The mass spectra of singly charmed and bottom baryons, $Λ_{c/b}(1/2^\pm,3/2^-)$ and $Ξ_{c/b}(1/2^\pm,3/2^-)$, are investigated using a nonrelativistic potential model with a heavy quark and a light diquark. The masses of the scalar and pseudoscalar diquarks are taken from a chiral effective theory. The effect of $U_A(1)$ anomaly induces an inverse hierarchy between the masses of strange and non-strange pseudoscalar diquarks, which leads to a similar inverse mass ordering in $ρ$-mode excitations of singly heavy baryons.
Inspired by the discovery of the doubly-charmed and doubly-charged $Ξ_{cc}^{++}$ baryon, in this present work, we investigate spin-1/2 and spin-3/2 mass spectra and magnetic moments of $ccu$ baryon in quark-diquark model with a nonrelativistic potential. In the quark-diquark picture, the three-body problem of the $ccu$ baryon is reduced to the two-body bound state problem. We obtained ground and radially excited mass spectra and magnetic moments of the ground state. Ground state mass spectra agree well with the results in the literature, especially with lattice QCD computations. Predictions fo…
Electromagnetic form factors of singly charmed baryons $Σ_c$ and $Λ_c$ in a covariant quark-diquark model
Southern Center for Nuclear-Science Theory (SCNT), Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所南方核科学理论中心）；State Key Laboratory of Heavy Ion Science and Technology, Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所重离子科学与技术国家重点实验室）；School of Nuclear Sciences and Technology, University of Chinese Academy of Sciences（中国科学院大学核科学与技术学院）；College of Physics, Guizhou University（贵州大学物理学院）
Triply heavy baryons are investigated in the framework of the relativistic quark model based on the quark-diquark picture in the quasipotential approach in QCD. Masses of the ground and excited states of the $Ω_{ccc}$, $Ω_{bbb}$, $Ω_{ccb}$ and $Ω_{cbb}$ baryons are calculated. Orbital and radial excitations between the diquark and quark as well as between quarks inside the diquark are considered. The diquark internal structure is consistently taken into account by the form factor of the diquark-gluon interaction expressed through the overlap integral of the diquark wave functions. The detailed…
Mass spectra of heavy baryons are calculated in the heavy-quark--light-diquark picture in the framework of the QCD-motivated relativistic quark model. The dynamics of light quarks in the diquark as well as the dynamics of the heavy quark and light diquark in the baryon are treated completely relativistically without application of nonrelativistic v/c and heavy quark 1/m_Q expansions. Such approach allows us to get predictions for the heavy baryon masses for rather high orbital and radial excitations. On this basis the Regge trajectories of heavy baryons for orbital and radial excitations are c…
We construct a leading-order effective field theory for both scalar and axial-vector heavy diquarks, and consider its power expansion in the heavy diquark limit. By assuming the transition from QCD to diquark effective theory, we derive the most general form for the effective diquark transition currents based on the heavy diquark symmetry. The short-distance coefficients between QCD and heavy diquark effective field theory are also obtained by a tree level matching. With the effective currents in the heavy diquark limit, we perform a reduction of the form factors for semi-leptonic decays of do…
A pion mean-field approach allows one to investigate light and singly heavy baryons on an equal footing. In the large $N_c$ limit, the light and singly heavy baryons are viewed respectively as $N_c$ and $N_c-1$ valence quarks bound by the pion mean fields created self-consistently, since a heavy quark can be regarded as a static color source in the limit of the infinitely heavy quark mass. The transition magnetic moments of the baryon sextet are determined entirely by using the parameters fixed in the light-baryon sector without any additional parameters introduced. Assuming that the transitio…
We investigate the mass spectra of the lowest-lying singly heavy baryons, based on the self-consistent chiral quark-soliton model. We take into account the rotational $1/N_c$ and strange current quark mass ($m_{\mathrm{s}}$) corrections. Regarding $m_{\mathrm{s}}$ as a small perturbation, we expand the effective chiral action to the second order with respect to $m_{s}$. The mass spectra of heavy baryons are computed and compared with the experimental data. Fitting the classical masses of the heavy baryon to the center mass of each representation, we determine the masses of all the lowest-lying…
The masses of the ground state heavy baryons consisting of two light (u,d,s) and one heavy (c,b) quarks are calculated in the heavy-quark--light-diquark approximation within the constituent quark model. The light quarks, forming the diquark, and the light diquark in the baryon are treated completely relativistically. The expansion in v/c up to the second order is used only for the heavy (b and c) quarks. The diquark-gluon interaction is taken modified by the form factor describing the light diquark structure in terms of the diquark wave functions. An overall reasonable agreement of the obtaine…
In this study, the magnetic moments of the spin-1/2 triply-heavy baryons have been calculated using both light-cone QCD sum rules and Quark-diquark model. Theoretical investigations on magnetic moments of the triply-heavy baryons, are crucial as their results can help us better understand their internal structure and the dynamics of the QCD as the theory of the strong interaction. We compare the results extracted for the magnetic moment with the existing theoretical predictions. It is seen that the obtained magnetic moment values are quite compatible with the results in the literature.
