# Effective field theory of fluctuating wall in open systems: from a kink in Josephson junction to general domain wall

### Submission summary

 Authors (as Contributors): Keisuke Fujii
Submission information
Date accepted: 2022-04-19
Date submitted: 2022-02-23 19:02
Submitted by: Fujii, Keisuke
Submitted to: SciPost Physics
Ontological classification
Specialties:
• High-Energy Physics - Theory
Approach: Theoretical

### Abstract

We investigate macroscopic behaviors of fluctuating domain walls in nonequilibrium open systems with the help of the effective field theory based on symmetry. Since the domain wall in open systems breaks the translational symmetry, there appears a gapless excitation identified as the Nambu-Goldstone (NG) mode, which shows the non-propagating diffusive behavior in contrast to those in closed systems. After demonstrating the presence of the diffusive NG mode in the $(2+1)$-dimensional dissipative Josephson junction, we provide a symmetry-based general analysis for open systems breaking the one-dimensional translational symmetry. A general effective Lagrangian is constructed based on the Schwinger-Keldysh formalism, which supports the presence of the gapless diffusion mode in the fluctuation spectrum in the thin wall regime. Besides, we also identify a term peculiar to the open system, which possibly leads to the instability in the thick-wall regime or the nonlinear Kardar-Parisi-Zhang coupling in the thin-wall regime although it is absent in the Josephson junction.

Published as SciPost Phys. 12, 160 (2022)

### List of changes

We modified some sentences to reflect the comments of the referees.

### Submission & Refereeing History

Resubmission 2109.10335v3 on 23 February 2022
Submission 2109.10335v2 on 4 October 2021

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The authors have addressed my questions and comments. I recommend this manuscript for publication.

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### Report

The points in my previous report have been addressed. I am happy to recommend the paper for publication.

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