Branch Point Twist Field Form Factors in the sine-Gordon Model II: Composite Twist Fields and Symmetry Resolved Entanglement

In this paper we continue the program initiated in Part I, that is study of entanglement measures sine-Gordon model. both parts, have focussed on one specific technique, well-known connection between branch point twist field correlators and 1+1D integrable quantum theory. Our papers apply technique for first time to a non-diagonal theory with an involved particle spectrum, II focus different measure, symmetry resolved entanglement, develop its associated description, exploiting underlying U(1) context, conventional fields are no longer required, but instead must work their composite generalisations, which can be understood as resulting from fusion standard exponential symmetry. The has usual admit form factor expansion. write equations solve them various examples breather sector by using method angular quantisation. We show that, attractive regime, provides leading contribution entropies, R\'enyi von Neumann. compute latter limit large region size they satisfy property equipartition, independent sector.