Constraints on the χ c 1 versus χ c 2 Polarizations in Proton-Proton Collisions at √ s = 8 TeV
© 2020 CERN. The polarizations of promptly produced χc1 and χc2 mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at s=8 TeV. The χc states are reconstructed via their radiative decays χc→J/ψγ, with the photons being measured through conversions to...
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| Format: | Article |
| Language: | English |
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American Physical Society (APS)
2021
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| Online Access: | https://hdl.handle.net/1721.1/133569 |
| _version_ | 1826214122353590272 |
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| author | The CMS Collaboration |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics The CMS Collaboration |
| author_sort | The CMS Collaboration |
| collection | MIT |
| description | © 2020 CERN. The polarizations of promptly produced χc1 and χc2 mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at s=8 TeV. The χc states are reconstructed via their radiative decays χc→J/ψγ, with the photons being measured through conversions to e+e-, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χc2 to χc1 yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ→μ+μ- decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum. |
| first_indexed | 2024-09-23T16:00:10Z |
| format | Article |
| id | mit-1721.1/133569 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T16:00:10Z |
| publishDate | 2021 |
| publisher | American Physical Society (APS) |
| record_format | dspace |
| spelling | mit-1721.1/1335692023-01-05T20:16:22Z Constraints on the χ c 1 versus χ c 2 Polarizations in Proton-Proton Collisions at √ s = 8 TeV The CMS Collaboration Massachusetts Institute of Technology. Department of Physics Massachusetts Institute of Technology. Laboratory for Nuclear Science © 2020 CERN. The polarizations of promptly produced χc1 and χc2 mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at s=8 TeV. The χc states are reconstructed via their radiative decays χc→J/ψγ, with the photons being measured through conversions to e+e-, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χc2 to χc1 yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ→μ+μ- decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum. 2021-10-27T19:53:34Z 2021-10-27T19:53:34Z 2020 2021-07-08T18:07:16Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/133569 en 10.1103/PHYSREVLETT.124.162002 Physical Review Letters Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/ application/pdf American Physical Society (APS) APS |
| spellingShingle | The CMS Collaboration Constraints on the χ c 1 versus χ c 2 Polarizations in Proton-Proton Collisions at √ s = 8 TeV |
| title | Constraints on the χ c 1 versus χ c 2 Polarizations in Proton-Proton Collisions at √ s = 8 TeV |
| title_full | Constraints on the χ c 1 versus χ c 2 Polarizations in Proton-Proton Collisions at √ s = 8 TeV |
| title_fullStr | Constraints on the χ c 1 versus χ c 2 Polarizations in Proton-Proton Collisions at √ s = 8 TeV |
| title_full_unstemmed | Constraints on the χ c 1 versus χ c 2 Polarizations in Proton-Proton Collisions at √ s = 8 TeV |
| title_short | Constraints on the χ c 1 versus χ c 2 Polarizations in Proton-Proton Collisions at √ s = 8 TeV |
| title_sort | constraints on the χ c 1 versus χ c 2 polarizations in proton proton collisions at √ s 8 tev |
| url | https://hdl.handle.net/1721.1/133569 |
| work_keys_str_mv | AT thecmscollaboration constraintsonthechc1versuschc2polarizationsinprotonprotoncollisionsats8tev |