TY - JOUR

T1 - On enhanced corrections from quasi-degenerate states to heavy quarkonium observables

AU - Kiyo, Y.

AU - Mishima, G.

AU - Sumino, Y.

N1 - Funding Information:
The authors are grateful to Jorge Segovia for bringing their attention to the corrections from quasi-degenerate states. The works of Y.K. and Y.S., respectively, were supported in part by Grant-in-Aid for scientific research Nos. 26400255 and 26400238 from MEXT , Japan.
Publisher Copyright:
© 2016 The Author(s)

PY - 2016/10/10

Y1 - 2016/10/10

N2 - 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.

AB - 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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U2 - 10.1016/j.physletb.2016.08.026

DO - 10.1016/j.physletb.2016.08.026

M3 - Article

AN - SCOPUS:84983542173

VL - 761

SP - 184

EP - 189

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

SN - 0370-2693

ER -