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Register a new userStrong $B_{QQ}^*B_{QQ}V$ vertices and the radiative decays of $B_{QQ}^* to B_{QQ}gamma$ in the light-cone sum rules
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Ka\\u{g}an \\c{S}im\\c{s}ek
Publication date
2021
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English
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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.
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As a continuation of our previous work, we investigate the weak decays of doubly-heavy baryons $Xi_{QQ^{prime}}$ into sextet $Sigma_{Q^{prime}}$ with light-cone sum rules. We calculate the form factors for these decays with the parallel light-cone distribution amplitudes of $Sigma_{Q^{prime}}$. Numerical results of these form factors are used to predict the decay widths and branching ratios of the corresponding semi-leptonic processes. Parametric uncertainties and theoretical analyses are also given in detail. We find that the decay widths of $Xi_{cc}$ and $Xi_{bc}$ decays are several orders of magnitude larger than those of $Xi_{bb}$ decays.
We analyze the weak decay of doubly-heavy baryon decays into anti-triplets $Lambda_Q$ with light-cone sum rules. To calculate the decay form factors, both bottom and charmed anti-triplets $Lambda_b$ and $Lambda_c$ are described by the same set of leading twist light-cone distribution functions. With the obtained form factors, we perform a phenomenology study on the corresponding semi-leptonic decays. The decay widths are calculated and the branching ratios given in this work are expected to be tested by future experimental data, which will help us to understand the underlying dynamics in doubly-heavy baryon decays.
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.
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.
We use QCD sum rules to study the possible existence of $QQ-bar{u}bar{d}$ mesons, assumed to be a state with $J^{P}=1^{+}$. For definiteness, we work with a current with an axial heavy diquark and a scalar light antidiquark, at leading order in $alpha_s$. We consider the contributions of condensates up to dimension eight. For the $b$-quark, we predict $M_{T_{bb}}= (10.2pm 0.3) {rm GeV}$, which is below the $bar{B}bar{B}^*$ threshold. For the $c$-quark, we predict $M_{T_{cc}}= (4.0pm 0.2) {rm GeV}$, in agreement with quark model predictions.
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