Extending the Higgs sector: an extra singlet S I. Godunov, A. N. Rozanov, M. I. Vysotsky and E. V. Zhemchugov Eur. Phys. J. C, 76 1 (2016) 1 Published online: 02 January 2016 DOI: 10.1140/epjc/s10052-015-3826-6