Remarks on MAMI's recent determination of $B_{\Lambda }({}_{\Lambda }^3\mathrm{H})$

Abstract

A recent report on ${}^7\mathrm{Li}(e,e^{\prime }{K}^{+})$ electroproduction runs by the A1 collaboration at the Mainz Microtron (MAMI) assigns a sharp pion-momentum line at $p_{{\pi }^{-}}\approx 113.8\pm 0.1$ MeV/c to ${}_{\Lambda }^3\mathrm{H}\to {\pi }^{-}+{}^3\mathrm{He}$ weak decay, resulting in exceptionally large ${}_{\Lambda }^3\mathrm{H}$ binding-energy $B_{\Lambda }({}_{\Lambda }^3\mathrm{H})=0.523\pm 0.013\pm 0.075$ MeV. Here I discuss an alternative interpretation of the observed sharp line in terms of ${}_{\Lambda }^7{\mathrm{He}}_{g.s.}\to {\pi }^{-}+{}^7\mathrm{Li}(E_{\mathrm{x}}=478$ keV) weak decay and its implications for $B_{\Lambda }({}_{\Lambda }^7\mathrm{He})$.

v1: 9 pages, 2 figures, 2 tables, to be submitted for publication, comments are welcome! v2: very slight changes, version submitted for publication. v3: paragraph added on pp. 5-6. v4: title changed (Questioning --> Remarks on) reflecting a weaker claim, see last text sentence