In this paper, we analyze the doubly heavy spin-3/2--spin-1/2 baryons and light meson vertices within the method of light-cone QCD sum rules. These vertices are parametrized in terms of one (three) coupling constant(s) for the pseudoscalar (vector) mesons. The said coupling constants are calculated for all possible transitions. The results presented here can serve to be useful information in experimental as well as theoretical studies of the properties of doubly heavy baryons.
The strong coupling constant of doubly heavy baryons with light pseudoscalar mesons $ π$ and $ K $ are computed within the light cone sum rules. We take into account two-particle and three-particle distribution amplitudes of the said pseudoscalar mesons. We compare our result with the one existing in the literature.
The magnetic dipole moments of the spin-$\frac{1}{2}$ doubly heavy baryons are extracted in the framework of light-cone QCD sum rule. The electromagnetic properties of the doubly heavy baryons encodes important information of their internal structure. The results for the magnetic dipole moments of doubly heavy baryons acquired in this work are compared with the predictions of the other theoretical approaches.
We study $ϕa_0γ$- and $ϕσγ$-vertices in the framework of the light cone QCD sum rules and we estimate the coupling constants g$_{ϕa_0γ}$ and g$_{ϕσγ}$ utilizing $ωϕ$-mixing. We compare our results with the previous estimations of these coupling constants in the literature obtained from phenomenological considerations.
We analyze the weak decay of doubly-heavy baryon decays into anti-triplets $Λ_Q$ with light-cone sum rules. To calculate the decay form factors, both bottom and charmed anti-triplets $Λ_b$ and $Λ_c$ 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 …
In this article, we study the vertices $DDV$ and $D^*DV$ with the light-cone QCD sum rules. The strong coupling constants $g_{DDV}$ and $f_{D^*DV}$ play an important role in understanding the final-state re-scattering effects in the hadronic B decays. They are related to the basic parameters $β$ and $λ$ respectively in the heavy quark effective Lagrangian, our numerical values are smaller than the existing estimations.
The strong $D^{*}_sD_{s}η^{(\prime)}$ and $B^{*}_sB_{s}η^{(\prime)}$ vertices are studied and the relevant couplings are calculated in the context of the light-cone QCD sum rule method with twist-4 accuracy by including the next-to-leading order corrections. In the analysis, both the quark and gluon components of the $η$ and $η^{\prime}$ mesons and the axial anomaly corrected higher twist distributions are included.
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 ansätz, the widths of radiative decays $B_{QQ}^* \to B_{QQ} γ$ are calculated. The results for the said decay widths are compared to the predictions of other approaches.
Using the most general form of the interpolating current for baryons, the strong electric and magnetic coupling constants of light vector mesons $ ρ$ and $ K^* $ with doubly heavy baryons are computed within the light-cone sum rules. We consider 2- and 3-particle distribution amplitudes of the aforementioned vector mesons. The obtained results can be useful in the analysis of experimental data on the properties of doubly heavy baryons conducted at LHC.
We investigate the strong coupling constants of $D D A$, $D^{*}D^{*}A$ and $D^{*} D A$ vertices in the framework of the light-cone QCD sum rules, where $A$ is an axial vector meson such as $a_1, b_1, K_{1A}, K_{1B}, K_1(1270)$ and $K_1(1400)$. Using the strong coupling constants of $D_s D K_1$, $D_s^* D K_1$ and $D_s^* D^* K_1$ vertices for $K_1(1270)$ and $K_1(1400)$ mesons, we evaluated the branching ratios of the non-leptonic decays $B^0\to {K}_{1}^{+}(1270,1400) π^-$. Our results for the branching ratios of these decays are a good agreement with the experimental values.
