Fysik & material 3.7

Physicists observe rare particle decay, advancing understanding of matter

Researchers at CERN have directly observed four types of exotic particle decay for the first time, filling a gap in the Standard Model of physics. The findings, based on trillions of collisions, refine measurements that help validate fundamental theories underlying particle physics and may eventually inform new technologies in high-energy detection and materials science.

Originaltitel: First observation of Λb0 → Σc(*)++D(*)-K- decays

Abstrakt

The four decays, Λb0 →Σ(*)++𝐷(*)−⁢𝐾−, are observed for the first time using proton-proton collision data collected with the LHCb detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb−1. By considering the Λb0 →Λc+⁢𝐷<over bar>0⁢𝐾− decay as reference channel, the following branching fraction ratios are measured to be ℬ⁡(Λ𝑏0→Σ𝑐++⁢𝐷−⁢𝐾−) / ℬ⁡(Λ𝑏0→Λ𝑐+⁢𝐷<over bar>0⁢𝐾−)=0.282±0.016±0.016±0.005, ℬ⁡(Λ𝑏0→Σ𝑐⁢*++𝐷−⁢𝐾−) / ℬ⁡(Λ𝑏0→Σ𝑐⁢++𝐷−⁢𝐾−)=0.460±0.052±0.028, ℬ⁡(Λ𝑏0→Σ𝑐++⁢𝐷*−⁢𝐾−) / ℬ⁡(Λ𝑏0→Σ𝑐++⁢𝐷−⁢𝐾−)=2.261±0.202±0.129±0.046, ℬ⁡(Λ𝑏0→Σ𝑐*++⁢𝐷*−⁢𝐾−) / ℬ⁡(Λ𝑏0→Σ𝑐++⁢𝐷−⁢𝐾−)=0.896±0.137±0.066±0.018, where the first uncertainties are statistical, the second are systematic, and the third are due to uncertainties in the branching fractions of intermediate particle decays. These initial observations mark the beginning of pentaquark searches in these modes, with more datasets to become available following the LHCb upgrade.

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