Hypernuclear Weak Decays

Experimental Studies on the Weak Decay of Λ-Hypernuclei

“…(7) (fourth column). The FINUDA determinations [32] are compared with previous experimental data, when available, (fifth column) and with the outcome of a quite recent theoretical work (sixth column) [5]. (adapted from Ref.…”

“…Such a strong interest is testified by several review papers on the subject from both the experimental [1][2][3] and the theoretical [4,5] point of view (just to mention the most recently published).…”

“…On the basis of some early measurements (see Ref. [3] for a compilation of the available experimental results) and of different theoretical calculations [5][6][7], it was expected that the bound Λ measured lifetime exhibit a smooth trend as a function of A, starting from a value close to the free Λ lifetime (τ Λ free = 263.2 ps) for light systems and asymptotically approaching to a value of about 80% of the τ Λ free for heavier hypernuclei. However, some recent measurements seem to clearly indicate that the Λ lifetime in light hypernuclei is significantly shorter than τ Λ free .…”

On the Measurement of the Lifetime of Hydrogen Hyperisotopes at J-PARC and JLab

“…For 4 Λ H, which has a quite higher Λ binding energy, the only available calculation [17] gives an overestimated value, 264.1 ps, due to underestimate of the non-mesonic decay rate, which is, however, expected to be quite small for A=4. Moreover, [17] evaluates 4 Λ He lifetime to be 307.2 ps, with an increase from 4 Λ H to 4 Λ He of ∼ 14% due to missing two-body π − decay mode for 4 Λ He, to be compared with the experimental value of ∼ 23%. A general disagreement appears between the theoretical expectations and the experimental results, which are often affected by large errors; updated precise values for 3 Λ H and 4 Λ H lifetimes are needed and in this article evaluations of the feasibility of their experimental determination are given considering the presently-operating two facilities in the world which include hypernuclear physics in their scientific programs, J-PARC and JLab.…”

“…Total decay width values Γ( 3 Λ H) = (1.03 ÷ 1.10) Γ Λ have been evaluated in [15] and a lifetime of 256 ps is predicted in [16]. For 4 Λ H, which has a quite higher Λ binding energy, the only available calculation [17] gives an overestimated value, 264.1 ps, due to underestimate of the non-mesonic decay rate, which is, however, expected to be quite small for A=4. Moreover, [17] evaluates 4 Λ He lifetime to be 307.2 ps, with an increase from 4 Λ H to 4 Λ He of ∼ 14% due to missing two-body π − decay mode for 4 Λ He, to be compared with the experimental value of ∼ 23%.…”