2018 Impact factor 4.843
Particles and Fields
Eur. Phys. J. C 11, 501-506
DOI 10.1007/s100529900952

Twist-3 contribution to the pion electromagnetic form factor

Fu-Guang Cao1,2 - Yuan-Ben Dai1,2 - Chao-Shang Huang1,2

1 CCAST (World Laboratory), P.O. Box 8730, Beijing 100080, P.R. China
2 Institute of Theoretical Physics, Academia Sinica, P.O. Box 2735, Beijing 100080, P.R. China

Received: 23 March 1998 / Published online: 3 November 1999

Non-leading contribution to the pion electromagnetic form factor which comes from the pion twist-3 wave function is analyzed in the modified hard scattering approach (MHSA) proposed by Li and Sterman. This contribution is enhanced significantly due to bound state effect (the twist-3 wave function is independent of the fractional momentum carried by the parton and has a large factor $\sim m_\pi^2/m_0$ with $m_\pi$ being the pion meson mass and m0 being the mean u- and d-quark masses). Consequently, although it is suppressed by the factor 1/Q2, the twist-3 contribution is comparable with and even larger than the leading twist (twist-2) contribution at intermediate energy region of Q2 being $2 \sim 40 \,{\rm GeV}^2$.

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