Heavy-to-light form factors: Sum rules on the light cone and beyond

Journal Article · Tue May 01 04:00:00 EDT 2007 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.75.096002· OSTI ID:21020515

Lucha, Wolfgang ^[1]; Melikhov, Dmitri ^[1]; Simula, Silvano ^[2]

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1. Institute for High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, A-1050, Vienna (Austria)
2. INFN, Sezione di Roma III, Via della Vasca Navale 84, I-00146, Rome (Italy)

We report the first systematic analysis of the off-light-cone effects in sum rules for heavy-to-light form factors. These effects are investigated in a model based on scalar constituents, which allows a technically rather simple analysis but has the essential features of the analogous QCD calculation. The correlator relevant for the extraction of the heavy-to-light form factor is calculated in two different ways: first, by adopting the full Bethe-Salpeter amplitude of the light meson and, second, by performing the expansion of this amplitude near the light cone x{sup 2}=0. We demonstrate that the contributions to the correlator from the light-cone term x{sup 2}=0 and the off-light-cone terms x{sup 2}{ne}0 have the same order in the 1/m{sub Q} expansion. The light-cone correlator, corresponding to x{sup 2}=0, is shown to systematically overestimate the full correlator, the difference being {approx}{lambda}{sub QCD}/{delta}, with {delta} the continuum subtraction parameter of order 1 GeV. Numerically, this difference is found to be 10 divide 20%.

• OSTI ID: 21020515
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 9 Vol. 75; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AMPLITUDES
BETHE-SALPETER EQUATION
FORM FACTORS
GEV RANGE
LIGHT CONE
MESONS
QUANTUM CHROMODYNAMICS
SUM RULES