We have presented a theoretical study of exclusive rare W-boson decays,
WβVβΞ½Λββ with V denoting a neutral vector meson and
β=e or ΞΌ, in the standard model. The leading-order contributions to
these processes are given by WβΞ³ββΞ½Λββ with the
subsequent Ξ³ββV transition. Branching fractions of these decay
modes, for V=Ο, Ο, Ο, and J/Ξ¨, respectively, have been
calculated and predicted around 10β6βΌ10β7, which are surprisingly
larger than those of two-body hadronic radiative decays WΒ±βMΒ±Ξ³
with M denoting a pseudoscalar or vector meson. Thus it is expected that rare
W decays into a neutral vector meson plus lepton pair may be the promising
channels in future experimental facilities with a large number of W-boson
events produced.Comment: 8 pages, 3 figures. Some discussions added. Published versio