  We present a new model of "Stealth Dark Matter": a composite baryonic scalar
of an $SU(N_D)$ strongly-coupled theory with even $N_D \geq 4$. All mass scales
are technically natural, and dark matter stability is automatic without
imposing an additional discrete or global symmetry. Constituent fermions
transform in vector-like representations of the electroweak group that permit
both electroweak-breaking and electroweak-preserving mass terms. This gives a
tunable coupling of stealth dark matter to the Higgs boson independent of the
dark matter mass itself. We specialize to $SU(4)$, and investigate the
constraints on the model from dark meson decay, electroweak precision
measurements, basic collider limits, and spin-independent direct detection
scattering through Higgs exchange. We exploit our earlier lattice simulations
that determined the composite spectrum as well as the effective Higgs coupling
of stealth dark matter in order to place bounds from direct detection,
excluding constituent fermions with dominantly electroweak-breaking masses. A
lower bound on the dark baryon mass $m_B \gtrsim 300$ GeV is obtained from the
indirect requirement that the lightest dark meson not be observable at LEP II.
We briefly survey some intriguing properties of stealth dark matter that are
worthy of future study, including: collider studies of dark meson production
and decay; indirect detection signals from annihilation; relic abundance
estimates for both symmetric and asymmetric mechanisms; and direct detection
through electromagnetic polarizability, a detailed study of which will appear
in a companion paper.
