Marco	Roncaglia -	Politecnico di Torino	#	
Hidden XY structure of the bond-charge Hubbard model 	
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The repulsive one-dimensional Hubbard model with bond-charge interaction 
(HBC) in the superconducting regime is mapped onto the 
spin-1/2 XY model with transverse field, after assuming 
short-ranged antiferromagnetic correlations between electrons. 
We calculate density correlations and phase boundaries, 
realizing an excellent agreement with numerical results. The 
critical line for the superconducting transition is shown to 
coincide with the analytical factorization line identifying 
the commensurate-incommensurate transition in the XY model.