Ratio of $J/Ψ$ and $Ψ(2s)$ exclusive photoproduction cross-sections as an indicator for the presence of non-linear QCD evolution
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arXiv
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| Format: | Preprint |
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2023
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| author | Peredo, Marco Alcazar Hentschinski, Martin |
| author_facet | Peredo, Marco Alcazar Hentschinski, Martin |
| contents | We investigate the proposal that the rise with energy of the ratio of the exclusive photo-production cross-sections of vector mesons $Ψ(2s)$ and $J/Ψ$ can serve as an indicator for the presence of high gluon densities and associated non-linear high energy evolution; we study this proposal for both photoproduction on a proton and a lead nucleus. While previous studies were based on unintegrated gluon distributions subject to linear (Balitsky-Fadin-Kuraev-Lipatov) and non-linear (Balitsky-Kovchegov) evolution equations, the current study is based on the Golec-Biernat Wüsthoff (GBW) and Bartels Golec-Biernat Kowalski (BGK) models, which allow assessing more directly the relevance of non-linear corrections for the description of the energy dependence of the photoproduction cross-section. We find that the rise of the ratio is directly related to the presence of a node in the $Ψ(2s)$ wave function and only manifests itself for the complete non-linear models, while it is absent for their linearized versions. We further provide predictions based on leading order collinear factorization and examine to which extent such an approach can mimic a ratio rising with energy. We also provide a description of recent ALICE data on the energy dependence of the photonuclear $J/Ψ$ production cross-section and give predictions for the energy dependence of the ratio of $Ψ(2s)$ and $J/Ψ$ photoproduction cross-sections for both scattering on a proton and a lead nucleus. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2308_15430 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Ratio of $J/Ψ$ and $Ψ(2s)$ exclusive photoproduction cross-sections as an indicator for the presence of non-linear QCD evolution Peredo, Marco Alcazar Hentschinski, Martin High Energy Physics - Phenomenology We investigate the proposal that the rise with energy of the ratio of the exclusive photo-production cross-sections of vector mesons $Ψ(2s)$ and $J/Ψ$ can serve as an indicator for the presence of high gluon densities and associated non-linear high energy evolution; we study this proposal for both photoproduction on a proton and a lead nucleus. While previous studies were based on unintegrated gluon distributions subject to linear (Balitsky-Fadin-Kuraev-Lipatov) and non-linear (Balitsky-Kovchegov) evolution equations, the current study is based on the Golec-Biernat Wüsthoff (GBW) and Bartels Golec-Biernat Kowalski (BGK) models, which allow assessing more directly the relevance of non-linear corrections for the description of the energy dependence of the photoproduction cross-section. We find that the rise of the ratio is directly related to the presence of a node in the $Ψ(2s)$ wave function and only manifests itself for the complete non-linear models, while it is absent for their linearized versions. We further provide predictions based on leading order collinear factorization and examine to which extent such an approach can mimic a ratio rising with energy. We also provide a description of recent ALICE data on the energy dependence of the photonuclear $J/Ψ$ production cross-section and give predictions for the energy dependence of the ratio of $Ψ(2s)$ and $J/Ψ$ photoproduction cross-sections for both scattering on a proton and a lead nucleus. |
| title | Ratio of $J/Ψ$ and $Ψ(2s)$ exclusive photoproduction cross-sections as an indicator for the presence of non-linear QCD evolution |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2308.15430 |