In the context of quantum field theory (QFT), unstable particles are associated with complex-valued poles two-body scattering matrices in unphysical sheet rapidity space. The Breit-Wigner formula relates this pole to mass and life-time particle, observed events. paper, we uncover new, dynamical signatures excitations show that they have a strong effect on non-equilibrium properties QFT. Focusin...

Starting from an effective action for the order parameter field, we derive a coupled set of generalized hydrodynamic equations for a Bose condensate in an optical lattice at finite temperatures. Using the linearized hydrodynamic equations, we study the microscopic mechanism of the Landau instability due to the collisional damping process between condensate and noncondensate atoms. It is shown t...

Aims. We study stability of differentially rotating non-magnetic proto-neutron stars. Methods. Linear stability properties are considered taking into account neutrino transport. Results. If neutrino transport is efficient, the star can be subject to a diffusive instability that can occur even in the convectively stable region. The instability arises on the time-scale comparable to the time-scal...

Paul Chaikin Department of Physics, New York University, New York, NY 10003, USA. Abstract We derive a minimal continuum model to investigate the hydrodynamic mechanism behind the fingering instability recently discovered in a suspension of microrollers near a floor [Driscoll et al. Nature Physics, 2016]. Our model, consisting of two continuous lines of rotlets, exhibits a linear instability dr...