Experimental bound on the charge radius of the electron neutrino

A limit on the electron-neutrino charge radius {vert bar}{ital r}{vert bar} is derived from a measurement of the weak-neutral-current vector coupling constant {ital g}{sub {ital V}} obtained in electron-neutrino electron elastic scattering. The 90%-confidence interval for {ital g}{sub {ital V}} is {minus}0.177{lt}{ital g}{sub {ital V}}{lt}0.187, which for sin{sup 2}{theta}{sub {ital W}}=0.227 implies that the {nu}{sub {ital e}} mean-square charge radius is in the range {minus}2.74{times}10{sup {minus}32}{lt}{l angle}{ital r}{sup 2}{r angle}{lt}4.88{times}10{sup {minus}32} cm{sup 2}, or simply {vert bar}{ital r}{vert bar}{lt}2.2{times}10{sup {minus}16} cm. This is the first experimental bound on the {nu}{sub {ital e}} charge radius, and is the same order of magnitude as bounds for {nu}{sub {mu}} structure.