Breit-Wigner approximation for propagators of mixed unstable states
Abstract For systems of unstable particles that mix with each other, an approximation of the fully momentum- dependent propagator matrix is presented in terms of a sum of simple Breit-Wigner propagators that are multiplied with finite on-shell wave function normalisation factors. The latter are eval...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2017-09-01
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| Series: | Journal of High Energy Physics |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1007/JHEP09(2017)079 |
| _version_ | 1811205202167988224 |
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| author | Elina Fuchs Georg Weiglein |
| author_facet | Elina Fuchs Georg Weiglein |
| author_sort | Elina Fuchs |
| collection | DOAJ |
| description | Abstract For systems of unstable particles that mix with each other, an approximation of the fully momentum- dependent propagator matrix is presented in terms of a sum of simple Breit-Wigner propagators that are multiplied with finite on-shell wave function normalisation factors. The latter are evaluated at the complex poles of the propagators. The pole structure of general propagator matrices is carefully analysed, and it is demonstrated that in the proposed approximation imaginary parts arising from absorptive parts of loop integrals are properly taken into account. Applying the formalism to the neutral MSSM Higgs sector with complex parameters, very good numerical agreement is found between cross sections based on the full propagators and the corresponding cross sections based on the described approximation. The proposed approach does not only technically simplify the treatment of propagators with non-vanishing off-diagonal contributions, it is shown that it can also facilitate an improved theoretical prediction of the considered observables via a more precise implementation of the total widths of the involved particles. It is also well-suited for the incorporation of interference effects arising from overlapping resonances. |
| first_indexed | 2024-04-12T03:26:44Z |
| format | Article |
| id | doaj.art-f5432b16ec8a44909f33fb9ceca6e96a |
| institution | Directory Open Access Journal |
| issn | 1029-8479 |
| language | English |
| last_indexed | 2024-04-12T03:26:44Z |
| publishDate | 2017-09-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj.art-f5432b16ec8a44909f33fb9ceca6e96a2022-12-22T03:49:41ZengSpringerOpenJournal of High Energy Physics1029-84792017-09-012017914510.1007/JHEP09(2017)079Breit-Wigner approximation for propagators of mixed unstable statesElina Fuchs0Georg Weiglein1Department of Particle Physics and Astrophysics, Weizmann Institute of ScienceDESY, Deutsches Elektronen-SynchrotronAbstract For systems of unstable particles that mix with each other, an approximation of the fully momentum- dependent propagator matrix is presented in terms of a sum of simple Breit-Wigner propagators that are multiplied with finite on-shell wave function normalisation factors. The latter are evaluated at the complex poles of the propagators. The pole structure of general propagator matrices is carefully analysed, and it is demonstrated that in the proposed approximation imaginary parts arising from absorptive parts of loop integrals are properly taken into account. Applying the formalism to the neutral MSSM Higgs sector with complex parameters, very good numerical agreement is found between cross sections based on the full propagators and the corresponding cross sections based on the described approximation. The proposed approach does not only technically simplify the treatment of propagators with non-vanishing off-diagonal contributions, it is shown that it can also facilitate an improved theoretical prediction of the considered observables via a more precise implementation of the total widths of the involved particles. It is also well-suited for the incorporation of interference effects arising from overlapping resonances.http://link.springer.com/article/10.1007/JHEP09(2017)079Beyond Standard ModelCP violationHiggs PhysicsSupersymmetric Standard Model |
| spellingShingle | Elina Fuchs Georg Weiglein Breit-Wigner approximation for propagators of mixed unstable states Journal of High Energy Physics Beyond Standard Model CP violation Higgs Physics Supersymmetric Standard Model |
| title | Breit-Wigner approximation for propagators of mixed unstable states |
| title_full | Breit-Wigner approximation for propagators of mixed unstable states |
| title_fullStr | Breit-Wigner approximation for propagators of mixed unstable states |
| title_full_unstemmed | Breit-Wigner approximation for propagators of mixed unstable states |
| title_short | Breit-Wigner approximation for propagators of mixed unstable states |
| title_sort | breit wigner approximation for propagators of mixed unstable states |
| topic | Beyond Standard Model CP violation Higgs Physics Supersymmetric Standard Model |
| url | http://link.springer.com/article/10.1007/JHEP09(2017)079 |
| work_keys_str_mv | AT elinafuchs breitwignerapproximationforpropagatorsofmixedunstablestates AT georgweiglein breitwignerapproximationforpropagatorsofmixedunstablestates |