We extend our recent computation of the low-energy limit of the linear O(4) Quark-Meson Model. The present analysis focuses on the transformation of the resulting effective action into a nonlinearly realized effective pion action, whose higher-derivative interaction terms are parametrized by so-called low-energy couplings. Their counterparts in the linear model are determined from the Functional Renormalization Group flow of the momentum-dependent four-pion vertex, which is calculated in a fully O(4)-symmetric approximation by including also momentum-dependent σπ interactions as well as σ self-interactions. Consequently, these higher-derivative couplings are dynamically generated solely from quark and meson fluctuations, initialized at a hadronic scale. Despite our restriction to low-energy degrees of freedom, we find that the qualitative features of the fluctuation dynamics allow us to comment on the range of validity and on appropriate renormalization scales for purely pionic effective models.
We investigate decay modes of B mesons emitting two pseudoscalar (P) mesons in the Quark Diagram Scheme at SU(3) level. Several relations among the decay amplitudes are obtained and various branching ratios are predicted.
Screening effects from sea pairs on the quark-antiquark static potential are analyzed phenomenologically from the light-quark to the heavy-quark meson spectra. From the high excited light-quark meson spectrum a universal form for the screened static potential is proposed. This potential is then succesfully applied to heavy quarkonia. Our results suggest the assignment of X(4260) to the 4s state of charmonium and the possible existence of a 5s bottomonium resonance around 10748 MeV.
Exclusive semileptonic B meson decays to orbitally excited D mesons are investigated in the infinitely heavy quark limit in the framework of the relativistic quark model based on the quasipotential approach. The B\to D^{**}eνIsgur-Wise functions τ_{3/2}(w) and τ_{1/2}(w) are determined. It is found that the relativistic transformation of the meson wave functions (Wigner rotation of the light quark spin) contribute already at the leading order of the heavy quark expansion.
In order to investigate the tomographical structure of light pseudoscalar mesons, particularly, pion and kaon, we study the valence quark distribution function (PDF) and the generalized parton distributions (GPDs) using light-cone quark model (LCQM).
The harmonic quarks are applied to the analysis of quark structures of long-lived $D$-mesons and $ψ/J$. In the harmonic quark model the quarks of long-lived mesons ($π^0$, $π^\pm$, $K^\pm$, $K^0$, $B^0$, $B^\pm$) are weakly relativistic objects with the excess energy of valent quarks less than 7 MeV. In contrast to this, the long-lived $D$-mesons in two-quark standard have the apparent excess energies of a few hundred MeV. It was established that all long-lived $D$-mesons and $ψ/J$ have the six-quark structures. There are two valent quarks and two additional neutral quark-antiquark $u$-pairs. …
After describing the SU(2) linear sigma model (L$σ$M), we dynamically generate it using the B.W. Lee null tadpole sum (characterizing the true vacuum) together with the dimensional regularization lemma. Next we generate the chiral-limiting (CL) nonstrange and strange constituent quark masses ${\hat m}=325.7$ MeV; $m_s=486$ MeV away from the CL. Finally, we study vector meson dominance (VMD) and the pion, kaon charge radii and the loop-order $ρ\toπγ$, $π^0\toγγ$ amplitudes in the quark model. Lastly, we verify this procedure using tree-order VMD graphs.
We propose that there coexist two scalar mesons of different structures (a conventional meson and a four-quark meson) in the recently observed broad bumps just below the large peak of the tensor meson in the D-pi mass distribution. We base this proposal on the interpretation of the charm-strange scalar meson of mass 2317 MeV as a four-quark meson. The strange counterparts of these scalar mesons are also studied.
The contributions of one-loop diagrams with dynamical vector mesons to masses and decay constants of pseudoscalar mesons are determined. Hereby, a relativistic Lagrangian for both the pseudoscalar-meson octet and the vector-meson nonet is used. The vector mesons are given in the antisymmetric tensor representation. Both the differences between static and dynamical vector mesons and the differences between calculations with and without vector mesons are studied as functions of the light quark mass.
By assigning the narrow scalar resonance (which has been recently observed at the B-factories) to one of iso-triplet four-quark mesons containing a charm quark, two body decays of the four-quark mesons are studied. It is predicted that some of them can be observed as narrow resonances.
