Tetraquarks with charm in coupled-channel formalism

The relativistic four-quark equations are found in the framework of coupled-channel formalism. The dynamical mixing of the meson-meson states with the four-quark states is considered. The approximate solutions of these equations using the method based on the extraction of leading singularities of the amplitudes are obtained. The four-quark amplitudes of cryptoexotic mesons including the quarks of three flavours (u, d, s) and the charmed quark are constructed. The poles of these amplitudes determine the masses of tetraquarks. The mass values of low-lying tetraquarks are calculated.Comment: 21 pages, pdf, minor typos in the text correcte

Excited (70,L+)(70,L^+) baryon resonances in the relativistic quark model

The masses of positive parity $(70,0^+)$ and $(70,2^+)$ nonstrange and strange baryons are calculated in the relativistic quark model. The relativistic three-quark equations of the $(70,L^+)$ multiplets are found in the framework of the dispersion relation technique. The approximate solutions of these equations using the method based on the extraction of leading singularities of the amplitude are obtained. The calculated mass values of the $(70,L^+)$ multiplets are in good agreement with the experimental ones.Comment: latex, 23 pages, 3 figure

Charmed (70,1−){\bf (70,1^-)} baryon multiplet

The masses of negative parity $(70,1^-)$ charmed nonstrange baryons are calculated in the relativistic quark model. The relativistic three-quark equations of the $(70,1^-)$ charmed baryon multiplet are found in the framework of the dispersion relation technique. The approximate solutions of these equations using the method based on the extraction of leading singularities of the amplitude are obtained. The calculated mass values of the $(70,1^-)$ charmed baryons are in good agreement with the experimental data.Comment: 23 pages, late

S-wave bottom tetraquarks

The relativistic four-quark equations are found in the framework of coupled-channel formalism. The dynamical mixing of the meson-meson states with the four-quark states is considered. The four-quark amplitudes of the tetraquarks, including $u$, $d$, $s$ and bottom quarks, are constructed. The poles of these amplitudes determine the masses and widths of $S$-wave bottom tetraquarks.Comment: 8 pages, late