# Cosmic microwave background constraints on secret interactions among sterile neutrinos

## Abstract

Secret contact interactions among eV sterile neutrinos, mediated by a massive gauge boson X (with M {sub X} || M {sub W} ), and characterized by a gauge coupling g {sub X} , have been proposed as a mean to reconcile cosmological observations and short-baseline laboratory anomalies. We constrain this scenario using the latest Planck data on Cosmic Microwave Background anisotropies, and measurements of baryon acoustic oscillations (BAO). We consistently include the effect of secret interactions on cosmological perturbations, namely the increased density and pressure fluctuations in the neutrino fluid, and still find a severe tension between the secret interaction framework and cosmology. In fact, taking into account neutrino scattering via secret interactions, we derive our own mass bound on sterile neutrinos and find (at 95 % CL) m {sub s} < 0.82 eV or m {sub s} < 0.29 eV from Planck alone or in combination with BAO, respectively. These limits confirm the discrepancy with the laboratory anomalies. Moreover, we constrain, in the limit of contact interaction, the effective strength G {sub X} to be < 2.8 (2.0) × 10{sup 10} G {sub F} from Planck (Planck+BAO). This result, together with the mass bound, strongly disfavours the region withmore »

- Authors:

- Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Via Giuseppe Saragat 1, I-44122 Ferrara (Italy)
- Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara, Via Giuseppe Saragat 1, I-44122 Ferrara (Italy)
- Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Complesso Univ. Monte S.Angelo, I-80126 Napoli (Italy)
- Dipartimento Interateneo di Fisica 'Michelangelo Merlin,' Via Amendola 173, 70126 Bari (Italy)
- PRISMA Cluster of Excellence and Mainz Institute for Theoretical Physics, JohannesGutenberg-Universität Mainz, 55099 Mainz (Germany)

- Publication Date:

- OSTI Identifier:
- 22676089

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 07; Other Information: Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; BARYONS; BOSONS; COSMOLOGY; COUPLING; DENSITY; DISTURBANCES; FLUCTUATIONS; FLUIDS; INTERACTIONS; MASS; MATHEMATICAL SOLUTIONS; MEV RANGE; NONLUMINOUS MATTER; OSCILLATIONS; PERTURBATION THEORY; RELICT RADIATION; SCATTERING; STERILE NEUTRINOS

### Citation Formats

```
Forastieri, Francesco, Natoli, Paolo, Lattanzi, Massimiliano, Mangano, Gianpiero, Mirizzi, Alessandro, and Saviano, Ninetta, E-mail: francesco.forastieri@unife.it, E-mail: lattanzi@fe.infn.it, E-mail: mangano@na.infn.it, E-mail: alessandro.mirizzi@ba.infn.it, E-mail: natoli@fe.infn.it, E-mail: nsaviano@uni-mainz.de.
```*Cosmic microwave background constraints on secret interactions among sterile neutrinos*. United States: N. p., 2017.
Web. doi:10.1088/1475-7516/2017/07/038.

```
Forastieri, Francesco, Natoli, Paolo, Lattanzi, Massimiliano, Mangano, Gianpiero, Mirizzi, Alessandro, & Saviano, Ninetta, E-mail: francesco.forastieri@unife.it, E-mail: lattanzi@fe.infn.it, E-mail: mangano@na.infn.it, E-mail: alessandro.mirizzi@ba.infn.it, E-mail: natoli@fe.infn.it, E-mail: nsaviano@uni-mainz.de.
```*Cosmic microwave background constraints on secret interactions among sterile neutrinos*. United States. doi:10.1088/1475-7516/2017/07/038.

```
Forastieri, Francesco, Natoli, Paolo, Lattanzi, Massimiliano, Mangano, Gianpiero, Mirizzi, Alessandro, and Saviano, Ninetta, E-mail: francesco.forastieri@unife.it, E-mail: lattanzi@fe.infn.it, E-mail: mangano@na.infn.it, E-mail: alessandro.mirizzi@ba.infn.it, E-mail: natoli@fe.infn.it, E-mail: nsaviano@uni-mainz.de. Sat .
"Cosmic microwave background constraints on secret interactions among sterile neutrinos". United States.
doi:10.1088/1475-7516/2017/07/038.
```

```
@article{osti_22676089,
```

title = {Cosmic microwave background constraints on secret interactions among sterile neutrinos},

author = {Forastieri, Francesco and Natoli, Paolo and Lattanzi, Massimiliano and Mangano, Gianpiero and Mirizzi, Alessandro and Saviano, Ninetta, E-mail: francesco.forastieri@unife.it, E-mail: lattanzi@fe.infn.it, E-mail: mangano@na.infn.it, E-mail: alessandro.mirizzi@ba.infn.it, E-mail: natoli@fe.infn.it, E-mail: nsaviano@uni-mainz.de},

abstractNote = {Secret contact interactions among eV sterile neutrinos, mediated by a massive gauge boson X (with M {sub X} || M {sub W} ), and characterized by a gauge coupling g {sub X} , have been proposed as a mean to reconcile cosmological observations and short-baseline laboratory anomalies. We constrain this scenario using the latest Planck data on Cosmic Microwave Background anisotropies, and measurements of baryon acoustic oscillations (BAO). We consistently include the effect of secret interactions on cosmological perturbations, namely the increased density and pressure fluctuations in the neutrino fluid, and still find a severe tension between the secret interaction framework and cosmology. In fact, taking into account neutrino scattering via secret interactions, we derive our own mass bound on sterile neutrinos and find (at 95 % CL) m {sub s} < 0.82 eV or m {sub s} < 0.29 eV from Planck alone or in combination with BAO, respectively. These limits confirm the discrepancy with the laboratory anomalies. Moreover, we constrain, in the limit of contact interaction, the effective strength G {sub X} to be < 2.8 (2.0) × 10{sup 10} G {sub F} from Planck (Planck+BAO). This result, together with the mass bound, strongly disfavours the region with M {sub X} ∼ 0.1 MeV and relatively large coupling g {sub X} {sub ∼} 10{sup −1}, previously indicated as a possible solution to the small scale dark matter problem.},

doi = {10.1088/1475-7516/2017/07/038},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 07,

volume = 2017,

place = {United States},

year = {Sat Jul 01 00:00:00 EDT 2017},

month = {Sat Jul 01 00:00:00 EDT 2017}

}