In this article, we study the vertices $D^*D^*P$, $D^*DV$ and DDV with the light-cone QCD sum rules. The strong coupling constants g_{D^*D^*P}, g_{D^*DP}, f_{D^*DV}, f_{D^*D^*V}, g_{DDV} and g_{D^*D^*V} play an important role in understanding the final-state interactions in the hadronic B decays. They relate to the basic parameters g, $λ$ and $β$ in the heavy quark effective Lagrangian respectively. Our numerical values of the g, $β$ and $λ$ are much smaller than most of the existing estimations. If the predictions from the light-cone QCD sum rules are robust, the final-state interaction effec…
The full version of QCD light-cone sum rule method is applied to tetraquarks containing a single heavy $b$ or $c$ quark. To this end, investigations of the strong vertices $X_{b}X_{b}ρ$ and $X_{c}X_{c}ρ$ are performed, where $X_b=[su][\bar b\bar d]$ and $X_c=[su][\bar c\bar d]$ are the exotic states built of four quarks of different flavors. The strong coupling constants $G_{X_{b}X_{b}ρ}$ and $G_{X_{c}X_{c}ρ}$ corresponding to these vertices are found using the $ρ$-meson leading and higher-twist distribution amplitudes. In the calculations $X_{b}$ and $X_{c}$ are treated as scalar bound states…
In this article, we calculate the strong coupling constants of the $ρNN$, $ρΣΣ$ and $ρΞΞ$ in the framework of the light-cone QCD sum rules approach. The strong coupling constants of the meson-baryon-baryon are the fundamental parameters in the one-boson exchange model which describes the baryon-baryon interactions successfully. The numerical values are in agreement with the existing calculations in part. The electric and magnetic $F/(F+D)$ ratios deviate from the prediction of the vector meson dominance theory, the SU(3) symmetry breaking effects are very large.
The strong coupling constants are basic quantities that carry information of the strong interactions among the baryon and meson multiplets as well as information on the natures and internal structures of the involved hadrons. These parameters enter to the transition matrix elements of various decays as main inputs and they play key roles in analyses of the experimental data including various hadrons. We determine the strong coupling constants among the doubly heavy spin-$ 3/2 $ baryons, $Ξ^*_{QQ'} $ and $Ω^*_{QQ'}$, and light pseudoscalar mesons, $π$, $K$ and $η$, using the light-cone QCD. The…
In this article, we analyze the vertices $D^*D_sK$, $D^*_sDK$, $D_0D_sK$ and $D_{s0}DK$ within the framework of the light-cone QCD sum rules approach in an unified way. The strong coupling constants $G_{D^*D_sK}$ and $G_{D^*_sDK}$ are important parameters in evaluating the charmonium absorption cross sections in searching for the quark-gluon plasmas, our numerical values of the $G_{D^*D_sK}$ and $G_{D^*_sDK}$ are compatible with the existing estimations although somewhat smaller, the SU(4) symmetry breaking effects are very large, about 60%. For the charmed scalar mesons $D_0$ and $D_{s0}$, we…
The light-front (LF) quantization of QCD in light-cone gauge has a number of remarkable advantages, including explicit unitarity, a physical Fock expansion, the absence of ghost degrees of freedom, and the decoupling properties needed to prove factorization theorems in high momentum transfer inclusive and exclusive reactions. We present a systematic study of LF-quantized gauge theory following the Dirac method and construct the Dyson-Wick S-matrix expansion based on LF-time-ordered products. The free theory gauge field is shown to satisfy the Lorentz condition as an operator equation as well a…
In this work, we investigate the semi-leptonic weak decays of spin-1/2 doubly-heavy baryons $Ξ_{QQ^{\prime}}$ into spin-3/2 singly-heavy baryons $Σ_{Q^{\prime}}^*$ within light-cone sum rules. Using the parallel components of the light-cone distribution amplitudes of $Σ_{Q^{\prime}}^*$, the transition form factors for these decays are calculated both analytically and numerically. The numerical results for these semi-leptonic weak decays widths and branching ratios are also predicted, which are compared with the same predictions by other theoretical approaches in the literatures. These phenomen…
As a continuation of our previous work, we investigate the weak decays of doubly-heavy baryons $Ξ_{QQ^{\prime}}$ into sextet $Σ_{Q^{\prime}}$ with light-cone sum rules. We calculate the form factors for these decays with the parallel light-cone distribution amplitudes of $Σ_{Q^{\prime}}$. 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 $Ξ_{cc}$ and $Ξ_{bc}$ decays are several orders of magnit…
The gauge-invariant, nonlocal, dynamical quark model is proved to generate the minimal vertices which satisfy the Ward-Takahashi identities. In the chiral limit, the momentum-dependent quark self-energy results in a flat-like form with some end point delta-funtions for the light-cone pion distribution amplitudes, similarly found in the Nambu Jona-Lasino model with constant constituent mass. The leading order nonzero pion and current quark masses corrections lead concave type asymptotic-like form modifications to twist-2 pion distribution amplitude with end point pillars and twist-3 tensor pion…
The similarity of massive CSW scalar vertices and quark vertices can be understood using a kind of light-cone SUSY transformation presented in this paper. We also show that the canonical transformation generating the MHV-SQCD lagrangian, can be fixed by applying this light-cone SUSY transformation to the canonical transformation for MHV-QCD obtained in paper arxiv:0805.0239. Most of the massive CSW vertices for SQCD can also be pinned down in this way.
