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

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dc.creatorLucha, Wolfgang
dc.creatorMelikhov, Dmitri
dc.creatorSimula, Silvano
dc.date2007-02-01
dc.date2007-04-12
dc.date.accessioned2026-07-07T11:02:40Z
dc.date.available2026-07-07T11:02:40Z
dc.descriptionWe 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 $x^2=0$. We demonstrate that the contributions to the correlator from the light-cone term $x^2=0$ and the off-light-cone terms $x^2\ne 0$ have the same order in the $1/m_Q$ expansion. The light-cone correlator, corresponding to $x^2=0$, is shown to systematically overestimate the full correlator, the difference being $\sim Λ_{\rm QCD}/δ$, with $δ$ the continuum subtraction parameter of order 1 GeV. Numerically, this difference is found to be 10-20%.
dc.descriptionrevtex 14 pages, version to be published in Phys. Rev. D (discussion in Sect. 3 extended, example in Sect. 4 added)
dc.identifierhttps://arxiv.org/abs/hep-ph/0702009
dc.identifierhttp://arxiv.org/abs/hep-ph/0702009
dc.identifierPhys.Rev.D75:096002,2007
dc.identifierdoi:10.1103/PhysRevD.75.096002
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/188326
dc.subjectHigh Energy Physics - Phenomenology
dc.titleHeavy-to-light form factors: sum rules on the light cone and beyond
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