Weak and electromagnetic form factors of baryons at large momentum transfer

Abstract

Perturbative quantum-chromodynamic predictions are given for the weak and electromagnetic elastic and transition form factors of baryons at large momentum transfer $Q$. The leading (helicity-conserving) octet and decuplet form factors can all be expressed as linear combinations of the proton and neutron magnetic form factors. The predictions for the spin structure and relative normalization of the baryon form factors reflect the assumed $\mathrm{SU}{(2)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1)$ structure of the electromagnetic and weak currents, quark and gluon hard-scattering dynamics, and the helicity-flavor symmetry of baryon wave functions at short distances. The results hold to all orders in ${\ensuremath{\alpha}}_{s}({Q}^{2})$ and to leading order in $\frac{m}{Q}$. We also discuss the special features of the contribution of the end-point $x\ensuremath{\sim}1$ region to baryon form factors.