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1. Search for $D^0$ meson decays to ${\pi }^{+}{\pi }^{-}{e}^{+}{e}^{-}$ and $K^{+}{K}^{-}{e}^{+}{e}^{-}$ final states

   https://doi.org/10.1103/PhysRevD.111.L091101  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (May 2025, Physical Review D)

   A search for $D^0$meson decays to the ${\pi }^{+}{\pi }^{-}{e}^{+}{e}^{-}$and $K^{+}{K}^{-}{e}^{+}{e}^{-}$final states is reported using a sample of proton-proton collisions collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $6{\mathrm{fb}}^{-1}$. The decay $D^0\to {\pi }^{+}{\pi }^{-}{e}^{+}{e}^{-}$is observed for the first time when requiring that the two electrons are consistent with coming from the decay of a $\varphi$or ${\rho }^0/\omega$meson. The corresponding branching fractions are measured relative to the $D^0\to K^{-}{\pi }^{-}[e^{+}{e}^{-}{]}_{{\rho }^0/\omega }$decay, where the two electrons are consistent with coming from the decay of a ${\rho }^0$or $\omega$meson. No evidence is found for the $D^0\to K^{+}{K}^{-}{e}^{+}{e}^{-}$decay and world-best limits are set on its branching fraction. The results are compared to, and found to be consistent with, the branching fractions of the $D^0\to {\pi }^{+}{\pi }^{-}{\mu }^{+}{\mu }^{-}$and $D^0\to K^{+}{K}^{-}{\mu }^{+}{\mu }^{-}$decays recently measured by LHCb and confirm lepton universality at the current precision. © 2025 CERN, for the LHCb Collaboration2025CERN 

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2. Angular analysis of the low $K^{+}{K}^{-}$ invariant mass enhancement in $B^{+}\to K^{+}{K}^{-}{\pi }^{+}$ decays

   https://doi.org/10.1103/PhysRevD.107.032013  

   Hsu, C.-L.; Sevior, M. E.; Adachi, I.; Aihara, H.; Al Said, S.; Asner, D. M.; Atmacan, H.; Aulchenko, V.; Aushev, T.; Ayad, R.; et al (February 2023, Physical Review D)
3. Test of Lepton Flavor Universality with $B^{+}\to K^{+}{\pi }^{+}{\pi }^{-}{\ell }^{+}{\ell }^{-}$ Decays

   https://doi.org/10.1103/PhysRevLett.134.181803  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (May 2025, Physical Review Letters)

   The first test of lepton flavor universality between muons and electrons using $B^{+}\to K^{+}{\pi }^{+}{\pi }^{-}{\ell }^{+}{\ell }^{-}$( $\ell =e$, $\mu$) decays is presented. The measurement is performed with data from proton-proton collisions collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of $9{\mathrm{fb}}^{-1}$. The ratio of branching fractions between $B^{+}\to K^{+}{\pi }^{+}{\pi }^{-}{e}^{+}{e}^{-}$and $B^{+}\to K^{+}{\pi }^{+}{\pi }^{-}{\mu }^{+}{\mu }^{-}$decays is measured in the dilepton invariant-mass-squared range $1.1<q^2<7.0{\mathrm{GeV}}^2/c^4$and is found to be $R_{K\pi \pi }^{-1}=1.31_{-0.17}^{+0.18}\left(\mathrm{stat}){}_{-0.09}^{+0.12}\right(\mathrm{syst})$, in agreement with the standard model prediction. The first observation of the $B^{+}\to K^{+}{\pi }^{+}{\pi }^{-}{e}^{+}{e}^{-}$decay is also reported. © 2025 CERN, for the LHCb Collaboration2025CERN 

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4. Test of lepton flavor universality in ${\text{B}}^{\pm }\to {\text{K}}^{\pm }{\mu }^{+}{\mu }^{-}$ and ${\text{B}}^{\pm }\to {\text{K}}^{\pm }{\text{e}}^{+}{\text{e}}^{-}$ decays in proton-proton collisions at $\sqrt{\text{s}}=\text{13}\text{TeV}$

   https://doi.org/10.1088/1361-6633/ad4e65  

   CMS_Collaboration, The (July 2024, Reports on Progress in Physics)

   Abstract A test of lepton flavor universality in ${\text{B}}^{\pm }\to {\text{K}}^{\pm }{\mu }^{+}{\mu }^{-}$and ${\text{B}}^{\pm }\to {\text{K}}^{\pm }{\text{e}}^{+}{\text{e}}^{-}$decays, as well as a measurement of differential and integrated branching fractions of a nonresonant ${\text{B}}^{\pm }\to {\text{K}}^{\pm }{\mu }^{+}{\mu }^{-}$decay are presented. The analysis is made possible by a dedicated data set of proton-proton collisions at $\sqrt{s}=13\text{TeV}$recorded in 2018, by the CMS experiment at the LHC, using a special high-rate data stream designed for collecting about 10 billion unbiased b hadron decays. The ratio of the branching fractions $B({\text{B}}^{\pm }\to {\text{K}}^{\pm }{\mu }^{+}{\mu }^{-})$to $B({\text{B}}^{\pm }\to {\text{K}}^{\pm }{\text{e}}^{+}{\text{e}}^{-})$is determined from the measured double ratio $R\left(\text{K}\right)$of these decays to the respective branching fractions of the ${\text{B}}^{\pm }\to \text{J}/\text{ψ}{\text{K}}^{\pm }$with $\text{J}/\text{ψ}\to {\mu }^{+}{\mu }^{-}$and ${\text{e}}^{+}{\text{e}}^{-}$decays, which allow for significant cancellation of systematic uncertainties. The ratio $R\left(\text{K}\right)$is measured in the range $1.1<q^2<6.0{\text{GeV}}^2$, whereqis the invariant mass of the lepton pair, and is found to be $R\left(\text{K}\right)={0.78}_{-0.23}^{+0.47}$, in agreement with the standard model expectation $R\left(\text{K}\right)\approx 1$. This measurement is limited by the statistical precision of the electron channel. The integrated branching fraction in the sameq²range, $B({\text{B}}^{\pm }\to {\text{K}}^{\pm }{\mu }^{+}{\mu }^{-})=(12.42\pm 0.68)\times {10}^{-8}$, is consistent with the present world-average value and has a comparable precision. 

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5. Search for the Lepton Flavor Violating Decays $B^{+}\to K^{+}{\tau }^{\pm }{\ell }^{\mp }$ ( $\ell =e$ , $\mu$ ) at Belle

   https://doi.org/10.1103/PhysRevLett.130.261802  

   Watanuki, S.; de Marino, G.; Trabelsi, K.; Adachi, I.; Aihara, H.; Asner, D. M.; Atmacan, H.; Aulchenko, V.; Aushev, T.; Ayad, R.; et al (June 2023, Physical Review Letters)