# Halo-independent direct detection analyses without mass assumptions

## Abstract

Results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the m{sub χ}−σ{sub n} plane. Recently methods which are independent of the DM halo velocity distribution have been developed which present results in the v{sub min}− g-tilde plane, but these in turn require an assumption on the dark matter mass. Here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. With a change of variables from v{sub min} to nuclear recoil momentum (p{sub R}), the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call h-tilde (p{sub R}). The entire family of conventional halo-independent g-tilde (v{sub min}) plots for all DM masses are directly found from the single h-tilde (p{sub R}) plot through a simple rescaling of axes. By considering results in h-tilde (p{sub R}) space, one can determine if two experiments are inconsistent for all masses and all physically possible halos, or for what range of dark matter masses themore »

- Authors:

- Laboratory for Nuclear Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Building 26-505, Cambridge, MA 02139 (United States)
- Theoretical Physics Department, MS 106, Fermilab, PO Box 500, Batavia, IL 60510-0500 (United States)
- Center for Theoretical Physics and Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 (United States)
- Theory Division, CERN, 1211 Geneva 23 (Switzerland)

- Publication Date:

- OSTI Identifier:
- 22525290

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Cosmology and Astroparticle Physics

- Additional Journal Information:
- Journal Volume: 2015; Journal Issue: 10; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; DETECTION; MASS; NONLUMINOUS MATTER; RECOILS; SPACE; VELOCITY

### Citation Formats

```
Anderson, Adam J., Fox, Patrick J., Kahn, Yonatan, and McCullough, Matthew, E-mail: adama@mit.edu, E-mail: pjfox@fnal.gov, E-mail: ykahn@mit.edu, E-mail: matthew.mccullough@cern.ch.
```*Halo-independent direct detection analyses without mass assumptions*. United States: N. p., 2015.
Web. doi:10.1088/1475-7516/2015/10/012.

```
Anderson, Adam J., Fox, Patrick J., Kahn, Yonatan, & McCullough, Matthew, E-mail: adama@mit.edu, E-mail: pjfox@fnal.gov, E-mail: ykahn@mit.edu, E-mail: matthew.mccullough@cern.ch.
```*Halo-independent direct detection analyses without mass assumptions*. United States. doi:10.1088/1475-7516/2015/10/012.

```
Anderson, Adam J., Fox, Patrick J., Kahn, Yonatan, and McCullough, Matthew, E-mail: adama@mit.edu, E-mail: pjfox@fnal.gov, E-mail: ykahn@mit.edu, E-mail: matthew.mccullough@cern.ch. Thu .
"Halo-independent direct detection analyses without mass assumptions". United States. doi:10.1088/1475-7516/2015/10/012.
```

```
@article{osti_22525290,
```

title = {Halo-independent direct detection analyses without mass assumptions},

author = {Anderson, Adam J. and Fox, Patrick J. and Kahn, Yonatan and McCullough, Matthew, E-mail: adama@mit.edu, E-mail: pjfox@fnal.gov, E-mail: ykahn@mit.edu, E-mail: matthew.mccullough@cern.ch},

abstractNote = {Results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the m{sub χ}−σ{sub n} plane. Recently methods which are independent of the DM halo velocity distribution have been developed which present results in the v{sub min}− g-tilde plane, but these in turn require an assumption on the dark matter mass. Here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. With a change of variables from v{sub min} to nuclear recoil momentum (p{sub R}), the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call h-tilde (p{sub R}). The entire family of conventional halo-independent g-tilde (v{sub min}) plots for all DM masses are directly found from the single h-tilde (p{sub R}) plot through a simple rescaling of axes. By considering results in h-tilde (p{sub R}) space, one can determine if two experiments are inconsistent for all masses and all physically possible halos, or for what range of dark matter masses the results are inconsistent for all halos, without the necessity of multiple g-tilde (v{sub min}) plots for different DM masses. We conduct a sample analysis comparing the CDMS II Si events to the null results from LUX, XENON10, and SuperCDMS using our method and discuss how the results can be strengthened by imposing the physically reasonable requirement of a finite halo escape velocity.},

doi = {10.1088/1475-7516/2015/10/012},

journal = {Journal of Cosmology and Astroparticle Physics},

issn = {1475-7516},

number = 10,

volume = 2015,

place = {United States},

year = {2015},

month = {10}

}