TY  - JOUR
AU  - Ireland, D. G.
AU  - Döring, M.
AU  - Glazier, D. I.
AU  - Haidenbauer, J.
AU  - Mai, M.
AU  - Murray-Smith, R.
AU  - Rönchen, D.
TI  - Kaon Photoproduction and the Λ Decay Parameter α −
JO  - Physical review letters
VL  - 123
IS  - 18
SN  - 1079-7114
CY  - College Park, Md.
PB  - APS
M1  - FZJ-2019-05272
SP  - 182301
PY  - 2019
AB  - The weak decay parameter α− of the Λ is an important quantity for the extraction of polarization observables in various experiments. Moreover, in combination with α+ from ¯Λ decay it provides a measure for matter-antimatter asymmetry. The weak decay parameter also affects the decay parameters of the Ξ and Ω baryons and, in general, any quantity in which the polarization of the Λ 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 α−, 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 α− is significantly larger than the previous PDG value. Any experimental quantity relying on the value of α− should therefore be reconsidered.
LB  - PUB:(DE-HGF)16
C6  - pmid:31763878
UR  - <Go to ISI:>//WOS:000492984300001
DO  - DOI:10.1103/PhysRevLett.123.182301
UR  - https://juser.fz-juelich.de/record/866012
ER  -