  Extensive searches to probe the particle nature of dark matter (DM) have been
going on for some decades now but, so far, no conclusive evidence has been
found. Among various options, the Weakly Interacting Massive Particles (WIMP)
remains one of the prime possibilities as candidates for DM near the TeV scale.
Taking a phenomenological view, such null results may be explained for a
generic WIMP in a Higgs-portal scenario if we allow the light-quark Yukawa
couplings to assume non-Standard Model (non-SM)-like values. This follows from
a cancellation among different terms in the DM-nucleon scattering which can, in
turn, lead to a vanishingly small direct-detection cross section. It might also
lead to isospin violation in the DM-nucleon scattering. Such non-SM values of
light-quark Yukawa couplings may be probed in the high luminosity run of the
LHC.
