Search for D∗(2007)0→μ+μ−D^{*}(2007)^0\to\mu^+\mu^- in B−→π−μ+μ−B^-\to\pi^-\mu^+\mu^- decays

The very rare $D^{*}(2007)^0\to\mu^+\mu^-$ decay is searched for by analysing $B^-\to\pi^-\mu^+\mu^-$ decays. The analysis uses a sample of beauty mesons produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb$^{-1}$. The signal signature corresponds to simultaneous peaks in the $\mu^+\mu^-$ and $\pi^-\mu^+\mu^-$ invariant masses. No evidence for an excess of events over background is observed and an upper limit is set on the branching fraction of the decay at ${\cal B}(D^{*}(2007)^0\to\mu^+\mu^-) < 2.6\times 10^{-8}$ at $90\%$ confidence level. This is the first limit on the branching fraction of $D^{*}(2007)^0\to\mu^+\mu^-$ decays and the most stringent limit on $D^{*}(2007)^0$ decays to leptonic final states. The analysis is the first search for a rare charm-meson decay exploiting production via beauty decays.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-004.html (LHCb public pages

A study of C P violation in the decays B± → [K+K-π+π-] Dh± (h = K, π) and B± → [π+π-π+π-] Dh±

The first study of CP violation in the decay mode B±→[K+K-π+π-]Dh±, with h=K, π, is presented, exploiting a data sample of proton–proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of 9\,fb-1. The analysis is performed in bins of phase space, which are optimised for sensitivity to local CP asymmetries. CP-violating observables that are sensitive to the angle γ of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for B±→[K+K-π+π-]Dh± and B±→[π+π-π+π-]Dh± decays

Open charm production and asymmetry in pNe collisions at √sNN = 68.5 GeV

AbstractA measurement of $${{D}} ^0$$ D 0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of $${{D}} ^0$$ D 0 mesons is studied with a beam of 2.5 $$\,\text {Te\hspace{-1.00006pt}V}$$ Te V protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of $$\sqrt{s_{\scriptscriptstyle \text {NN}}} = 68.5\,\,\text {Ge\hspace{-1.00006pt}V}$$ s NN = 68.5 Ge V . The sum of the $${{D}} ^0$$ D 0 and $${\hspace{0.0pt}\overline{\hspace{0.0pt}{D}}} {}^0$$ D ¯ 0 production cross-section in $$p\text {Ne}$$ p Ne collisions in the centre-of-mass rapidity range $$y^{\star }\in [-2.29, 0]$$ y ⋆ ∈ [ - 2.29 , 0 ] is found to be \sigma _{D^{0}}^{y^\star \in [-2.29, 0]} = 48.2 \pm 0.3 \pm 4.5 \,\upmu \text {b}/\text {nucleon} σ D 0 y ⋆ ∈ [ - 2.29 , 0 ] = 48.2 ± 0.3 ± 4.5 μ b / nucleon where the first uncertainty is statistical and the second is systematic. The $${{{D}} ^0}-{{\hspace{0.0pt}\overline{\hspace{0.0pt}{D}}} {}^0}$$ D 0 - D ¯ 0 production asymmetry is also evaluated and suggests a trend towards negative values at large negative $$y^{\star }$$ y ⋆ . The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1$$\%$$ % intrinsic charm and 10$$\%$$ % recombination contributions better describe the data than the other models considered.</jats:p

Observation of Λ0b → Λ+cD¯(∗)0K− and Λ0b → Λ+cD∗−s decays

Abstract available from publisher's website

Charmonium production in pNe collisions at sNN=68.5\sqrt{s_{\scriptscriptstyle \text {NN}}} =68.5 s NN = 68.5 GeV

Abstract The measurement of charmonium states produced in proton-neon ( $$p\text {Ne}$$ p Ne ) collisions by the LHCb experiment in its fixed-target configuration is presented. The production of $${{J} \hspace{-1.66656pt}/\hspace{-1.111pt}\psi }$$ J / ψ and $$\psi {(2S)}$$ ψ ( 2 S ) mesons is studied with a beam of 2.5 $$\mathrm{\,Te\hspace{-1.00006pt}V}$$ Te V protons colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy $$\sqrt{s_{\scriptscriptstyle \text {NN}}} =68.5\mathrm{\,Ge\hspace{-1.00006pt}V}$$ s NN = 68.5 Ge V . The data sample corresponds to an integrated luminosity of $$21.7\pm 1.4$$ 21.7 ± 1.4 nb $$^{-1}$$ - 1 . The $${{J} \hspace{-1.66656pt}/\hspace{-1.111pt}\psi }$$ J / ψ and $$\psi {(2S)}$$ ψ ( 2 S ) hadrons are reconstructed in $$\mu ^+$$ μ + $$\mu ^-$$ μ - final states. The $${{J} \hspace{-1.66656pt}/\hspace{-1.111pt}\psi }$$ J / ψ production cross-section per target nucleon in the centre-of-mass rapidity range $$y^\star \in [-2.29, 0]$$ y ⋆ ∈ [ - 2.29 , 0 ] is found to be $$506 \pm 8 \pm 46 \text { nb/nucleon}$$ 506 ± 8 ± 46 nb/nucleon . The ratio of $${{J} \hspace{-1.66656pt}/\hspace{-1.111pt}\psi }$$ J / ψ and $$D^0$$ D 0 cross-sections is evaluated to $$(1.06 \pm 0.02 \pm 0.09)\%$$ ( 1.06 ± 0.02 ± 0.09 ) % . The $$\psi {(2S)}$$ ψ ( 2 S ) to $${{J} \hspace{-1.66656pt}/\hspace{-1.111pt}\psi }$$ J / ψ relative production rate is found to be $$(1.67 \pm 0.27\pm 0.10)\%$$ ( 1.67 ± 0.27 ± 0.10 ) % in good agreement with other measurements involving beam and target nuclei of similar sizes

Open charm production and asymmetry in p Ne collisions at s NN = 68.5 Ge V

A measurement of D0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of D0 mesons is studied with a beam of 2.5 TeV protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of sNN=68.5GeV. The sum of the D0 and D¯0 production cross-section in pNe collisions in the centre-of-mass rapidity range y⋆∈[-2.29, 0] is found to be σD0y⋆∈[-2.29, 0]=48.2±0.3±4.5μb/nucleon where the first uncertainty is statistical and the second is systematic. The D0-D¯0 production asymmetry is also evaluated and suggests a trend towards negative values at large negative y⋆. The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1% intrinsic charm and 10% recombination contributions better describe the data than the other models considered

Open charm production and asymmetry in p Ne collisions at s NN = 68.5 Ge V

A measurement of D0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of D0 mesons is studied with a beam of 2.5 TeV protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of sNN=68.5GeV. The sum of the D0 and D¯0 production cross-section in pNe collisions in the centre-of-mass rapidity range y⋆∈[-2.29, 0] is found to be σD0y⋆∈[-2.29, 0]=48.2±0.3±4.5μb/nucleon where the first uncertainty is statistical and the second is systematic. The D0-D¯0 production asymmetry is also evaluated and suggests a trend towards negative values at large negative y⋆. The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1% intrinsic charm and 10% recombination contributions better describe the data than the other models considered