Lifetimes of Light Hyperfragments

Publisher Website
Google Scholar
Abstract
We have studied the lifetimes of light hyperfragments, making use of two stacks of nuclear-emulsion pellicles exposed to K−-meson beams at the Bevatron and the Brookhaven A. G. S. In these two stacks we obtained 18 mesonic decays in flight from a total of 258 mesonic decays of hyperfragments. The values we found for the lifetimes are the following: For He4Λ, He5Λ, and He4,5Λ events combined (8 in flight, 117 at rest), we obtained the value τ(He4,5Λ)=(2.2−0.6+1.5)×10−10 sec. By suitably apportioning the He4,5Λ events between He4Λ and He5Λ we obtain the values τ(He5Λ)=(1.8−0.6+1.5)×10−10 sec and τ(He4Λ)≥1.0×10−10 sec. For H3Λ, using only two-body decays (3 in flight, 4 at rest), we obtain τ(H3Λ)=(0.8−0.3+1.9)×10−10 sec. Using both two-body and three-body decays (5 in flight, 18 at rest), we obtain τ(H3Λ)=(3.4−1.4+8.2)×10−10 sec. This value may be an overestimate owing to H4Λ contamination in the three-body H3Λ events. This point is discussed in the text. For H4Λ we obtain τ(H4Λ)=(2.4−1.0+6.0)×10−10 sec using only three-body decays (4 in flight, 14 at rest), and τ(H4Λ)=(3.6−1.3+4.9)×10−10 sec using all H4Λ decays (5 in flight, 40 at rest). This last value may suffer from a bias against finding two-body H4Λ decays in flight which simulate small-angle scatterings under low magnifying power, although all scatterings were examined closely. The above results are compared with theoretical estimates of hyperfragment lifetimes.

This publication has 16 references indexed in Scilit: