<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi mathvariant="double-struck">Z</mml:mi><mml:mi>n</mml:mi></mml:msub></mml:math> modified XY and Goldstone models and vortex confinement transition
Physical review. D/Physical review. D.