SciPost logo

SciPost Submission Page

Coupled dynamics of resource competition and constrained entrances in a multi-lane bidirectional exclusion process

by Ashish Kumar Pandey, Arvind Kumar Gupta

This Submission thread is now published as

Submission summary

Authors (as registered SciPost users): Arvind Kumar Gupta
Submission information
Preprint Link: scipost_202508_00043v1  (pdf)
Date accepted: Nov. 11, 2025
Date submitted: Aug. 20, 2025, 7:42 a.m.
Submitted by: Arvind Kumar Gupta
Submitted to: SciPost Physics Core
Ontological classification
Academic field: Physics
Specialties:
  • Statistical and Soft Matter Physics
Approaches: Theoretical, Computational

Abstract

Motivated by the role of limited particle resources in multi-species bidirectional transport processes observed in various biological and physical systems, we investigate a one-dimensional closed system consisting of two parallel lanes with narrow entrances, where each lane accommodates two oppositely directed particle species. Each particle species is linked to a separate finite reservoir, which is coupled to both lanes and regulates the entry rates of particle into the lanes. To analyze the effect of finite particle reservoirs on the stationary properties of the system, we employ a mean-field theoretical framework to characterize the density profiles, particle currents, and phase behavior, complemented by a boundary layer analysis based on fixed point methods to capture spatial variations near the boundaries. The impact of individual species population, quantified by species-specific filling factors, is systematically examined under both equal and unequal conditions. For equal filling factors, system undergoes spontaneous symmetry breaking and supports both symmetric and asymmetric phases. In contrast, for unequal filling factors, only asymmetric phases are realized, with the phase diagram exhibiting up to five distinct phases. A striking feature observed in both scenarios is the emergence of a back-and-forth transition, along with a non-monotonic dependence of the number of phases on the filling factors. All theoretical findings are extensively validated through stochastic simulations based on the Gillespie algorithm, confirming the robustness of the analytical results.

Published as SciPost Phys. Core 8, 089 (2025)


Reports on this Submission

Report #2 by Anonymous (Referee 2) on 2025-10-8 (Invited Report)

  • Cite as: Anonymous, Report on arXiv:scipost_202508_00043v1, delivered 2025-10-08, doi: 10.21468/SciPost.Report.12081

Strengths

  1. The paper is a complete study of the phases of a transport model as a function of its parameters.
  2. The study includes both mean field theory and simulations.
  3. The paper is well written and mostly complete.
  4. This is one more example of a phase diagram of a transport model that can be added to a catalogue of phase diagrams of transport models.

Weaknesses

  1. There is very little new from the methodological side.
  2. There does no appear to be anything qualitatively new with respect to other transport models studied in the literature.

Report

I recommend to publish the paper after the revisions below have been considered. Although the work is not orginal, the research is well done and reported. Given that the results exist, I see no reason not to publish them.

Requested changes

  1. Please explain in more detail how the right-hand sides in (18) are obtained (i.e. the second equality signs)

  2. Section 3.2: It is said "numerical investigations corroborated by Monte Carlo Simulations confirm the absence of several theoretical feasible phases".

Could you please elaborate on this? Does this imply that there parameter regimes for which multiple phases can exist, but only one is observed?

  1. At present figures captions say "Solid lines represent theoretical predictions". It would be helpful if this can be made more precise, and the captions refer to specific equations in the main text that have been used to plot the solid lines.

  2. Figure 13 and 14: Figure 13 shows that for beta=0.25 and alpha=10 or beta=0.28 and alpha=4 the theory deviates significantly from the numerical simulations. Figure 14 seems to indicate that this is a finite size effect. However, Figure 14 is not showing resuls for th same parameters as Figure 13. Therefore, this is inconclusive. I think the authors should show a figure 14 for exactly the same parameters as figure 13, and overlay it with theoretical results, demonstrating that numerics converges towards theory. Otherwise, it remains inconclusive that the shock is localised as claimed in the paper.

  3. In the legend of figure 14: it is not clear what is meant by MCS.

Recommendation

Ask for major revision

  • validity: high
  • significance: low
  • originality: low
  • clarity: high
  • formatting: perfect
  • grammar: perfect

Author:  Arvind Kumar Gupta  on 2025-10-14  [id 5922]

(in reply to Report 2 on 2025-10-08)

Please see attachment.

Attachment:

Scipost_Rebuttal__reviewer_2.pdf

Report #1 by Anatoly Kolomeisky (Referee 1) on 2025-10-7 (Invited Report)

  • Cite as: Anatoly Kolomeisky, Report on arXiv:scipost_202508_00043v1, delivered 2025-10-07, doi: 10.21468/SciPost.Report.12079

Strengths

1) Important scientific subject. 2) Multi-disciplinary application. 3) Comprehensive analysis that combines analytical, numerical calculations, and boundary layer analysis. 4) Excellent explanations of details and calculations. 5) Well-written manuscript that can be easily followed.

Weaknesses

None

Report

This is an outstanding theoretical work that combines analytical calculations and computer simulations to investigate a complex bidirectional transport system stimulated by biological observations. The paper is well-written, and the results are clearly explained. The authors did an excellent job of explaining the physical meaning of the results. It is definitely an important advancement in the field.

Requested changes

I have several minor suggestions for improvement: 1) Eq. (3) - It is the simplest assumption about the entrance rates, but it is not the only one. Will the results change if other choices are made? Some brief discussions might be useful here. 2) I would add more discussion on the expectation of what might happen when q<1. Specifically, if mean-field theory could capture the processes well. 3) I would mention that the success of mean-field theory for this model is because the coupling (correlations) are very local (only at the entrances).

Recommendation

Publish (surpasses expectations and criteria for this Journal; among top 10%)

  • validity: top
  • significance: top
  • originality: high
  • clarity: top
  • formatting: perfect
  • grammar: perfect

Author:  Arvind Kumar Gupta  on 2025-10-14  [id 5923]

(in reply to Report 1 by Anatoly Kolomeisky on 2025-10-07)

Please see attachment.

Attachment:

Scipost_Rebuttal__reviewer_1.pdf

Login to report or comment