In the present talk, we report recent results on electromagnetic properties of the baryon decuplet within the SU(3) chiral quark-soliton model, taking into account the effects of explicit flavor SU(3) symmetry breaking. We focus on the comparison of the present results on the electromagnetic form factors of the $Δ^{+}$ baryon with the lattice data.
The diquark is a strongly correlated quark pair that plays an important role in hadrons and hadronic matter. In order to treat the diquak as a building block of hadrons, we formulate an effective theory of diquark fields with $SU(3)_R \times SU(3)_L$ chiral symmetry. We concentrate on the scalar ($0^+$) and pseudoscalar ($0^-$) diquarks and construct a linear-sigma-model Lagrangian. It is found that the effective Lagrangian contains a new type of chirally symmetric meson-diquark-diquark coupling that breaks axial $U_A(1)$ symmetry. We discuss consequences of the $U_A(1)$ anomaly term to the di…
We analyze the hidden charm $P$-wave tetraquarks in the diquark model, using an effective Hamiltonian incorporating the dominant spin-spin, spin-orbit and tensor interactions. We compare with other $P$-wave system such as $P$-wave charmonia and the newly discovered $Ω_c$ baryons, analysed recently in this framework. Given the uncertain experimental situation on the $Y$ states, we allow for different spectra and discuss the related parameters in the diquark model. In addition to the presently observed ones, we expect many more states in the supermultiplet of $L=1$ diquarkonia, whose $J^{PC}$ qu…
A new scheme of state classification is proposed and applied to analyze masses of the heavy baryons $Ω_{Q}$, $Σ_{Q}$ and $Ξ_{Q}^{\prime}$ in P-waves. The results confirm all excited $Ω_{c}$ and $Ω_{b}$ baryons reported recently by LHCb to be bound states of a P-wave $ss$-diquark and a respective charm or bottom quark, and thereby predict Regge trajectories for more excited $Ω_{c}$ and $Ω_{b}$ baryons. We suggest one excited {$J^{P}=5/2^{-}$} $Ω_{b}$ state to be unseen by LHCb around $6352$ MeV, and predict P-wave masses of all spin-partners of the odd-parity baryons $Σ_{c}(2800)/Ξ_{c}^{\prime}…
Assuming that vector and scalar diquarks exist in the Quark-Gluon Plasma near the critical temporature $T_c$, baryons can be produced through the processes of quarks and diquarks forming $({1/2})^+$ baryon states. Ratios of different baryons can be estimated through this method, if such kind of QGP with diquarks can exists.
A simple quark-diquark model for the baryons is constructed as a partial solution to the well known missing resonances problem. A complete classification of the baryonic states in the quark-diquark framework is given and the spectrum is calculated through a mass formula built to reproduce the rotational and vibrational Regge trajectories.
Mass spectra of strange baryons are calculated in the framework of the relativistic quark model based on the quasipotential approach. Baryons are treated as the relativistic quark-diquark bound systems. It is assumed that two quarks with equal constituent masses form a diquark. The diquark excitations and its internal structure are consistently taken into account. Calculations are performed up to rather high orbital and radial excitations of strange baryons. On this basis the Regge trajectories are constructed. The obtained results are compared with available experimental data and previous pre…
We provide an extensive study of the lifetimes of singly charmed baryons and mesons, within the heavy quark expansion with all known corrections included. A special attention is devoted to the choice of the charm mass and wavefunctions of heavy baryons. We give our predictions for lifetimes, lifetime ratios, and semileptonic branching ratios of singly charmed baryons. Our results accommodate the experimentally-favoured hierarchy of singly charmed baryon lifetimes \begin{eqnarray*} τ\left(Ξ_c^{0}\right) < τ\left(Λ_c^{+}\right)< τ\left(Ω_c^{0}\right) < τ\left(Ξ_c^{+}\right)\, \end{eqnarray*} in …
Mass spectra of baryons consisting of two heavy (b or c) and one light quarks are calculated in the framework of the relativistic quark model. The light quark-heavy diquark structure of the baryon is assumed. Under this assumption the ground and excited states of both the diquark and quark-diquark bound system are considered. The quark-diquark potential is constructed. The light quark is treated completely relativistically, while the expansion in the inverse heavy quark mass is used revealing the close similarity with the mass spectra of B and D mesons. We find that the relativistic treatment …
The wave functions in the diquark-quark model for baryons are modified to take into account the effect of the different masses of the quarks in diquark formation. A spatial wave function is introduced multiplying each flavour-spin configuration in the quark-diquark model. Futhermore a numerical coefficient is introduced which weighes the contribution of each configuration.
