# Extended maximum likelihood halo-independent analysis of dark matter direct detection data

## Abstract

We extend and correct a recently proposed maximum-likelihood halo-independent method to analyze unbinned direct dark matter detection data. Instead of the recoil energy as independent variable we use the minimum speed a dark matter particle must have to impart a given recoil energy to a nucleus. This has the advantage of allowing us to apply the method to any type of target composition and interaction, e.g. with general momentum and velocity dependence, and with elastic or inelastic scattering. We prove the method and provide a rigorous statistical interpretation of the results. As first applications, we find that for dark matter particles with elastic spin-independent interactions and neutron to proton coupling ratio f{sub n}/f{sub p}=−0.7, the WIMP interpretation of the signal observed by CDMS-II-Si is compatible with the constraints imposed by all other experiments with null results. We also find a similar compatibility for exothermic inelastic spin-independent interactions with f{sub n}/f{sub p}=−0.8.

- Authors:

- Department of Physics and Astronomy, UCLA,475 Portola Plaza, Los Angeles, CA, 90095 (United States)
- Department of Physics and Astronomy, University of Utah,115 South 1400 East #201, Salt Lake City, UT, 84112 (United States)

- Publication Date:

- Sponsoring Org.:
- SCOAP3, CERN, Geneva (Switzerland)

- OSTI Identifier:
- 22458405

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2015; Journal Issue: 11; Other Information: PUBLISHER-ID: JCAP11(2015)038; OAI: oai:repo.scoap3.org:12773; Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; DETECTION; ELEMENTARY PARTICLES; INELASTIC SCATTERING; MAXIMUM-LIKELIHOOD FIT; NEUTRONS; NONLUMINOUS MATTER; NUCLEI; PROTONS; RECOILS; SI SEMICONDUCTOR DETECTORS; SIGNALS; SPIN; VELOCITY

### Citation Formats

```
Gelmini, Graciela B., Georgescu, Andreea, Gondolo, Paolo, and Huh, Ji-Haeng.
```*Extended maximum likelihood halo-independent analysis of dark matter direct detection data*. United States: N. p., 2015.
Web. doi:10.1088/1475-7516/2015/11/038.

```
Gelmini, Graciela B., Georgescu, Andreea, Gondolo, Paolo, & Huh, Ji-Haeng.
```*Extended maximum likelihood halo-independent analysis of dark matter direct detection data*. United States. doi:10.1088/1475-7516/2015/11/038.

```
Gelmini, Graciela B., Georgescu, Andreea, Gondolo, Paolo, and Huh, Ji-Haeng. Tue .
"Extended maximum likelihood halo-independent analysis of dark matter direct detection data". United States.
doi:10.1088/1475-7516/2015/11/038.
```

```
@article{osti_22458405,
```

title = {Extended maximum likelihood halo-independent analysis of dark matter direct detection data},

author = {Gelmini, Graciela B. and Georgescu, Andreea and Gondolo, Paolo and Huh, Ji-Haeng},

abstractNote = {We extend and correct a recently proposed maximum-likelihood halo-independent method to analyze unbinned direct dark matter detection data. Instead of the recoil energy as independent variable we use the minimum speed a dark matter particle must have to impart a given recoil energy to a nucleus. This has the advantage of allowing us to apply the method to any type of target composition and interaction, e.g. with general momentum and velocity dependence, and with elastic or inelastic scattering. We prove the method and provide a rigorous statistical interpretation of the results. As first applications, we find that for dark matter particles with elastic spin-independent interactions and neutron to proton coupling ratio f{sub n}/f{sub p}=−0.7, the WIMP interpretation of the signal observed by CDMS-II-Si is compatible with the constraints imposed by all other experiments with null results. We also find a similar compatibility for exothermic inelastic spin-independent interactions with f{sub n}/f{sub p}=−0.8.},

doi = {10.1088/1475-7516/2015/11/038},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 11,

volume = 2015,

place = {United States},

year = {Tue Nov 24 00:00:00 EST 2015},

month = {Tue Nov 24 00:00:00 EST 2015}

}