CAS Key Laboratory of Theoretical Physics

Institute of Theoretical Physics

 Chinese Academy of Sciences

Seminar

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Dynamics of meson-baryon systems with strangeness -2 and Cascade resonances

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Abstract

摘要

In this talk I will review our recent study on meson-baryon systems with strangeness $-2$. The motivation of our work is to find resonances generated as a consequence of  coupled channel meson-baryon interactions. The coupled channels considered are all meson-baryon systems formed by combining a pseudoscalar or  a vector meson with an octet baryon such that the system has the strange quantum number equal to -2. The lowest order meson-baryon interaction amplitudes are obtained from Lagrangians based on the chiral and the hidden local symmetry related to the treatment of the vector mesons as the gauge boson. These lowest order amplitudes are used as an input to solve Bethe-Salpeter equation and a search for poles is made in the resulting amplitudes, in the complex plane. As I will show, we find two narrow resonances which can be well associated with Xi(1690) and Xi(2120). I will discuss the properties of these states and compare with experimental data, when available. Besides, I will raise a question if we can rely on the standard nonrelativistic treatment of the lowest order amplitudes in such studies and show the differences in the results obtained when treating the amplitudes both relativistically and nonrelativisically. 

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