The double radiative annihilation of the heavy-light fermion bound states

Scientific paper - Original scientific paper

• Author: Jan O. Eeg
• Author: Krešimir Kumerički
• Author: Ivica Picek
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

We consider the double-radiative decays of heavy-light QED and QCD atoms, μ^+ e^- → γγ and [ B]^0_s → γγ. Especially, we take under scrutiny contributions coming from operators that vanish on the free-quark mass shell. We show that by field redefinitions, these operators are converted into contact terms attached to the bound state dynamics. A net off-shell contribution is suppressed with respect to the effect of the well known flavour-changing magnetic-moment operator by the bound-state binding factor. The negligible off-shellness of the weakly-bound QED atoms becomes more relevant for strongly bound QCD atoms. We analyse this off-shellness in model-approaches to QCD, one of them enabling us to keep close contact to the related effect in QED. We also comment on the off-shell effect in the corresponding process [ B]d → K^* γ, and discuss possible hindering of the claimed beyond-standard-model discovery in this decay mode.

• Keywords (english): bound state; off-shellness; flavour-changing transition; rare decays
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review
• Publication version: Published version
• Journal title: Fizika B
• Numbering: vol. 10, no. 1, pp. 285-306
• p-ISSN: 1330-0016
• URN:NBN: urn:nbn:hr:217:424525
• Publication: 2001
• Document URL: http://fizika.hfd.hr/fizika_b/bv01/b10p285.htm
• Type of resource: Text
• Access conditions: Open access
• Created on: 2019-10-11 13:56:16