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arXiv · 2008.06169

Nonperturbative quark-antiquark interactions in mesonic form factors

Edward Shuryak·Ismail Zahed
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Abstract

The existing theory of hard exclusive QCD processes is based on two assumptions: (i) $factorization$ into a $hard\,block$ times light front distribution amplitudes (DA's); (ii) use of perturbative gluon exchanges within the hard block. However, unlike DIS and jet physics, the characteristic momentum transfer $Q$ involved in the factorized block is not large enough for this theory to be phenomenologically successful. In this work, we revisit the latter assumption (ii), by explicitly calculating the $instanton-induced$ contributions to the hard block, and show that they contribute substantially to the vector, scalar and gravitational form factors of the pseudoscalar, scalar and vector mesons, over a wide range of momentum transfer.

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Edward Shuryak, Ismail Zahed. 2020-08-14. Nonperturbative quark-antiquark interactions in mesonic form factors. https://doi.org/10.1103/physrevd.103.054028

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