# Forecasting neutrino masses from combining KATRIN and the CMB observations: Frequentist and Bayesian analyses

## Abstract

We present a showcase for deriving bounds on the neutrino masses from laboratory experiments and cosmological observations. We compare the frequentist and Bayesian bounds on the effective electron neutrino mass m{sub {beta}} which the KATRIN neutrino mass experiment is expected to obtain, using both an analytical likelihood function and Monte Carlo simulations of KATRIN. Assuming a uniform prior in m{sub {beta}}, we find that a null result yields an upper bound of about 0.17 eV at 90% confidence in the Bayesian analysis, to be compared with the frequentist KATRIN reference value of 0.20 eV. This is a significant difference when judged relative to the systematic and statistical uncertainties of the experiment. On the other hand, an input m{sub {beta}}=0.35 eV, which is the KATRIN 5{sigma} detection threshold, would be detected at virtually the same level. Finally, we combine the simulated KATRIN results with cosmological data in the form of present (post-WMAP) and future (simulated Planck) observations. If an input of m{sub {beta}}=0.2 eV is assumed in our simulations, KATRIN alone excludes a zero neutrino mass at 2.2{sigma}. Adding Planck data increases the probability of detection to a median 2.7{sigma}. The analysis highlights the importance of combining cosmological and laboratory datamore »

- Authors:

- Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)
- (United Kingdom)
- (Germany)

- Publication Date:

- OSTI Identifier:
- 21023910

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Physical Review. D, Particles Fields; Journal Volume: 76; Journal Issue: 11; Other Information: DOI: 10.1103/PhysRevD.76.113005; (c) 2007 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; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; COSMOLOGY; ELECTRON NEUTRINOS; EV RANGE; MONTE CARLO METHOD; NEUTRINO DETECTION; NEUTRINO REACTIONS; PROBABILITY; REST MASS

### Citation Formats

```
Host, Ole, Lahav, Ofer, Abdalla, Filipe B., Eitel, Klaus, Department of Physics and Astronomy, University College London, Gower St., London WC1E 6BT, and Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, 76021 Karlsruhe.
```*Forecasting neutrino masses from combining KATRIN and the CMB observations: Frequentist and Bayesian analyses*. United States: N. p., 2007.
Web. doi:10.1103/PHYSREVD.76.113005.

```
Host, Ole, Lahav, Ofer, Abdalla, Filipe B., Eitel, Klaus, Department of Physics and Astronomy, University College London, Gower St., London WC1E 6BT, & Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, 76021 Karlsruhe.
```*Forecasting neutrino masses from combining KATRIN and the CMB observations: Frequentist and Bayesian analyses*. United States. doi:10.1103/PHYSREVD.76.113005.

```
Host, Ole, Lahav, Ofer, Abdalla, Filipe B., Eitel, Klaus, Department of Physics and Astronomy, University College London, Gower St., London WC1E 6BT, and Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, 76021 Karlsruhe. Sat .
"Forecasting neutrino masses from combining KATRIN and the CMB observations: Frequentist and Bayesian analyses". United States. doi:10.1103/PHYSREVD.76.113005.
```

```
@article{osti_21023910,
```

title = {Forecasting neutrino masses from combining KATRIN and the CMB observations: Frequentist and Bayesian analyses},

author = {Host, Ole and Lahav, Ofer and Abdalla, Filipe B. and Eitel, Klaus and Department of Physics and Astronomy, University College London, Gower St., London WC1E 6BT and Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, 76021 Karlsruhe},

abstractNote = {We present a showcase for deriving bounds on the neutrino masses from laboratory experiments and cosmological observations. We compare the frequentist and Bayesian bounds on the effective electron neutrino mass m{sub {beta}} which the KATRIN neutrino mass experiment is expected to obtain, using both an analytical likelihood function and Monte Carlo simulations of KATRIN. Assuming a uniform prior in m{sub {beta}}, we find that a null result yields an upper bound of about 0.17 eV at 90% confidence in the Bayesian analysis, to be compared with the frequentist KATRIN reference value of 0.20 eV. This is a significant difference when judged relative to the systematic and statistical uncertainties of the experiment. On the other hand, an input m{sub {beta}}=0.35 eV, which is the KATRIN 5{sigma} detection threshold, would be detected at virtually the same level. Finally, we combine the simulated KATRIN results with cosmological data in the form of present (post-WMAP) and future (simulated Planck) observations. If an input of m{sub {beta}}=0.2 eV is assumed in our simulations, KATRIN alone excludes a zero neutrino mass at 2.2{sigma}. Adding Planck data increases the probability of detection to a median 2.7{sigma}. The analysis highlights the importance of combining cosmological and laboratory data on an equal footing.},

doi = {10.1103/PHYSREVD.76.113005},

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

number = 11,

volume = 76,

place = {United States},

year = {Sat Dec 01 00:00:00 EST 2007},

month = {Sat Dec 01 00:00:00 EST 2007}

}