title: Emergent Lorentz symmetry with vanishing velocity in a critical two-subband quantum wire.
abstract: We consider a quantum wire with two subbands of spin-polarized electrons in the presence of strong interactions. We focus on the quantum phase transition when the second subband starts to get filled as a function of gate voltage. Performing a one-loop renormalization group analysis of the effective Hamiltonian, we identify the critical fixed-point theory as a conformal field theory having an enhanced SU(2) symmetry and central charge 3/2. While the fixed point is Lorentz invariant, the effective "speed of light" nevertheless vanishes at low energies due to marginally irrelevant operators leading to a diverging critical specific heat coefficient.
authors.affiliation: Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Sitte
authors.forename: A
authors.initials: A
authors.lastname: Rosch
authors.forename: J S
authors.initials: JS
authors.lastname: Meyer
authors.forename: K A
authors.initials: KA
authors.lastname: Matveev
authors.forename: M
authors.initials: M
authors.lastname: Garst