Stable scalar tetraquark

S. S. Agaev; K. Azizi; B. Barsbay; H. Sundu

doi:10.1140/epja/s10050-020-00187-9

EPJ

Stable scalar tetraquark $T_{bb;\bar{u}\bar{d}}^{-}$

S. S. Agaev¹, K. Azizi²^,3^,4^*, B. Barsbay³^,5 and H. Sundu⁵

¹ Institute for Physical Problems, Baku State University, 1148, Baku, Azerbaijan
² Department of Physics, University of Tehran, North Karegar Avenue, Tehran, 14395-547, Iran
³ Department of Physics, Doǧuş University, Acibadem-Kadiköy, 34722, Istanbul, Turkey
⁴ School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran
⁵ Department of Physics, Kocaeli University, 41380, Izmit, Turkey

Received: 18 April 2020
Accepted: 24 June 2020
Published online: 6 July 2020

Abstract

The mass and coupling of the scalar tetraquark $T_{bb;\overline{u}\overline{d }}^{-}$ (hereafter $T_{b:\overline{d}}^{-}$ ) are calculated in the context of the QCD two-point sum rule method. In computations we take into account effects of various quark, gluon and mixed condensates up to dimension ten. The result obtained for the mass of this state $m=(10135\pm 240)~\mathrm {MeV}$ demonstrates that it is stable against the strong and electromagnetic decays. We also explore the dominant semileptonic $T_{b:\overline{d}}^{-} \rightarrow \widetilde{Z}_{bc;\bar{u}\bar{d}}^{0}l\overline{\nu }_{l}$ and nonleptonic decays $T_{b:\overline{d}}^{-} \rightarrow \widetilde{Z}_{bc;\bar{u}\bar{ d}}^{0}M$ , where $\widetilde{Z}_{bc;\bar{u}\bar{d}}^{0}$ is the scalar tetraquark composed of color-sextet diquark and antidiquark, and M is one of the final-state pseudoscalar mesons $\pi ^{-}, K^{-}, D^{-}$ and $D_s^{-}$ , respectively. The partial widths of these processes are calculated in terms of the weak form factors $G_{1(2)}(q^2)$ , which are determined from the QCD three-point sum rules. Predictions for the mass, full width $\Gamma _{\mathrm {full}} =(10.88\pm 1.88)\times 10^{-10}~\mathrm {MeV}$ , and mean lifetime $\tau =0.61_{-0.09}^{+0.13}~\mathrm {ps}$ of the $T_{b:\overline{d} }^{-}$ obtained in the present work can be used in theoretical and experimental studies of this exotic state.

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Stable scalar tetraquark

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Stable scalar tetraquark $T_{bb;\bar{u}\bar{d}}^{-}$