Exotic hadron production in hard exclusive reactions

Abstract

We consider hard exclusive production of exotic hadrons to study their internal structure. Revisiting the constituent-counting rule for the large-angle exclusive scattering, we discuss general features expected for the production cross section of exotic hadrons whose leading Fock states are given by multi-quark states other than the ordinary baryon ($qqq$) or meson ($q\bar{q}$) states.We take the production of $\Lambda (1405)$ as an example and propose to study its partonic configuration from the asymptotic scaling of the cross section, which is measurable at J-PARC. We also discuss the production of a pair of the light-hadrons such as $f_0(980)$s and $a_0(980)$s in ${\gamma }^{\ast }\gamma$ collisions in the framework of QCD factorization, in which the cross section is expressed as a convolution of the perturbative coefficients and the generalized distribution amplitudes (GDAs). We demonstrate how the internal structure of $f_0(980)$ or $a_0(980)$ can be explored by measuring the GDAs at $e^{+}{e}^{-}$ experiments such as the B-factories.

Comments: 5pages, 4 figures, talk given at XV International Conference on Hadron Spectroscopy (Hadron 2013), Nara, Japan, 4-8 November 2013; minor corrections, a reference added