A measurement of the top quark mass is reported
in events containing a single top quark produced via the elec-
troweak
t
channel. The analysis is performed using data from
proton-proton collisions collected with the CMS detector at
the LHC at a centre-of-mass energy of 8 TeV, corresponding
to an integrated luminosity of 19.7 fb
−
1
. Top quark candi-
dates are reconstructed from their decay to a W boson and a b
quark, with the W boson decaying leptonically to a muon and
a neutrino. The final state signature and kinematic properties
of single top quark events in the
t
channel are used to enhance
the purity of the sample, suppressing the contribution from
top quark pair production. A fit to the invariant mass distribu-
tion of reconstructed top quark candidates yields a value of
the top quark mass of 172
.
95
±
0
.
77 (stat)
+
0
.
97
−
0
.
93
(syst) GeV.
This result is in agreement with the current world average,
and represents the first measurement of the top quark mass
in event topologies not dominated by top quark pair produc-
tion, therefore contributing to future averages with partially
uncorrelated systematic uncertainties and a largely uncorre-
lated statistical uncertainty.