The effect of initial nuclear deformation on dielectron photoproduction in hadronic heavy-ion collisions
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arXiv
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| Format: | Preprint |
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2023
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| author | Luo, Jiaxuan. Li, Xinbai. Tang, Zebo. Wu, Xin. Zha, Wangmei. |
| author_facet | Luo, Jiaxuan. Li, Xinbai. Tang, Zebo. Wu, Xin. Zha, Wangmei. |
| contents | Significant excesses of $e^+e^-$ pair production at very low transverse momentum ($p_T <$ 0.15 GeV/c) were observed by the STAR collaboration in hadronic heavy-ion collisions. Such enhancement is assumed to be a sign of photon-photon production in heavy-ion collisions with hadronic overlap, based on comparisons with model calculations for spherical Au + Au collisions. However, there is a lack of calculations for $e^+e^-$ pair production from coherent photon-photon interactions in hadronic U + U collisions, due to the deformity of Uranium nuclei. In this article, we present calculations for $e^+e^-$ pair photoproduction at $\sqrt{s_{NN}}$ = 193 GeV in both spherical and deformed U + U collisions within STAR detector acceptance using the equivalent photon approximation (EPA). We conduct event-by-event analysis to investigate the effects of initial nuclear deformation on pair production. Our numerical results show good agreement with experimental data for the 40%--60% and 60%--80% centrality classes in U + U collisions, and the differences between spherical and deformed configurations are approximately 3\%. We also calculate the yields of the photoproduced $e^+e^-$ pair in hadronic deformed Ru + Ru and Zr + Zr collisions at $\sqrt{s_{NN}}$ = 200 GeV. The results reveal that the ratios of the yields of Ru to Zr exhibit very small differences ($<$ 1%) between spherical and deformed cases. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2308_03070 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | The effect of initial nuclear deformation on dielectron photoproduction in hadronic heavy-ion collisions Luo, Jiaxuan. Li, Xinbai. Tang, Zebo. Wu, Xin. Zha, Wangmei. High Energy Physics - Phenomenology Nuclear Theory Significant excesses of $e^+e^-$ pair production at very low transverse momentum ($p_T <$ 0.15 GeV/c) were observed by the STAR collaboration in hadronic heavy-ion collisions. Such enhancement is assumed to be a sign of photon-photon production in heavy-ion collisions with hadronic overlap, based on comparisons with model calculations for spherical Au + Au collisions. However, there is a lack of calculations for $e^+e^-$ pair production from coherent photon-photon interactions in hadronic U + U collisions, due to the deformity of Uranium nuclei. In this article, we present calculations for $e^+e^-$ pair photoproduction at $\sqrt{s_{NN}}$ = 193 GeV in both spherical and deformed U + U collisions within STAR detector acceptance using the equivalent photon approximation (EPA). We conduct event-by-event analysis to investigate the effects of initial nuclear deformation on pair production. Our numerical results show good agreement with experimental data for the 40%--60% and 60%--80% centrality classes in U + U collisions, and the differences between spherical and deformed configurations are approximately 3\%. We also calculate the yields of the photoproduced $e^+e^-$ pair in hadronic deformed Ru + Ru and Zr + Zr collisions at $\sqrt{s_{NN}}$ = 200 GeV. The results reveal that the ratios of the yields of Ru to Zr exhibit very small differences ($<$ 1%) between spherical and deformed cases. |
| title | The effect of initial nuclear deformation on dielectron photoproduction in hadronic heavy-ion collisions |
| topic | High Energy Physics - Phenomenology Nuclear Theory |
| url | https://arxiv.org/abs/2308.03070 |