002960711 001__ 2960711
002960711 005__ 20260511095643.0
002960711 0248_ $$aoai:cds.cern.ch:2960711$$pcerncds:FULLTEXT$$pcerncds:CERN:FULLTEXT$$pcerncds:CERN
002960711 035__ $$9INSPIRE$$a3152373
002960711 037__ $$aCERN-EP-2026-123
002960711 037__ $$9arXiv$$aarXiv:2605.04348
002960711 041__ $$aeng
002960711 088__ $$9LHCB-PAPER-2026-004-003
002960711 088__ $$aLHCB-PAPER-2026-004
002960711 110__ $$aLHCb Collaboration
002960711 245__ $$aObservation of the charmless purely baryonic decay $\mathinner{\mathit{\Lambda}^0_b\!\to \mathit{\Lambda} p \overline{p}}$
002960711 260__ $$c2026
002960711 269__ $$aGeneva$$bCERN$$c07 May 2026
002960711 520__ $$aA search for the charmless purely baryonic decay $\mathinner{\mathit{\Lambda}^0_b\!\to \mathit{\Lambda} p \overline{p}}$ is performed using proton-proton collision data recorded by the LHCb experiment at a centre-of-mass energy of $\sqrt{s}=13\,\text{TeV}$ and corresponding to an integrated luminosity of $6.0\,\text{fb}^{-1}$. The signal decay is observed with a significance of 5.1 standard deviations. Its branching fraction is measured for the first time, relative to that of the topologically similar decay $\mathinner{\mathit{\Lambda}^0_b\!\to \mathit{\Lambda} K^+ K^-}$. Contributions from intermediate charmonium resonances decaying to the $p \overline{p}$ and $K^+ K^-$ final states are explicitly excluded with a requirement on the invariant mass of the companion hadron system, $m(h\bar{h}) < 2.85\,\text{GeV}$, where $h$ stands for a proton or a charged kaon. The relative branching fraction is found to be$$ \frac{\mathcal{B}(\mathinner{\mathit{\Lambda}^0_b\!\to \mathit{\Lambda} p\overline{p}})}{\mathcal{B}(\mathinner{\mathit{\Lambda}^0_b\!\to \mathit{\Lambda} K^+ K^-})} = (5.1 \pm 1.3_{\text{(stat)}} \pm 0.3_{\text{(syst)}}) \times 10^{-2} \,.$$
002960711 540__ $$3Preprint$$aCC-BY-4.0
002960711 542__ $$3Preprint$$dCERN$$g2026
002960711 65017 $$2SzGeCERN$$aParticle Physics - Experiment
002960711 6531_ $$9CERN$$aLHCb
002960711 693__ $$aCERN LHC$$eLHCb
002960711 690C_ $$aLHCb_Papers
002960711 690C_ $$aCERN
002960711 690C_ $$aPREPRINT
002960711 710__ $$gLHCb Collaboration
002960711 710__ $$5EP
002960711 859__ $$flhcb.secretariat@cern.ch
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002960711 916__ $$sn$$w202618
002960711 925__ $$b21 May 2026
002960711 960__ $$a11
002960711 980__ $$aLHCb_Papers
002960711 980__ $$aPREPRINT
002960711 980__ $$aLHCBPUBDRAFTFINAL