Physicists nail down lifetime of rare particle with twice the precision
Researchers at Europe's particle physics lab have doubled the measurement precision of how long an exotic baryon lives before decaying. The finding—which matches theoretical predictions—strengthens our understanding of matter's fundamental rules, crucial for validating the physics models that guide next-generation detector design and particle research investment.
Originaltitel: Precision measurement of the Ξ<em><sub>b</sub></em><sup>-</sup> baryon lifetime
<p>A sample of <em>pp</em> collision data, corresponding to an integrated luminosity of 5.5 fb<sup>-1</sup> and collected by the LHCb experiment during LHC Run 2, is used to measure the ratio of the lifetime of the Ξ<sub>b</sub><sup>-</sup> baryon to that of the Λ<sub>b</sub><sup>0</sup> baryon, r(τ) ≡ τ(Ξ<sub>b</sub><sup>-</sup>)/tau(Λ<sub>b</sub><sup>0</sup>). The value r(τ)= 1.076 ± 0.013 ± 0.006 is obtained, where the first uncertainty is statistical and the second systematic. This value is averaged with the corresponding value from Run 1 to obtain r<sub>τ</sub><sup>Run 1,2</sup> = 1.078 ± 0.012 ± 0.007. Multiplying by the world -average value of the Λ<sub>b</sub><sup>0</sup> lifetime yields τ(Ξ <sub>b</sub><sup>-</sup>)(Run 1,2) = 1.578 ± 0.018 ± 0.010 ± 0.011 ps, where the uncertainties are statistical, systematic, and due to the limited knowledge of the Λ<sub>b</sub><sup>0</sup>, lifetime. This measurement improves the precision of the current world average of the Ξ<sub>b</sub><sup>-</sup> lifetime by about a factor of 2, and is in good agreement with the most recent theoretical predictions.</p>