학술논문
A study of the proton spectra following the capture of $K^-$ in $^6$Li and $^{12}$C with FINUDA
Document Type
Working Paper
Author
Agnello, M.; Beer, G.; Benussi, L.; Bertani, M.; Bhang, H. C.; Bianco, S.; Bonomi, G.; Botta, E.; Bregant, M.; Bressani, T.; Bufalino, S.; Busso, L.; Calvo, D.; Camerini, P.; Cerello, P.; Dalena, B.; De Mori, F.; D'Erasmo, G.; Di Santo, D.; Elia, D.; Fabbri, F. L.; Faso, D.; Feliciello, A.; Filippi, A.; Filippini, V.; Fini, R. A.; Fiore, E. M.; Fujioka, H.; Gianotti, P.; Grion, N.; Hartmann, O.; Krasnoperov, A.; Lenti, V.; Lucherini, V.; Manzari, V.; Marcello, S.; Maruta, T.; Mirfakhrai, N.; Morra, O.; Nagae, T.; Olin, A.; Outa, H.; Pace, E.; Pallotta, M.; Palomba, M.; Pantaleo, A.; Panzarasa, A.; Paticchio, V.; Piano, S.; Pompili, F.; Rui, R.; Simonetti, G.; So, H.; Tereshchenko, V.; Tomassini, S.; Toyoda, A.; Wheadon, R.; Zenoni, A.
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Subject
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Abstract
Momenta spectra of protons emitted following the capture of $K^-$ in $^6$Li and $^{12}$C have been measured with 1% resolution. The $^{12}$C spectrum is smooth whereas for $^6$Li a well defined peak appears at about 500 MeV/$c$. The first observation of a structure in this region was identified as a strange tribaryon or, possibly, a $\bar K$-nuclear state. The peak is correlated with a $\pi^-$ coming from $\Sigma^-$ decay in flight, selected by setting momenta larger than 275 MeV/$c$. The $\Sigma^-$ could be produced, together with a 500 MeV/$c$ proton, by the capture of a $K^-$ in a deuteron-cluster substructure of the $^6$Li nucleus. The capture rate for such a reaction is $(1.62\pm 0.23_{stat} ^{+0.71}_{-0.44}(sys))%/K^-_{stop}$, in agreement with the existing observations on $^4$He targets and with the hypothesis that the $^6$Li nucleus can be interpreted as a $(d+\alpha)$ cluster.
Comment: 21 pages, 10 figures. Accepted for publication in NPA
Comment: 21 pages, 10 figures. Accepted for publication in NPA