On Particle Production from Bubble Collisions in the Non-runaway Regime

Particle production from bubble collisions during First-Order Phase Transitions has been studied as an efficient mechanism for baryogenesis and dark matter production, but existing semi-analytical treatments assume runaway bubbles with. The new analysis still awaits peer review, but it already lays out the central claim clearly.

This matters because cosmology operates at the edge of what current instruments can measure, where systematic errors and model assumptions are never trivial. Small discrepancies between independent measurements have historically pointed toward missing physics rather than simple calibration errors, and the ongoing tension in the Hubble constant is a live example of how a persistent disagreement between methods can reshape the theoretical landscape. Each new dataset that approaches this territory with independent systematics adds real information to a problem that has resisted easy resolution for more than a decade. Particle production from bubble collisions during First-Order Phase Transitions (FOPTs) has been studied as an efficient mechanism for baryogenesis and dark matter production, but. We generalize this treatment to arbitrary $v_w< 1$, relevant for scenarios such as electroweak baryogenesis and transitions with significant wall friction.

We first extend the analytical trapping-equation approach to finite-thickness boosted kink profiles for both elastic and inelastic collisions, then go beyond this by numerically. We find the analytical generalization underestimates the true efficiency factor by orders of magnitude away from $v_w\to 1$, and provide new semi-analytic fit functions consisting.

Applying these to a toy dark sector model, we show particle production is strongly suppressed as $v_w$ decreases from unity, enhanced for lighter produced particles, and that the. We also discuss limitations of the trapping equation and the off-shell effective-action truncation underlying this formalism.

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The relevance goes beyond one dataset because even small shifts in measured parameters can matter when the field is testing the limits of the standard cosmological model. The Lambda-CDM framework describes the observable universe with remarkable economy, but its success rests on two components, dark matter and dark energy, whose physical nature remains entirely unknown. Any credible measurement that tightens or loosens the constraints on those components moves the entire theoretical enterprise forward, regardless of whether the immediate result looks dramatic on its own terms.

Have an idea for a project that will add value for arXiv's community. On Particle Production from Bubble Collisions in the Non-runaway Regime Authors: Fayez Abu-Ajamieh.

Because this is still a preprint, the result should be read with genuine interest and proportionate caution. Peer review is not a guarantee of correctness, but it is a process that forces authors to respond to technical criticism from specialists who have no stake in a particular outcome. Preprints that survive that process, often with substantive revisions, emerge with a stronger evidential base than the version that first appeared. Until that stage is complete, the responsible reading keeps uncertainty explicitly visible rather than treating the claims as established findings.

The next step is to see whether the effect survives when independent surveys, different calibration strategies and tighter control of systematic uncertainties enter the picture. Programmes such as Euclid, DESI and the Rubin Observatory will deliver datasets over the next several years that cover the same parameter space with largely independent methods. If the current signal persists through those tests, its theoretical implications will become impossible to set aside. Until peer review and independent follow-up address those open questions, skepticism is not a failure of appreciation for the work; it is part of how science decides what to keep.

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