  Strongly-interacting systems consisting of particles that interact through a
large scattering length satisfy universal relations that relate many of their
central properties to the contact, which measures the number of pairs with
small separations. We use the operator product expansion of quantum field
theory to derive the universal relation for the inelastic 2-body loss rate. A
simple universal relation between the loss rate and the contact is obtained by
truncating the expansion after the lowest dimension operator. We verify the
universal relation explicitly by direct calculations in the low-density limit
at nonzero temperature. This universal relation can be tested experimentally
using ultracold quantum gases of atoms in hyperfine states that have an
inelastic spin-relaxation channel.
