# Daya Bay's Sterile Neutrino Results in 2016

### From Daya Bay

## Data Release

1. Daya Bay 621 days sterile neutrino result χ^{2} map: Daya Bay Chi2 Map data . The Gaussian CL_{s} method is used to set the exclusion contour ^{[0]}, and here is a short note on how to use the χ^{2} map to calculate CL_{s} values: Gaussian CLs ReadMe

2. Daya Bay/Bugey-3 and MINOS sterile neutrino combined results data is here: MINOS, Daya Bay + Bugey-3, and the combination CLs surfaces

The results are also shown on the MINOS website

## Daya Bay/Bugey-3 and MINOS Combined Sterile Neutrino Result (October 2016)

Daya Bay/Bugey-3 and MINOS combined 90% CL_{s} limit on sin^{2}2θ_{μ}_{e} compared to the LSND and MiniBooNE 90% CL allowed regions. Regions of parameter space to the right of the red contour are excluded. The regions excluded at 90% CL by the KARMEN2 Collaboration ^{[1]} and the NOMAD Collaboration^{[2]} are also shown. We note that the excursion to small mixing in the exclusion contour at around Δm^{2}_{41} ∼ 5 × 10^{-3} eV^{2} is due to the degenerate island in the MINOS exclusion limit.

The PRL paper describing the details of this joint analysis can be found here: Phys. Rev. Lett. 117, 151801 (2016)

The arXiv paper can be found here: arXiv:1607.01177

The results are also shown in MINOS Official Website

## Daya Bay and Bugey-3 Combined Sterile Neutrino Result (October 2016)

Excluded regions for the original Bugey-3 Raster scan
(RS) result^{[3]}, for the reproduced Bugey-3 result with adjusted
fluxes, for the Daya Bay result^{[4]}, and for the combined Daya
Bay and reproduced Bugey-3 results. The region to the right of
the curve is excluded at the 90% CL_{s}.

The PRL paper describing the details of this joint analysis can be found here: Phys. Rev. Lett. 117, 151801 (2016)

The arXiv paper can be found here: arXiv:1607.01177

The results are also shown in MINOS Official Website

## Reproduced Bugey-3 Result (October 2016)

Comparison of the Bugey-3 90% CL (blue) and the reproduced 90% CL (red)

More information related to Bugey-3 result reproduction can be found here: Presentation: Sterile Neutrino Search at Daya Bay

## Daya Bay Sterile Neutrino Result with 8 anti-neutrino detectors configuration (October 2016)

Exclusion contours in the (sin^{2}2θ_{14}, Δm^{2}_{41}) plane under the assumption of Δm^{2}_{32} > 0 and Δm^{2}_{41} > 0. The red longdashed curve represents the 95% CL exclusion contour with the Feldman-Cousins method^{[5]}. The black solid curve represents the 95% CL_{s} exclusion contour^{[6]}. The expected 95% CL 1 σ band in yellow is centered around the sensitivity curve, shown as a thin blue line. The region of parameter space to the right side of the contours is excluded. For comparison, Bugey-3 90% CL limit^{[3]} is also shown as the green dashed curve.

The PRL paper describing the details of this analysis can be found here: Phys. Rev. Lett. 117, 151802 (2016)

The arXiv paper can be found here: arXiv:1607.01174

## Reference

[0] X. Qian et al. Nucl. Instr. Meth. A, 827 11 (2016).

[1] B. Armbruster et al. (KARMEN Collaboration), Phys. Rev.D 65, 112001 (2002).

[2] P. Astier et al. (NOMAD Collaboration), Phys. Lett. B 570, 19 (2003).

[3] B. Achkar et al., Nucl. Phys. B434, 503 (1995).

[4] F. P. An et al. (Daya Bay Collaboration), Phys. Rev. Lett. 117, 151802 (2016).

[5] G. J. Feldman and R. D. Cousins, Phys. Rev. D 57, 3873 (1998).

[6] A. L. Read, J. Phys. G 28, 2693 (2002).