Convergence of derivative expansions of the renormalization group
Author(s) -
Tim R. Morris,
John F. Tighe
Publication year - 1999
Publication title -
journal of high energy physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.998
H-Index - 261
eISSN - 1126-6708
pISSN - 1029-8479
DOI - 10.1088/1126-6708/1999/08/007
Subject(s) - cutoff , mathematics , renormalization group , mathematical analysis , radius of convergence , exponential function , momentum (technical analysis) , mathematical physics , scalar (mathematics) , derivative (finance) , convergence (economics) , asymptotic expansion , physics , quantum mechanics , power series , geometry , finance , economics , financial economics , economic growth
We investigate the convergence of the derivative expansion of the exactrenormalization group, by using it to compute the beta function of scalar fieldtheory. We show that the derivative expansion of the Polchinski flow equationconverges at one loop for certain fast falling smooth cutoffs. The derivativeexpansion of the Legendre flow equation trivially converges at one loop, butalso at two loops: slowly with sharp cutoff (as a momentum-scale expansion),and rapidly in the case of a smooth exponential cutoff. Finally, we show thatthe two loop contributions to certain higher derivative operators (not involvedin beta) have divergent momentum-scale expansions for sharp cutoff, but thesmooth exponential cutoff gives convergent derivative expansions for all suchoperators with any number of derivatives.Comment: Latex inc axodraw. 20 page
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