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

Y. Kiyo, G. Mishima, Y. Sumino

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)184-189
Number of pages6
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Publication statusPublished - 2016 Oct 10

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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