{"ID":23620894,"CreatedAt":"2026-09-18T06:47:37.825099056Z","UpdatedAt":"2026-09-18T06:47:37.825099056Z","DeletedAt":null,"paper_url":"https://arxiv.org/abs/2609.20705","arxiv_id":"2609.20705","title":"Adiabatic hydrodynamization with transverse spatial gradients in boost-invariant plasmas","abstract":"The quantitative success of relativistic viscous hydrodynamics in describing the short-lived quark--gluon plasma raises a fundamental question: how does far-from-equilibrium QCD matter approach hydrodynamic behavior so rapidly? Microscopic kinetic-theory studies have related this onset to attractor dynamics, but typically assume transverse homogeneity. We relax this assumption by introducing gradient modes with finite transverse wave number $k$, extending the analysis of arXiv:2212.00820. These couple different spherical harmonics of the momentum distribution, and the resulting dynamics is controlled by the competition among the expansion rate $1/τ$, the collision rate $1/τ_R$, and the gradient scale $k$. At early times, longitudinal expansion suppresses this coupling, and different spherical harmonic sectors follow their homogeneous attractors. We find that, at later times and sufficiently small $k$, this gradient coupling drives the system toward a global attractor manifold spanned by hydrodynamic sound and shear modes, on a timescale $τ_D$ that depends on both the azimuthal harmonic $m$ and $kτ_R$. For sufficiently large $kτ_R$, the spectral gap closes: perturbations retain finite damping rates and therefore equilibrate, but no longer follow an isolated hydrodynamic attractor or admit a reduced description involving only a few hydrodynamic modes.","short_abstract":"The quantitative success of relativistic viscous hydrodynamics in describing the short-lived quark--gluon plasma raises a fundamental question: how does far-from-equilibrium QCD matter approach hydrodynamic behavior so rapidly? Microscopic kinetic-theory studies have related this onset to attractor dynamics, but typica...","url_abs":"https://arxiv.org/abs/2609.20705","url_pdf":"https://arxiv.org/pdf/2609.20705v1","authors":"[\"Uri Sharell\",\"Jasmine Brewer\",\"Weiyao Ke\"]","published":"2026-09-17T17:05:16Z","proceeding":"hep-ph","tasks":"[\"hep-ph\",\"nucl-th\"]","methods":"[]","has_code":false}