Branching ratios for the π− mesonic decays of the hypernuclei Λ3H and Λ4H

Abstract

Results are presented concerning the expérimental détermination, with large statistics, of the branching ratios for the-n' mesonic decay of the hypernuclei and ^H. The spin assignments A^^H) = j and /(^H) = 0 are confirmed.

Strangeness nuclear physics: a critical review on selected topics

“…corresponding to the elementary reactions (30) and (31) for bound Λ; the final nuclear states in (39) and (40) [180][181][182][183] was done by applying the recently established properties of the free Λ mesonic decay (∆I = 1/2 rule; prevalence of the s-wave, parity-violating, spin-non-flip amplitude; π angular distribution dependence on Λ spin axis) to Λ bound in nuclear systems; see Ref. [184] for a recent summary.…”

“…The MWD rates obtained by the experiment are summarized in Tables 3 and 4 together with theoretical calculations from [200]. In Table 4 results of older visualizing techniques experiments [181,182] are also reported for 4 Λ He. From the comparison between the experimental results and the theoretical calculations of Ref.…”

“…It is thus evident that the study of the MWD spectra has strong potentialities for the determination of the ground state spin-parity for s-and p-shell Hypernuclei; for sd-shell strange nuclear systems too, the spectroscopy of particles emitted in the decay processes can help in fixing the spectroscopic configuration of the ground state, although the MWD branching ratios diminish below 10% for these Hypernuclei and the errors become consequently very sizable. The MWD spectra analysis has thus demonstrated its reliability as light-and medium-A Hypernuclei spectroscopic tool, complementary to the γ-ray spectroscopy of low-lying excited states [4] when the spin ordering cannot be determined; it represents a new version of the old technique based on the study of the angular distribution of the MWD π − , which allowed the ground state spin-parity determination of light Hypernuclei from emulsion experiments [180][181][182][183], based on the known properties of the free Λ weak decay.…”

“…MWD rates of 4 Λ He in units of the free Λ decay rate (ΓΛ) measured by the KEK-E167 experiment[167] and by Refs [181,182]…”

Richard Henry Dalitz. 28 February 1925 — 13 January 2006

“…He realized that the two-body decays 4 Λ H → 4 He + π − and 3 Λ H → 3 He + π − , then being studied in photographic emulsions, could be used to extract the parent hypernuclear ground-state spins and parities, and hence provide information about the spin dependence of the Λ-N force (10). An improved calculation by Dalitz and Liu (12) provided a plot of the branching ratio ( (Block et al 1964;Bertrand et al 1970;Ziemińska 1975). In particular, the ground-state spins 0 + for 4 Λ H and 1 -2 + for 3 Λ H showed that the s-wave Λ-N interaction was more attractive in the singlet state than in the triplet state.…”