Heavy Baryon Masses Research Articles

Screening of the quark charge and mixing effects on transition moments and M1 decay widths of baryons

Motivated by the precision measurements of heavy flavor baryon masses, we analyze the modification of quark charge by employing the screening effect inside the baryon. In addition, we calculate the isospin mass splitting up to charmed baryons employing isospin symmetry breaking. Consequently, we obtain the masses, magnetic moments, and transition moments of $J^P=\frac{1}{2}^+$ and $\frac{3}{2}^+$ baryons to predict radiative decay widths for $\frac{1}{2}^{\prime +} \to \frac{1}{2}^+$ and $\frac{3}{2}^+\to \frac{1}{2}^{(\prime)+}$ transitions. Finally, we include the effects of state mixing in flavor degenerate baryon magnetic and transition moments, as well as M1 transition decay widths.

Masses of Single, Double, and Triple Heavy Baryons in the Hyper-Central Quark Model by Using GF-AEIM

By using the generalized fractional analytical iteration method (GF-AEIM), the single, the double, and the triple heavy baryons masses are calculated in the hyper-central model in the two cases. In the first case, the potential is a combination of Coulombic potential, the linear confining potential, and the harmonic oscillator potential. In the second case, we add the hyperfine interaction. The energy eigenvalues and the baryonic wave function are obtained in the fractional forms. The present results are a good agreement with experimental data and are improved with other recent works.

Roper-like singly heavy baryons in a chiral model

We investigate the Roper-like singly heavy baryons such as Λc(2765) and Ξc(2967) in a chiral model. Based on chiral symmetry of diquarks inside the baryons, we propose that the Roper-like baryons are mostly pentaquark states (Qqqqq¯ ) while the corresponding ground-state ones Λc(2286) and Ξc(2470) are three-quark states (Qqq). Besides, the mass spectrum of negative-parity Λc and Ξc which are heavy quark spin-singlet is predicted by the linear representation of chiral symmetry. We also derive a sum rule of the heavy baryon masses and an extended Goldberger-Treiman relation. In addition to them, we demonstrate the parity-partner structure of the Λc’s and Ξc’s by showing mass degeneracies of them at the chiral restoration point. We expect that the present investigation leads to a better understanding of the diquarks inside hadrons from the viewpoint of chiral symmetry.

Heavy baryon spectrum with chiral multiplets of scalar and vector diquarks

Chiral effective theory of scalar and vector diquarks is formulated according to the linear sigma model. The main application is to describe the ground and excited states of singly heavy baryons with a charm or bottom quark. Applying the potential quark model between the diquark and the heavy quark ($Q=c, b$), we construct a heavy-quark--diquark model. The spectra of the positive- and negative-parity states of $\Lambda_Q$, $\Sigma_Q$, $\Xi^{(')}_Q$ and $\Omega_Q$ are obtained. The masses and interaction parameters of the effective theory are fixed partly from the lattice QCD data and also from fitting low-lying heavy baryon masses. We find that the negative parity excited states of $\Xi_Q$ (flavor $\bar{\bf 3}$) are different from those of $\Lambda_Q$, because of the inverse hierarchy of the pseudoscalar diquark. On the other hand, $\Sigma_Q, \Xi'_Q$ and $\Omega_Q$ (flavor ${\bf 6}$) baryons have similar spectra. We compare our results of the heavy-quark--diquark model with experimental data as well as the quark model.

Masses of doubly heavy tetraquarks with error bars

In the heavy-quark limit, the two heavy quarks in a doubly heavy baryon or a doubly heavy tetraquark are bound by their color-Coulomb potential into a compact diquark. The doubly heavy hadrons are related by the approximate heavy-quark--diquark symmetry of QCD to the heavy hadrons obtained by replacing the heavy diquark by a heavy antiquark. Effective field theories can be used to expand the masses of singly heavy hadrons and doubly heavy hadrons in inverse powers of the heavy quark masses. The coefficients in the expansions for doubly heavy tetraquarks can be determined from those for heavy mesons, heavy baryons, and doubly heavy baryons using heavy-quark--diquark symmetry. We predict the masses of the ground-state doubly heavy tetraquarks with error bars using as inputs the masses of heavy mesons and heavy baryons measured in experiments and the masses of doubly heavy baryons calculated using lattice QCD. The only doubly heavy tetraquarks predicted to be stable with respect to strong decays are $bb$ tetraquarks with light flavor $\bar u \bar d$, $\bar s \bar u$ and $\bar s \bar d$.

