Photoproduction and detection of $ρ'\rightarrowπ^+π^-π^+π^-$ decays in ultra-peripheral collisions and at an electron-ion collider
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| Autores principales: | , , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866911297365344256 |
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| author | Devi, Neha Kim, Minjung Klein, Spencer R. Seger, Janet |
| author_facet | Devi, Neha Kim, Minjung Klein, Spencer R. Seger, Janet |
| contents | Vector meson photoproduction is an important probe of nuclear structure. Light vector mesons are most sensitive to low$-x$ structure, as long as they are not too light for perturbative QCD calculations. The $ρ'$ is of interest as an intermediate mass state (between the $ρ$ and $J/ψ$) that is easier to detect than the $ϕ$.
Using HERA data on proton targets, we make projections for lead/gold targets in UPCs at the Large Hadron Collider and RHIC, and for $ep$ and $eA$ collisions at a future Electron-Ion Collider (EIC). We compare the UPC projections with ALICE data, and constrain the branching ratio divided by the square of the photon-$ρ'$ coupling. The data prefer large couplings and small branching ratio, probably less than 25\%. The photon-meson coupling predicted by generalized vector meson dominance does not fit the data. The HERA $ep$ and ALICE UPC $e$Pb data exhibit very similar $4π$ mass spectra, indicating that, if the system is composed of two resonances, the products of their photon couplings with their four-pion branching ratios are similar.
The predicted rates are high for both UPCs and the EIC. The $ρ'\rightarrowπ^+π^-π^+π^-$ decay can be observed at the EIC with high efficiency. In $ep$ collisions at the highest energy, the forward B0 detector is needed to observe this channel down to the lowest achievable Bjorken$-x$ values. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_00916 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Photoproduction and detection of $ρ'\rightarrowπ^+π^-π^+π^-$ decays in ultra-peripheral collisions and at an electron-ion collider Devi, Neha Kim, Minjung Klein, Spencer R. Seger, Janet High Energy Physics - Phenomenology Nuclear Experiment Vector meson photoproduction is an important probe of nuclear structure. Light vector mesons are most sensitive to low$-x$ structure, as long as they are not too light for perturbative QCD calculations. The $ρ'$ is of interest as an intermediate mass state (between the $ρ$ and $J/ψ$) that is easier to detect than the $ϕ$. Using HERA data on proton targets, we make projections for lead/gold targets in UPCs at the Large Hadron Collider and RHIC, and for $ep$ and $eA$ collisions at a future Electron-Ion Collider (EIC). We compare the UPC projections with ALICE data, and constrain the branching ratio divided by the square of the photon-$ρ'$ coupling. The data prefer large couplings and small branching ratio, probably less than 25\%. The photon-meson coupling predicted by generalized vector meson dominance does not fit the data. The HERA $ep$ and ALICE UPC $e$Pb data exhibit very similar $4π$ mass spectra, indicating that, if the system is composed of two resonances, the products of their photon couplings with their four-pion branching ratios are similar. The predicted rates are high for both UPCs and the EIC. The $ρ'\rightarrowπ^+π^-π^+π^-$ decay can be observed at the EIC with high efficiency. In $ep$ collisions at the highest energy, the forward B0 detector is needed to observe this channel down to the lowest achievable Bjorken$-x$ values. |
| title | Photoproduction and detection of $ρ'\rightarrowπ^+π^-π^+π^-$ decays in ultra-peripheral collisions and at an electron-ion collider |
| topic | High Energy Physics - Phenomenology Nuclear Experiment |
| url | https://arxiv.org/abs/2505.00916 |