低能等效理论下扭度为4的离壳光子光锥波函数

Off-Shell Twist-4 Light-Cone Photon Wave Function in the Low-Energy Effective Theory

从光子通过夸克-反夸克非局域流到真空的跃迁振幅σΠμ出发,利用Lorentz分解将光子光锥波函数gγ3(u,P2)分离出来.在低能等效理论框架下求出了该波函数的解析表达式,并分析了波函数随着夸克动量份额u变化的行为.同时,得到了正反夸克矢量流与虚光子的耦合常数Gγ(P2)的表达式.结果表明,不同虚度下的波函数关于变换u→u对称(u=1-u),并且在端点u=0和u=1时不为零.耦合常数Gγ(P2)在P2=0时为零,保证了非局域夸克矢量流与波函数退耦,因此P2=0时的实光子波函数没有实际的物理效应.

Starting with the transition amplitude of a photon to the vacuum through the non-local quark-antiquark current, the light-cone photon wave function gγ3 （u,P^2） is singled out from the Lorentz decomposition. Its analytic expression is obtained in the framework of the quantum chromodynamics （QCD） low-energy effective theory, and its behavior and trend with respect to the fraction （u） of the quark momentum are analyzed. The coupling constant, Gy（P^2）, of the quark-antiquark vector current to the vir- tual photon state is also obtained. The wave functions corresponding to different virtuality are symmetric with the transformation u→u^-（u^-=1-u） and they are not zero at the end pointsu=0 and u=1. The real photon wave function according to P^2= 0 has no physical meaning, since the coupling constant Gγ（P^2） vanishes at P^2 =0 which guarantees that the non-local vector quark current is decoupled from the wave function.