Rare W → B c + γ decay up to the NNLO and NLL accuracy in QCD
Abstract We perform a detailed theoretical study of the rare radiative decay of the W boson into a B c meson and an on-shell photon. The decay amplitude is described by two independent form factors, which are calculated up to the next-to-next-to-leading order (NNLO) in QCD within the nonrelativistic...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2025-07-01
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| Series: | Journal of High Energy Physics |
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| Online Access: | https://doi.org/10.1007/JHEP07(2025)042 |
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| author | Xin-Qiang Li Ya-Dong Yang Yu-Dong Zhang Dong-Hui Zheng |
| author_facet | Xin-Qiang Li Ya-Dong Yang Yu-Dong Zhang Dong-Hui Zheng |
| author_sort | Xin-Qiang Li |
| collection | DOAJ |
| description | Abstract We perform a detailed theoretical study of the rare radiative decay of the W boson into a B c meson and an on-shell photon. The decay amplitude is described by two independent form factors, which are calculated up to the next-to-next-to-leading order (NNLO) in QCD within the nonrelativistic QCD (NRQCD) factorization formalism. Since the two typical energy scales, the W -boson mass m W and the B c -meson mass m B c $$ {m}_{B_c} $$ , involved in the process are widely separated, large logarithms of m W 2 / m B c 2 $$ {m}_W^2/{m}_{B_c}^2 $$ present in the NRQCD short-distance coefficients are also resummed to all orders in α s up to the next-to-leading logarithmic (NLL) accuracy, by employing the light-cone factorization approach. Taking into account all these corrections, we then perform a phenomenological exploration of this rare decay. It is found that, relative to the leading-order result, the decay width of the process is reduced by the next-to-leading-order and NNLO corrections, with a net effect of ∼ −19% and of ∼ −31%, respectively. Furthermore, the NLL resummation can considerably alter the fixed-order NRQCD predictions, especially for the 𝒪(α s ) correction. We also find that the radiative corrections increase the renormalization scale dependence of the branching fraction, which is however significantly reduced by the NLL resummation. The dependence of the branching fraction on the heavy-quark masses m b,c is also investigated, which shows a monotonic decrease (increase) with m c (m b ). |
| format | Article |
| id | doaj-art-667b94d052a2489591b5ceef0f18f06e |
| institution | Kabale University |
| issn | 1029-8479 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj-art-667b94d052a2489591b5ceef0f18f06e2025-08-20T03:45:44ZengSpringerOpenJournal of High Energy Physics1029-84792025-07-012025713010.1007/JHEP07(2025)042Rare W → B c + γ decay up to the NNLO and NLL accuracy in QCDXin-Qiang Li0Ya-Dong Yang1Yu-Dong Zhang2Dong-Hui Zheng3Institute of Particle Physics and Key Laboratory of Quark and Lepton Physics (MOE), Central China Normal UniversityInstitute of Particle Physics and Key Laboratory of Quark and Lepton Physics (MOE), Central China Normal UniversityInstitute of Particle Physics and Key Laboratory of Quark and Lepton Physics (MOE), Central China Normal UniversityInstitute of Particle Physics and Key Laboratory of Quark and Lepton Physics (MOE), Central China Normal UniversityAbstract We perform a detailed theoretical study of the rare radiative decay of the W boson into a B c meson and an on-shell photon. The decay amplitude is described by two independent form factors, which are calculated up to the next-to-next-to-leading order (NNLO) in QCD within the nonrelativistic QCD (NRQCD) factorization formalism. Since the two typical energy scales, the W -boson mass m W and the B c -meson mass m B c $$ {m}_{B_c} $$ , involved in the process are widely separated, large logarithms of m W 2 / m B c 2 $$ {m}_W^2/{m}_{B_c}^2 $$ present in the NRQCD short-distance coefficients are also resummed to all orders in α s up to the next-to-leading logarithmic (NLL) accuracy, by employing the light-cone factorization approach. Taking into account all these corrections, we then perform a phenomenological exploration of this rare decay. It is found that, relative to the leading-order result, the decay width of the process is reduced by the next-to-leading-order and NNLO corrections, with a net effect of ∼ −19% and of ∼ −31%, respectively. Furthermore, the NLL resummation can considerably alter the fixed-order NRQCD predictions, especially for the 𝒪(α s ) correction. We also find that the radiative corrections increase the renormalization scale dependence of the branching fraction, which is however significantly reduced by the NLL resummation. The dependence of the branching fraction on the heavy-quark masses m b,c is also investigated, which shows a monotonic decrease (increase) with m c (m b ).https://doi.org/10.1007/JHEP07(2025)042Bottom QuarksHigher-Order Perturbative CalculationsRare DecaysResummation |
| spellingShingle | Xin-Qiang Li Ya-Dong Yang Yu-Dong Zhang Dong-Hui Zheng Rare W → B c + γ decay up to the NNLO and NLL accuracy in QCD Journal of High Energy Physics Bottom Quarks Higher-Order Perturbative Calculations Rare Decays Resummation |
| title | Rare W → B c + γ decay up to the NNLO and NLL accuracy in QCD |
| title_full | Rare W → B c + γ decay up to the NNLO and NLL accuracy in QCD |
| title_fullStr | Rare W → B c + γ decay up to the NNLO and NLL accuracy in QCD |
| title_full_unstemmed | Rare W → B c + γ decay up to the NNLO and NLL accuracy in QCD |
| title_short | Rare W → B c + γ decay up to the NNLO and NLL accuracy in QCD |
| title_sort | rare w b c γ decay up to the nnlo and nll accuracy in qcd |
| topic | Bottom Quarks Higher-Order Perturbative Calculations Rare Decays Resummation |
| url | https://doi.org/10.1007/JHEP07(2025)042 |
| work_keys_str_mv | AT xinqiangli rarewbcgdecayuptothennloandnllaccuracyinqcd AT yadongyang rarewbcgdecayuptothennloandnllaccuracyinqcd AT yudongzhang rarewbcgdecayuptothennloandnllaccuracyinqcd AT donghuizheng rarewbcgdecayuptothennloandnllaccuracyinqcd |