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Beyond-mean-field analysis of the Townes soliton and its breathing mode

by Dmitry S. Petrov

Submission summary

Authors (as registered SciPost users): Dmitry Petrov
Submission information
Preprint Link: scipost_202412_00042v3  (pdf)
Date accepted: June 10, 2025
Date submitted: May 28, 2025, 1:09 p.m.
Submitted by: Petrov, Dmitry
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
Specialties:
  • Atomic, Molecular and Optical Physics - Theory
Approach: Theoretical

Abstract

By using the Bogoliubov perturbation theory we describe the self-bound ground state and excited breathing states of $N$ two-dimensional bosons with zero-range attractive interactions. Our results for the ground state energy $B_N$ and size $R_N$ improve previously known large-$N$ asymptotes and we better understand the crossover to the few-body regime. The breathing oscillations, absent on the mean-field level, result from the quantum-mechanical breaking of the mean-field scale symmetry. The breathing-mode frequency scales as $\Omega\propto |B_N|/\sqrt{N}$ at large $N$.

Author indications on fulfilling journal expectations

  • Provide a novel and synergetic link between different research areas.
  • Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
  • Detail a groundbreaking theoretical/experimental/computational discovery
  • Present a breakthrough on a previously-identified and long-standing research stumbling block

Author comments upon resubmission

Dear Editors,

I thank the referees for the reports. I slightly modify the manuscript in response to Referee #1. I hope you find it suitable for publication.

Sincerely,
Dmitry Petrov

List of changes

1) In the abstract I replaced the sentence

"The oscillatory breathing motion results from the quantum-mechanical breaking of the mean-field scaling symmetry."

by

"The breathing oscillations, absent on the mean-field level, result from the quantum-mechanical breaking of the mean-field scale symmetry."

2) In the last paragraph of the introduction I added two sentences:

"We thus predict the preexponential factor in the dependence of the ground state energy on the particle number."

and

"We also make a few conjectures concerning the next-order correction to the soliton's energy and the nature of its excitation spectrum."

3) After Eq.(12) in the paragraph starting with "The equation of motion corresponding..." I replaced R(t)^2 by R^2(t).

4) On page 5 in the paragraph starting with "A technical difficulty with..." I replaced the phrase "to formally set g = g_c" by "to use the approximation g = g_c" and added the sentence

"Distinguishing between g and g_c in this case would exceed the Bogoliubov accuracy."

Current status:
Accepted in target Journal

Editorial decision: For Journal SciPost Physics: Publish
(status: Editorial decision fixed and (if required) accepted by authors)

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