On the minimum of $σ$-Brjuno functions

Fuente: arXiv
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Hauptverfasser: Bakhtawar, Ayreena, Carminati, Carlo, Marmi, Stefano
Format: Preprint
Veröffentlicht: 2026
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author Bakhtawar, Ayreena
Carminati, Carlo
Marmi, Stefano
author_facet Bakhtawar, Ayreena
Carminati, Carlo
Marmi, Stefano
contents $σ$-Brjuno functions were introduced in \cite{MaMoYo_06} as an interesting variant of the classical Brjuno function, where one substitutes the $\log$ singularity at $x=0$ with the power law divergence $x^{-1/σ},$ $(σ>0).$ As in the classical case, $B_σ$ is a locally unbounded, highly irregular lower semi continuous function; from semi continuity property it easily follows that $B_σ$ admits a global minimum but to locate it is quite a challenging problem. We prove that for $σ=n \in \mathbb{N}$, the unique global minimum of $B_n$ is achieved at the fixed point $ [0; \overline{n+1}]$. Furthermore, we prove that these minimizers are locally stable, showing that the point of minimum remains constant for $σ$ in a neighborhood of $n$. Finally, we discuss the scaling behavior near these minima and we formulate a conjecture about the phase transitions for the location of the minimizer as $σ$ varies.
format Preprint
id arxiv_https___arxiv_org_abs_2603_08378
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the minimum of $σ$-Brjuno functions
Bakhtawar, Ayreena
Carminati, Carlo
Marmi, Stefano
Dynamical Systems
$σ$-Brjuno functions were introduced in \cite{MaMoYo_06} as an interesting variant of the classical Brjuno function, where one substitutes the $\log$ singularity at $x=0$ with the power law divergence $x^{-1/σ},$ $(σ>0).$ As in the classical case, $B_σ$ is a locally unbounded, highly irregular lower semi continuous function; from semi continuity property it easily follows that $B_σ$ admits a global minimum but to locate it is quite a challenging problem. We prove that for $σ=n \in \mathbb{N}$, the unique global minimum of $B_n$ is achieved at the fixed point $ [0; \overline{n+1}]$. Furthermore, we prove that these minimizers are locally stable, showing that the point of minimum remains constant for $σ$ in a neighborhood of $n$. Finally, we discuss the scaling behavior near these minima and we formulate a conjecture about the phase transitions for the location of the minimizer as $σ$ varies.
title On the minimum of $σ$-Brjuno functions
topic Dynamical Systems
url https://arxiv.org/abs/2603.08378