Nonleptonic and semileptonic {Lambda _b} rightarrow {Lambda _c} transitions in a potential quark model

Nonleptonic and semileptonic decay widths of {Lambda _b} rightarrow {Lambda _c} are analyzed within heavy quark limit and Isgur-Wise formalism. A modified QCD Cornell interaction with the additional logarithmic term in the hyperspherical coordinates is considered and the masses of heavy flavour baryons are calculated. The obtained masses are consequently employed to study the rates of {Lambda _b} rightarrow {Lambda _c}. The achieved results are motivating.

Heavy Baryon Spectroscopy in the Relativistic Quark Model

Masses of heavy baryons are calculated in the framework of the relativistic quark-diquark picture and QCD. The obtained results are in good agreement with available experimental data including recent measurements by the LHCb Collaboration. Possible quantum numbers of excited heavy baryon states are discussed.

Masses of light and heavy mesons and baryons: A unified picture

We compute masses of positive parity spin-$1/2$ and $3/2$ baryons composed of $u$, $d$, $s$, $c$ and $b$ quarks in a quark-diaquark picture. The mathematical foundation for this analysis is implemented through a symmetry-preserving Schwinger-Dyson equations treatment of a vector-vector contact interaction, which preserves key features of quantum chromodynamics, such as confinement, chiral symmetry breaking and low energy Goldberger-Treiman relations. This study requires a computation of diquark correlations containing these quarks which in turn are readily inferred from solving the Bethe-Salpeter equations of the corresponding mesons. Therefore, it serves as a unified formalism for a multitude of mesons and baryons. It builds on our previous works on the study of masses, decay constants and form factors of quarkonia and light mesons, employing the same model. We use two sets of parameters, one which remains exactly the same for both the light and heavy sector hadrons, and another where the coupling strength is allowed to evolve according to the available mass scales of quarks. Our results are in very good agreement with the existing experimental data as well as predictions of other theoretical approaches whenever comparison is possible.

Heavy baryon spectroscopy

Masses of heavy baryons are calculated in the relativistic quarkdiquark picture. Obtained results are in good agreement with available experimental data including recent measurements by the LHCb Collaboration. Possible quantum numbers of excited heavy baryon states are discussed.

Pentaquark states with the QQQqbar{q} configuration in a simple model

We discuss the mass splittings for the S-wave triply heavy pentaquark states with the QQQqbar{q}(Q=b,c;q=u,d,s) configuration which is a mirror structure of Qbar{Q}qqq. The latter configuration is related with the nature of P_c(4380) observed by the LHCb Collaboration. The considered pentaquark masses are estimated with a simple method. One finds that such states are probably not narrow even if they do exist. This leaves room for molecule interpretation for a state around the low-lying threshold of a doubly heavy baryon and a heavy-light meson, e.g. Xi _{cc}D, if it were observed. As a by product, we conjecture that upper limits for the masses of the conventional triply heavy baryons can be determined by the masses of the conventional doubly heavy baryons.

Heavy baryon decay widths in the large $$N_c$$ N c limit in chiral theory

We propose large N_c generalizations for the “diquark” representations of hbox {SU}(3)_mathrm{flav} relevant for positive parity heavy baryons, including putative exotic states. Next, within the framework of the Chiral Quark Soliton Model, we calculate heavy baryon masses and decay widths. We show that in the limit of N_c rightarrow infty all decay widths vanish, including the widths of exotica. This result is in fact more general than the model itself, as it relies only on the underlying symmetries: i.e. hbox {SU}(3)_mathrm{flav} and hedgehog symmetry. Furthermore, using explicit model formulae for the decay constants in the non-realtivistic limit, we show that there is a hierarchy of the decay couplings, which may explain observed pattern of experimental widths.

