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Register a new userMasses of doubly heavy-quark baryons in an extended chromomagnetic model
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We extend the chromomagnetic model by further considering the effect of color interaction. The effective mass parameters between quark pairs ($m_{qq}$ or $m_{qbar{q}}$) are introduced to account both the effective quark masses and the color interaction between the two quarks. Using the experimental masses of hadrons, the quark pair parameters are determined between the light quark pairs and the light-heavy quark pairs. Then the parameters of heavy quark pairs ($cc$, $cb$, $bb$) are estimated based on simple quark model assumption. We calculate all masses of doubly and triply heavy-quark baryons. The newly discovered doubly charmed baryon $Xi_{cc}$ fits into the model with an error of 12 MeV.
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Using an extended chromomagnetic model, we perform a systematic study of the masses of the doubly heavy tetraquarks. We find that the ground states of the doubly heavy tetraquarks are dominated by color-triplet $ket{(qq)^{bar{3}_{c}}(bar{Q}bar{Q})^{3_{c}}}$ configuration, which is opposite to that of the fully heavy tetraquarks. The combined results suggest that the color-triplet configuration becomes more important when the mass difference between the quarks and antiquarks increases. We find three stable states which lie below the thresholds of two pseudoscalar mesons. They are the $IJ^{P}=01^{+}$ $nnbar{b}bar{b}$ tetraquark, the $IJ^{P}=00^{+}$ $nnbar{c}bar{b}$ tetraquark and the $J^{P}=1^{+}$ $nsbar{b}bar{b}$ tetraquark.
Doubly heavy tetraquark $(QQbar qbar q)$ states are the prime candidates of tightly bound exotic systems and weakly decaying. In the framework of the improved chromomagnetic interaction (ICMI) model, we complete a systematic study on the mass spectra of the $S$-wave doubly heavy tetraquark states $QQbar{q}bar{q}$ ($q=u, d, s$ and $Q=c, b$) with different quantum numbers $J^P=0^+$, $1^+$, and $2^+$. The parameters in the ICMI model are extracted by fitting the conventional hadron spectra and used directly to predict the masses of tetraquark states. For heavy quarks, the uncertainties of the parameters are acquired by comparing the masses of doubly (triply) heavy baryons with these given by lattice QCD, QCD sum rule, and potential models. Several compact and stable bound states are found in both charm and bottom tetraquark sectors. The predicted mass of $ccbar ubar d$ state is compatible with the recent result of the LHCb collaboration.
The masses of baryons containing two heavy quarks and their couplings to the corresponding quark currents are evaluated in the framework of NRQCD sum rules. The coulomb-like corrections in the system of doubly heavy diquark are taken into account, and the contribution of nonperturbative terms coming from the quark, gluon and mixed condensates as well as the product of quark and gluon condensates, is analyzed. The higher condensates destroy the factorization of baryon and diquark correlators and provide the convergency of sum rule method. As a result the accuracy of estimates is improved.
We report results from a study of heavy-baryon spectroscopy within a relativistic constituent- quark model, whose hyperfine interaction is based on Goldstone-boson-exchange dynamics. While for light-flavor constituent quarks it is now commonly accepted that the effective quark-quark interaction is (predominantly) furnished by Goldstone-boson exchange - due to spontaneous chiral-symmetry breaking of quantum chromodynamics at low energies - there is currently still much speculation about the light-heavy and heavy-heavy quark-quark interactions. With the increasing amount of experimental data on heavy-baryon spectroscopy these issues might soon be settled. Here, we show, how the relativistic constituent-quark model with Goldstone-boson-exchange hyperfine interactions can be extended to charm and bottom baryons. It is found that the same model that has previously been successful in reproducing the light and strange baryon spectra is also in line with the existing phenomenological data on heavy-baryon spectroscopy. An analogous model with one-gluon-exchange hyperfine interactions for light-heavy flavors does not achieve a similarly good performance.
Exclusive nonleptonic decays of bottom and charm baryons are studied within a relativistic quark model. We include factorizing as well as nonfactorizing contributions to the decay amplitudes.
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