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Typical working day..

Roman Pasechnik

Senior lecturer

Typical working day..

The γ∗γ∗→ ηc (1S; 2S) transition form factor from quarkonium wave functions


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


  • Gennaro Corcella
  • Erika De Lucia
  • Pasquale Di Nezza
  • Paola Gianotti
  • Giulia Pancheri

Summary, in English

We discuss γ ∗γ ∗→ ηc(1S) ; ηc (2S) transition form factor for both virtual photons. The general formula is given. We use difierent models for the cc̄ wave function obtained from the solution of the Schrödinger equation for diffierent cc̄ 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 cc̄. We compare our results to the BaBar experimental data for ηc(1S), with one real and one virtual photon, and to the values collected by the Particle Data Group for the form factor F(0; 0), decay width τγ γ and decay constant fηc . We also consider the non-relativistic limit for F(0; 0) with the wave function evaluated at the origin R(0).


  • Theoretical Particle Physics

Publishing year







Frascati Physics Series



Document type

Conference paper


Istituto Nazionale di Fisica Nucleare


  • Mathematical Analysis

Conference name

2019 International Conference on the Structure and the Interactions of the Photon, PHOTON 2019, Satellite Workshop on Photon Physics and Simulation at Hadron Colliders

Conference date

2019-06-03 - 2019-06-07

Conference place

Frascati, Italy




  • ISSN: 1122-5157
  • ISBN: 9788886409704