Hua-Yong Han, Xing-Gang Wu, Hai-Bing Fu, Qiong-Lian Zhang, Tao Zhong
We investigate the twist-3 light cone distribution amplitudes (LCDAs) of the scalar mesons $a_0$, $K^{\ast}_0$ and $f_0$ within the QCD sum rules. The sum rules are improved by a consistent treatment of the sizable mass effects. Adopting the valence quark component $(\bar{q}_1 q_2)$ as the dominant structure of the scalar mesons, our estimation for their masses are close to the measured $a_0(1450)$, $K^{\ast}_0(1430)$ and $f_0(1710)$. From the sum rules, we obtain the first two non-zero moments of the twist-3 DAs $\phi^{s,\sigma}_{a_0}$: $<\xi_{s,a_0}^{2(4)}>=0.369 (0.245)$ and $<\xi_{\sigma,a_0}^{2(4)}>=0.203 (0.093)$; those of the twist-3 DAs $\phi_{K^*_0}^{s,\sigma}$: $<\xi_{s,K^{\ast}_0}^{1(2)}> =0.004 (0.355)$ and $<\xi_{\sigma,K^{\ast}_0}^{1(2)}> =0.018 (0.207)$; and those of the twist-3 DAs $\phi_{f_0}^{s,\sigma}$: $<\xi_{s,f_0}^{2(4)}>=0.335 (0.212)$ and $<\xi_{\sigma,f_0}^{2(4)}>=0.196 (0.088)$, respectively. As an application of these twist-3 LCDAs, we study the $B \to S$ transition form factors by introducing proper chiral currents in the correlator, which is constructed such that the twist-3 DAs give dominant contribution and the twist-2 DAs make negligible contribution. Our results of the $B \to S$ form factors at the large recoil region $q^2 \simeq 0$ are consistent with those obtained in the literature.
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http://arxiv.org/abs/1301.3978
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