Probabilities of rare events in product kernel aggregation: An exact formula and phase diagram

Fuente: arXiv
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Autores principales: Goutham, R., Rajesh, R., Subashri, V., Zaboronski, Oleg
Formato: Preprint
Publicado: 2026
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author Goutham, R.
Rajesh, R.
Subashri, V.
Zaboronski, Oleg
author_facet Goutham, R.
Rajesh, R.
Subashri, V.
Zaboronski, Oleg
contents We present an exact method for calculating the large deviation function describing rare fluctuations in the number of particles for product-kernel aggregation. Starting from the master equation, we derive an exact integral representation for the probability $P(M,N,t)$ of observing $N$ particles at time $t$ starting from $M$ monomers for any finite $M, N, t$. From this, we obtain an exact expression for the exponential moment $\langle p^N\rangle$ for integer $p$. Employing a replica conjecture -- numerically validated by finite-$M$ scaling -- we extend this result to real $p \geq 0$. The convex envelope of the large deviation function, obtained via a Legendre-Fenchel transform of the exponential moment, shows singular behavior. The singular structure allows us to construct the full phase diagram of product-kernel aggregation, which contains a tricritical point, separating continuous and discontinuous transitions. We also compute the asymptotic form of the LDF for small $N/M$.
format Preprint
id arxiv_https___arxiv_org_abs_2602_04363
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Probabilities of rare events in product kernel aggregation: An exact formula and phase diagram
Goutham, R.
Rajesh, R.
Subashri, V.
Zaboronski, Oleg
Statistical Mechanics
We present an exact method for calculating the large deviation function describing rare fluctuations in the number of particles for product-kernel aggregation. Starting from the master equation, we derive an exact integral representation for the probability $P(M,N,t)$ of observing $N$ particles at time $t$ starting from $M$ monomers for any finite $M, N, t$. From this, we obtain an exact expression for the exponential moment $\langle p^N\rangle$ for integer $p$. Employing a replica conjecture -- numerically validated by finite-$M$ scaling -- we extend this result to real $p \geq 0$. The convex envelope of the large deviation function, obtained via a Legendre-Fenchel transform of the exponential moment, shows singular behavior. The singular structure allows us to construct the full phase diagram of product-kernel aggregation, which contains a tricritical point, separating continuous and discontinuous transitions. We also compute the asymptotic form of the LDF for small $N/M$.
title Probabilities of rare events in product kernel aggregation: An exact formula and phase diagram
topic Statistical Mechanics
url https://arxiv.org/abs/2602.04363