<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Q</mml:mi><mml:mi>Q</mml:mi><mml:mover accent="true"><mml:mi>s</mml:mi><mml:mo stretchy="false">¯</mml:mo></mml:mover><mml:mover accent="true"><mml:mi>s</mml:mi><mml:mo stretchy="false">¯</mml:mo></mml:mover></mml:math> tetraquarks in the chiral quark model

Abstract

The low-lying $S$-wave $QQ\overline{s}\overline{s}$ ($Q=c$, $b$) tetraquark states with $I({J}^{P})=0({0}^{+})$, $0({1}^{+})$ and $0({2}^{+})$ are systematically investigated in the framework of complex scaling range of chiral quark model. Every structure including meson-meson, diquark-antidiquark and K-type configurations, and all possible color channels in four-body sector are considered by means of a commonly extended variational approach, Gaussian expansion method. Within the studied mass region, several narrow and wide resonance states are obtained for $cc\overline{s}\overline{s}$ and $bb\overline{s}\overline{s}$ tetraquarks with $I({J}^{P})=0({0}^{+})$ and $0({2}^{+})$. Meanwhile, narrow resonances for $cb\overline{s}\overline{s}$ tetraquarks are also found in $I({J}^{P})=0({0}^{+})$, $0({1}^{+})$ and $0({2}^{+})$ states. The possibility of finding tetraquark structures with masses $\ensuremath{\sim}0.6\text{ }\text{ }\mathrm{GeV}$ above the non-interacting hadron-hadron thresholds (and not close to them) is a feature related with the absence of the one-pion exchange interaction in the $QQ\overline{s}\overline{s}$ sector and thus it could deserve experimental confirmation.

Topics & Concepts