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| Format: | Preprint |
| Published: |
2023
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| Online Access: | https://arxiv.org/abs/2308.16590 |
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| _version_ | 1866913311835029504 |
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| author | ALICE Collaboration |
| author_facet | ALICE Collaboration |
| contents | Correlations in azimuthal angle extending over a long range in pseudorapidity between particles, usually called the "ridge" phenomenon, were discovered in heavy-ion collisions, and later found in pp and p$-$Pb collisions. In large systems, they are thought to arise from the expansion (collective flow) of the produced particles. Extending these measurements over a wider range in pseudorapidity and final-state particle multiplicity is important to understand better the origin of these long-range correlations in small-collision systems. In this Letter, measurements of the long-range correlations in p$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV are extended to a pseudorapidity gap of $Δη\sim 8$ between particles using the ALICE, forward multiplicity detectors. After suppressing non-flow correlations, e.g., from jet and resonance decays, the ridge structure is observed to persist up to a very large gap of $Δη\sim 8$ for the first time in p$-$Pb collisions. This shows that the collective flow-like correlations extend over an extensive pseudorapidity range also in small-collision systems such as p$-$Pb collisions. The pseudorapidity dependence of the second-order anisotropic flow coefficient, $v_{2}(η)$, is extracted from the long-range correlations. The $v_{2}(η)$ results are presented for a wide pseudorapidity range of $-3.1 < η< 4.8$ in various centrality classes in p$-$Pb collisions. To gain a comprehensive understanding of the source of anisotropic flow in small-collision systems, the $v_{2}(η)$ measurements are compared to hydrodynamic and transport model calculations. The comparison suggests that the final-state interactions play a dominant role in developing the anisotropic flow in small-collision systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2308_16590 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Measurements of long-range two-particle correlation over a wide pseudorapidity range in p$-$Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV ALICE Collaboration Nuclear Experiment High Energy Physics - Experiment Correlations in azimuthal angle extending over a long range in pseudorapidity between particles, usually called the "ridge" phenomenon, were discovered in heavy-ion collisions, and later found in pp and p$-$Pb collisions. In large systems, they are thought to arise from the expansion (collective flow) of the produced particles. Extending these measurements over a wider range in pseudorapidity and final-state particle multiplicity is important to understand better the origin of these long-range correlations in small-collision systems. In this Letter, measurements of the long-range correlations in p$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV are extended to a pseudorapidity gap of $Δη\sim 8$ between particles using the ALICE, forward multiplicity detectors. After suppressing non-flow correlations, e.g., from jet and resonance decays, the ridge structure is observed to persist up to a very large gap of $Δη\sim 8$ for the first time in p$-$Pb collisions. This shows that the collective flow-like correlations extend over an extensive pseudorapidity range also in small-collision systems such as p$-$Pb collisions. The pseudorapidity dependence of the second-order anisotropic flow coefficient, $v_{2}(η)$, is extracted from the long-range correlations. The $v_{2}(η)$ results are presented for a wide pseudorapidity range of $-3.1 < η< 4.8$ in various centrality classes in p$-$Pb collisions. To gain a comprehensive understanding of the source of anisotropic flow in small-collision systems, the $v_{2}(η)$ measurements are compared to hydrodynamic and transport model calculations. The comparison suggests that the final-state interactions play a dominant role in developing the anisotropic flow in small-collision systems. |
| title | Measurements of long-range two-particle correlation over a wide pseudorapidity range in p$-$Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV |
| topic | Nuclear Experiment High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2308.16590 |