Neutrino and axion bounds from the globular cluster M5 (NGC 5904).
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.
Instituto 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.
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Viaux
Instituto 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.
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Catelan
National Research Council, 5071 West Saanich Road, Victoria, British Columbia V9E 2E7, Canada.
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Stetson
Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München, Germany.
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Raffelt
Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München, Germany and Arnold Sommerfeld Center, Ludwig-Maximilians-University, Theresienstrasse 37, 80333 München, Germany.
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Redondo
Departamento de Física, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
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Valcarce
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, 85748 Garching, Germany.
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Weiss