Quark Confinement Model Research Articles

Thickness and Color Structure of Center Vortices in Gluonic SU(2) QCD

In search for an effective model of quark confinement we study the vacuum of SU(2) quantum chromodynamic with lattice simulations using Wilson action. Assuming that center vortices are the relevant excitations causing confinement, we analyzed their physical size and their color structure. We present confirmations for a vanishing thickness of center vortices in the continuum limit and hints at their color structure. This is the first time that algorithms for the detection of thick center vortices based on non-trivial center regions has been used.

Quark confinement, new cosmic expansion and general Yang-Mills symmetry**Supported in part by the Jingshin Resealch Fund of the UMassD Foundation

We discuss a unified model of quark confinement and new cosmic expansion with linear potentials based on a general (SU3)color×(U1)baryon symmetry. The phase functions in the usual gauge transformations are generalized to new ‘action integrals’. The general Yang-Mills transformations have group properties and reduce to usual gauge transformations in special cases. Both quarks and ‘gauge bosons’ are permanently confined by linear potentials. In this unified model of particle-cosmology, physics in the largest cosmos and that in the smallest quark system appear to both be dictated by the general Yang-Mills symmetry and characterized by a universal length. The basic force between two baryons is independent of distance. However, the cosmic repulsive force exerted on a baryonic supernova by a uniform sphere of galaxies is proportional to the distance from the center of the sphere. The new general Yang-Mills field may give a field-theoretic explanation of the accelerated cosmic expansion. The prediction could be tested experimentally by measuring the frequency shifts of supernovae at different distances.

Properties of strangelets in a new quark mass confinement model with one-gluon-exchange interaction

The properties of strangelets at zero temperature with a new quark model that includes both the confinement and one-gluon-exchange interactions is studied in a fully self-consistent method. The charge and parameter dependence of the stability of strangelets are discussed. It is found that the one-gluon-exchange interaction lowers the energy of a strangelet, and consequently allows the strangelet to be absolutely stable. The stable strangelet radius in the present model is smaller in comparison with the absence of one-gluon-exchange interaction, and can thus be much less than that of a normal nucleus with the same baryon number, according to the strength of the confinement and one-gluon-exchange interactions.

Properties of strangelets at zero temperature in a new quark mass confinement model

We investigate the properties of strangelets at zero temperature with a new quark model in which the linear confinement and one-gluon-exchange (OGE) interactions are integrated as a whole. The charge, parameters dependence and the stability of strangelets are discussed. Our results showed that the OGE interaction lowers the energy of a strangelet, and consequently makes its stable radius smaller than that in the case of not including this interaction, and less than that of a nucleus with the same baryon number. Therefore, the strangelet in the present model has more chance to be absolutely stable.

Dynamical Model of QCD Vacuum and Quark Confinement**The project supported by Science Foundation of the Ministry of Science and Technology of China under Grant No. 2100CCA00700

The phase transition of a simple local gauge model is investigated in terms of the Nambu–Jona-Lasinio mechanism and it is pointed out that the physical vacuum of QCD is bound state of quark-antiquark pairs which can be viewed, generally, as a nearly perfect color dia-electric medium. An important relation between the vacuum expectation value of gauge fields and scalar fields is also derived by solving the Euler equation for the gauge fields. Based on this relation the gauge potential is given which can be used to explain the asymptotic behavior and confinement of quarks in a hadron, and at the same time the Yukawa potential of strong interaction can be given too.

Metastable strange matter and compact quark stars

Strange quark matter in beta equilibrium at high densities is studied in a quark confinement model. Two equations of state are dynamically generated for the same set of model parameters used to describe the nucleon: one corresponds to a chiral restored phase with almost massless quarks and the other to a chiral broken phase. The chiral symmetric phase saturates at around five times the nuclear matter density. Using the equation of state for this phase, compact bare quark stars are obtained with radii and masses in the ranges R ∼ 5–8 km and M ∼ M⊙. The energy per baryon number decreases very slowly from the centre of the star to the periphery, remaining above the corresponding values for iron or nuclear matter, even at the edge. Our results point out that strange quark matter at very high densities may not be absolutely stable and the existence of an energy barrier between the two phases may prevent the compact quark stars from decaying to hybrid stars.

