Novel Cross Section Ratios as Possible Signals of Saturation in UPCs
| Title: | Novel Cross Section Ratios as Possible Signals of Saturation in UPCs |
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| Authors: | Kovchegov, Yuri V., Sun, Huachen, Tu, Zhoudunming |
| Publication Year: | 2023 |
| Collection: | High Energy Physics - Experiment High Energy Physics - Phenomenology Nuclear Experiment Nuclear Theory |
| Subject Terms: | High Energy Physics - Phenomenology, High Energy Physics - Experiment, Nuclear Experiment, Nuclear Theory |
| More Details: | We propose new cross section ratios in ultra-peripheral A$+$A and $p+$A collisions (UPCs) as a potential experimental signal of saturation physics. We consider the ratio $R_1$ of elastic vector meson photoproduction cross section to the inclusive hadron or jet photoproduction cross section. The ratio can be measured in the $\gamma +$A and $\gamma + p$ collisions taking place in the UPCs. We label the ratios $R_1 ({\rm A})$ and $R_1 (p)$, respectively. Constructing the double ratio $R_{\rm{UPC}} ({\rm A}) = R_1 ({\rm A})/R_1 (p)$, and performing a small-$x$ calculation both in the quasi-classical approximation and by including small-$x$ evolution, we observe that $R_{\rm{UPC}} ({\rm A})$ exhibits a markedly different dependence on the nuclear atomic number inside and outside the saturation region. This result indicates that $R_{\rm{UPC}} ({\rm A})$ and $R_1 ({\rm A})$ measurements in UPCs may help in the experimental searches for the evidence of saturation physics. Comment: Final version published in Journal |
| Document Type: | Working Paper |
| DOI: | 10.1103/PhysRevD.109.094028 |
| Access URL: | http://arxiv.org/abs/2311.12208 |
| Accession Number: | edsarx.2311.12208 |
| Database: | arXiv |
| DOI: | 10.1103/PhysRevD.109.094028 |
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