This paper studies the leading chiral corrections to heavy quark-diquark symmetry predictions for doubly heavy baryon semileptonic decay form factors. We derive the coupling between heavy diquarks and weak current in the limit of heavy quark-diquark symmetry, and construct the chiral Lagrangian for doubly heavy baryons coupled to weak current. We evaluate chiral corrections to doubly heavy baryon zero-recoil semileptonic decay for both unquenched and partially quenched QCD. This theory is used to derive chiral extrapolation expressions for measurements of form factors of doubly heavy baryon ze…
A composite Fermion (CF) model of quasi particle has been used to describe a diquark. Considering baryons in quark-diquark configuration,the masses of the heavy light baryons like $Λ_{c}^{+}$, $Σ_{c}^{+}$, $Ξ_{c}^{0}$, $Ω_{c}^{0}$ and $Λ_{b}^{+}$, $Σ_{b}^{+}$, $Ξ_{b}^{0}$, $Ω_{b}^{-}$ have been computed using this CF model of the diquark. The results are found to be in good agreement with the corresponding experimental findings. It has been suggested that the diquark can be well described in the framework of CF model in a gauge invariant way.
The decays $Ξ_b \to Λ_b π$ are strangeness changing weak transitions involving only the light diquark in the baryon. Thus these decays can test the properties of such diquarks, in particular the suggestions existing in the literature of enhanced correlations in $J^P=0^+$ light diquarks. We revisit the estimates of the rates of these decays and point out that with the enhanced correlation their branching fraction can reach a few percent and may become visible in the measurements of differences of the lifetimes of $b$ baryons.
A simple quark-diquark model of baryons with direct and exchange interactions is constructed. Spectrum and form factors are calculated and compared with experimental data. Advantages and disadvantages of the model are discussed.
In this presentation, we summarize selectively recent results of the electromagnetic form factors of singly heavy baryons with spin 1/2 and related quantities, which were derived within a framework of the self-consistent chiral quark-soliton model. The results are compared with those from the lattice QCD and their physical implications are discussed.
A review of the underlying ideas of the Interacting Quark Diquark Model (IQDM) that asses the baryon spectroscopy in terms of quark diquark degrees of freedom is given, together with a discussion of the missing resonances problem. Some ideas about its generalization the heavy baryon spectroscopy is given.s of freedom is given, together with a discussion of the missing resonances problem. Some ideas about its generalization the heavy baryon spectroscopy is given.The results are compared to the existing experimental data.
A diquark model is used to investigate single charmed baryons. In this model, baryon is composed of two diquarks and an antiquark. Masses of lowest lying states with $J^P= 1/2 ^ \pm$ are obtained. Some masses are smaller than other theoretic predictions which indicates that these baryons of pentaquark structure could be relatively stable. The results also show that $Λ(2882)$ may be a pentaquark with $J^P=1/2^-$ and $Ξ(3125)$ may be a pentaquark with $J^P=1/2^+$.
We briefly discuss the relativistic interacting quark-diquark model formalism and its application to the calculation of strange and nonstrange baryon spectra. The results are compared to the existing experimental data.
Recently, some singly bottom baryons have been established experimentally, but none of doubly or triply bottom baryons has been observed. Under the Regge phenomenology, the mass of a ground state unobserved doubly or triply bottom baryon is expressed as a function of masses of the well established light baryons and singly bottom baryons. Then, the values of Regge slopes and Regge intercepts for baryons containing one, two, or three bottom quarks are calculated. After that, masses of the orbitally excited singly, doubly, and triply bottom baryons are estimated. Our predictions may be useful for…
Using a geometric model for the study of the structure of hadrons, we study baryons having one, two and three heavy quarks. The study reveals diquark structure in baryons with one and two heavy quarks but not with three heavy identical quarks.
