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Search for the $$ {B}_c^{+} $$ → χc1(3872)π+ decay

https://doi.org/10.1007/JHEP06(2025)013

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 (June 2025, Journal of High Energy Physics)

A<sc>bstract</sc> A search for the decay$$ {B}_c^{+} $$ $B_{c}^{+}$ → χ_c1(3872)π⁺is reported using proton-proton collision data collected with the LHCb detector between 2011 and 2018 at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb⁻¹. No significant signal is observed. Using the decay$$ {B}_c^{+} $$ $B_{c}^{+}$ →ψ(2S)π⁺as a normalisation channel, an upper limit for the ratio of branching fractions$$ {\mathcal{R}}_{\psi (2S)}^{\chi_{c1}(3872)}=\frac{{\mathcal{B}}_{B_c^{+}\to {\chi}_{c1}(3872){\pi}^{+}}}{{\mathcal{B}}_{B_c^{+}\to \psi (2S){\pi}^{+}}}\times \frac{{\mathcal{B}}_{\chi_{c1}(3872)\to J/\psi {\pi}^{+}{\pi}^{-}}}{{\mathcal{B}}_{\psi (2S)\to J/\psi {\pi}^{+}{\pi}^{-}}}<0.05(0.06), $$ $R_{ψ (2 S)}^{χ_{c 1} (3872)} = \frac{B_{B_{c}^{+} \to χ_{c 1} (3872) π^{+}}}{B_{B_{c}^{+} \to ψ (2 S) π^{+}}} \times \frac{B_{χ_{c 1} (3872) \to J / ψ π^{+} π^{-}}}{B_{ψ (2 S) \to J / ψ π^{+} π^{-}}} < 0.05 (0.06),$ is set at the 90 (95)% confidence level.
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Free, publicly-accessible full text available June 1, 2026
Measurement of $C P$ asymmetries in $Λ_{b}^{0} \to p h^{-}$ decays

https://doi.org/10.1103/PhysRevD.111.092004

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 $C P$ violation in $Λ_{b}^{0} \to p K^{-}$ and $Λ_{b}^{0} \to p π^{-}$ decays is presented using the full Run 1 and Run 2 data samples of $p p$ collisions collected with the LHCb detector, corresponding to an integrated luminosity of $9 {fb}^{- 1}$ at center-of-mass energies of 7, 8, and 13 TeV. For the Run 2 data sample, the $C P$ -violating asymmetries are measured to be $A_{C P}^{p K^{-}} = (- 1.4 \pm 0.7 \pm 0.4) %$ and $A_{C P}^{p π^{-}} = (0.4 \pm 0.9 \pm 0.4) %$ , where the first uncertainty is statistical and the second is systematic. Following significant improvements in the evaluation of systematic uncertainties compared to the previous LHCb measurement, the Run 1 dataset is reanalyzed to update the corresponding results. When combining the Run 2 and updated Run 1 measurements, the final results are found to be $A_{C P}^{p K^{-}} = (- 1.1 \pm 0.7 \pm 0.4) %$ and $A_{C P}^{p π^{-}} = (0.2 \pm 0.8 \pm 0.4) %$ , constituting the most precise measurements of these asymmetries to date. © 2025 CERN, for the LHCb Collaboration2025CERN
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Free, publicly-accessible full text available May 1, 2026
Search for $D^{0}$ meson decays to $π^{+} π^{-} e^{+} e^{-}$ 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 $π^{+} π^{-} e^{+} e^{-}$ 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 $6 {fb}^{- 1}$ . The decay $D^{0} \to π^{+} π^{-} e^{+} e^{-}$ is observed for the first time when requiring that the two electrons are consistent with coming from the decay of a $ϕ$ or $ρ^{0} / ω$ meson. The corresponding branching fractions are measured relative to the $D^{0} \to K^{-} π^{-} [e^{+} e^{-}]_{ρ^{0} / ω}$ decay, where the two electrons are consistent with coming from the decay of a $ρ^{0}$ or $ω$ 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 $D^{0} \to π^{+} π^{-} μ^{+} μ^{-}$ and $D^{0} \to K^{+} K^{-} μ^{+} μ^{-}$ decays recently measured by LHCb and confirm lepton universality at the current precision. © 2025 CERN, for the LHCb Collaboration2025CERN
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Free, publicly-accessible full text available May 1, 2026
Search for resonance-enhanced $C P$ and angular asymmetries in the $Λ_{c}^{+} \to p μ^{+} μ^{-}$ decay at LHCb

https://doi.org/10.1103/PhysRevD.111.L091102

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)

The first measurement of the $C P$ asymmetry of the decay rate ( $A_{C P}$ ) and the $C P$ average ( $Σ A_{FB}$ ) and $C P$ asymmetry ( $Δ A_{FB}$ ) of the forward-backward asymmetry in the muon system of $Λ_{c}^{+} \to p μ^{+} μ^{-}$ decays is reported. The measurement is performed using a data sample of proton-proton collisions, recorded by the LHCb experiment from 2016 to 2018 at a center-of-mass energy of 13 TeV, which corresponds to an integrated luminosity of $5.4 {fb}^{- 1}$ . The asymmetries are measured in two regions of dimuon mass near the $ϕ$ -meson mass peak. The dimuon-mass integrated results are $A_{C P} = (- 1.1 \pm 4.0 \pm 0.5) %$ , $Σ A_{FB} = (3.9 \pm 4.0 \pm 0.6) %$ , $Δ A_{FB} = (3.1 \pm 4.0 \pm 0.4) %$ , where the first uncertainty is statistical and the second systematic. The results are consistent with the conservation of $C P$ symmetry and the Standard Model expectations. © 2025 CERN, for the LHCb Collaboration2025CERN
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Free, publicly-accessible full text available May 1, 2026

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