Semileptonic and nonleptonic decays of the B_c meson to B_s and B mesons, caused by the c\to s,d quark transitions, are studied in the framework of the relativistic quark model. The heavy quark expansion in inverse powers of the active c and spectator \bar b quark is used to simplify calculations while the final s and d quarks in the B_s and B mesons are treated relativistically. The decay form factors are explicitly expressed through the overlap integrals of the meson wave functions in the whole accessible kinematical range. The obtained results are compared with the predictions of other appr…
The physics of charm has become one of the best laboratories exposing the limitations of the naive constituent quark model and also giving hints into a more mature description of meson spectroscopy, beyond the simple quark--antiquark configurations. In this talk we review some recent studies of multiquark components in the charm sector and discuss in particular exotic and non-exotic four-quark systems.
We consider meson radiative decays within the framework of $U_0(1)\times U(1)\times SU(2)$ gauge symmetry. This approach is based on the linear sigma-model extended by the gauge and quark-meson interactions. Physical content and parameters of the model are discussed. Theoretical predictions for some radiative decays of vector mesons are in a good agreement with the experimental data.
We consider the quark antiquark potential of a quarkonium moving with velocity $v$ through a quark-gluon plasma at temperature T. An explicit, configuration-space expression is found for the screened interaction between the quarks constituting the meson. This potential is non-spherical, but axially symmetric about the direction of $v$.
Using the quark spectrum of the BCC Quark Model [1] and the phenomenological formula for the binding energies of the mesons, not only have we deduced the intrinsic quantum numbers (I, S, C, b, and Q) of all mesons as was done with the Quark Model [2], but also we deduced the meson mass spectrum in agreement with experimental results [3] that we could not deduce using the Quark Model. The experimental meson spectrum gives some evidence of the existence of the new quarks $q_S^*(1391)$, $q_S^*(2551)$ and $q_C^*(6591)$..., which are predicted by the BCC Quark Model. The meson $χ(1600)$ $[2^+(2^{++…
The present talk consists of two parts. The first one is allocated for consideration of the dimension of bilocal meson fields for quark-antiquark meson systems, which have been so far treated as the bosonic fields independent of constituent quark flavors, in the covariant oscillator quark model. Revisiting the electromagnetic currents of quark-antiquark meson systems, we show that the bilocal meson fields should be bosonic for light-quark meson systems, while fermionic for heavy-light and heavy-heavy meson systems. In the second part we apply the effective electromagnetic interactions of meson…
With usage of obvious mechanisms of quark currents the amplitudes of leptonic decaies of pseudoscalar mesons are investigated. The estimation for a constant of leptonic decay of the D+ meson is obtained, f_D+ ~ 0.23 GeV.
An effective potential in a meson-meson system is discussed based on the SU(3) chiral constituent quark model, and the analytic form of the potential is explicitly given. In addition, the effective potential is employed to study the bound state problem of $ωϕ$, which is related to the new resonance of $f_0(1810)$ observed in BESII very recently.
We present an exact calculation of $S$ and $P$ wave $QQ\bar n\bar n$ states using different standard nonrelativistic quark--quark potentials. We explore in detail the charm and bottom sectors looking for bound states that could be measured within existing facilities. Against the proliferation of four--quark states sometimes predicted in the literature, we found a small number of candidates to be stable. We analyze their properties in a trial to distinguish between compact and molecular states. Possible decay modes are discussed.
The calculation of the partial width of the rare t-quark decay into Upsilon-meson, W-boson and b-quark (t -> ΥW b) is presented. The branching ratio equals Br(t -> Upsilon W b) = 1.3 * 10^{-5} that make possible searches for this rare $t$-quark decay at LHC.
Using phenomenological formulae, we deduce the masses and quantum numbers of the quarks from two elementary quarks ($ε_{u}$ and $ε_{d}$) first. Then using the sum laws and a binding energy formula, in terms of the qqq baryon model and SU(4), we deduce the masses and quantum numbers of the important baryons from the deduced quarks. At the same time, using the sum laws and a binding energy formula, in terms of the quark-antiquark bound state meson model, we deduce the masses and quantum numbers of the mesons from the deduced quarks. The deduced masses of the baryons and mesons are 98% consistent…
The D-and F-wave quark-quark amplitudes are constructed in the framework of the dispersion N/D-method. The mass values of meson multiplets with $J^{PC}=1^{--},2^{--},2^{-+},3^{--}$ and $J^{PC}=2^{++},3^{++},3^{+-},4^{++}$ are calculated. The Regge trajectories of mesonic resonances with orbital numbers L=0,1,2,3 are obtained.
