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تسجيل مستخدم جديدWeak decays of the axial-vector tetraquark $T_{bb;bar{u} bar{d}}^{-}$
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The weak decays of the axial-vector tetraquark $T_{bb;bar{u} bar{d}}^{-}$ to the scalar state $Z_{bc;bar{u} bar{d}}^{0}$ are investigated using the QCD three-point sum rule approach. In order to explore the process $T_{bb; bar{u} bar{d}}^{-} to Z_{bc;bar{u} bar{d}}^{0}l bar{ u_l}$, we recalculate the spectroscopic parameters of the tetraquark $T_{bb;bar{u} bar{d}}^{-}$ and find the mass and coupling of the scalar four-quark system $Z_{bc;bar{u} bar{d}}^{0}$, which are important ingredients of calculations. The spectroscopic parameters of these tetraquarks are computed in the framework of the QCD two-point sum rule method by taking into account various condensates up to dimension ten. The mass of the $T_{bb;bar{u} bar{ d}}^{-}$ state is found to be $m=(10035~pm 260)~mathrm{MeV}$, which demonstrates that it is stable against the strong and electromagnetic decays. The full width $Gamma$ and mean lifetime $tau$ of $T_{bb;bar{u} bar{d} }^{-}$ are evaluated using its semileptonic decay channels $T_{bb; bar{u} bar{d}}^{-} to Z_{bc;bar{u} bar{d}}^{0}l bar{ u_l}$, $l=e,mu$ and $tau$. The obtained results, $Gamma=(7.17pm 1.23)times 10^{-8 } mathrm{MeV}$ and $tau =9.18_{-1.34}^{+1.90}~mathrm{fs}$, can be useful for experimental investigations of the doubly-heavy tetraquarks.
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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=(10135pm 240)~mathrm{MeV} $ demonstrates that it is stable against the strong and electromagnetic decays. We also explore the dominant semileptonic $T_{b:overline{d}}^{-} to widetilde{Z}_{bc;bar{u}bar{d}}^{0}loverline{ u }_{l}$ and nonleptonic decays $T_{b:overline{d}}^{-} to widetilde{Z}_{bc;bar{u}bar{ d}}^{0}M$, 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 $Gamma _{mathrm{full}} =(10.88pm 1.88)times 10^{-10}~mathrm{MeV}$, 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.
The spectroscopic parameters and decay channels of the axial-vector tetraquark $T_{bb;overline{u}overline{s}}^{-}$ (in what follows, $T_{b: overline{s}}^{mathrm{AV}}$) are explored using the quantum chromodynamics (QCD) sum rule method. The mass and
coupling of this state are calculated using two-point sum rules by taking into account various vacuum condensates, up to 10 dimensions. Our prediction for the mass of this state $m=(10215pm 250)~ mathrm{MeV}$ confirms that it is stable with respect to strong and electromagnetic decays and can dissociate to conventional mesons only via weak transformations. We investigate the dominant semileptonic $T_{b:overline{s} }^{mathrm{AV}} to mathcal{Z}_{b:overline{s}}^{0}loverline{ u}_l$ and nonleptonic $T_{b:overline{s}}^{mathrm{AV}} to mathcal{Z}_{b:overline{s} }^{0}M$ decays of $T_{b:overline{s}}^{mathrm{AV}}$. In these processes, $ mathcal{Z}_{b:overline{s}}^{0}$ is a scalar tetraquark $[bc][overline{u} overline{s}]$ built of a color-triplet diquark and an antidiquark, whereas $M$ is one of the vector mesons $rho ^{-}$, $K^{ast}(892)$, $D^{ast }(2010)^{-}$, and $D_{s}^{ast -}$. To calculate the partial widths of these decays, we use the QCD three-point sum rule approach and evaluate the weak transition form factors $G_{i}$ $(i=0,1,2,3)$, which govern these processes. The full width $Gamma _{mathrm{full}} =(12.9pm 2.1)times 10^{-8}~mathrm{MeV}$ and the mean lifetime $ tau=5.1_{-0.71}^{+0.99}~mathrm{fs}$ of the tetraquark $T_{b:overline{s}}^{ mathrm{AV}}$ are computed using the aforementioned weak decays. The obtained information about the parameters of $T_{b:overline{s}}^{mathrm{AV}}$ and $ mathcal{Z}_{b:overline{s}}^{0}$ is useful for experimental investigations of these double-heavy exotic mesons.