We use the method of light-cone sum rules to study the electromagnetic transition of the $Ξ^{*++}_{cc}$ into $Ξ^{++}_{cc}γ$, whose decay width is estimated to be $13.7~{^{+17.7}_{-~7.9}}$ keV. This value is large enough for the $Ξ^{*++}_{cc}$ to be observed in the $Ξ^{++}_{cc}γ$ channel, and we propose to continually search for it in future LHCb and BelleII experiments.
All transitions among the heavy spin--3/2 sextet baryons with participation of the light vector mesons $(B_Q^* B_Q V)$ are investigated in the framework of the light cone sum rules. These vertices are described by four coupling constants. The corresponding sum rules are derived for each coupling constant. It is shown that the correlation functions of different transitions can be described by only one invariant function.
The strong coupling constants between light vector mesons and octet-decuplet baryons are calculated in framework of the light cone QCD sum rules, taking into account SU(3) flavor symmetry breaking effects. It is shown that all strong coupling constants can be represented in terms of a single universal function. Size of the SU(3) symmetry breaking effects are estimated.
Motivated by the latest discovery of doubly-charmed tetraquark $T^+_{cc}$ by LHCb collaboration, we have studied the magnetic moments of the possible doubly-heavy pentaquark states with quantum numbers $J^P = 1/2^-$ and $J^P = 3/2^-$ within the light-cone sum rules method. In the analysis, these possible pentaquark states are considered in diquark-diquark-antiquark structure. The magnetic moments of hadrons encode helpful details about the distributions of the charge and magnetization inside the hadrons, which help us to figure out their geometric configurations. As a by product, the electric …
The heavy spin--3/2 baryon--heavy spin--1/2 baryon vertices with light vector mesons are studied within the light cone QCD sum rules method. These vertices are parametrized in terms of three coupling constants. These couplings are calculated for all possible transitions. It is shown that correlation functions for these transitions are described by only one invariant function for every Lorenz structure. The obtained relations between the correlation functions of the different transitions are structure independent while explicit expressions of invariant functions depend on the Lorenz structure.
The strong coupling constants of hadronic multiplets are fundamental parameters which carry information of the strong interactions among participating particles. These parameters can help us construct the hadron-hadron strong potential and gain information about the structure of the involved hadrons. Motivated by the recent observation of the doubly charmed $Ξ_{cc}$ state by LHCb, we determine the strong coupling constants among the doubly heavy spin-1/2 baryons, $ Ξ^{(\prime)}_{QQ^\prime }$, $ Ω^{(\prime)}_{QQ^\prime}$ and light pseudoscalar mesons, $ π$, $ K $, $η$ and $ η^\prime $ within th…
We calculate the strong coupling constants among the doubly heavy spin-$ \frac{3}{2} $ baryons $Ξ^*_{QQ}$ and $Ω^*_{QQ}$, with $ Q $ and $ Q' $ being $ c$ or $ b $ quark, with light vector meson by means of the light-cone QCD sum rules. The matrix elements defining these vertices are described by four coupling constants $ g_1$, $ g_2$, $ g_3$, and $ g_4 $. The unwanted pollution coming from the doubly heavy spin-$ \frac{1}{2} $ baryons are removed by a special ordering of Dirac matrices and selection of appropriate Lorentz structures. The strong coupling constants are basic parameters that car…
The magnetic dipole moments of the spin-$\frac{3}{2}$ doubly charmed, bottom and charmed-bottom baryons are obtained by means of the light-cone QCD sum rule. The magnetic dipole moments of these baryons encode essential knowledge of their inner structure and shape deformations. The numerical results are given as, $μ_{Ξ_{cc}^{*++}} = 2.94 \pm 0.95$, $μ_{Ξ_{cc}^{*+}} = - 0.67 \pm 0.11$, $μ_{Ω_{cc}^{*+}} =- 0.52 \pm 0.07$, $μ_{Ξ_{bb}^{*0}} = 2.30 \pm 0.55$, $μ_{Ξ_{bb}^{*-}} = -1.39 \pm 0.32$, $μ_{Ω_{bb}^{*-}} = -1.56 \pm 0.33$, $μ_{Ξ_{bc}^{*+}} = 2.63 \pm 0.82$, $μ_{Ξ_{bc}^{*0}} = - 0.96 \pm 0.32…
