Vector-like quark interpretation for the CKM unitarity violation, excess in Higgs signal strength, and bottom quark forward-backward asymmetry
Abstract Due to a recent more precise evaluation of V ud and V us , the unitarity condition of the first row in the Cabibbo-Kobayashi-Maskawa (CKM) matrix: |V ud | 2 +|Vus| 2 +|V ub | 2 = 0.99798 ± 0.00038 now stands at a deviation more than 4σ from unity. Furthermore, a mild excess in the overall H...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2020-05-01
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| Series: | Journal of High Energy Physics |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1007/JHEP05(2020)117 |
| _version_ | 1818609886272946176 |
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| author | Kingman Cheung Wai-Yee Keung Chih-Ting Lu Po-Yan Tseng |
| author_facet | Kingman Cheung Wai-Yee Keung Chih-Ting Lu Po-Yan Tseng |
| author_sort | Kingman Cheung |
| collection | DOAJ |
| description | Abstract Due to a recent more precise evaluation of V ud and V us , the unitarity condition of the first row in the Cabibbo-Kobayashi-Maskawa (CKM) matrix: |V ud | 2 +|Vus| 2 +|V ub | 2 = 0.99798 ± 0.00038 now stands at a deviation more than 4σ from unity. Furthermore, a mild excess in the overall Higgs signal strength appears at about 2σ above the standard model (SM) prediction, as well as the long-lasting discrepancy in the forward-backward asymmetry A FB b $$ {\mathcal{A}}_{\mathrm{FB}}^b $$ in Z → b b ¯ $$ Z\to b\overline{b} $$ at LEP. Motivated from the above three anomalies we investigate an extension of the SM with vector-like quarks (VLQs) associated with the down-quark sector, with the goal of alleviating the tension among these datasets. We perform global fits of the model under the constraints coming from the unitarity condition of the first row of the CKM matrix, the Z -pole observables A FB b $$ {\mathcal{A}}_{\mathrm{FB}}^b $$ , R b and Γhad, Electro-Weak precision observables ∆S and ∆T , B-meson observables B d 0 − B ¯ d 0 $$ {B}_d^0-{\overline{B}}_d^0 $$ mixing, B + → π +ℓ+ℓ − and B 0 → μ + μ − and direct searches for VLQs at the Large Hadron Collider (LHC). Our results suggest that adding VLQs to the SM provides better agreement than the SM. |
| first_indexed | 2024-12-16T15:05:40Z |
| format | Article |
| id | doaj.art-a7fa1207bd534682b2aa8ca9e29f3d72 |
| institution | Directory Open Access Journal |
| issn | 1029-8479 |
| language | English |
| last_indexed | 2024-12-16T15:05:40Z |
| publishDate | 2020-05-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj.art-a7fa1207bd534682b2aa8ca9e29f3d722022-12-21T22:27:09ZengSpringerOpenJournal of High Energy Physics1029-84792020-05-012020512810.1007/JHEP05(2020)117Vector-like quark interpretation for the CKM unitarity violation, excess in Higgs signal strength, and bottom quark forward-backward asymmetryKingman Cheung0Wai-Yee Keung1Chih-Ting Lu2Po-Yan Tseng3Physics Division, National Center for Theoretical SciencesDepartment of Physics, University of IllinoisSchool of Physics, KIASDepartment of Physics and IPAP, Yonsei UniversityAbstract Due to a recent more precise evaluation of V ud and V us , the unitarity condition of the first row in the Cabibbo-Kobayashi-Maskawa (CKM) matrix: |V ud | 2 +|Vus| 2 +|V ub | 2 = 0.99798 ± 0.00038 now stands at a deviation more than 4σ from unity. Furthermore, a mild excess in the overall Higgs signal strength appears at about 2σ above the standard model (SM) prediction, as well as the long-lasting discrepancy in the forward-backward asymmetry A FB b $$ {\mathcal{A}}_{\mathrm{FB}}^b $$ in Z → b b ¯ $$ Z\to b\overline{b} $$ at LEP. Motivated from the above three anomalies we investigate an extension of the SM with vector-like quarks (VLQs) associated with the down-quark sector, with the goal of alleviating the tension among these datasets. We perform global fits of the model under the constraints coming from the unitarity condition of the first row of the CKM matrix, the Z -pole observables A FB b $$ {\mathcal{A}}_{\mathrm{FB}}^b $$ , R b and Γhad, Electro-Weak precision observables ∆S and ∆T , B-meson observables B d 0 − B ¯ d 0 $$ {B}_d^0-{\overline{B}}_d^0 $$ mixing, B + → π +ℓ+ℓ − and B 0 → μ + μ − and direct searches for VLQs at the Large Hadron Collider (LHC). Our results suggest that adding VLQs to the SM provides better agreement than the SM.http://link.springer.com/article/10.1007/JHEP05(2020)117Beyond Standard ModelHeavy Quark PhysicsHiggs PhysicsQuark Masses and SM Parameters |
| spellingShingle | Kingman Cheung Wai-Yee Keung Chih-Ting Lu Po-Yan Tseng Vector-like quark interpretation for the CKM unitarity violation, excess in Higgs signal strength, and bottom quark forward-backward asymmetry Journal of High Energy Physics Beyond Standard Model Heavy Quark Physics Higgs Physics Quark Masses and SM Parameters |
| title | Vector-like quark interpretation for the CKM unitarity violation, excess in Higgs signal strength, and bottom quark forward-backward asymmetry |
| title_full | Vector-like quark interpretation for the CKM unitarity violation, excess in Higgs signal strength, and bottom quark forward-backward asymmetry |
| title_fullStr | Vector-like quark interpretation for the CKM unitarity violation, excess in Higgs signal strength, and bottom quark forward-backward asymmetry |
| title_full_unstemmed | Vector-like quark interpretation for the CKM unitarity violation, excess in Higgs signal strength, and bottom quark forward-backward asymmetry |
| title_short | Vector-like quark interpretation for the CKM unitarity violation, excess in Higgs signal strength, and bottom quark forward-backward asymmetry |
| title_sort | vector like quark interpretation for the ckm unitarity violation excess in higgs signal strength and bottom quark forward backward asymmetry |
| topic | Beyond Standard Model Heavy Quark Physics Higgs Physics Quark Masses and SM Parameters |
| url | http://link.springer.com/article/10.1007/JHEP05(2020)117 |
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