Fernández Pérez, Luis AntonioMuñoz Sudupe, AntonioRuiz Lorenzo, J. J.2023-06-202023-06-201994-11-010556-282110.1103/PhysRevD.50.5935https://hdl.handle.net/20.500.14352/60108© 1994 American Physical Society. We acknowledge CICyT for partial financial support with the projects AEN93-0604, AEN93-0776, and AEN94-218. One of us (J.J.R.L.) thanks the MEC (Spain) for a grant.We propose a new real space renormalization group transformation useful for Monte Carlo calculations in theories with global or local symmetries. From relaxation arguments we de6ne the block-spin transformation with two tunable free parameters, adapted to the system's action. Varying them it is possible to place the Sxed point very close to the simulation point. We show how the method works in a simple model with global symmetry: the three dimensional XY model.engjournal articlehttp://doi.org/10.1103/PhysRevD.50.5935http://journals.aps.orgopen access5351-73Gauge-theorySu(3)Física (Física)Física-Modelos matemáticos22 Física