Sub-leading power corrections to transition form factors of $\eta$ and ${\eta }^{\prime }$ mesons from twist-six contributions

Abstract

Using collinear factorization, we have calculated twist-six corrections to $\eta \gamma$ and ${\eta }^{\prime }\gamma$ transition form factors in QCD. Only a sub-set of light-cone operators of twist-six which can be factorized as a product of two gauge invariant operators has been considered. Resulting power corrections start as $1/Q^4$ but coefficients are smaller compared to their counterparts for twist-four operators. Matrix element of pseudoscalar quark densities for $u$- and $d$-quarks between vacuum and meson state, $h_q$, has considerable influence on the result. Results obtained by superimposing our results on those obtained in literature for leading and sub-leading power corrections for lower twists have been plotted and compared with data.

18 pages, 9 figures, 2 tables

References in corpus (9)

• Measurement of gamma gamma* --> pi0 transition form factor at Belle
• Light Cone Sum Rules for the pi0-gamma*-gamma Form Factor Revisited
• Transition form factors ${\gamma }^{\ast }\gamma \to \eta$ and ${\gamma }^{\ast }\gamma \to {\eta }^{\prime }$ in QCD
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• Axial anomaly as a collective effect of meson spectrum
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• Axial and pseudoscalar current correlators and their couplings to eta and etaprime mesons
• Leading SU(3) breaking in lightcone distribution amplitudes