Temperature dependence of the quark condensate is studied in the Nambu--Jona-Lasinio model with meson loops. Substantial differences are found compared to the results with quark loops only.
The investigation in the work of the reaction electron-positron to omega and pi0 mesons in the 3P0 nonrelativistic quark model reveals that the reaction electron-positron to omega and pi0 mesons process at the energy region from the omega and pi mesons threshold to 2.0 GeV is dominated by the two-step process in which the primary quark-antiquark pair first forms rho and rho' mesons and then the vector mesons decay into omega and pi. With rho(1450) and rho(1700) mainly in 2S and 1D states respectively, the experimental data for the cross section of the reaction electron-positron to omega and pi…
In this paper, we calculate mass and probability fractions of meson-meson components of $X(3872)$ in an unquenched quark model. Different from most of other unquenched quark models, the quark pairs creation operator from $^3P_0$ is modified by considering effects of the created quark pair energy and separation between the created quark pair and the valence quark-pair. In the calculation, all the wavefunctions of mesons and the relative motion between two mesons are obtained by solving the corresponding Schrödinger equation with the help of gaussian expansion method. The multi-channel coupling …
It is well known that large nonfragmentational contributions to inclusive production of charmed particles appear at low energies. In the case of charm production in $B$-meson decays these contributions arise from the participation of the light valent quark from the $B$-meson and can be easily described phenomenologically. These contributions affect $D$-meson spectra and essentially change ratios between yields of different $D$-meson states.
To analyze an electromagnetic and strong hadron processes at low energies, we consider the renormalizable model with the U0(1) x U(1) x SU(2) gauge symmetry. This approach is based on the linear sigma-model extended by the gauge and quark-meson interactions. Physical content and parameters of the model are discussed. Theoretical predictions for some radiative decays of vector mesons are in a good agreement with the experimental data.
For top quark decays into heavy quark mesons $Υ$ and $\bar{B}_c^*$ , a complete calculation to the leading order both in QCD coupling constant $α_s$ and in $v$, the typical velocity of the heavy quarks inside the mesons, is performed. Relatons between the top quark mass and the decay branching ratios are studied. Comparion with the results which are obtained by using the quark frangmentation functions is also discussed. The branching ratios are consistent (within a factor of $2\sim 3 $) with that obtained using fragmentation functions at $m_t\sim 150$ GeV.
We describe the effective heavy meson lagrangian for S- and P-wave heavy-light mesons in terms of a model based on meson-quark interactions, where mesonic transition amplitudes are represented by diagrams with heavy mesons attached to loops containing heavy and light constituent quarks. The model is relativistic and incorporates the heavy quark symmetries. The universal form factors of the heavy meson transition amplitudes are calculated together with their slopes and compared to existing data and limits. As further applications of the model, strong and radiative decays of D* and B* are consid…
The spin-averaged binding energy and the hyperfine mass splitting of heavy-light mesons are investigated within the constituent quark model as a function of the inverse heavy-quark mass. It is shown that the so-called heavy-quark kinetic energy, -lambda1 / 2mQ, may differ remarkably from the non-relativistic expectation <p**2> / 2mQ, thanks to relativistic effects in the effective interquark potential for heavy-light mesons, which may yield substantial 1 / mQ corrections to the heavy-quark static limit. The determination of the difference of the hadronic parameter lambda1 in the B(u(d)) and B(…
The relativistic quark potential model (QPM) is developed for describingvector mesons and their leptonic decays. The new representation Salpeter equation for vector mesons is proposed. Studying the $τ\toρν$ decay theexpression for $ρ$-meson leptonic decay constant $f_ρ$ isobtained. It is shown that quark model describes on a satisfactory level both theconstant $f_ρ$ and the masses of other charged vector mesons. Thevalues for the leptonic decay constants of $K^{*},D^{*},D^{*}_s,B^{*},B^{*}_c$ mesons are predicted.
We present a detailed analysis of the Bc form factors in the BSW framework, by investigating the effects of the flavor dependence on the average transverse quark momentum inside a meson. Branching ratios of two body decays of Bc meson to pseudoscalar and vector mesons are predicted.
Using a quite accurate flavour-independence of $nS$-level mass differences in heavy quarkonia and a corresponding quasiclassical expression for the heavy quark binding energy, one shows that experimental data on masses of mesons with heavy quarks allow one to make the estimate $\bar Λ= 0.63\pm 0.03$ GeV.
