On enhanced corrections from quasi-degenerate states to heavy quarkonium observables

It is well known that in perturbation theory existence of quasi-degenerate states can rearrange the order counting. For a heavy quarkonium system, naively, enhanced effects (l-changing mixing effects) could contribute already to the first-order and third-order corrections to the wave function and th...

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Main Authors: Y. Kiyo, G. Mishima, Y. Sumino
Format: Article
Language:English
Published: Elsevier 2016-10-01
Series:Physics Letters B
Online Access:http://www.sciencedirect.com/science/article/pii/S0370269316304464
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author Y. Kiyo
G. Mishima
Y. Sumino
author_facet Y. Kiyo
G. Mishima
Y. Sumino
author_sort Y. Kiyo
collection DOAJ
description It is well known that in perturbation theory existence of quasi-degenerate states can rearrange the order counting. For a heavy quarkonium system, naively, enhanced effects (l-changing mixing effects) could contribute already to the first-order and third-order corrections to the wave function and the energy level, respectively, in expansion in αs. We present a formulation and note that the corresponding (lowest-order) corrections vanish due to absence of the relevant off-diagonal matrix elements. As a result, in the quarkonium energy level and leptonic decay width, the enhanced effects are expected to appear, respectively, in the fifth- and fourth-order corrections and beyond.
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spelling doaj.art-d6a06ad0ea9f4f49a9e82d3cb942702b2022-12-21T19:28:33ZengElsevierPhysics Letters B0370-26931873-24452016-10-01761C18418910.1016/j.physletb.2016.08.026On enhanced corrections from quasi-degenerate states to heavy quarkonium observablesY. Kiyo0G. Mishima1Y. Sumino2Department of Physics, Juntendo University, Inzai, Chiba 270-1695, JapanDepartment of Physics, Tohoku University, Sendai, 980-8578, JapanDepartment of Physics, Tohoku University, Sendai, 980-8578, JapanIt is well known that in perturbation theory existence of quasi-degenerate states can rearrange the order counting. For a heavy quarkonium system, naively, enhanced effects (l-changing mixing effects) could contribute already to the first-order and third-order corrections to the wave function and the energy level, respectively, in expansion in αs. We present a formulation and note that the corresponding (lowest-order) corrections vanish due to absence of the relevant off-diagonal matrix elements. As a result, in the quarkonium energy level and leptonic decay width, the enhanced effects are expected to appear, respectively, in the fifth- and fourth-order corrections and beyond.http://www.sciencedirect.com/science/article/pii/S0370269316304464
spellingShingle Y. Kiyo
G. Mishima
Y. Sumino
On enhanced corrections from quasi-degenerate states to heavy quarkonium observables
Physics Letters B
title On enhanced corrections from quasi-degenerate states to heavy quarkonium observables
title_full On enhanced corrections from quasi-degenerate states to heavy quarkonium observables
title_fullStr On enhanced corrections from quasi-degenerate states to heavy quarkonium observables
title_full_unstemmed On enhanced corrections from quasi-degenerate states to heavy quarkonium observables
title_short On enhanced corrections from quasi-degenerate states to heavy quarkonium observables
title_sort on enhanced corrections from quasi degenerate states to heavy quarkonium observables
url http://www.sciencedirect.com/science/article/pii/S0370269316304464
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