  The discovery of a new boson with a mass of approximately 125 GeV in 2012 at
the LHC has heralded a new era in understanding the nature of electroweak
symmetry breaking and possibly completing the standard model of particle
physics. Since the first observation in decays to gamma gamma, WW, and ZZ boson
pairs, an extensive set of measurements of the mass and couplings to W and Z
bosons, as well as multiple tests of the spin-parity quantum numbers, have
revealed that the properties of the new boson are consistent with those of the
long-sought agent responsible for electroweak symmetry breaking. An important
open question is whether the new particle also couples to fermions, and in
particular to down-type fermions, since the current measurements mainly
constrain the couplings to the up-type top quark. Determination of the
couplings to down-type fermions requires direct measurement of the
corresponding Higgs boson decays, as recently reported by the CMS experiment in
the study of Higgs decays to bottom quarks and tau leptons. In this paper we
report the combination of these two channels which results, for the first time,
in strong evidence for the direct coupling of the 125 GeV Higgs boson to
down-type fermions, with an observed significance of 3.8 standard deviations,
when 4.4 are expected.
