Shesha D. Patel | Searcharxiv

arXiv2019

Eta-nucleon and eta-prime-nucleon coupling constants in QCD and the role of gluons

Coupling constants of $η$ and $η^{\prime}$ mesons with nucleons have been calculated using the method of QCD sum rules. Starting from vacuum-to-meson correlation function of interpolating fields of two nucleons, its matrix element with respect to nucleon spinors has been considered. Coupling constants at the physical points have been estimated from extrapolation of results obtained at two other points. Anomalous glue has been found to give substantial contribution to the coupling constants and also accounts for a significant OZI-rule violation.

hep-ph↗

arXiv2018

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

Using collinear factorization, we have calculated twist-six corrections to $ηγ$ and $η^{\prime}γ$ 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.

hep-ph↗