Observation of Long-Range Elliptic Azimuthal Anisotropies in √s = 13 and 2.76 TeV p p Collisions with the ATLAS Detector
ATLAS has measured two-particle correlations as a function of the relative azimuthal angle, Δϕ, and pseudorapidity, Δη, in √s=13 and 2.76 TeV pp collisions at the LHC using charged particles measured in the pseudorapidity interval |η|<2.5. The correlation functions evaluated in different interval...
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| Format: | Article |
| Language: | en_US |
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American Physical Society
2017
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| Online Access: | http://hdl.handle.net/1721.1/110670 https://orcid.org/0000-0002-7586-7253 |
| _version_ | 1826199950878310400 |
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| author | Taylor, Frank E |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Taylor, Frank E |
| author_sort | Taylor, Frank E |
| collection | MIT |
| description | ATLAS has measured two-particle correlations as a function of the relative azimuthal angle, Δϕ, and pseudorapidity, Δη, in √s=13 and 2.76 TeV pp collisions at the LHC using charged particles measured in the pseudorapidity interval |η|<2.5. The correlation functions evaluated in different intervals of measured charged-particle multiplicity show a multiplicity-dependent enhancement at Δϕ∼0 that extends over a wide range of Δη, which has been referred to as the “ridge.” Per-trigger-particle yields, Y(Δϕ), are measured over 2<|Δη|<5. For both collision energies, the Y(Δϕ) distribution in all multiplicity intervals is found to be consistent with a linear combination of the per-trigger-particle yields measured in collisions with less than 20 reconstructed tracks, and a constant combinatoric contribution modulated by
cos (2Δϕ). The fitted Fourier coefficient, v2, 2, exhibits factorization, suggesting that the ridge results from per-event cos(2ϕ) modulation of the single-particle distribution with Fourier coefficients v[subscript 2]. The v[subscript 2] values are presented as a function of multiplicity and transverse momentum. They are found to be approximately constant as a function of multiplicity and to have a pT dependence similar to that measured in p+Pb and Pb+Pb collisions. The v[subscript 2] values in the 13 and 2.76 TeV data are consistent within uncertainties. These results suggest that the ridge in pp collisions arises from the same or similar underlying physics as observed in p+ Pb collisions, and that the dynamics responsible for the ridge has no strong
√s dependence. |
| first_indexed | 2024-09-23T11:28:23Z |
| format | Article |
| id | mit-1721.1/110670 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T11:28:23Z |
| publishDate | 2017 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | mit-1721.1/1106702022-09-27T19:48:16Z Observation of Long-Range Elliptic Azimuthal Anisotropies in √s = 13 and 2.76 TeV p p Collisions with the ATLAS Detector Taylor, Frank E Massachusetts Institute of Technology. Department of Physics Taylor, Frank E ATLAS has measured two-particle correlations as a function of the relative azimuthal angle, Δϕ, and pseudorapidity, Δη, in √s=13 and 2.76 TeV pp collisions at the LHC using charged particles measured in the pseudorapidity interval |η|<2.5. The correlation functions evaluated in different intervals of measured charged-particle multiplicity show a multiplicity-dependent enhancement at Δϕ∼0 that extends over a wide range of Δη, which has been referred to as the “ridge.” Per-trigger-particle yields, Y(Δϕ), are measured over 2<|Δη|<5. For both collision energies, the Y(Δϕ) distribution in all multiplicity intervals is found to be consistent with a linear combination of the per-trigger-particle yields measured in collisions with less than 20 reconstructed tracks, and a constant combinatoric contribution modulated by cos (2Δϕ). The fitted Fourier coefficient, v2, 2, exhibits factorization, suggesting that the ridge results from per-event cos(2ϕ) modulation of the single-particle distribution with Fourier coefficients v[subscript 2]. The v[subscript 2] values are presented as a function of multiplicity and transverse momentum. They are found to be approximately constant as a function of multiplicity and to have a pT dependence similar to that measured in p+Pb and Pb+Pb collisions. The v[subscript 2] values in the 13 and 2.76 TeV data are consistent within uncertainties. These results suggest that the ridge in pp collisions arises from the same or similar underlying physics as observed in p+ Pb collisions, and that the dynamics responsible for the ridge has no strong √s dependence. United States. Department of Energy National Science Foundation (U.S.). Division of Physics 2017-07-12T15:43:33Z 2017-07-12T15:43:33Z 2016-04 2015-09 Article http://purl.org/eprint/type/JournalArticle 0031-9007 1079-7114 http://hdl.handle.net/1721.1/110670 Aad, G. et al. “Observation of Long-Range Elliptic Azimuthal Anisotropies in √S = 13 and 2.76 TeV P P Collisions with the ATLAS Detector.” Physical Review Letters 116.17 (2016): n. pag. © 2016 CERN for the ATLAS Collaboration https://orcid.org/0000-0002-7586-7253 en_US http://dx.doi.org/10.1103/PhysRevLett.116.172301 Physical Review Letters Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Physical Society APS |
| spellingShingle | Taylor, Frank E Observation of Long-Range Elliptic Azimuthal Anisotropies in √s = 13 and 2.76 TeV p p Collisions with the ATLAS Detector |
| title | Observation of Long-Range Elliptic Azimuthal Anisotropies in √s = 13 and 2.76 TeV p p Collisions with the ATLAS Detector |
| title_full | Observation of Long-Range Elliptic Azimuthal Anisotropies in √s = 13 and 2.76 TeV p p Collisions with the ATLAS Detector |
| title_fullStr | Observation of Long-Range Elliptic Azimuthal Anisotropies in √s = 13 and 2.76 TeV p p Collisions with the ATLAS Detector |
| title_full_unstemmed | Observation of Long-Range Elliptic Azimuthal Anisotropies in √s = 13 and 2.76 TeV p p Collisions with the ATLAS Detector |
| title_short | Observation of Long-Range Elliptic Azimuthal Anisotropies in √s = 13 and 2.76 TeV p p Collisions with the ATLAS Detector |
| title_sort | observation of long range elliptic azimuthal anisotropies in √s 13 and 2 76 tev p p collisions with the atlas detector |
| url | http://hdl.handle.net/1721.1/110670 https://orcid.org/0000-0002-7586-7253 |
| work_keys_str_mv | AT taylorfranke observationoflongrangeellipticazimuthalanisotropiesins13and276tevppcollisionswiththeatlasdetector |