New CAST limit on the axion–photon interaction

V. Anastassopoulos, S. Aune, K. Barth, A. Belov, H. Bräuninger, G. Cantatore, J. M. Carmona, J. F. Castel, S. A. Cetin, Finn Erland Christensen, J. I. Collar, T. Dafni, M. Davenport, T. A. Decker, A. Dermenev, K. Desch, C. Eleftheriadis, G. Fanourakis, E. Ferrer-Ribas, H. FischerJ. A. García, A. Gardikiotis, J. G. Garza, E. N. Gazis, T. Geralis, I Giomataris, S. Gninenko, C. J. Hailey, M. D. Hasinoff, D H H Hoffmann, F. J. Iguaz, I G Irastorza, A. Jakobsen, J. Jacoby, K Jakovčić, J Kaminski, M. Karuza, N. Kralj, M Krčmar, S. Kostoglou, Ch. Krieger, B Lakić, J. M. Laurent, A. Liolios, A. Ljubicic, G. Luzón, M. Maroudas, L. Miceli, S. Neff, I. Ortega, T Papaevangelou, K. Paraschou, M. J. Pivovaro, G Raffelt, M. Rosu, J Ruz, E. Ruiz Chóliz, I Savvidis, S. Schmidt, Y. K. Semertzidis, S. K. Solanki, L. Stewart, T Vafeiadis, J. K. Vogel, S. C. Yildiz, K Zioutas

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Hypothetical low-mass particles, such as axions, provide a compelling explanation for the dark matter in the universe. Suchparticles are expected to emerge abundantly from the hot interior of stars. To test this prediction, the CERN Axion SolarTelescope (CAST) uses a 9 T refurbished Large Hadron Collider test magnet directed towards the Sun. In the strong magneticfield, solar axions can be converted to X-ray photons which can be recorded by X-ray detectors. In the 2013–2015 run, thanksto low-background detectors and a new X-ray telescope, the signal-to-noise ratio was increased by about a factor of three.Here, we report the best limit on the axion–photon coupling strength (0.66x10-10 GeV-1 at 95% confidence level) set byCAST, which now reaches similar levels to the most restrictive astrophysical bounds.
Original languageEnglish
JournalNature Physics
Pages (from-to)584-591
Publication statusPublished - 2017

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