Disentangling running coupling and conformal effects in QCD
(2001) In Physical Review D - Particles, Fields, Gravitation and Cosmology 63(9).- Abstract
We investigate the relation between a postulated skeleton expansion and the conformal limit of QCD. We begin by developing some consequences of an Abelian-like skeleton expansion, which allows one to disentangle running-coupling effects from the remaining skeleton coefficients. The latter are by construction renormalon free, and hence hopefully better behaved. We consider a simple ansatz for the expansion, where an observable is written as a sum of integrals over the running coupling. We show that in this framework one can set a unique Brodsky-Lepage-Mackenzie (BLM) scale-setting procedure as an approximation to the running-coupling integrals, where the BLM coefficients coincide with the skeleton ones. Alternatively, the... (More)
We investigate the relation between a postulated skeleton expansion and the conformal limit of QCD. We begin by developing some consequences of an Abelian-like skeleton expansion, which allows one to disentangle running-coupling effects from the remaining skeleton coefficients. The latter are by construction renormalon free, and hence hopefully better behaved. We consider a simple ansatz for the expansion, where an observable is written as a sum of integrals over the running coupling. We show that in this framework one can set a unique Brodsky-Lepage-Mackenzie (BLM) scale-setting procedure as an approximation to the running-coupling integrals, where the BLM coefficients coincide with the skeleton ones. Alternatively, the running-coupling integrals can be approximated using the effective charge method. We discuss the limitations in disentangling running coupling effects in the absence of a diagrammatic construction of the skeleton expansion. Independently of the assumed skeleton structure we show that BLM coefficients coincide with conformal coefficients defined in the small (Formula presented) (Banks-Zaks) limit where a perturbative infrared fixed point is present. This interpretation of the BLM coefficients should explain their previously observed simplicity and smallness. Numerical examples are critically discussed.
(Less)
- author
- Brodsky, S. J. ; Gardi, E. ; Grunberg, G. and Rathsman, J. LU
- publishing date
- 2001-01-01
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Physical Review D - Particles, Fields, Gravitation and Cosmology
- volume
- 63
- issue
- 9
- article number
- 094017
- publisher
- American Physical Society
- external identifiers
-
- scopus:0034895558
- scopus:85038310282
- ISSN
- 1550-7998
- DOI
- 10.1103/PhysRevD.63.094017
- language
- English
- LU publication?
- no
- id
- 10e32e97-f3ec-4472-9e80-78ad916ffbc4
- date added to LUP
- 2019-05-14 13:47:21
- date last changed
- 2024-03-19 07:16:51
@article{10e32e97-f3ec-4472-9e80-78ad916ffbc4,
abstract = {{<p>We investigate the relation between a postulated skeleton expansion and the conformal limit of QCD. We begin by developing some consequences of an Abelian-like skeleton expansion, which allows one to disentangle running-coupling effects from the remaining skeleton coefficients. The latter are by construction renormalon free, and hence hopefully better behaved. We consider a simple ansatz for the expansion, where an observable is written as a sum of integrals over the running coupling. We show that in this framework one can set a unique Brodsky-Lepage-Mackenzie (BLM) scale-setting procedure as an approximation to the running-coupling integrals, where the BLM coefficients coincide with the skeleton ones. Alternatively, the running-coupling integrals can be approximated using the effective charge method. We discuss the limitations in disentangling running coupling effects in the absence of a diagrammatic construction of the skeleton expansion. Independently of the assumed skeleton structure we show that BLM coefficients coincide with conformal coefficients defined in the small (Formula presented) (Banks-Zaks) limit where a perturbative infrared fixed point is present. This interpretation of the BLM coefficients should explain their previously observed simplicity and smallness. Numerical examples are critically discussed.</p>}},
author = {{Brodsky, S. J. and Gardi, E. and Grunberg, G. and Rathsman, J.}},
issn = {{1550-7998}},
language = {{eng}},
month = {{01}},
number = {{9}},
publisher = {{American Physical Society}},
series = {{Physical Review D - Particles, Fields, Gravitation and Cosmology}},
title = {{Disentangling running coupling and conformal effects in QCD}},
url = {{http://dx.doi.org/10.1103/PhysRevD.63.094017}},
doi = {{10.1103/PhysRevD.63.094017}},
volume = {{63}},
year = {{2001}},
}