Precise Measurement of Differential Cross Sections of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi mathvariant="normal">Σ</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mi>p</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi mathvariant="normal">Λ</mml:mi><mml:mi>n</mml:mi></mml:math> Reaction in Momentum Range <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>470</mml:mn><mml:mo>–</mml:mo><mml:mn>650</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>MeV</mml:mi><mml:mo stretchy="false">/</mml:mo><mml:mi>c</mml:mi></mml:mrow></mml:math>
K. Miwa, J. K. Ahn, Y. Akazawa, T. Aramaki, S. Ashikaga, S. Callier, N. Chiga, S.W. Choi, H. Ekawa, P. Evtoukhovitch, N. Fujioka, M. Fujita, T. Gogami, T. Harada, S. Hasegawa, S. Hayakawa, R. Honda, S. Hoshino, K. Hosomi, M. Ichikawa, Y. Ichikawa, M. Ieiri, M. Ikeda, K. Imai, Y. Ishikawa, S. Ishimoto, W.S. Jung, S. Kajikawa, H. Kanauchi, H. Kanda, T. Kitaoka, B.M. Kang, H. Kawai, S.H. Kim, K. Kobayashi, T. Koike, K. Matsuda, Y. Matsumoto, S. Nagao, R. Nagatomi, Y. Nakada, M. Nakagawa, I. Nakamura, T. Nanamura, M. Naruki, S. Ozawa, L. Raux, T.G. Rogers, A. Sakaguchi, T. Sakao, H. Sako, S. Sato, T. Shiozaki, K. Shirotori, K.N. Suzuki, S. Suzuki, M. Tabata, C. D L. Taille, H. Takahashi, T.N. Takahashi, T. N. Takahashi, H. Tamura, M. Tanaka, K. Tanida, Z. Tsamalaidze, M. Ukai, H. Umetsu, S. Wada, T. O. Yamamoto, J. Yoshida, K. Yoshimura
Abstract
The differential cross sections of the ${\mathrm{\ensuremath{\Sigma}}}^{\ensuremath{-}}p\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}n$ reaction were measured accurately for the ${\mathrm{\ensuremath{\Sigma}}}^{\ensuremath{-}}$ momentum (${p}_{\mathrm{\ensuremath{\Sigma}}}$) ranging from 470 to $650\text{ }\text{ }\mathrm{MeV}/c$ at the J-PARC Hadron Experimental Facility. Precise angular information about the ${\mathrm{\ensuremath{\Sigma}}}^{\ensuremath{-}}p\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}n$ reaction was obtained for the first time by detecting approximately 100 reaction events at each angular step of $\mathrm{\ensuremath{\Delta}}\mathrm{cos}\ensuremath{\theta}=0.1$. The obtained differential cross sections show a slightly forward-peaking structure in the measured momentum regions. The cross sections integrated for $\ensuremath{-}0.7\ensuremath{\le}\mathrm{cos}\ensuremath{\theta}\ensuremath{\le}1.0$ were obtained as $22.5\ifmmode\pm\else\textpm\fi{}0.68$ [statistical error(stat.)] $\ifmmode\pm\else\textpm\fi{}0.65$ [systematic error(syst.)] mb and $15.8\ifmmode\pm\else\textpm\fi{}0.83(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.52(\mathrm{syst})\text{ }\text{ }\mathrm{mb}$ for $470<{p}_{\mathrm{\ensuremath{\Sigma}}}(\mathrm{MeV}/c)<550$ and $550<{p}_{\mathrm{\ensuremath{\Sigma}}}(\mathrm{MeV}/c)<650$, respectively. These results show a drastic improvement compared with past measurements of the hyperon-proton scattering experiments. They will play essential roles in updating the theoretical models of the baryon-baryon interactions.