Guralnik, G.S.; Hagen, C.R.; Kibble, T.W.B.; Global Conservation Laws and Massless Particles
Phys. Rev. Lett. 13 (1964) 585;
... In summary then, we have established that it may be possible consistently to break a symmetry by requiring that the vacuum expectation value of a field operator be nonvanishing without generating zero-mass particles. If the theory lacks manifest covariance it may happen that what should be the generator of the theory fail to be time-independent, despite the existence of a local conservation law. Thus the absence of massless bosons is a consequence of the inapplicability of Goldstone's theorem
rather than a contradiction of it. Preliminary investigations indicate that superconductivity displays an analogous behavior. (Extracted from introductory part of the paper.).
Related references See also J. Goldstone, Nuovo Cim. 19 (1961) 154;
J. Goldstone, A. Salam, and S. Weinberg, Phys. Rev. 127 (1962) 965;
S. A. Bludman and A. Klein, Phys. Rev. 131 (1963) 2364;
D. G. Boulware and W. Gilbert, Phys. Rev. 126 (1962) 1563;
P. W. Higgs, Phys. Lett. 12 (1964) 132;
B. Zumino, Phys. Lett. 10 (1964) 224;
F. Englert and R. Brout, Phys. Rev. Lett. 13 (1964) 321;
W. Gilbert, Phys. Rev. Lett. 12 (1964) 713;
Example of a field theory with spontaneous symmetry breakdown, no massless goldstone boson, and massive vector bosons.