A search for a light charged Higgs boson, originating from the decay of a top
quark and subsequently decaying into a charm quark and a strange antiquark, is presented.
The data used in the analysis correspond to an integrated luminosity of 19.7 fb−1
recorded
in proton-proton collisions at √
s = 8 TeV by the CMS experiment at the LHC. The search
is performed in the process t¯t → W±bH∓b, where the W boson decays to a lepton (electron ¯
or muon) and a neutrino. The decays lead to a final state comprising an isolated lepton,
at least four jets and large missing transverse energy. No significant deviation is observed
in the data with respect to the standard model predictions, and model-independent upper
limits are set on the branching fraction B(t → H+b), ranging from 1.2 to 6.5% for a charged
Higgs boson with mass between 90 and 160 GeV, under the assumption that B(H+ → c¯s)
= 100%.