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1991

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June

  

Reviews of topical problems


Summary of the search for four-quark states in γγ collisions

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S.L. Sobolev Institute for Mathematics, Siberian Branch of the Russian Academy of Sciences, prosp. akad. Koptyuga 4, Novosibirsk, 630090, Russian Federation

A review of the results of the search for four-quark states in $\gamma\gamma$ collisions during the last decade is presented. The resonance phenomena in the reactions $\gamma\gamma\to\rho^0\rho^0$, $\gamma\gamma\to\rho^+\rho^-$, $\gamma\gamma\to\omega\rho^0$, $\gamma\gamma\to\mathbf{K}^*\bar{\mathbf{K}}^*$, $\gamma\gamma\to\omega\omega$, $\gamma\gamma\to\varphi V$, $\gamma\gamma\to\pi^0\eta$ and $\gamma\gamma\to\pi\pi$ are discussed in detail. In particular, it is shown that presently there are telling arguments for observation of a tensor exotic $\mathbf{q}^2\bar{\mathbf{q}}^2$, resonance with isospin $I=2$ near the $\rho\rho$ threshold in $\gamma\gamma\to\rho^0\rho^0$ and $\gamma\gamma\to\rho^+\rho^-$. A set of new experiments for the elucidation of the physical nature of the considered phenomena is also suggested.

Fulltext pdf (1.6 MB)
Fulltext is also available at DOI: 10.1070/PU1991v034n06ABEH002384
PACS: 14.40.Cs, 14.40.Ev, 14.40.Aq, 12.39.Ba (all)
DOI: 10.1070/PU1991v034n06ABEH002384
URL: https://ufn.ru/en/articles/1991/6/b/
Citation: Achasov N N, Shestakov G N "Summary of the search for four-quark states in γγ collisions" Sov. Phys. Usp. 34 (6) 471–496 (1991)
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Оригинал: Ачасов Н Н, Шестаков Г Н «Итоги поисков четырехкварковых состояний в γγ-столкновениях» УФН 161 (6) 53–108 (1991); DOI: 10.3367/UFNr.0161.199106b.0053

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