Olalla A. Castro-Alvaredo, Cecilia De Fazio, Benjamin Doyon, Aleksandra A. Ziółkowska
SciPost Phys. 12, 115 (2022) ·
published 31 March 2022
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In the context of quantum field theory (QFT), unstable particles are
associated with complex-valued poles of two-body scattering matrices in the
unphysical sheet of rapidity space. The Breit-Wigner formula relates this pole
to the mass and life-time of the particle, observed in scattering events. In
this paper, we uncover new, dynamical signatures of unstable excitations and
show that they have a strong effect on the non-equilibrium properties of QFT.
Focusing on a 1+1D integrable model, and using the theory of Generalized
Hydrodynamics, we study the formation and decay of unstable particles by
analysing the release of hot matter into a low-temperature environment. We
observe the formation of tails and the decay of the emitted nonlinear waves, in
sharp contrast to the situation without unstable excitations. We also uncover a
new phenomenon by which a wave of a stable population of unstable particles may
persist without decay for long times. We expect these signatures of the
presence of unstable particles to have a large degree of universality. Our
study shows that the out-of-equilibrium dynamics of many-body systems can be
strongly affected not only by the spectrum, but also by excitations with finite
life-times.
SciPost Phys. 8, 044 (2020) ·
published 19 March 2020
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We consider Lindblad equations for one dimensional fermionic models and quantum spin chains.
By employing a (graded) super-operator formalism we identify a number of Lindblad equations
than can be mapped onto non-Hermitian interacting Yang-Baxter integrable models. Employing Bethe Ansatz techniques we show that the late-time dynamics of some of these models is
diffusive.