The semileptonic form factors of B and D mesons in the Quark Confinement Model

The form factors of the weak currents, which appear in the semileptonic decays of the heavy pseudoscalar mesons, are calculated within the quark confinement model by taking into account, for the first time, the structure of heavy meson vertex and the finite quark mass contribution in the heavy quark propagators. The results are in quite good agreement with the experimental data.

Singular solutions of the Yang-Mills equations and bag models

A model of quark confinement based on a singular solution of classical YM equation is proposed. Within the framework of this model we have calculated hadron masses that correspond to ground state configurations of quarks. Our results are in agreement with the experiment data with accuracy 3-7 percents for all hadronic masses except those of light pseudoscalar mesons.

Mean-field effects on neutrinoless double beta decay

Mean-field effects on the nuclear matrix elements involved in the neutrinoless double beta (0νββ) decay of several double-electron and double-positron emitters have been studied within the framework of the relativistic quark-confinement model and the quasiparticle random-phase approximation. The single-particle energies of the model space have been generated both by using the standard Woods-Saxon parametrization of the mean field and adjusting the quasiparticle spectra with the data from neutron- and proton-odd nuclei. The 0νββ rates are found to be much less affected by the energies of the mean-field orbitals than the rates of the two-neutrino double beta decay. The present study suggests that the extracted effective neutrino masses vary within a factor of two when using different realistic single-particle bases in the calculations.

Decays of heavy vector mesons in the quark confinement model

We analyze the radiative and hadronic decays of vector heavy mesons within the relativistic quark model with confined light quarks. The only adjustable parameters in this approach are the values of constituent masses of heavy quarks (Mc andMb). We adjust them using the available experimental data from CLEO and ARGUS-collaborations for theD*→Dγ andD*→Dπ branching ratios. It is found that the value ofMc varies approximately in the interval 1.3 GeV<Mc<1.65 GeV. We give the predictions for the absolute values of decay widths and compare our results with those obtained in other approaches. Also we consider the heavy quark limitMQ→∞ withE=MH−MQ=const for the decay amplitudes.

Calculation of the beta and beta beta decay observables of 48Ca using QRPA with and without particle-number projection

The double beta decay ( beta beta ) of 48Ca to the ground state of 48Ti is analysed using the quasiparticle random phase approximation with (PQRPA) and without (QRPA) particle-number projection. The pairing interaction strength and the strength of other multipole channels of the renormalized G matrix interaction are adjusted to yield optimal beta - and beta + decay properties of 48Ca and 48Ti and to comply with the experimental limits of the 2 nu beta beta decay half-life. Nuclear matrix elements of the 0 nu beta beta decay transition are then calculated using the QRPA and PQRPA parameter-free to yield an estimate of the Majorana neutrino mass. In addition, the contribution of the right-handed weak currents is studied. The number projection is found to be important for light nuclei near magic numbers. The gA/gV ratio of the weak axial vector and vector coupling coefficients is found to be renormalized by the dynamics of the effective weak transition operators derived from a relativistic quark-confinement model.

Form factors of semileptonic decays of heavy mesons in the quark confinement model.

We compute form factors of the semileptonic decay $B(D)\ensuremath{\rightarrow}\mathrm{Xl}\ensuremath{\nu}$ (we denote by $X$ the final pseudoscalar or vector state) within the quark confinement model. As ${M}_{Q}\ensuremath{\rightarrow}\ensuremath{\infty}$, one finds that the form factors of the $B\ensuremath{\rightarrow}D({D}^{*})e\ensuremath{\nu}$ decay state are expressed in terms of the universal function being dependent on the product of the four-velocities of initial and final heavy mesons in accordance with Isgur-Wise symmetry. At the same time, the form factors of decays with the final light state are found to be monopole functions except the axial-vector form factor ${A}_{1}(t)$, which goes to a constant in this limit. We compare our results obtained by explicit and asymptotic formulas with other approaches and available experimental data.

B→c flavour-changing decays of baryons containing a single heavy quark

We present a detailed description of semileptonic decays of baryonsΛ 0 →Λ + and∑ + →∑ ++ in the framework of the quark confinement model, which is a relativistic quark model based on definite asumptions about hadronization and confinement of light quarks. Weak form factors, decay rates and differential distributions of semileptonic decaysΛ 0 →Λ + and∑ + →∑ ++ are calculated. The heavy quark limitm Q →∞ (Isgur-Wise symmetry) is also examined.

