title: Competing regimes of motion of 1D mobile impurities.
abstract: We show that a distinguishable mobile impurity inside a one-dimensional many-body state at zero temperature generally does not behave like a quasiparticle. Instead, both the impurity dynamics as well as the ground state of the bath are fundamentally transformed by a diverging number of zero-energy excitations being generated, leading to what we call infrared-dominated (ID) dynamics. Combining analytics and density matrix renormalization group numerics, we provide a general formula for the power law governing ID dynamics at zero momentum, discuss a threshold beyond which quasiparticle dynamics may occur again, and study the competition between the ID and quasiparticle universality classes at larger impurity momenta.
authors.affiliation: DPMC-MaNEP, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Kantian
authors.affiliation: Department für Physik, LMU München, Theresienstrasse 37, 80333 München, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Schollwöck
authors.affiliation: DPMC-MaNEP, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Giamarchi