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Updated: May 3, 2026

Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
Neutrino and axion bounds from the globular cluster M5 (NGC 5904)
N Viaux1, M Catelan1, P B Stetson2
1Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile and Centro de Astroingeniería, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackena 4860, 782-0436 Macul, Santiago, Chile and The Milky Way Millennium Nucleus, Avenida Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile.
Abstract:
The red-giant branch (RGB) in globular clusters is extended to larger brightness if the degenerate helium core loses too much energy in "dark channels." Based on a large set of archival observations, we provide high-precision photometry for the Galactic globular cluster M5 (NGC 5904), allowing for a detailed comparison between the observed tip of the RGB with predictions based on contemporary stellar evolution theory. In particular, we derive 95% confidence limits of g(ae)<4.3×10(-13) on the axion-electron coupling and μ(ν)<4.5×10(-12)μ(B) (Bohr magneton μ(B)=e/2m(e)) on a neutrino dipole moment, based on a detailed analysis of statistical and systematic uncertainties. The cluster distance is the single largest source of uncertainty and can be improved in the future.
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