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Free, publicly-accessible full text available April 1, 2025
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A bstract A comprehensive study of the local and nonlocal amplitudes contributing to the decay
B 0→K *0(→K +π − )μ +μ − is performed by analysing the phase-space distribution of the decay products. The analysis is based onpp collision data corresponding to an integrated luminosity of 8.4 fb− 1collected by the LHCb experiment. This measurement employs for the first time a model of both one-particle and two-particle nonlocal amplitudes, and utilises the complete dimuon mass spectrum without any veto regions around the narrow charmonium resonances. In this way it is possible to explicitly isolate the local and nonlocal contributions and capture the interference between them. The results show that interference with nonlocal contributions, although larger than predicted, only has a minor impact on the Wilson Coefficients determined from the fit to the data. For the local contributions, the Wilson Coefficient , responsible for vector dimuon currents, exhibits a 2.1$$ {\mathcal{C}}_9 $$ σ deviation from the Standard Model expectation. The Wilson Coefficients ,$$ {\mathcal{C}}_{10} $$ and$$ {\mathcal{C}}_9^{\prime } $$ are all in better agreement than$$ {\mathcal{C}}_{10}^{\prime } $$ with the Standard Model and the global significance is at the level of 1.5$$ {\mathcal{C}}_9 $$ σ . The model used also accounts for nonlocal contributions fromB 0→ K *0[τ +τ − → μ +μ − ] rescattering, resulting in the first direct measurement of thebsττ vector effective-coupling .$$ {\mathcal{C}}_{9\tau } $$ Free, publicly-accessible full text available September 1, 2025 -
A search for hidden-charm pentaquark states decaying to a range ofandfinal states, as well as doubly charmed pentaquark states toand, is made using samples of proton-proton collision data corresponding to an integrated luminosity ofrecorded by the LHCb detector at. Since no significant signals are found, upper limits are set on the pentaquark yields relative to that of thebaryon in thedecay mode. The known pentaquark states are also investigated, and their signal yields are found to be consistent with zero in all cases.
© 2024 CERN, for the LHCb Collaboration 2024 CERN Free, publicly-accessible full text available August 1, 2025 -
A bstract A search for the fully reconstructed
$$ {B}_s^0 $$ → μ +μ − γ decay is performed at the LHCb experiment using proton-proton collisions at = 13 TeV corresponding to an integrated luminosity of 5$$ \sqrt{s} $$ . 4 fb− 1. No significant signal is found and upper limits on the branching fraction in intervals of the dimuon mass are set$$ {\displaystyle \begin{array}{cc}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[2{m}_{\mu },1.70\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<7.7\times {10}^{-8},&\ m\left({\mu}^{+}{\mu}^{-}\right)\in \left[\textrm{1.70,2.88}\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[3.92,{m}_{B_s^0}\right]\textrm{GeV}/{c}^2,\end{array}} $$ at 95% confidence level. Additionally, upper limits are set on the branching fraction in the [2
m μ , 1. 70] GeV/c 2dimuon mass region excluding the contribution from the intermediateϕ (1020) meson, and in the region combining all dimuon-mass intervals.Free, publicly-accessible full text available July 1, 2025