Assuming that the lightest neutral component in an SU(2)L gauge multiplet is
the main ingredient of dark matter in the universe, we calculate the elastic
scattering cross section of the dark matter with nucleon, which is an important
quantity for the direct detection experiments. When the dark matter is a real
scalar or a Majorana fermion which has only electroweak gauge interactions, the
scattering with quarks and gluon are induced through one- and two-loop quantum
processes, respectively, and both of them give rise to comparable contributions
to the elastic scattering cross section. We evaluate all of the contributions
at the leading order and find that there is an accidental cancellation among
them. As a result, the spin-independent cross section is found to be
O(10^-(46-48)) cm^2, which is far below the current experimental bounds.Comment: 19 pages, 7 figures, published versio
