspired models, and shows that some models cannot realise strong thermal leptogenesis for any value of m{sub 1}. A scatter plot analysis fully supports the analytical results. We also briefly discuss the interplay with absolute neutrino mass scale experiments concluding that they will be able in the coming years to either corner strong thermal leptogenesis or findmore »

- Authors:

- School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom)

- Publication Date:

- OSTI Identifier:
- 22370602

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 03; Other Information: Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; FLAVOR MODEL; MASS; MEV RANGE; NEUTRINO OSCILLATION; NEUTRINOS; PARTICLE PRODUCTION; SIGNALS; TUNING; WEINBERG ANGLE

### Citation Formats

```
Bari, Pasquale Di, King, Sophie E., and Fiorentin, Michele Re, E-mail: pdb1d08@soton.ac.uk, E-mail: sk1806@soton.ac.uk, E-mail: m.re-fiorentin@soton.ac.uk.
```*Strong thermal leptogenesis and the absolute neutrino mass scale*. United States: N. p., 2014.
Web. doi:10.1088/1475-7516/2014/03/050.

```
Bari, Pasquale Di, King, Sophie E., & Fiorentin, Michele Re, E-mail: pdb1d08@soton.ac.uk, E-mail: sk1806@soton.ac.uk, E-mail: m.re-fiorentin@soton.ac.uk.
```*Strong thermal leptogenesis and the absolute neutrino mass scale*. United States. doi:10.1088/1475-7516/2014/03/050.

```
Bari, Pasquale Di, King, Sophie E., and Fiorentin, Michele Re, E-mail: pdb1d08@soton.ac.uk, E-mail: sk1806@soton.ac.uk, E-mail: m.re-fiorentin@soton.ac.uk. Sat .
"Strong thermal leptogenesis and the absolute neutrino mass scale". United States. doi:10.1088/1475-7516/2014/03/050.
```

```
@article{osti_22370602,
```

title = {Strong thermal leptogenesis and the absolute neutrino mass scale},

author = {Bari, Pasquale Di and King, Sophie E. and Fiorentin, Michele Re, E-mail: pdb1d08@soton.ac.uk, E-mail: sk1806@soton.ac.uk, E-mail: m.re-fiorentin@soton.ac.uk},

abstractNote = {We show that successful strong thermal leptogenesis, where the final asymmetry is independent of the initial conditions and in particular a large pre-existing asymmetry is efficiently washed-out, favours values of the lightest neutrino mass m{sub 1}∼>10 meV for normal ordering (NO) and m{sub 1}∼>3 meV for inverted ordering (IO) for models with orthogonal matrix entries respecting |Ω{sub ij}{sup 2}|∼<2. We show analytically why lower values of m{sub 1} require a higher level of fine tuning in the seesaw formula and/or in the flavoured decay parameters (in the electronic for NO, in the muonic for IO). We also show how this constraint exists thanks to the measured values of the neutrino mixing angles and could be tightened by a future determination of the Dirac phase. Our analysis also allows us to place a more stringent constraint for a specific model or class of models, such as SO(10)-inspired models, and shows that some models cannot realise strong thermal leptogenesis for any value of m{sub 1}. A scatter plot analysis fully supports the analytical results. We also briefly discuss the interplay with absolute neutrino mass scale experiments concluding that they will be able in the coming years to either corner strong thermal leptogenesis or find positive signals pointing to a non-vanishing m{sub 1}. Since the constraint is much stronger for NO than for IO, it is very important that new data from planned neutrino oscillation experiments will be able to solve the ambiguity.},

doi = {10.1088/1475-7516/2014/03/050},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 03,

volume = 2014,

place = {United States},

year = {Sat Mar 01 00:00:00 EST 2014},

month = {Sat Mar 01 00:00:00 EST 2014}

}