The spectroscopic parameters and decay channels of the scalar tetraquark $ T_{bb;overline{u}overline{s}}^{-}$ (in what follows $T_{b:overline{s} }^{-} $) are investigated. The mass and coupling of the $T_{b:s}^{-}$ are calculated using the two-point
sum rules by taking into account quark, gluon and mixed vacuum condensates up to dimension 10. Our result for its mass $m=(10250 pm 270)~mathrm{MeV}$ demonstrates that $T_{b:overline{s}}^{-} $ is stable against the strong and electromagnetic decays. Therefore to find the width and mean lifetime of the $T_{b:overline{s}}^{-}$, we explore its dominant weak decays generated by the transition $b to W^{-}c$. These channels embrace the semileptonic decay $T_{b:overline{s}}^{-} to Z_{bc;overline{u}overline{s}}^{0}loverline{ u }_{l}$ and nonleptonic modes $T_{b:overline{s}}^{-} to Z_{bc;overline{ u}overline{s}}^{0}pi^{-}(K^{-}, D^{-}, D_s^{-})$, which at the final state contain the scalar tetraquark $Z_{bc;overline{u}overline{s}}^{0}$. Key quantities to compute partial widths of the weak decays are the form factors $G_1(q^2)$ and $G_2(q^2)$: they determine differential rate $dGamma/dq^2$ of the semileptonic and partial widths of the nonleptonic processes, respectively. These form factors are extracted from relevant three-point sum rules at momentum transfers $q^2$ accessible for such analysis. By means of the fit functions $F_{1(2)}(q^2)$ they are extrapolated to cover the whole integration region $m_l^{2}leq q2leq(m-widetilde m)^2$, where $widetilde m$ is the mass of $Z_{bc;overline{u}overline{s}}^{0}$. Predictions for the full width $Gamma _{mathrm{full}}=(15.21pm 2.59)times 10^{-10}~mathrm{ MeV}$ and mean lifetime $4.33_{-0.63}^{+0.89}times 10^{-13}~mathrm{s}$ of the $T_{b:s}^{-} $ are useful for experimental and theoretical investigations of this exotic meson.
The mass and coupling of the doubly charmed $J^P=0^{-}$ diquark-antidiquark states $T_{cc;bar{s} bar{s}}^{++}$ and $T_{cc;bar{d} bar{s}}^{++}$ that bear two units of the electric charge are calculated by means of QCD two-point sum rule method. Comput
ations are carried out by taking into account vacuum condensates up to and including terms of tenth dimension. The dominant $S$-wave decays of these tetraquarks to a pair of conventional $ D_{s}^{+}D_{s0}^{ast +}(2317)$ and $D^{+}D_{s0}^{ast +}(2317)$ mesons are explored using QCD three-point sum rule approach, and their widths are found. The obtained results $m_{T}=(4390~pm 150)~mathrm{MeV}$ and $Gamma =(302 pm 113~mathrm{MeV}$) for the mass and width of the state $T_{cc;bar{ s} bar{s}}^{++}$, as well as spectroscopic parameters $widetilde{m} _{T}=(4265pm 140)~mathrm{MeV}$ and $widetilde{Gamma }=(171~pm 52)~ mathrm{MeV}$ of the tetraquark $T_{cc;bar{d} bar{s}}^{++}$ may be useful in experimental studies of exotic resonances.
We systematically study the mass spectrum and strong decays of the S-wave $bar cbar s q q$ states in the compact tetraquark scenario with the quark model. The key ingredients of the model are the Coulomb, the linear confinement, and the hyperfine int
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