The linear–non-linear frontier for the Goldstone Higgs M. B. Gavela, K. Kanshin, P. A. N. Machado and S. Saa Eur. Phys. J. C, 76 12 (2016) 690 Published online: 17 December 2016 DOI: 10.1140/epjc/s10052-016-4541-7