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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.

Free, publicly-accessible full text available June 1, 2026

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

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