Journal of High Energy Physics

, 2016:162 | Cite as

Exclusive radiative Z-boson decays to mesons with flavor-singlet components

  • Stefan Alte
  • Matthias König
  • Matthias NeubertEmail author
Open Access
Regular Article - Theoretical Physics


We present a detailed study of the exclusive radiative decays Zη (′) γ employing the QCD factorization approach. We derive a factorization formula for the decay amplitudes valid at leading power in an expansion in (ΛQCD /m Z )2, which includes convolutions of calculable hard-scattering kernels with the leading-twist quark and gluon light-cone distribution amplitudes of the mesons. Large logarithms arising in the evolution from the high scale m Z down to hadronic scales are resummed using the renormalization group, carefully accounting for the effects of the heavy bottom and charm quarks. Our results for the branching ratios are very sensitive to hadronic input parameters, such as the decay constants and mixing angle characterizing the η − η system. Using the most recent estimates of these parameters, we obtain the branching ratios Br(Zηγ) ∼ 1.6 · 10−10 and Br(Zη γ) ∼ 4.7 · 10−9. A measurement of these processes at a future high-luminosity Z factory could provide interesting information on the gluon distribution amplitude.


Effective field theories Resummation Renormalization Group 


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This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.


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© The Author(s) 2016

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Authors and Affiliations

  • Stefan Alte
    • 1
  • Matthias König
    • 1
  • Matthias Neubert
    • 1
    • 2
    Email author
  1. 1.PRISMA Cluster of Excellence & Mainz Institute for Theoretical PhysicsJohannes Gutenberg UniversityMainzGermany
  2. 2.Department of Physics & LEPPCornell UniversityIthacaU.S.A.

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