6a-J-11 The Ξ_Q-Ξ'_Q Mixing and Heavy Baryon Masses

6a-J-11 The Ξ_Q-Ξ'_Q Mixing and Heavy Baryon Masses

Pion mean fields and heavy baryons

We show that the masses of the lowest-lying heavy baryons can be very well described in a pion mean-field approach. We consider a heavy baryon as a system consisting of the $N_c-1$ light quarks that induce the pion mean field, and a heavy quark as a static color source under the influence of this mean field. In this approach we derive a number of \textit{model-independent} relations and calculate the heavy baryon masses using those of the lowest-lying light baryons as input. The results are in remarkable agreement with the experimental data. In addition, the mass of the $\Omega_b^*$ baryon is predicted.

Heavy baryons in the large [formula omitted] limit

It is shown that in the large Nc limit heavy baryon masses can be estimated quantitatively in a 1/Nc expansion using the Hartree approximation. The results are compared with available lattice calculations for different values of the ratio between the square root of the string tension and the heavy quark mass σ/mQ. These estimates implement important 1/Nc corrections and assume a string tension independent of Nc. Using a potential adjusted to agree with the one obtained in lattice QCD, a variational analysis of the ground state spin averaged baryon mass is performed using Gaussian Hartree wave functions. Relativistic corrections through the quark kinetic energy are included. The results provide good estimates for the first sub-leading in 1/Nc corrections.

Mass and axial charge of heavy baryons

We investigate the antitriplet and sextet heavy baryon systems with ${J}^{P}={\frac{1}{2}}^{+},{\frac{3}{2}}^{+}$ in the framework of the heavy baryon chiral perturbation theory. We first calculate the chiral corrections to the heavy baryon mass from the SU(3) flavor breaking effect up to $O({p}^{3})$. Then we extend the same formalism to calculate the chiral corrections to the axial charges of the heavy baryons in the isospin symmetry limit.

Ground-state masses and magnetic moments of heavy baryons

In this work, we study single, double and triple heavy-flavor baryons using the hypercentral approach in the framework of the non-relativistic quark model. Considering two different confining potentials and an improved form of the hyperfine interaction, we calculate the ground-state masses of heavy baryons and also the ground-state magnetic moments of single charm and beauty baryons with JP = 3/2+. The obtained results are in good agreement with experimental data and those of other works.

Study of Charmed and Bottom Baryons in a Variational Approach and Chiral Interactions

Models have been widely used to study charmed and bottom baryons. In this work using the confining, one gluon exchange and Goldstone boson exchange terms as inter-quark interactions, we study the heavy flavour baryon spectrum in the framework of the constituent quark model. We use a variational method to solve the non-relativistic three-body problem for baryons in the hypercentral approach. The masses of heavy baryons containing one, two, and three heavy flavour quarks are found to be in accordance with the existing experimental values or with other theoretical predictions. The magnetic moments of single heavy baryons with J^p=3/2^+ are also obtained.

A first estimate of triply heavy baryon masses from the pNRQCD perturbative static potential

Within pNRQCD we compute the masses of spin-averaged triply heavy baryons using the now-available NNLO pNRQCD potentials and three-body variational approach. We focus in particular on the role of the purely three-body interaction in perturbation theory. This we find to be reasonably small and of the order 25 MeV. Our prediction for the Ω ccc baryon mass is 4900(250) MeV in keeping with other approaches. We propose to search for this hitherto unobserved state at B factories by examining the end point of the recoil spectrum against triple charm.

MASSES OF CHARM AND BEAUTY BARYONS IN THE CONSTITUENT QUARK MODEL

The masses of the ground state heavy baryons are studied using the hypercentral approach. The considered potential is a combination of Coulombic, linear confining and harmonic oscillator terms. An improved form of the hyperfine interaction and isospin dependent quark potential is introduced. By solving the Schrödinger equation for three particles system, we calculate the ground state masses of the baryons containing one, two and three heavy quarks. The obtained results are very close to the ones obtained in experiments or in the other works.

The Heavy Baryon Masses and Spin-Isospin Dependence

Heavy flavour baryons containing one charm (beauty) quark with light flavour combinations are studied using the hypercentral approach. The considered potential is a combination of Coulombic, linear confining and harmonic oscillator terms. An improved form of the hyperfine interaction and isospin dependent quark potential is introduced. The ground state masses of heavy baryons are computed. Also the magnetic moments of heavy baryons are computed using the effective mass of the confined quarks. The obtained results are very close to the ones obtained in experiments or in other works.