The baryon structure is investigated in a covariant diquark-quark model. In this approach baryons emerge as relativistic bound states of a constituent quark and a $0^{+}$ or $1^{+}$ diquark. After solving the Bethe-Salpeter Equation for the scalar diquark quark system in ladder approximation we couple various external currents to the constituents of the baryon to probe its internal structure. The quark and the diquarks are assumed to be confined which is implemented by suitable choices for the propagators. This leads to nontrivial vertex functions between the constituents and the external curr…
The relativistic interacting quark-diquark model of baryons, recently developed, is here extended to introduce a spin-isospin transition interaction into the mass operator. The refined version of the model is used to calculate the non strange baryon spectrum. The results are compared to the present experimental data.
We describe the relativistic interacting quark-diquark model formalism and its application to the calculation of strange and nonstrange baryon spectra. The results are compared to the existing experimental data. We also discuss the application of the model to the calculation of other baryon observables, like baryon magnetic moments, open-flavor strong decays and baryon masses with self-energy corrections.
The yield of doubly charmed baryons with excited heavy diquark in $S$ wave and $P$ wave states has been estimated at LHC energies. The observation possibility of such baryons is discussed.
We study the isospin mass differences of singly heavy baryons, based on a pion mean-field approach. We consider both the electromagnetic interactions and the hadronic contributions that arise from the mass difference of the up and down quarks. The relevant parameters have been already fixed by the baryon octet. In addition, we introduce the strong hyperfine interactions between the light quarks inside a chiral soliton and the Coulomb interactions between the chiral soliton and a heavy quark. The numerical results are in good agreement with the experimental data. In particular, the results for …
In the heavy quark limit, a doubly heavy baryon is regarded as composed of a heavy diquark and a light quark. We establish the Bethe-Salpeter (BS) equations for the heavy diquarks and the doubly heavy baryons, respectively, to leading order in a $1/m_{Q}$ expansion. The BS equations are solved numerically under the covariant instantaneous approximation with the kernels containing scalar confinement and one-gluon-exchange terms. The masses for the heavy diquarks and the doubly heavy baryons are obtained and the non-leptonic decay widths for the doubly heavy baryons emitting a pseudo-scalar meso…
In the framework of the nonrelativistic QCD and a quark-diquark model of baryons we have obtained the fragmentation functions for heavy quark to split into spin-1/2 and spin-3/2 double heavy baryons. It was predicted the production rates as well as the shape of the energy spectra for the $cc-$ and $bc-$baryons in the region of $Z^o$ peak at LEP collider.
The mass spectra of the excited heavy baryons consisting of two light (u,d,s) and one heavy (c,b) quarks are calculated in the heavy-quark--light-diquark approximation within the constituent quark model. The light quarks, forming the diquark, and the light diquark in the baryon are treated completely relativistically. The expansion in v/c up to the second order is used only for the heavy (b and c) quarks. The internal structure of the diquark is taken into account by inserting the diquark-gluon interaction form factor. An overall good agreement of the obtained predictions with available experi…
The baryonic decays of $J/ ψ$ provide a new way to study the internal structure of baryons. We apply a simple diquark model to the calculation of the decay cross-sections for the reactions $J/ ψ\longrightarrow \bar{p}p$, $\bar pN^*(1440)$, $\bar{N}^{\ast}N^{\ast}$, $\barΛΛ$ and $\barΣ^0Σ^0$. The results are different from those given by the ordinary constituent quark model. Hence these reactions may provide a new check of two different pictures for the baryons.
It is shown that the number of independent weak form factors collapses if the heavy diquark exists inside the baryons containing a single heavy quark. The relations between the weak form factors are quite different in the case of light diquark. So a careful analysis on the future data of the weak form factors would clarify that in those baryons the correlation between the heavy quark and a light quark is stronger or weaker than the one between two light quarks.
