  We propose the boost asymmetry of the diboson productions in pp collisions as
a new experimental observable, which can provide unique information on the
proton structure. The boost asymmetry rises as the difference in the kinematics
of the two bosons, that are coupled to the two different quark and antiquark
initial states, respectively, and thus reflects different features of the quark
and antiquark parton densities. By comparing the kinematics of the two bosons,
such as the boson energy or rapidity, the diboson events with antiquark having
higher energy than quark can be distinguished from those with quark having
higher energy than antiquark. This would provide unique information in some
special parton momentum fraction regions, which cannot be directly proved by
current W and Z measurements at the Large Hadron Collider or other deep
inelastic scattering experients.