In the framework of QCD sum rules one uses a scheme, allowing one to apply the conditions of both nonrelativistic heavy quark motion inside mesons and independence of nonsplitting nS-state density on the heavy quark flavours. In the leading order an analitic expression is derived for leptonic constants of both heavy quarkonia and heavy mesons with a single heavy quark. The expression allows one explicitly to determine scaling properties of the constants.
By bosonization of an extended NJL model we derive an effective meson theory which describes the interplay between chiral symmetry and heavy quark dynamics. This effective theory is worked out in the low-energy regime using the gradient expansion. The resulting effective lagrangian describes strong and weak interactions of heavy $B$ and $D$ mesons with pseudoscalar Goldstone bosons and light vector and axial--vector mesons. Heavy meson weak decay constants, coupling constants and the Isgur--Wise function are predicted in terms of the model parameters partially fixed from the light quark sector…
The amplitudes for one-pion mediated transitions between heavy meson excited states are obtained in the framework of the relativistic chiral quark model. The effective coupling constants to pions and the decay widths of excited heavy mesons with l<=2 for non-radially excited, and the l=0 radially excited mesons are presented for both charmed and beauty mesons. We also discuss the allowed decays of strange excited heavy mesons by emission of a K-meson.
The spectra and branching ratios of the weak semi-leptonic B meson decays to the first excited D mesons are predicted, taking into account the confined effects of quarks using the covariant oscillator quark model (COQM). In the COQM the same relation between general weak transition form factors as that in HQET is derived, and the concrete form of the Isgur-Wise function is given with no free parameters. Our results are somewhat different from those of other models. The present experimental data are not sufficient for comparison.
The QCD anomaly leads to an abnormal mixing and mass pattern for the pseudoscalar mesons. Furthermore it is responsible for the quality of isospin symmetry in the meson spectrum. Similarities between the large mixing angles among the neutral 0^-+ mesons and the large mixing angles observed in neutrino oscillations are pointed out.
The new narrow resonance which has been observed at the B factories is assigned to the I_z=0 component of iso-triplet charmed four-quark mesons, and as its consequence, existence of additional narrow resonances in different channels is predicted.
We review studies of inelastic meson-meson scattering. In nonperturbative schemes with chiral-perturbation-theory Lagrangians and in models based on effective meson Lagrangians, inelastic meson-meson scattering leads to the successful identification of resonances in meson-meson reactions, adequate inclusion of final state interactions in particle decays, and so on. For mesons of which each consists of a quark and an antiquark, inelastic meson-meson scattering may be caused by quark-antiquark annihilation, quark-antiquark creation, quark interchange, and quark-antiquark annihilation and creatio…
In a nonrelativistic constituent quark model we find a constraint on the mixing angle of the strange axial-vector mesons, $35^o\stackrel{<}{\sim } θ_K\stackrel{<}{\sim }55^o,$ determined solely by two parameters: the mass difference of the $a_1$ and $b_1$ mesons and the ratio of the constituent quark masses.
Assuming the spin-independence for confining force, we give a covariant quark representation of general composite meson systems with definite Lorentz transformation properties. For benefit of this representation we are able to deduce automatically the transformation rules of composite mesons for general symmetry operations from those of constituent (exciton) quarks. Applying this we investigate especially physical implication of chiral symmetry for the meson systems, and point out a possibility of existence of new meson multiplets.
Exclusive nonleptonic bottom meson decays are studied in the covariant osillator quark model using the factorization assumption. The main feature of this model is that it can simultaniously be applied to both heavy to heavy and heavy to light transitions, satisfying the constraints of the heavy quark effective theory (HQET) in the appropriate limit. The results obtained are in overall agreement with the present experimental data for various B decays.
The semileptonic decay form factors of the double heavy $B_{c}$ meson provide a unique opportunity to study the strong interactions between two heavy quarks. A fully relativistic model, with effective non-local quark-meson interactions, is used to compute semileptonic decay form factors, for both the $B_{c}$ and a wide range of other heavy-light mesons. Using these form factors predictions for decay rates and branching ratios are obtained. The results are compared to other theoretical approaches and, where available, to experimental results. In addition the radiative decay of $B^*_{c}$ is disc…
Mass spectra of excited meson states consisting of u-, d-quarks and antiquarks with I = 1 are considered. The comparison between the existing experimental data and the mass values evaluated with phenomenological formulae is carried out. Problems of identification of vector and scalar meson excited states are discussed.
