  A search for physics beyond the standard model in the final state with two
same-flavour leptons (electrons or muons) and two quarks produced in
proton-proton collisions at sqrt(s) = 13 TeV is presented. The data were
recorded by the CMS experiment at the CERN LHC and correspond to an integrated
luminosity of 2.3 inverse femtobarns. The observed data are in good agreement
with the standard model background prediction. The results of the measurement
are interpreted in the framework of a recently proposed model in which a heavy
Majorana neutrino, N(l), stems from a composite-fermion scenario. Exclusion
limits are set for the first time on the mass of the heavy composite Majorana
neutrino, m[N(l)], and the compositeness scale Lambda. For the case m[N(l)] =
Lambda, the existence of N(e) (N(mu)) is excluded for masses up to 4.60 (4.70)
TeV at 95% confidence level.
