Superfluids in expanding backgrounds and attractor times

Buza, Guri K. (author), Mitra, Toshali (author), Soloviev, Alexander (author)

We determine the behavior of an out-of-equilibrium superfluid, composed of a U⁡(1) Goldstone mode coupled to hydrodynamic modes in a Müller-Israel-Stewart theory, in expanding backgrounds relevant to heavy ion collision experiments and cosmology. For suitable initial conditions, the evolution of the hydrodynamic variables leads to a change in the potential of the Goldstone mode, spontaneously breaking the symmetry. After some time, the condensate becomes small, leading the system evolution to be well described via hydrodynamic attractors for a timescale that we determine in Bjorken and Gubser flows. We define this new timescale as the attractor time and show its dependence on initial conditions. In the case of the Gubser flow, we provide for the first time a complete description of the nonlinear evolution of the system, including a novel nonlinear regime of constant anisotropy not found in the Bjorken evolution. Finally, we consider the superfluid in the dynamical Friedmann-Lemaitre-Roberston-Walker (FLRW) background, where we observe a similar attractor behavior, dependent on the initial conditions, that at late times approaches a regime dominated by the condensate.

• Language: English
• Keywords: effective field theory, phase transitions, spontaneous symmetry breaking, relativistic hydrodynamics
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: Str. 076022-1-076022-20
• Numbering: Vol. 112, iss. 7
• PID: 20.500.12556/RUL-175230
• UDC: 532/533
• ISSN on article: 2470-0010
• DOI: 10.1103/45fr-wb1w
• COBISS.SI-ID: 254286339
• Publication date in RUL: 22.10.2025

Record is a part of a journal

• Title: Physical review
• Shortened title: Phys. rev., D
• Publisher: American Physical Society
• ISSN: 2470-0010
• COBISS.SI-ID: 29757223

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: efektivna teorija polja, fazni prehodi, spontani zlom simetrije, relativistična hidrodinamika