Magnons in Sr${}_2$CuO${}_3$: possible evidence for Goldstone-Higgs interaction in a weakly ordered spin-1/2 chain antiferromagnet

E. G. Sergeicheva, S. S. Sosin, L. A. Prozorova +2

The Goldstone theorem mandates that a spontaneous symmetry breaking entails the emergence of gap(mass)less excitations. In the case where a rotational invariance of a system of spi…