2β0v-decay mediated by heavy Majorana neutrinos and nucleon weak magnetism and pseudoscalar coupling

The role of the nucleon weak magnetism and pseudoscalar coupling interactions in the calculation of the 2β0v-decay of48Ca mediated by heavy Majorana neutrinos has been examined. The effect of a finite nucleon size has been taken into account by employing the phenomenological form factors and form factors calculated in the framework of the quark confinement model. By using the PCAC predictions it has been found that by taking into account these interactions the absolute values of the 2β0v-decay matrix elements of48Ca reduces considerably, which provides us with less stringent limits on the parameter of the non-conservation of the lepton charge.

Pion and kaon polarizabilities in the quark confinement model.

The Dubna quark confinement model is applied to the study of electromagnetic polarizabilities of the \ensuremath{\pi} and K mesons. Within this model it is found that the effect of quark confinement reduces the value of the pion polarizability from that obtained in such approaches as chiral quark loop and linear \ensuremath{\sigma} models. In the chiral limit our result coincides with the one found in chiral perturbation theory. For the charged kaon we find the electric polarizability considerably larger than the chiral prediction. This is due to the strong meson-mass dependence not expected from the pointlike interaction in effective meson Lagrangian approaches.

Calculation of the neutrinoless ββ decay of 76Ge using a quark model with harmonic confinement

The half-life of the neutrinoless double beta decay of 76Ge into the ground state of 76Se is calculated in a relativistic quark confinement model. The proton-neutron quasi-particle random-phase approximation is used to evaluate the s- and p-wave nuclear matrix elements contained in the decay amplitude. We avoid the closure approximation and calculate the effective vector and axial-vector coupling constants of the hadronic currents using our quark model. In our formulation the recoil matrix element arises from the quark recoil in the decaying neutrons. The recoil and the p-wave effect are discussed and compared with other calculations. From the experimental lower bound for the decay half-life an upper limit for the effective Majorana mass of the neutrino is deduced and the right-handed contribution to the charged weak current estimated.

Predictions for semileptonic decay rates of charmed baryons in the quark confinement model

Baryons as relativistic three-quark states are investigated in the quark confinement model (QCM), a relativistic quark model based on some assumptions about hadronization and quark confinement. In the framework of the quark-diquark approximation of the three-quark structure of baryons, the main characteristics of light (noncharmed) baryons are calculated. The obtained results agree with experimental data. Predictions are also given for semileptonic decay of charmed baryons and differential production cross-sections in quasielastic neutrino scattering of charmed baryons.

Rare kaon decaysK L(S) 0 ??0?+?? in the quark confinement model

K 0 →π0l+l−. The rare decaysK 0 →π0l+l−(l=e or μ) are investigated in the Quark Confinement Model (QCM), a relativistic quark model, based on some assumptions about hadronization and quark confinement. Using the effective electroweak Lagrangian (with QCD corrections), proposed by Gilman and Wise, the matrix elements of kaon transitions to a pion and lepton pair are calculated. The obtained results for the decay widths are in agreement with the experimental data for upper limits on branching ratios and the theoretical predictions calculated by effective chiral Lagrangian method.

Quark-diquark approximation of the three-quark structure of baryons in the quark confinement model

Octet (1/2+) and decuplet (3/2+) baryons as relativistic three-quark states are investigated using the quark confinement model (QCM), the relativistic quark model, based on some assumptions about hadronization and quark confinement. The quark-diquark approximation of the three-quark, structure of baryons is proposed. In the framework of this approach, the main low-energy characteristics of baryons, such as magnetic moments, electromagnetic radii and form factors, the ratio of axial and vector constants in semileptonic baryon decays, strong form factors and decay widths, are described. The obtained results agree with experimental data.

Confined quarks and the neutrinoless ββ decay

The half life of the neutrinoless double beta decay of 76Ge into the ground state of 76Se is calculated in a relativistic quark confinement model. The neutron-proton quasi-particle random phase approximation is used to evaluate the nuclear matrix elements involved in the decay amplitude. We avoid the closure approximation, but compare our results with this approximation. From the experimental half life we deduce an upper limit for the Majorana mass of the neutrino and estimate the right-handed contribution to the charged weak current.