Jung Keun Ahn

Λ(1405) photoproduction at SPring-8/LEPS

Abstract The nature of Λ(1405) hyperon is still mystery for the distinction between an unstable K N bound state and L = 1 SU (3)-singlet three quark state coupled with the S-wave K N channels. Recent theoretical works predict its lineshape to be different in terms of different charge combinations of the πΣ decay channels in the context of chiral dynamics plus final-state interaction. We have measured the lineshape of Λ(1405) in charged πΣ channels through p (γ, K + π)Σ reaction at 1.5–2.4 GeV. The observed lineshapes in π − Σ + and π + Σ − channels are different, which implies that the Λ(1405) could be interpreted as a bound-state of meson-baryon states.

First search for KL→π0π0νν̄

The first search for the rare kaon decay

Search for the decay K{sub L}{sup 0}{yields}3{gamma}

\kppnn

Experimental study of the decay K{sub L}{sup 0{yields}{pi}0{nu}{nu}}

has been performed by the E391a collaboration at the KEK 12-GeV proton synchrotron. An upper limit of

Search for the Decay K{sub L}{sup 0}{yields}{pi}{sup 0}{nu}{nu}

4.7\times10^{-5}

New limit on the K{sub L}{sup 0}{yields}{pi}{sup 0}{nu}{nu} decay rate

at the 90 % confidence level was set for the branching ratio of the decay

2π0 photoproduction experiment at SPring-8

\kppnn

KL → π0νν ̄experiment at KEK 12-GeV PS - E391a -

using about 10 % of the data collected during the first period of data taking. First limits for the decay mode

KL → π0ηη experiment at KEK12-GeV PS — E391a

\kppP

Time and Amplitude of Afterpulse Measured with a Large Size Photomultiplier Tube

, where