First observation of the $$ {\Lambda}_b^0 $$ → D+D−Λ decay

Medientyp: E-Artikel

Titel: First observation of the $$ {\Lambda}_b^0 $$ → D+D−Λ decay

Beteiligte: Aaij, R.; Abdelmotteleb, A. S. W.; Abellan Beteta, C.; Abudinén, F.; Ackernley, T.; Adams, J. A.; Adefisoye, A. A.; Adeva, B.; Adinolfi, M.; Adlarson, P.; Agapopoulou, C.; Aidala, C. A.; Ajaltouni, Z.; Akar, S.; Akiba, K.; Albicocco, P.; Albrecht, J.; Alessio, F.; Alexander, M.; Aliouche, Z.; Alvarez Cartelle, P.; Amalric, R.; Amato, S.; Amey, J. L.; [...]

Erschienen: Springer Science and Business Media LLC, 2024

Sprache: Englisch

DOI: 10.1007/jhep07(2024)140

ISSN: 1029-8479

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Beschreibung: Abstract The $$ {\Lambda}_b^0 $$ Λ b 0 → D+D−Λ decay is observed for the first time using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.3 fb−1. Using the B0 → $$ {D}^{+}{D}^{-}{K}_S^0 $$ D + D − K S 0 decay as a reference channel, the product of the relative production cross-section and decay branching fractions is measured to be$$ \mathcal{R}=\frac{\sigma_{\Lambda_b^0}}{\sigma_{B^0}}=\frac{\mathcal{B}\left({\Lambda}_b^0\to {D}^{+}{D}^{-}\Lambda \right)}{\mathcal{B}\left({B}^0\to {D}^{+}{D}^{-}{K}_{\textrm{S}}^0\right)}=0.179\pm 0.022\pm 0.014, $$ R = σ Λ b 0 σ B 0 = B Λ b 0 → D + D − Λ B B 0 → D + D − K S 0 = 0.179 ± 0.022 ± 0.014 , where the first uncertainty is statistical and the second is systematic. The known branching fraction of the reference channel, $$ \mathcal{B}\left({B}^0\to {D}^{+}{D}^{-}{K}_{\textrm{S}}^0\right) $$ B B 0 → D + D − K S 0 , and the cross-section ratio, $$ {\sigma}_{\Lambda_b^0}/{\sigma}_{B^0} $$ σ Λ b 0 / σ B 0 , previously measured by LHCb are used to derive the branching fraction of the $$ {\Lambda}_b^0 $$ Λ b 0 → D+D−Λ decay$$ \mathcal{B}\left({\Lambda}_b^0\to {D}^{+}{D}^{-}\Lambda \right)=\left(1.24\pm 0.15\pm 0.10\pm 0.28\pm 0.11\right)\times {10}^{-4}, $$ B Λ b 0 → D + D − Λ = 1.24 ± 0.15 ± 0.10 ± 0.28 ± 0.11 × 10 − 4 , where the third and fourth contributions are due to uncertainties of $$ \mathcal{B}\left({B}^0\to {D}^{+}{D}^{-}{K}_{\textrm{S}}^0\right) $$ B B 0 → D + D − K S 0 and $$ {\sigma}_{\Lambda_b^0}/{\sigma}_{B^0} $$ σ Λ b 0 / σ B 0 , respectively. Inspection of the D+Λ and D+D− invariant-mass distributions suggests a rich presence of intermediate resonances in the decay. The $$ {\Lambda}_b^0 $$ Λ b 0 → D*+D−Λ decay is also observed for the first time as a partially reconstructed component in the D+D−Λ invariant mass spectrum.

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