2019/04/30 by D. G. Ireland, M. Döring, D. I. Glazier +6 · 41 citations
Physics and Astronomy · #Asymmetry #Baryon #Charge (physics) #High-Energy Particle Collisions Research #Lambda #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Physics beyond the Standard Model #Polarization (electrochemistry) #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #nucl-ex #nucl-th
paper · pdf · open access · doi:10.1103/physrevlett.123.182301
published in Physical Review Letters 123(18), 182301 (American Physical Society) · 6 pages, 1 figure;
openalex created_date 2019/06/27 · arxiv created 2019/10/28 · openalex publication_date 2019/10/28 · arxiv updated 2019/10/29 · openalex updated_date 2026/08/06
The weak decay parameter \ensuremathα_\ensuremath- of the \mathrm\ensuremathΛ is an important quantity for the extraction of polarization observables in various experiments. Moreover, in combination with \ensuremathα+ from \mathrm\ensuremathΛ decay it provides a measure for matter-antimatter asymmetry. The weak decay parameter also affects the decay parameters of the \mathrm\ensuremathΞ and \mathrm\ensuremathΩ baryons and, in general, any quantity in which the polarization of the \mathrm\ensuremathΛ is relevant. The recently reported value by the BESIII Collaboration of 0.750(9)(4) is significantly larger than the previous PDG value of 0.642(13) that had been accepted and used for over 40 years. In this work we make an independent estimate of \ensuremathα_\ensuremath-, using an extensive set of polarization data measured in kaon photoproduction in the baryon resonance region and constraints set by spin algebra. The obtained value is 0.721(6)(5). The result is corroborated by multiple statistical tests as well as a modern phenomenological model, showing that our new value yields the best description of the data in question. Our analysis supports the new BESIII finding that \ensuremathα_\ensuremath- is significantly larger than the previous PDG value. Any experimental quantity relying on the value of \ensuremathα_\ensuremath- should therefore be reconsidered.