The Similarity Renormalization Group
Abstract
Quantum field theories require a cutoff to regulate divergences that result from local interactions, and yet physical results can not depend on the value of this cutoff. The renormalization group employs a transformation that changes the cutoff to isolate hamiltonians that produce cutoffindependent eigenvalues. The similarity renormalization group is based on similarity transformations that regulate offdiagonal matrix elements, forcing the hamiltonian towards a banddiagonal form as the cutoff is lowered. This avoids pathologies that plagued tradition transformations acting on hamiltonians, making it possible to produce a wellbehaved perturbative approximation of renormalized hamiltonians in asymptotically free theories. We employ a simple twodimensional delta function example to illustrate this new renormalization technique.
 Publication:

arXiv eprints
 Pub Date:
 September 2000
 arXiv:
 arXiv:hepph/0009071
 Bibcode:
 2000hep.ph....9071S
 Keywords:

 High Energy Physics  Phenomenology;
 High Energy Physics  Theory;
 Nuclear Theory
 EPrint:
 28 pages, 7 postscript figures