  We study the effect of electron-electron interaction on the transport
properties of short clean quantum wires adiabatically connected to reservoirs.
Interactions lead to resonances in a multi-channel wire at particular values of
the Fermi energy. We investigate in detail the resonance in a two-channel wire.
The (negative) conductance correction peaks at the resonance, and decays
exponentially as the Fermi energy is tuned away; the resonance width being
given by the temperature. Likewise, the thermopower shows a characteristic
structure, which is surprisingly well approximated by the so-called Mott
formula. Finally, four-fold splitting of the resonance in a magnetic field
provides a unique signature of the effect.
