Low-energy theorem revisited and OPE in massless QCD

Abstract We revisit a low-energy theorem (LET) of NSVZ type in SU(N) QCD with N f massless quarks derived in [1] by implementing it in dimensional regularization. The LET relates n-point correlators in the l.h.s. to n + 1-point correlators with the extra insertion of TrF 2 at zero momentum in the r....

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Main Authors: Marco Bochicchio, Elisabetta Pallante
Format: Article
Language:English
Published: SpringerOpen 2024-08-01
Series:Journal of High Energy Physics
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Online Access:https://doi.org/10.1007/JHEP08(2024)145
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author Marco Bochicchio
Elisabetta Pallante
author_facet Marco Bochicchio
Elisabetta Pallante
author_sort Marco Bochicchio
collection DOAJ
description Abstract We revisit a low-energy theorem (LET) of NSVZ type in SU(N) QCD with N f massless quarks derived in [1] by implementing it in dimensional regularization. The LET relates n-point correlators in the l.h.s. to n + 1-point correlators with the extra insertion of TrF 2 at zero momentum in the r.h.s. We demonstrate that, for 2-point correlators of an operator O in the l.h.s., the LET implies that, in general, the integrated 3-point correlator in the r.h.s. needs in perturbation theory an infinite additive renormalization in addition to the multiplicative one. We relate the above counterterm to a corresponding divergent contact term in a certain coefficient of the OPE of TrF 2 with O in the momentum representation, thus extending to any operator O an independent argument that first appeared for O = TrF 2 in [2]. Finally, we demonstrate that in the asymptotically free phase of QCD the aforementioned counterterm in the LET is actually finite nonperturbatively after resummation to all perturbative orders. We also briefly recall the implications of the LET in the gauge-invariant framework of dimensional regularization for the perturbative and nonperturbative renormalization in large-N QCD. The implications of the LET inside and above the conformal window of SU(N) QCD with N f massless quarks will appear in a forthcoming paper.
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spelling doaj-art-e2735822055f43f5b448cfa2892aac7f2024-11-24T12:04:55ZengSpringerOpenJournal of High Energy Physics1029-84792024-08-012024816510.1007/JHEP08(2024)145Low-energy theorem revisited and OPE in massless QCDMarco Bochicchio0Elisabetta Pallante1Physics Department, INFN Roma1Van Swinderen Institute for Particle Physics and Gravity, University of GroningenAbstract We revisit a low-energy theorem (LET) of NSVZ type in SU(N) QCD with N f massless quarks derived in [1] by implementing it in dimensional regularization. The LET relates n-point correlators in the l.h.s. to n + 1-point correlators with the extra insertion of TrF 2 at zero momentum in the r.h.s. We demonstrate that, for 2-point correlators of an operator O in the l.h.s., the LET implies that, in general, the integrated 3-point correlator in the r.h.s. needs in perturbation theory an infinite additive renormalization in addition to the multiplicative one. We relate the above counterterm to a corresponding divergent contact term in a certain coefficient of the OPE of TrF 2 with O in the momentum representation, thus extending to any operator O an independent argument that first appeared for O = TrF 2 in [2]. Finally, we demonstrate that in the asymptotically free phase of QCD the aforementioned counterterm in the LET is actually finite nonperturbatively after resummation to all perturbative orders. We also briefly recall the implications of the LET in the gauge-invariant framework of dimensional regularization for the perturbative and nonperturbative renormalization in large-N QCD. The implications of the LET inside and above the conformal window of SU(N) QCD with N f massless quarks will appear in a forthcoming paper.https://doi.org/10.1007/JHEP08(2024)145Renormalization and RegularizationRenormalization Group
spellingShingle Marco Bochicchio
Elisabetta Pallante
Low-energy theorem revisited and OPE in massless QCD
Journal of High Energy Physics
Renormalization and Regularization
Renormalization Group
title Low-energy theorem revisited and OPE in massless QCD
title_full Low-energy theorem revisited and OPE in massless QCD
title_fullStr Low-energy theorem revisited and OPE in massless QCD
title_full_unstemmed Low-energy theorem revisited and OPE in massless QCD
title_short Low-energy theorem revisited and OPE in massless QCD
title_sort low energy theorem revisited and ope in massless qcd
topic Renormalization and Regularization
Renormalization Group
url https://doi.org/10.1007/JHEP08(2024)145
work_keys_str_mv AT marcobochicchio lowenergytheoremrevisitedandopeinmasslessqcd
AT elisabettapallante lowenergytheoremrevisitedandopeinmasslessqcd