# Lepton-number violation and right-handed neutrinos in Higgsless effective theories

## Abstract

Following previous work, we identify a symmetry S{sub nat} that generalizes the concept of custodial symmetry, keeping under control deviations from the standard model (SM). To realize S{sub nat} linearly, the space of gauge fields has to be extended. Covariant constraints formulated in terms of spurions reduce S{sub nat} back to SU(2){sub L}xU(1){sub Y}. This allows for a covariant introduction of explicit S{sub nat}-breaking parameters. We assume that S{sub nat} is at play in a theory of electroweak symmetry-breaking without a light Higgs particle. We describe some consequences of this assumption, using a nondecoupling effective theory in which the loop expansion procedure is based on both momentum and spurion power-counting, as in chiral perturbation theory. A hierarchy of lepton-number violating effects follows. Leading corrections to the SM are nonoblique. The effective theory includes stable light right-handed neutrinos, with an unbroken Z{sub 2} symmetry forbidding neutrino Dirac masses. {nu}{sub R} contribution to dark matter places bounds on their masses.

- Authors:

- IFIC, Departament de Fisica Teorica, CSIC - Universitat de Valencia, Edifici d'Instituts de Paterna, Apt. Correus 22085, 46071 Valencia (Spain)
- Groupe Physique Theorique, Unite mixte de recherche 8608 du CNRS, IPN Orsay, Universite Paris-Sud XI, 91406 Orsay (France)

- Publication Date:

- OSTI Identifier:
- 20776905

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Physical Review. D, Particles Fields; Journal Volume: 73; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevD.73.056001; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CHIRAL SYMMETRY; CHIRALITY; CORRECTIONS; HIGGS BOSONS; HIGGS MODEL; LEPTON NUMBER; NEUTRINOS; NONLUMINOUS MATTER; PERTURBATION THEORY; REST MASS; SPURIONS; STANDARD MODEL; SU-2 GROUPS; SYMMETRY BREAKING; U-1 GROUPS; UNITARY SYMMETRY

### Citation Formats

```
Hirn, Johannes, and Stern, Jan.
```*Lepton-number violation and right-handed neutrinos in Higgsless effective theories*. United States: N. p., 2006.
Web. doi:10.1103/PhysRevD.73.056001.

```
Hirn, Johannes, & Stern, Jan.
```*Lepton-number violation and right-handed neutrinos in Higgsless effective theories*. United States. doi:10.1103/PhysRevD.73.056001.

```
Hirn, Johannes, and Stern, Jan. Wed .
"Lepton-number violation and right-handed neutrinos in Higgsless effective theories". United States.
doi:10.1103/PhysRevD.73.056001.
```

```
@article{osti_20776905,
```

title = {Lepton-number violation and right-handed neutrinos in Higgsless effective theories},

author = {Hirn, Johannes and Stern, Jan},

abstractNote = {Following previous work, we identify a symmetry S{sub nat} that generalizes the concept of custodial symmetry, keeping under control deviations from the standard model (SM). To realize S{sub nat} linearly, the space of gauge fields has to be extended. Covariant constraints formulated in terms of spurions reduce S{sub nat} back to SU(2){sub L}xU(1){sub Y}. This allows for a covariant introduction of explicit S{sub nat}-breaking parameters. We assume that S{sub nat} is at play in a theory of electroweak symmetry-breaking without a light Higgs particle. We describe some consequences of this assumption, using a nondecoupling effective theory in which the loop expansion procedure is based on both momentum and spurion power-counting, as in chiral perturbation theory. A hierarchy of lepton-number violating effects follows. Leading corrections to the SM are nonoblique. The effective theory includes stable light right-handed neutrinos, with an unbroken Z{sub 2} symmetry forbidding neutrino Dirac masses. {nu}{sub R} contribution to dark matter places bounds on their masses.},

doi = {10.1103/PhysRevD.73.056001},

journal = {Physical Review. D, Particles Fields},

number = 5,

volume = 73,

place = {United States},

year = {Wed Mar 01 00:00:00 EST 2006},

month = {Wed Mar 01 00:00:00 EST 2006}

}