  A search for the standard model Higgs boson (H) decaying to b b-bar when
produced in association with a weak vector boson (V) is reported for the
following channels: W(mu nu)H, W(e nu)H, W(tau nu)H, Z(mu mu)H, Z(e e)H, and
Z(nu nu)H. The search is performed in data samples corresponding to integrated
luminosities of up to 5.1 inverse femtobarns at sqrt(s) = 7 TeV and up to 18.9
inverse femtobarns at sqrt(s) = 8 TeV, recorded by the CMS experiment at the
LHC. An excess of events is observed above the expected background with a local
significance of 2.1 standard deviations for a Higgs boson mass of 125 GeV,
consistent with the expectation from the production of the standard model Higgs
boson. The signal strength corresponding to this excess, relative to that of
the standard model Higgs boson, is 1.0 +/- 0.5.