The mass spectra and wave functions for the doubly heavy baryons are computed under the picture that the two heavy quarks inside a doubly heavy baryon, such as two $c$-quarks in $Ξ_{cc}$, combine into a heavy `diquark core' in color anti-triplet firstly, then the diquark core turns into a color-less doubly heavy baryon via combining the light $q$-quark inside the baryon. Namely both of the combinations, the two heavy quarks inside the baryon into a diquark core in color anti-triplet and the heavy diquark core with the light quark into the baryon, are depicted by relativistic Bethe-Salpeter equ…
Mass spectra and wave functions of the $J^P=\frac{1}{2}^+$ $(bcq)$ baryons are calculated by the relativistic Bethe-Salpeter equation\,(BSE) with considering the mixing effects between the $1^+$ and $0^+$ $(bc)$-diquarks inside. Based on the diquark picture, the three-body problem of baryons is transformed into two two-body problems. The BSE and wave functions of the $0^+$ diquark are given, and then solved numerically to obtain the effective mass spectra and form factors. Also we present the wave functions at zero point for the $(bc)$-diquark. Considering the obtained diquark form factors, th…
The finite size of doubly heavy diquark gives a positive correction to the masses of baryons calculated in the local diquark approximation. We evaluate this correction for the basic states of doubly charmed baryons to give quite accurate predictions actual for current searches of those baryons at LHCb: $m[{Ξ_{cc}^{1/2}}^{+}]\approx m[{Ξ_{cc}^{1/2}}^{++}]=3615\pm 55$ MeV and $m[{Ξ_{cc}^{3/2}}^{+}]\approx m[{Ξ_{cc}^{3/2}}^{++}]=3747\pm 55$ MeV.
The approach of path integral hadronization, applied to a quark-diquark toy model, is used to derive an effective chiral meson-baryon Lagrangian. In this approach the Goldberger-Treiman relation, found at the quark-meson level, is re-established at the composite hadron level. For illu- strations, electromagnetic low energy characteristics of composite nucleons are estimated.
We treat baryons as bound states of scalar or axialvector diquarks and a constituent quark which interact through quark exchange. We obtain fully four-dimensional wave functions for both octet and decuplet baryons as solutions of the corresponding Bethe-Salpeter equation. Applications currently under investigation are: electromagnetic and strong form factors and strangeness production processes.
We study the role of diquarks in light baryons through point to point baryon correlators. We contrast results from quenched simulations with ones with two flavors of dynamical overlap fermions. The scalar, pseudoscalar and axial vector diquarks are combined with light quarks to form color singlets. The quenched simulation shows large zero mode effects in correlators containing the scalar and pseudoscalar diquark. The two scalar diquarks created by gamma_5 and gamma_0gamma_5 lead to different behavior in baryon correlators, showing that the interaction of diquarks with the third light quark mat…
The properties of the Theta^{+} and Xi^{--}_{3/2} exotic baryons have been investigated in the framework of diquark- diquark-antiquark system. A model for diquark suggested in an analogy with the quasi-particle in a crystal lattice has been used. The mass of the exotics have been computed. The Decay width of the Theta^{+} has been estimated to be ~ 11 MeV using effective diquark theory. The radius of the Xi^{--}_{3/2} has been extracted as 0.94fm using the experimental value of the frac{Γ_{Θ^{+}}}{Γ_{Ξ^{--}_{3/2}}}. The results obtained are found to be in good agreement with the present experi…
We study the electromagnetic form factors of the lowest-lying singly heavy baryons in a pion mean-field approach, which is also known as the SU(3) chiral quark-soliton model. In the limit of the heavy-quark mass, the dynamics inside a singly heavy baryon is governed by the $N_c-1$ valence quarks, while the heavy quark remains as a mere static color source. In this framework, a singly heavy baryon is described by combining the colored soliton with the singly heavy quark. In the infinitely heavy-quark mass limit, we can compute the electric quadrupole form factors of the baryon sextet with spin …
We describe baryons as quark-diquark bound states at finite temperature and density within the NJL model for chiral symmetry breaking and restoration in quark matter. Based on a generalized Beth-Uhlenbeck approach to mesons and diquarks we present in a first step the thermodynamics of quark-diquark matter which includes the Mott dissociation of diquarks at finite temperature. In a second step we solve the Bethe-Salpeter equation for the baryon as a quark-diquark bound state in quark-diquark matter. We obtain a stable, bound baryon even beyond the Mott temperature for diquark dissociation since…
The triply heavy flavour baryons are studied using the Quark-diquark description of the three-body system. The confinement potential for present study of triply heavy flavour baryons is assumed as coulomb plus power potential with power index $ν$. We have solved Schrodinger equation numerically to calculate the masses of triply heavy flavour baryons. The masses and magnetic moments of triply heavy flavour baryons are computed for different power indices, $ν$, starting from 0.4 to 1.0. The predicted masses and magnetic moments are in good agreement with other theoretical predictions.
