Salvato in:
| Autori principali: | , , , |
|---|---|
| Natura: | Preprint |
| Pubblicazione: |
2026
|
| Soggetti: | |
| Accesso online: | https://arxiv.org/abs/2601.05878 |
| Tags: |
Aggiungi Tag
Nessun Tag, puoi essere il primo ad aggiungerne!!
|
| _version_ | 1866908755448299520 |
|---|---|
| author | Bernard, Véronique Descotes-Genon, Sébastien Knecht, Marc Moussallam, Bachir |
| author_facet | Bernard, Véronique Descotes-Genon, Sébastien Knecht, Marc Moussallam, Bachir |
| contents | We propose a description of the $K^+$, $K_S$ radiative decay form factors $W_+$, $W_S$ based on general properties of analyticity and unitarity. Starting from the simple consideration of the asymptotic behaviour of the two combinations $2W_+-W_S$ and $W_+ +W_S$ we derive a dispersive representation involving only two parameters. Using the rich experimental information on the $K\to3π$ amplitudes, extended beyond the low energy region using the Khuri-Treiman formalism, we show that the sign of the $W_+$ form factor is unambiguously determined and its energy dependence can be well reproduced. We also show that the yet unknown $Δ{I}=1/2$ part of the $K_S \to π^+π^-π^0$ can be determined from the value of $W_+(0)+W_S(0)$. The possibility of fixing the sign of $W_S$ from experiment is discussed. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2601_05878 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Dispersive description of the $K \to π\ell^+ \ell^-$ radiative amplitudes Bernard, Véronique Descotes-Genon, Sébastien Knecht, Marc Moussallam, Bachir High Energy Physics - Phenomenology We propose a description of the $K^+$, $K_S$ radiative decay form factors $W_+$, $W_S$ based on general properties of analyticity and unitarity. Starting from the simple consideration of the asymptotic behaviour of the two combinations $2W_+-W_S$ and $W_+ +W_S$ we derive a dispersive representation involving only two parameters. Using the rich experimental information on the $K\to3π$ amplitudes, extended beyond the low energy region using the Khuri-Treiman formalism, we show that the sign of the $W_+$ form factor is unambiguously determined and its energy dependence can be well reproduced. We also show that the yet unknown $Δ{I}=1/2$ part of the $K_S \to π^+π^-π^0$ can be determined from the value of $W_+(0)+W_S(0)$. The possibility of fixing the sign of $W_S$ from experiment is discussed. |
| title | Dispersive description of the $K \to π\ell^+ \ell^-$ radiative amplitudes |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2601.05878 |