First Study of Reaction <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi mathvariant="normal">Ξ</mml:mi><mml:mn>0</mml:mn></mml:msup><mml:mi>n</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:msup><mml:mi mathvariant="normal">Ξ</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mi>p</mml:mi></mml:math> Using <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Ξ</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>-Nucleus Scattering at an Electron-Positron Collider
M. Ablikim, М. Н. Ачасов, P. Adlarson, R. Aliberti, A. Amoroso, M. R. An, Q. An, Y. Bai, O. Bakina, I. Balossino, Y. Ban, V. Batozskaya, K. Begzsuren, N. Berger, M. Berłowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, J. Bloms, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Çetin, J. F. Chang, T. T. Chang, W. L. Chang, G. R., G. Chelkov, C. Chen, Chao Chen, G. Chen, H. S. Chen, M. L. Chen, S. J. Chen, S. M. Chen, T. Chen, X. R. Chen, X. T. Chen, Y. B. Chen, Y. Q. Chen, Z. J. Chen, W. S. Cheng, S. K. Choi, X. Chu, G. Cibinetto, S. C. Coen, F. Cossio, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, B. Ding, X. X. Ding, Y. Ding, Y. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, S. X. Du, Z. H. Duan, P. Egorov, Y. L. Fan, J. Fang, S. S. Fang, Wenxing Fang, Y. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, K. Fischer, M. Fritsch, C. Fritzsch, C. D. Fu, J. Fu, Y. W. Fu, He Gao, Yang Gao, Yang Gao, S. Garbolino, I. Garzia, P. Ge, Z. W. Ge
Abstract
Using $(1.0087\ifmmode\pm\else\textpm\fi{}0.0044)\ifmmode\times\else\texttimes\fi{}{10}^{10}\text{ }\text{ }J/\ensuremath{\psi}$ events collected with the BESIII detector at the BEPCII storage ring, the process ${\mathrm{\ensuremath{\Xi}}}^{0}n\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}p$ is studied, where the ${\mathrm{\ensuremath{\Xi}}}^{0}$ baryon is produced in the process $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}^{0}{\overline{\mathrm{\ensuremath{\Xi}}}}^{0}$ and the neutron is a component of the $^{9}\mathrm{Be}$, $^{12}\mathrm{C}$, and $^{197}\mathrm{Au}$ nuclei in the beam pipe. A clear signal is observed with a statistical significance of $7.1\ensuremath{\sigma}$. The cross section of the reaction ${\mathrm{\ensuremath{\Xi}}}^{0}+^{9}\mathrm{Be}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}+p+^{8}\mathrm{Be}$ is determined to be $\ensuremath{\sigma}({\mathrm{\ensuremath{\Xi}}}^{0}+^{9}\mathrm{Be}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}+p+^{8}\mathrm{Be})=(22.1\ifmmode\pm\else\textpm\fi{}{5.3}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{4.5}_{\mathrm{sys}})\text{ }\text{ }\mathrm{mb}$ at the ${\mathrm{\ensuremath{\Xi}}}^{0}$ momentum of $0.818\text{ }\text{ }\mathrm{GeV}/c$, where the first uncertainty is statistical and the second is systematic. No significant $H$-dibaryon signal is observed in the ${\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}p$ final state. This is the first study of hyperon-nucleon interactions in electron-positron collisions and opens up a new direction for such research.