Effects of finite coverage on global polarization observables in heavy ion collisions
In non-central relativistic heavy ion collisions, the created matter possesses a large initial orbital angular momentum. Particles produced in the collisions could be polarized globally in the direction of the orbital angular momentum due to spin–orbit coupling. Recently, the STAR experiment has pre...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2018-05-01
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| Series: | Physics Letters B |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S037026931830203X |
| _version_ | 1818348886457057280 |
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| author | Shaowei Lan Zi-Wei Lin Shusu Shi Xu Sun |
| author_facet | Shaowei Lan Zi-Wei Lin Shusu Shi Xu Sun |
| author_sort | Shaowei Lan |
| collection | DOAJ |
| description | In non-central relativistic heavy ion collisions, the created matter possesses a large initial orbital angular momentum. Particles produced in the collisions could be polarized globally in the direction of the orbital angular momentum due to spin–orbit coupling. Recently, the STAR experiment has presented polarization signals for Λ hyperons and possible spin alignment signals for ϕ mesons. Here we discuss the effects of finite coverage on these observables. The results from a multi-phase transport and a toy model both indicate that a pseudorapidity coverage narrower than |η|<∼1 will generate a larger value for the extracted ϕ-meson ρ00 parameter; thus a finite coverage can lead to an artificial deviation of ρ00 from 1/3. We also show that a finite η and pT coverage affect the extracted pH parameter for Λ hyperons when the real pH value is non-zero. Therefore proper corrections are necessary to reliably quantify the global polarization with experimental observables. |
| first_indexed | 2024-12-13T17:57:11Z |
| format | Article |
| id | doaj.art-20e9ad4807ea4591bc6da67cfc3dec7e |
| institution | Directory Open Access Journal |
| issn | 0370-2693 |
| language | English |
| last_indexed | 2024-12-13T17:57:11Z |
| publishDate | 2018-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Physics Letters B |
| spelling | doaj.art-20e9ad4807ea4591bc6da67cfc3dec7e2022-12-21T23:36:20ZengElsevierPhysics Letters B0370-26932018-05-01780319324Effects of finite coverage on global polarization observables in heavy ion collisionsShaowei Lan0Zi-Wei Lin1Shusu Shi2Xu Sun3Key Laboratory of Quarks and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan, 430079, ChinaKey Laboratory of Quarks and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan, 430079, China; Department of Physics, East Carolina University, Greenville, NC 27858, USAKey Laboratory of Quarks and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan, 430079, China; Corresponding author.Key Laboratory of Quarks and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan, 430079, ChinaIn non-central relativistic heavy ion collisions, the created matter possesses a large initial orbital angular momentum. Particles produced in the collisions could be polarized globally in the direction of the orbital angular momentum due to spin–orbit coupling. Recently, the STAR experiment has presented polarization signals for Λ hyperons and possible spin alignment signals for ϕ mesons. Here we discuss the effects of finite coverage on these observables. The results from a multi-phase transport and a toy model both indicate that a pseudorapidity coverage narrower than |η|<∼1 will generate a larger value for the extracted ϕ-meson ρ00 parameter; thus a finite coverage can lead to an artificial deviation of ρ00 from 1/3. We also show that a finite η and pT coverage affect the extracted pH parameter for Λ hyperons when the real pH value is non-zero. Therefore proper corrections are necessary to reliably quantify the global polarization with experimental observables.http://www.sciencedirect.com/science/article/pii/S037026931830203X |
| spellingShingle | Shaowei Lan Zi-Wei Lin Shusu Shi Xu Sun Effects of finite coverage on global polarization observables in heavy ion collisions Physics Letters B |
| title | Effects of finite coverage on global polarization observables in heavy ion collisions |
| title_full | Effects of finite coverage on global polarization observables in heavy ion collisions |
| title_fullStr | Effects of finite coverage on global polarization observables in heavy ion collisions |
| title_full_unstemmed | Effects of finite coverage on global polarization observables in heavy ion collisions |
| title_short | Effects of finite coverage on global polarization observables in heavy ion collisions |
| title_sort | effects of finite coverage on global polarization observables in heavy ion collisions |
| url | http://www.sciencedirect.com/science/article/pii/S037026931830203X |
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