Light resonances and the low-q 2 bin of R K * $$ {R}_{K^{*}} $$
Abstract LHCb has reported hints of lepton-flavor universality violation in the rare decays B → K (*) ℓ + ℓ −, both in high- and low-q 2 bins. Although the high-q 2 hint may be explained by new short-ranged interactions, the low-q 2 one cannot. We thus explore the possibility that the latter is expl...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2018-03-01
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| Series: | Journal of High Energy Physics |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1007/JHEP03(2018)188 |
| _version_ | 1819155886232305664 |
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| author | Wolfgang Altmannshofer Michael J. Baker Stefania Gori Roni Harnik Maxim Pospelov Emmanuel Stamou Andrea Thamm |
| author_facet | Wolfgang Altmannshofer Michael J. Baker Stefania Gori Roni Harnik Maxim Pospelov Emmanuel Stamou Andrea Thamm |
| author_sort | Wolfgang Altmannshofer |
| collection | DOAJ |
| description | Abstract LHCb has reported hints of lepton-flavor universality violation in the rare decays B → K (*) ℓ + ℓ −, both in high- and low-q 2 bins. Although the high-q 2 hint may be explained by new short-ranged interactions, the low-q 2 one cannot. We thus explore the possibility that the latter is explained by a new light resonance. We find that LHCb’s central value of R K * $$ {R}_{K^{*}} $$ in the low-q 2 bin is achievable in a restricted parameter space of new-physics scenarios in which the new, light resonance decays preferentially to electrons and has a mass within approximately 10 MeV of the di-muon threshold. Interestingly, such an explanation can have a kinematic origin and does not require a source of lepton-flavor universality violation. A model-independent prediction is a narrow peak in the differential B → K * e + e − rate close to the di-muon threshold. If such a peak is observed, other observables, such as the differential B → Ke + e − rate and R K , may be employed to distinguish between models. However, if a low-mass resonance is not observed and the low-q 2 anomaly increases in significance, then the case for an experimental origin of the lepton-flavor universality violating anomalies would be strengthened. To further explore this, we also point out that, in analogy to J/ψ decays, e + e − and μ + μ − decays of ϕ mesons can be used as a cross check of lepton-flavor universality by LHCb with 5 fb−1 of integrated luminosity. |
| first_indexed | 2024-12-22T15:44:06Z |
| format | Article |
| id | doaj.art-77dbf1a8e9a346fbb22ec8f01681be7b |
| institution | Directory Open Access Journal |
| issn | 1029-8479 |
| language | English |
| last_indexed | 2024-12-22T15:44:06Z |
| publishDate | 2018-03-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj.art-77dbf1a8e9a346fbb22ec8f01681be7b2022-12-21T18:21:03ZengSpringerOpenJournal of High Energy Physics1029-84792018-03-012018312710.1007/JHEP03(2018)188Light resonances and the low-q 2 bin of R K * $$ {R}_{K^{*}} $$Wolfgang Altmannshofer0Michael J. Baker1Stefania Gori2Roni Harnik3Maxim Pospelov4Emmanuel Stamou5Andrea Thamm6Department of Physics, University of CincinnatiPhysik-Institut, Universität ZürichDepartment of Physics, University of CincinnatiTheoretical Physics Department, FermilabDepartment of Physics and Astronomy, University of VictoriaEnrico Fermi Institute, University of ChicagoTheoretical Physics Department, CERNAbstract LHCb has reported hints of lepton-flavor universality violation in the rare decays B → K (*) ℓ + ℓ −, both in high- and low-q 2 bins. Although the high-q 2 hint may be explained by new short-ranged interactions, the low-q 2 one cannot. We thus explore the possibility that the latter is explained by a new light resonance. We find that LHCb’s central value of R K * $$ {R}_{K^{*}} $$ in the low-q 2 bin is achievable in a restricted parameter space of new-physics scenarios in which the new, light resonance decays preferentially to electrons and has a mass within approximately 10 MeV of the di-muon threshold. Interestingly, such an explanation can have a kinematic origin and does not require a source of lepton-flavor universality violation. A model-independent prediction is a narrow peak in the differential B → K * e + e − rate close to the di-muon threshold. If such a peak is observed, other observables, such as the differential B → Ke + e − rate and R K , may be employed to distinguish between models. However, if a low-mass resonance is not observed and the low-q 2 anomaly increases in significance, then the case for an experimental origin of the lepton-flavor universality violating anomalies would be strengthened. To further explore this, we also point out that, in analogy to J/ψ decays, e + e − and μ + μ − decays of ϕ mesons can be used as a cross check of lepton-flavor universality by LHCb with 5 fb−1 of integrated luminosity.http://link.springer.com/article/10.1007/JHEP03(2018)188Beyond Standard ModelHeavy Quark Physics |
| spellingShingle | Wolfgang Altmannshofer Michael J. Baker Stefania Gori Roni Harnik Maxim Pospelov Emmanuel Stamou Andrea Thamm Light resonances and the low-q 2 bin of R K * $$ {R}_{K^{*}} $$ Journal of High Energy Physics Beyond Standard Model Heavy Quark Physics |
| title | Light resonances and the low-q 2 bin of R K * $$ {R}_{K^{*}} $$ |
| title_full | Light resonances and the low-q 2 bin of R K * $$ {R}_{K^{*}} $$ |
| title_fullStr | Light resonances and the low-q 2 bin of R K * $$ {R}_{K^{*}} $$ |
| title_full_unstemmed | Light resonances and the low-q 2 bin of R K * $$ {R}_{K^{*}} $$ |
| title_short | Light resonances and the low-q 2 bin of R K * $$ {R}_{K^{*}} $$ |
| title_sort | light resonances and the low q 2 bin of r k r k |
| topic | Beyond Standard Model Heavy Quark Physics |
| url | http://link.springer.com/article/10.1007/JHEP03(2018)188 |
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