Observation of CP violation in B+/- → DK+/- decays
<p>An accurate determination of the angle <em>γ</em> of the Unitary Triangle is one of the most important goals of the LHCb experiment. The LHCb detector is a single-arm spectrometer at the LHC, optimised for beauty and charm flavour physics. As the angle <em>γ</em> is...
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| Format: | Thesis |
| Language: | English |
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2012
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| _version_ | 1826292729496207360 |
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| author | Gandini, P |
| author2 | John, M |
| author_facet | John, M Gandini, P |
| author_sort | Gandini, P |
| collection | OXFORD |
| description | <p>An accurate determination of the angle <em>γ</em> of the Unitary Triangle is one of the most important goals of the LHCb experiment. The LHCb detector is a single-arm spectrometer at the LHC, optimised for beauty and charm flavour physics. As the angle <em>γ</em> is the least experimentally constrained parameter of the Unitary Triangle, its precise experimental determination can be used to test the validity of the Standard Model. The Unitary Triangle phase <em>γ</em> can be extracted in <em>B</em> → <em>DK</em> decays at tree-level, exploiting the interference between <em>b</em> → <em>c</em>(<em>ūs</em>) and <em>b</em> → <em>u</em>(<em>c̄s</em>) transitions. This interference is sensitive to <em>γ</em> and can give measurable charge asymmetries. In particular, <em>γ</em> ≠ 0 is required to produce <em>direct CP</em> violation in <em>B</em> decays and this is the only <em>CP</em>-violating mechanism for the decay of charged <em>B</em><sup>±</sup> mesons.</p> <p>In this thesis, an analysis of <em>CP</em> violation in <em>B</em><sup>±</sup> → <em>DK</em><sup>±</sup> and <em>B</em><sup>±</sup> → <em>Dπ</em><sup>±</sup> decays is presented, where the <em>D</em> meson is reconstructed in the two-body final states: <em>K</em><sup>±</sup><em>π</em><sup>∓</sup>, <em>K</em><sup>+</sup><em>K</em><sup>−</sup>, <em>π</em><sup>+</sup><em>π</em><sup>−</sup> and <em>π</em><sup>±</sup><em>K</em><sup>∓</sup>. The analysis uses the full 2011 LHCb dataset of 1.0 fb<sup>-1</sup>, collected from <em>pp</em> collisions at √<em>s</em> = 7 TeV. Several <em>CP</em>-related quantities, e.g the ratio of <em>B</em> → <em>DK</em> and <em>B</em> → <em>Dπ</em> branching fractions and their charge asymmetries, are measured via a simultaneous fit to the invariant mass distributions of the modes considered. The suppressed <em>B</em><sup>±</sup> → <em>DK</em><sup>±</sup> mode is observed for the first time with ≈ 10<em>σ</em> significance. Once all measurements are combined, direct <em>CP</em> violation is established in <em>B</em><sup>±</sup> decays with a total significance of 5.8<em>σ</em>.</p> |
| first_indexed | 2024-03-07T03:19:12Z |
| format | Thesis |
| id | oxford-uuid:b6db99c0-7b46-45af-8e7c-6b6fddd73abb |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T03:19:12Z |
| publishDate | 2012 |
| record_format | dspace |
| spelling | oxford-uuid:b6db99c0-7b46-45af-8e7c-6b6fddd73abb2022-03-27T04:44:04ZObservation of CP violation in B+/- → DK+/- decaysThesishttp://purl.org/coar/resource_type/c_db06uuid:b6db99c0-7b46-45af-8e7c-6b6fddd73abbParticle physicsEnglishOxford University Research Archive - Valet2012Gandini, PJohn, M<p>An accurate determination of the angle <em>γ</em> of the Unitary Triangle is one of the most important goals of the LHCb experiment. The LHCb detector is a single-arm spectrometer at the LHC, optimised for beauty and charm flavour physics. As the angle <em>γ</em> is the least experimentally constrained parameter of the Unitary Triangle, its precise experimental determination can be used to test the validity of the Standard Model. The Unitary Triangle phase <em>γ</em> can be extracted in <em>B</em> → <em>DK</em> decays at tree-level, exploiting the interference between <em>b</em> → <em>c</em>(<em>ūs</em>) and <em>b</em> → <em>u</em>(<em>c̄s</em>) transitions. This interference is sensitive to <em>γ</em> and can give measurable charge asymmetries. In particular, <em>γ</em> ≠ 0 is required to produce <em>direct CP</em> violation in <em>B</em> decays and this is the only <em>CP</em>-violating mechanism for the decay of charged <em>B</em><sup>±</sup> mesons.</p> <p>In this thesis, an analysis of <em>CP</em> violation in <em>B</em><sup>±</sup> → <em>DK</em><sup>±</sup> and <em>B</em><sup>±</sup> → <em>Dπ</em><sup>±</sup> decays is presented, where the <em>D</em> meson is reconstructed in the two-body final states: <em>K</em><sup>±</sup><em>π</em><sup>∓</sup>, <em>K</em><sup>+</sup><em>K</em><sup>−</sup>, <em>π</em><sup>+</sup><em>π</em><sup>−</sup> and <em>π</em><sup>±</sup><em>K</em><sup>∓</sup>. The analysis uses the full 2011 LHCb dataset of 1.0 fb<sup>-1</sup>, collected from <em>pp</em> collisions at √<em>s</em> = 7 TeV. Several <em>CP</em>-related quantities, e.g the ratio of <em>B</em> → <em>DK</em> and <em>B</em> → <em>Dπ</em> branching fractions and their charge asymmetries, are measured via a simultaneous fit to the invariant mass distributions of the modes considered. The suppressed <em>B</em><sup>±</sup> → <em>DK</em><sup>±</sup> mode is observed for the first time with ≈ 10<em>σ</em> significance. Once all measurements are combined, direct <em>CP</em> violation is established in <em>B</em><sup>±</sup> decays with a total significance of 5.8<em>σ</em>.</p> |
| spellingShingle | Particle physics Gandini, P Observation of CP violation in B+/- → DK+/- decays |
| title | Observation of CP violation in B+/- → DK+/- decays |
| title_full | Observation of CP violation in B+/- → DK+/- decays |
| title_fullStr | Observation of CP violation in B+/- → DK+/- decays |
| title_full_unstemmed | Observation of CP violation in B+/- → DK+/- decays |
| title_short | Observation of CP violation in B+/- → DK+/- decays |
| title_sort | observation of cp violation in b dk decays |
| topic | Particle physics |
| work_keys_str_mv | AT gandinip observationofcpviolationinbdkdecays |