Coincidence Measurement of the Nonmesonic Weak Decay of ^{12}_{Lambda}C

Abstract

We have measured the angular correlation of the pair nucleons np and nn emitted from the nonmesonic weak decay (NMWD) of ^{12}_{Lambda}C produced via the (pi^+,K^+) reaction in coincidence measurement. The Lambda p -> np and Lambda n -> nn modes were clearly identified by measuring the back-to-back correlation of the emitted nucleon pairs which is the characteristic of two-body kinematics. From the measured nucleon pair numbers N_{nn} and N_{np}, the ratio Gamma_n/Gamma_p of the partial decay widths Gamma_n(Lambda n -> nn) and Gamma_p(Lambda p -> np) of ^{12}_{Lambda}C was extracted to be 0.51+-0.13(stat) +- 0.05(syst); this result is almost free from the ambiguity due to the nuclear final state interaction and 3-body decay process, which were inherent in the previous results. The obtained Gamma_n/Gamma_p ratio of ^{12}_{Lambda}C (p-shell) is close to that of ^5_{Lambda}He (s-shell). The results are consistent with those of recent theoretical calculations.

13 pages, 4figures, 1 table,re-submitted to Physics Letters B

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• Exchange terms in the two--nucleon induced non--mesonic weak decay of $\Lambda$--hypernuclei
• On the role of ground state correlations in hypernuclear non-mesonic weak decay
• Single and double coincidence nucleon spectra in the weak decay of Lambda hypernuclei
• Two-pion-exchange in the non-mesonic weak decay of $\Lambda$-hypernuclei
• Microscopic Approach to Nucleon Spectra in Hypernuclear Non-Mesonic Weak Decay
• Quantum interference terms in nonmesonic weak decay of $\Lambda$-hypernuclei within a RPA formalism
• Kinetic energy sum spectra in nonmesonic weak decay of hypernuclei
• Current constraints on the EFT for the ΛN --> N N transition
• Relationships between nonmesonic-weak-decays in different hypernuclei
• Nonmesonic weak decay spectra of ${}_{\Lambda }^4$He
• On the effect of the Delta(1232) in hypernuclear non-mesonic weak decay: a microscopic approach
• Nonmesonic Hyperon Weak Decay Spectra in ${}_{\Lambda }^{12}$C}
• Nonmesonic weak decay spectra of light hypernuclei
• Nonmesonic Weak Decay Dynamics from proton spectra of $\Lambda$-Hypernuclei
• Relativistic model for the nonmesonic weak decay of single-lambda hypernuclei
• A Theoretical Determination of N_{nn}/N_{np} in Hypernuclear Non--Mesonic Weak Decay