Xing, ZZ (reprint author), CCAST, World Lab, POB 8730, Beijing 100080, Peoples R China.
It is known that neutrino oscillations may map phi(e)phi(mu)phi(tau)=120, the initial flavor ratios of ultrahigh-energy neutrino fluxes produced from a distant astrophysical source, into phi(D)(e)phi(D)(mu)phi(D)(tau)=1:1:1 at the detector of a neutrino telescope. We remark that this naive expectation is only valid in the mu-tau symmetry limit, in which two neutrino mixing angles satisfy theta(13)=0 and theta(23)=pi/4. Allowing for the slight breaking of mu-tau symmetry, we find phi(D)(e)phi(D)(mu)phi(D)(tau)=(1-2 Delta)(1+Delta)(1+Delta) with Delta characterizing the combined effect of theta(13)not equal 0 and theta(23)not equal pi/4. Current neutrino oscillation data indicate -0.1 less than or similar to Delta less than or similar to+0.1. We also look at the possibility to probe Delta by detecting the (nu) over bar (e) flux of E-(nu) over bare approximate to 6.3 PeV via the Glashow resonance channel (v) over bar (e)e -> W--> anything.