The four-quark equations are found in the framework of the dispersion relation technique. The approximate solutions of these equations using the method based on the extraction of leading singularities of the amplitudes are obtained. The four-quark amplitudes of cryptoexotic mesons including the quarks of three flavours (u, d, s) are calculated. The mass values of low-lying cryptoexotic mesons are calculated.
Since the discovery of the $J/ψ$, the quark model was very successful in describing the spectrum and properties of heavy mesons including only $q\bar q$ components. However since 2003, with the discovery of the $X(3872)$, many states that can not be accommodated on the naive quark model have been discovered, and they made unavoidable to include higher Fock components on the heavy meson states. We will give an overview of the success of the quark model for heavy mesons and point some of the states that are likely to be more complicated structures such as meson-meson molecules.
Semileptonic and nonleptonic decays of the B_c meson to charmonium and D mesons are studied in the framework of the relativistic quark model. The decay form factors are explicitly expressed through the overlap integrals of the meson wave functions in the whole accessible kinematical range. The relativistic meson wave functions are used for the calculation of the decay rates. The obtained results are compared with the predictions of other approaches.
Some charmonium-like resonances such as X(3872) can be interpreted as possible $D^{(*)}D^{(*)}$ molecular states. Within the quark model, we study the structure of such molecular states and the similar $B^{(*)}B^{(*)}$ molecular states by taking into account of the light meson exchange ($π$, $η$, $ρ$, $ω$ and $σ$) between two light quarks from different mesons.
We studied the high energy quark anti-quark elastic scattering with an exchange of a mesonic state in the $t$ channel with $-t/Λ_{QCD}^{2} \gg 1$. Two methods are proposed to eliminate the strong background from bare pomeron, reggized gluon and odderon exchange. The feasibility of measuring mesonic reggeon exchange is discussed.
We study the quark Wigner distributions of the pion meson which are the phase-space distributions containing the most general one-parton information.Using the pion wavefunctions deduced from a light-cone quark model, we calculate the Wigner distributions of the unpolarized, longitudinally polarized and transversely polarized quarks inside the pion meson via the Fock-state overlap representation, respectively.We present the numerical results of the transverse Wigner distributions in which the longitudinal momentum fraction is integrated out. The mixed Wigner distributions as functions of $b_y$ …
This review of the Quantum Chromodynamics (QCD),the early universe Cosmoloical Phase Transition from the Quark-Gluon Plasma (QGP) to our present universe (QCDPT), Relativistic Heavy Ion Collisions (RHIC) which can produce the QGP, the possible detection of the QGP produced by the production of mixed hybrid heavy quark mesons. We also review recent studies of the production of mixed heavy quark hybrids via RHIC and heavy quark meson supression in p-Pb and Pb-Pb collisions.
We study the nuclear matter solution in the chiral quark soliton model coupled to $ρ$ and $ω$ vector mesons based on the Wigner-Seitz approximation. It is shown that the vector mesons stabilize the soliton at high-density region. As a result, the saturation property and incompressibility are significantly improved.
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.
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.
The $ρ$ meson gravitational form factors are studied based on a light-front constituent quark model which has been successfully employed to calculate its generalized parton distributions and some low-energy observables. The distributions of energy, spin, pressures, and shear forces inside the $ρ$ meson are explicitly given.
We evaluate the form factors governing the exclusive decays B->rho l nu, B->a_1 l nu, by using an effective quark-meson lagrangian. The model is based on meson-quark interactions, and the computation of the mesonic transition amplitudes is performed by considering diagrams with heavy mesons attached to loops containing heavy and light constituent quarks. This approach was successfully employed to compute the Isgur-Wise form factors and other hadronic observables for negative and positive parity heavy mesons and is presently used for exclusive heavy-to-light weak transitions. We also evaluate a…
Relativistic properties of qqbar potentail, mass spectra of orbitally and radially excited B and D mesons as well as semileptonic decays of B mesons to orbitally excited D mesons are discussed in the framework of the relativistic quark model based on the quasipotential approach.
The features of a model interpreting the light scalar mesons as diquark-antidiquark bound states and the consequences of its natural extension to include heavy quarks are briefly reviewed.
In a recent comment [1] Blankleider and Kvinikhidze claim that our work [2] is based on a set of inconsistent Bethe-Salpeter equations for the coupling of four-quark to two-quark states. Here we demonstrate that their argument is insubstantial.
