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Typical working day..

Roman Pasechnik

Senior lecturer

Typical working day..

The γγ → ηc(1S,2S) transition form factors for two spacelike photons


  • Izabela Babiarz
  • Victor P. Goncalves
  • Roman Pasechnik
  • Wolfgang Schäfer
  • Antoni Szczurek

Summary, in English

We discuss γγ → ηc(1S), ηc(2S) transition form factors for both virtual photons. The general formula is given. We use different models for the cc¯ wave function obtained from the solution of the Schrödinger equation for different cc¯ potentials: harmonic oscillator, Cornell, logarithmic, power-law, Coulomb and Buchmüller-Tye. We showed some examples of wave functions in the Light Front representation as well as in the rest frame of cc¯ pair. We compare our results to the BaBar experimental data for ηc(1S), for one real and one virtual photon, and to the values collected by the Particle Data Group for F(0,0), decay width Γγγ and decay constant fηc. We also considered the non-relativistic limit for F(0,0) form factor with the wave function at the origin R(0).


  • Theoretical Particle Physics - Undergoing reorganization

Publishing year





Proceedings of Science



Document type

Conference paper


  • Subatomic Physics

Conference name

2019 European Physical Society Conference on High Energy Physics, EPS-HEP 2019

Conference date

2019-07-10 - 2019-07-17

Conference place

Ghent, Belgium




  • ISSN: 1824-8039