Light-front approach to axial-vector quarkonium γ*γ* form factors

Abstract

Abstract In this work, we perform a detailed study of transition form factors for axial- vector meson production via the two-photon fusion process γ*γ* → 1++, with space-like virtual photons in the initial state and a P-wave axial-vector quarkonium in the final state. In this analysis, we employ the formalism of light-front quarkonium wave functions obtained from a solution of the Schrödinger equation for a selection of interquark potentials for $$ Q\overline{Q} $$ Q Q ¯ interaction. We found the helicity structure and covariant decomposition of the matrix elements that can be generically applied for any $$ q\overline{q} $$ q q ¯ axial-vector meson γ*γ* → 1++ transition, while our numerical results are given for the phenomenologically relevant charmonium χc1 state. We present the helicity form factors as functions of both photon virtualities. We also obtain, that QFLT(Q2, 0)/FTT(Q2, 0) = const.