Analysis of a Single-Λ Hypernuclear Event in KEK-PS E373 Nuclear Emulsion Experiment

The purpose of this research is to identify a single-Λ hypernucleus and its decay products which support to get more information about hyperon-nucleon interaction. Before performing the analysis of a single-Λ hypernucleus, first, we have deduced the density of emulsion by calibrating the range-energy relation using alpha decay events data from thorium series. It is very important for the mass reconstruction of hypernucleus events in nuclear emulsion. And we have reconstructed a single-Λ hypernucleus event by using the kinematical reconstruction for mesonic and non-mesonic decay modes. From the result of our analysis, we can uniquely identify that single-Λ hypernucleus is $ {}_\Lambda ^9 B $ and decay products are 4He,3He, proton and neutron.

On the width of the Δ(1232) in NΔ and ΔΔ states

Due to the finite kinetic energy in the intermediate NΔ state the (internal) energy available for mesonic decay is decreased and consequently the effective NΔ width is suppressed in NN scattering. The same can happen also in ΔΔ case. Also the NΔ angular momentum suppresses the width as well, while the effect of the initial NN angular momentum is more subtle. The state dependence affects e.g. pion production observables and can also be seen as the origin of T = 1 “dibaryons”.

EXPERIMENTAL OVERVIEW AND CHALLENGE IN STRANGENESS NUCLEAR PHYSICS — STRANGENESS IN THE PAST AND COMING DECADES

A great progress has been made in strangeness nuclear physics in the past decade. Examples are; 1) The "hyperfine" structure of hypernuclei were measured with the Hyperball, and ΛN spin dependent interactions in p -shell hypernuclei were determined. 2) The "complete measurements" of the weak decay of hypernuclei were made and the np ratio puzzle in the non-mesonic decay was solved. 3) The discovery of a clean event of "Lambpha" and determination of its binding energy concluded that the Λ-Λ interaction is weak attractive. However, we still have important questions to be answered in this field, especially in relation with QCD and nuclear physics. For the future strangeness nuclear physics, we have and will have facilities such as JLab, SPring-8, Daphne, J-PARC, FAIR. We discuss experimental challenges in the strangeness nuclear physics and related fields in the next decade.

VARIATIONAL CALCULATION OF K-pp WITH CHIRAL SU(3)-BASED $\bar KN$ INTERACTION

The prototype of a [Formula: see text] nuclear cluster, K-pp, has been investigated using effective [Formula: see text] potentials based on chiral SU (3) dynamics. Variational calculation shows a bound state solution with shallow binding energy B(K-pp) = 20 ± 3 MeV and broad mesonic decay width [Formula: see text]. The [Formula: see text] pair in the K-pp system exhibits a similar structure as the Λ(1405). We have also estimated the dispersive correction, p-wave [Formula: see text] interaction, and two-nucleon absorption width.

RECENT RESULTS ON MESONIC WEAK DECAY OF Λ-HYPERNUCLEI

The FINUDA experiment has performed a systematic study of mesonic weak decay of p-shell Λ-hypernuclei. Recent results on the mesonic decay spectra and ratios are illustrated and discussed.

MESONIC WEAK DECAY OF Λ–HYPERNUCLEI: A NEW TOOL FOR HYPERNUCLEAR SPECTROSCOPY

The FINUDA experiment has performed a systematic study of the Mesonic Weak Decay (MWD) of Λ hypernuclei by analyzing all the data collected from 2003 up to 2007. Negatively charged pion spectra from mesonic decay were measured with magnetic analysis for the first time for [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]. Branching ratio Γπ-/Γtot were derived from the measured spectra. Based on these measurements, the spin-parity assignment 1/2+ for [Formula: see text] and 5/2+ for [Formula: see text] ground-state are confirmed and a spin-parity 3/2+ for [Formula: see text] ground-state is assigned for the first time. Ideas for precision measurements of MWD at the J-PARC accelerator's complex are finally presented.