Wed·Apr 17, 2019Wednesday·April 17, 2019

1. 01*

   Kaon Photoproduction and the $\Lambda$ Decay Parameter ${\alpha }_{-}$

   D. G. Ireland🇬🇧 · M. Döring🇺🇸 · D. I. Glazier🇬🇧 · J. Haidenbauer🇩🇪 · M. Mai🇺🇸 · R. Murray-Smith🇬🇧 · D. Rönchen🇩🇪

   The weak decay parameter ${\alpha }_{-}$ of the $\Lambda$ is an important quantity for the extraction of polarization observables in various experiments. Moreover, in combination with ${\alpha }_{+}$ from $\bar{\Lambda }$ decay it provides a measure for matter-antimatter asymmetry. The weak decay parameter also affects the decay parameters of the $\Xi$ and $\Omega$ baryons and, in general, any quantity in which the polarization of the $\Lambda$ 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 ${\alpha }_{-}$, 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 ${\alpha }_{-}$ is significantly larger than the previous PDG value. Any experimental quantity relying on the value of ${\alpha }_{-}$ should therefore be re-considered.

   nucl-exnucl-thPRL(2019)·57 citations
2. 02*

   Systematic study of proton radioactivity of spherical proton emitters within various versions of proximity potential formalisms

   Jun-Gang Deng · Xiao-Hua Li🇨🇳 · Jiu-Long Chen🇨🇳 · Jun-Hao Cheng🇨🇳 · Xi-Jun Wu

   In this work we present a systematic study of the proton radioactivity half-lives of spherical proton emitters within the Coulomb and proximity potential model. We investigate 28 different versions of the proximity potential formalisms developed for the description of proton radioactivity, $\alpha$ decay and heavy particle radioactivity. It is found that 21 of them are not suitable to deal with the proton radioactivity, because the classical turning points $r_{\text{in}}$ cannot be obtained due to the fact that the depth of the total interaction potential between the emitted proton and the daughter nucleus is above the proton radioactivity energy. Among the other 7 versions of the proximity potential formalisms, it is Guo2013 which gives the lowest rms deviation in the description of the experimental half-lives of the known spherical proton emitters. We use this proximity potential formalism to predict the proton radioactivity half-lives of 13 spherical proton emitters, whose proton radioactivity is energetically allowed or observed but not yet quantified, within a factor of 3.71.

   ↳ nucl-thnucl-exEPJA(2019)·27 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.