In collinear factorization, light-cone distribution amplitudes (LCDAs) are key ingredients to calculate the production rate of a hadron in high energy exclusive processes. For a doubly-heavy meson system (such as $B_c, J/ψ, Υ$ etc), the LCDAs contain perturbative scales that can be integrated out and then are re-factorized into products of perturbatively calculable distribution parts and non-relativistic QCD matrix elements. In this re-factorization scheme, the LCDAs are known at next-to-leading order in the strong coupling constant $α_s$ and at leading order in the velocity expansion. In this…
The weak decays of doubly heavy $Ξ_{QQ}$ baryon induced by flavor changing $b \to d$ and $ c \to u$ flavor changing neutral current within the light cone sum rules are studied. Using the parallel components of the light cone distribution amplitudes for $Λ_Q$ baryon, the sum rules are constructed and analyzed for the corresponding transition form factors. Having the results for the form factors, the corresponding branching ratios for $Ξ_{QQ} \to Λ_Q l^+ l^-$ decays are estimated. While the branching ratio due to $b \to d$ transition is around $10^{-9}$, in $c \to u$ transition case, it is found…
The doubly charmed $Ξ_{cc}^{++} (ccu)$ state is the only listed baryon in PDG, which was discovered in the experiment. The LHCb collaboration gets closer to discovering the second doubly charmed baryon $Ξ_{cc}^{+} (ccd)$, hence the investigation of the doubly charmed/bottom baryons from many aspects is of great importance that may help us not only get valuable knowledge on the nature of the newly discovered states, but also in the search for other members of the doubly heavy baryons predicted by the quark model. In this context, we investigate the strong coupling constants among the $Ξ_{cc}^{+…
We explore properties of the doubly charged vector tetraquark $Z_{\mathrm{V} }^{++}=[cu][\overline{s}\overline{d}]$ built of four quarks of different flavors using the QCD sum rule methods. The mass and current coupling of $Z_{ \mathrm{V}}^{++}$ are computed in the framework of the QCD two-point sum rule approach by taking into account quark, gluon and mixed vacuum condensates up to dimension $10$. The full width of this tetraquark is saturated by $S$-wave $Z_{\mathrm{V}}^{++} \to π^{+}D_{s1}(2460)^{+},\ ρ^{+}D_{s0}^{\ast }(2317)^{+}$, and $P$-wave $Z_{\mathrm{V}}^{++} \to π^{+}D_{s}^{+},\ K^{…
With the discovery of the doubly heavy $Ξ_{cc}$ baryon, comprehensive studies of the properties of the doubly heavy baryons are started. In the present work, we examine the $Ξ_{bb} \to Σ_b \ell^+ \ell^-$ and $Ξ_{cc} \to Σ_c \ell^+ \ell^-$ decays induced by flavor-changing neutral currents (FCNC) in the framework of the light-cone sum rules. After obtaining the sum rules for the form factors induced by the tensor current, the branching ratios of the relevant transitions are estimated. We found that the branching ratio for the $c \to u$ transition is around five orders smaller than the $b \to d$…
We apply the light-front reduction of the Bethe-Salpeter equation to matrix elements of the electromagnetic current between bound states. Using a simple (1+1)-dimensional model to calculate form factors, we focus on two cases. In one case, the interaction is dominated by a term instantaneous in light-cone time. Here effects of higher Fock states are negligible and the form factor can be effectively expressed using non-wave function vertices and crossed interactions. If the interaction is not instantaneous, non-wave function vertices are replaced by contributions from higher Fock states. These …
The recent discovery, by the LHCb collaboration, of the $Ξ_{cc}^{++}$ doubly charmed baryon, has renewed interest in the spectroscopy of doubly heavy hadrons. Experimentally, however, searches for such states appear highly challenging. The reconstructed final states tend to involve multiple heavy flavoured (beauty or charm) hadrons, so the yield for any exclusive decay mode will be suppressed to unobservably low levels by the product of several branching fractions, each of which is typically $10^{-3}$--$10^{-2}$. Noting that decays of double beauty hadrons are the only possible source of $B_c^…
