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Register a new userThe B_{s0} meson and the B_{s0}B K coupling from QCD sum rules
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We evaluate the mass of the $B_{s0}$ scalar meson and the coupling constant in the $B_{s0} B K$ vertex in the framework of QCD sum rules. We consider the $B_{s0}$ as a tetraquark state to evaluate its mass. We get $m_{B_s0}=(6.04pm 0.08) GeV$, which is bigger than predictions supposing it as a $bbar{s}$ state or a $Bbar{K}$ bound state with $J^{P}=0^+$. To evaluate the $g_{B_{s0}B K}$ coupling we use the three point correlation functions of the vertex, considering $ B_{s0} $ as a normal $bbar{s}$ state. The obtained coupling constant is: $g_{B_{s0} B K} =(16.3 pm 3.2) GeV$. This number is in agreement with light-cone QCD sum rules calculation. We have also compared the decay width of the $BSto BK$ process considering the $BS$ to be a $bbar{s}$ state and a $BK$ molecular state. The width obtained for the $BK$ molecular state is twice as big as the width obtained for the $bbar{s}$ state. Therefore, we conclude that with the knowledge of the mass and the decay width of the $BS$ meson, one can discriminate between the different theoretical proposals for its structure.
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The strong coupling constants of spin-3/2 to spin-1/2 doubly heavy baryon transitions with light vector mesons are estimated within the light-cone QCD sum rules method. Moreover, using the vector-meson dominance ansatz, the widths of radiative decays $B_{QQ}^* to B_{QQ} gamma$ are calculated. The results for the said decay widths are compared to the predictions of other approaches.
In order to make a further confirmation about the assignments of the excited bottom and bottom strange mesons $B_{1}(5721)$, $B_{2}^{*}(5747)$, $B_{s1}(5830)$, $B_{s2}^{*}(5840)$ and meanwhile identify the possible assignments of $B_{J}(5840)$, $B_{J}(5970)$, we study the strong decays of these states with the $^{3}P_{0}$ decay model. Our analysis support $B_{1}(5721)$ and $B_{2}^{*}(5747)$ to be the $1P_{1}$ and $1^{3}P_{2}$ assignments and the $B_{s1}(5830)$, $B_{s2}^{*}(5840)$ to be the strange partner of $B_{1}(5721)$ and $B_{2}^{*}(5747)$. Besides, we tentatively identify the recently observed $B_{J}(5840)$, $B_{J}(5970)$ as the $2^{3}S_{1}$ and $1^{3}D_{3}$ states, respectively. It is noticed that this conclusion needs further confirmation by measuring the decay channel to $Bpi$ of $B_{J}(5840)$ and $B_{J}(5970)$ in experiments.
Using three point QCD sum rules method, the form factors relevant to the semileptonic $B_{s}to D_{sJ}(2460)ell u$ decay are calculated. The $q^2$ dependencies of these form factors are evaluated. The dependence of the asymmetry parameter $alpha$, characterizing the polarization of $D_{sJ}$ meson, on $q^2$ is studied. This study gives useful information about the structure of the $D_{sJ}$ meson. Finally the branching ratio of this decay is also estimated and is shown that it can be easily detected at LHC.
The form factors and the coupling constant of the $B_s B^* K $ and $B_s B K^*$ vertices are calculated using the QCD sum rules method. Three point correlation functions are computed considering both the heavy and light mesons off-shell in each vertex, from which, after an extrapolation of the QCDSR results at the pole of the off-shell mesons, we obtain the coupling constant of the vertex. The form factors obtained have different behaviors but their simultaneous extrapolation reach the same value of the coupling constant $g_{B_s B^* K}=8.41 pm 1.23 $ and $g_{B_s BK^*}=3.3 pm 0.5$. We compare our result with other theoretical estimates and compute the uncertainties of the method.
The scalar meson $D_{s0}^*(2317)$ is found 37(17)MeV below DK threshold in a lattice simulation of the $J^P=0^+$ channel using, for the first time, both DK as well as $bar sc$ interpolating fields. The simulation is done on $N_f=2+1$ gauge configurations with $m_pisimeq 156 $MeV, and the resulting $M_{D_{s0}^*}-tfrac{1}{4}(M_{D_s}+3M_{D_s^*})=266(16)$ MeV is close to the experimental value 241.5(0.8)MeV. The energy level related to the scalar meson is accompanied by additional discrete levels due to DK scattering states. The levels near threshold lead to the negative DK scattering length $a_0=-1.33(20)$ fm that indicates the presence of a state below threshold.
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