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
SN - 0370-2693
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
ER -