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arXiv · 2206.10900

Observation of $\Xi^{-}$ Hyperon Transverse Polarization in $\psi(3686)\rightarrow\Xi^{-}\bar\Xi^{+}$

BESIII Collaboration·M. Ablikim·M. N. Achasov·P. Adlarson·M. Albrecht·R. Aliberti·A. Amoroso·M. R. An·Q. An·Y. Bai·O. Bakina·R. Baldini Ferroli·I. Balossino·Y. Ban·V. Batozskaya·K. Begzsuren·N. Berger·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. Cetin·J. F. Chang·W. L. Chang·G. R. Che·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·Z. J. Chen·W. S. Cheng·S. K. Choi·X. Chu·G. Cibinetto·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. DeMori·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·W. X. 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·H. Gao·Y. N. Gao·Yang Gao·S. Garbolino·I. Garzia·P. T. Ge·Z. W. Ge·C. Geng·E. M. Gersabeck·A Gilman·K. Goetzen·L. Gong·W. X. Gong
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Abstract

Using a sample of $(448.1~\pm~2.9)$ $\times 10^{6}$ $\psi(3686)$ decays collected with the BESIII detector at BEPCII, we report an observation of $\Xi^{-}$ transverse polarization with a significance of $7.3 \sigma$ in the decay $\psi(3686)\rightarrow\Xi^{-}\bar\Xi^{+}$ ($\Xi^{-}\rightarrow\pi^{-}\Lambda$, $\bar\Xi^{+}\rightarrow\pi^{+}\bar\Lambda$, $\Lambda\to p\pi^{-}$, $\bar\Lambda\to\bar{p}\pi^{+}$). The relative phase of the electric and magnetic form factors is determined to be $\Delta\Phi = (0.667 \pm 0.111 \pm 0.058)$ rad. This is the first measurement of the relative phase for a $\psi(3686)$ decay into a pair of $\Xi^{-}\bar\Xi^{+}$ hyperons. The $\Xi^{-}$ decay parameters ($\alpha_{\Xi^{-}}$, $\phi_{\Xi^-}$) and their conjugates ($\alpha_{\bar\Xi^{+}}$, $\phi_{\bar{\Xi}^{+}}$), the angular-distribution parameter $\alpha_{\psi}$, and the strong-phase difference $\delta_{p}-\delta_{s}$ for $\Lambda$-$\pi^-$ scattering are measured to be consistent with previous BESIII results.

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BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, M. Albrecht, R. Aliberti, A. Amoroso, M. R. An, Q. An, Y. Bai, O. Bakina, R. Baldini Ferroli, I. Balossino, Y. Ban, V. Batozskaya, K. Begzsuren, N. Berger, 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. Cetin, J. F. Chang, W. L. Chang, G. R. Che, 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, Z. J. Chen, W. S. Cheng, S. K. Choi, X. Chu, G. Cibinetto, 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. DeMori, 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, W. X. 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, H. Gao, Y. N. Gao, Yang Gao, S. Garbolino, I. Garzia, P. T. Ge, Z. W. Ge, C. Geng, E. M. Gersabeck, A Gilman, K. Goetzen, L. Gong, W. X. Gong. 2022-06-22. Observation of $\Xi^{-}$ Hyperon Transverse Polarization in $\psi(3686)\rightarrow\Xi^{-}\bar\Xi^{+}$. https://doi.org/10.1103/physrevd.106.l091101

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