arXiv subjects
Publications and source records attributed to Yu. L. Kalinovsky.
We summarise a Dyson-Schwinger-equation-based calculation of an extensive range of light- and heavy-meson observables, characterised by heavy-meson leptonic decays, semileptonic heavy-to-heavy and heavy-to-light transitions, radiative and strong decays, and the rare flavour-changing neutral-current process. In the calculation the heavy-quark mass functions are approximated by constants, interpreted as their constituent mass.
We consider an extension of the finite-temperature Dyson-Schwinger equation (DSE) approach to heavy mesons and quarkonia and apply it to calculate the cross section for the J/Psi breakup reaction J/Psi + pi --> D + D. We study the effects of chiral symmetry restoration in the light quark sector on this process and obtain a critical enhancement of the reaction rate at the chiral/ deconfinement transition. Implications for the kinetics of charmonium production in ultrarelativistic heavy-ion collisions are discussed with particular emphasis on the recently observed anomalous J/Psi suppression as a possible signal for quark matter formation.
Two-body pion-radiating and weak decays of light axial-vector mesons and the rho are studied as a phenomenological application of the QCD Dyson-Schwinger equations. Models based on the rainbow-ladder truncation are capable of providing a good description and, in particular, yield the correct sign and magnitude of the a1 -> rho pi and b1 -> omega pi D/S ratios, with no additional mechanism necessary.
We employ a Dyson-Schwinger equation model to effect a unified and uniformly accurate description of light- and heavy-meson observables, which we characterise by heavy-meson leptonic decays, semileptonic heavy-to-heavy and heavy-to-light transitions - B -> D*, D, rho, pi; D -> K*, K, pi, radiative and strong decays - B(s)* -> B(s) gamma; D(s)* -> D(s) gamma, D pi, and the rare B-> K* gamma flavour-changing neutral-current process. We elucidate the heavy-quark limit of these processes and, using a model-independent mass formula valid for all nonsinglet pseudoscalar mesons, demonstrate that their mass rises linearly with the mass of their heaviest constituent. In our numerical calculations we eschew a heavy-quark expansion and rely instead on the observation that the dressed c,b-quark mass functions are well approximated by a constant, interpreted as their constituent-mass: we find M_c=1.32 GeV and M_b=4.65 GeV. The calculated heavy-meson leptonic decay constants and transition form factors are a necessary element in the experimental determination of CKM matrix elements. The results also show that this framework, as employed hitherto, is well able to describe vector meson polarisation observables.
An accurate and unified description of the non-hadronic electroweak interactions of light- and heavy-mesons is possible when the dressing of quark propagators and the finite size of hadronic bound states is explicitly accounted for.
A simple confining separable interaction Ansatz for the rainbow-ladder truncated QCD Dyson-Schwinger equations is used to study quark deconfinement and meson states at finite temperature. The model is fixed at T=0 to implement quark confinement while preserving the Goldstone mechanism for the $π$. Within the Matsubara formalism, a very slow temperature dependence is found for the $π$ and $ρ$ meson masses $M_H(T)$ until near the deconfinement temperature $T_c=143$ MeV. Related to rapid decrease of the dynamically-generated quark mass function for $T>T_c$, this model produces $π$ and $ρ$ masses that rise significantly and are better interpreted as spatial screening masses. The $T$-dependent screening mass defect $ΔM_H = 2πT-M_H(T)$ is compared to results of lattice gauge theory simulations and also to those of an infrared dominant analytic model.
Dyson-Schwinger equation (DSE) studies show that the b-quark mass-function is approximately constant, and that this is true to a lesser extent for the c-quark. These observations provide the basis for a study of the leptonic and semileptonic decays of heavy pseudoscalar mesons using a ``heavy-quark'' limit of the DSEs. When exact, this limit reduces the number of independent form factors. Semileptonic decays with light mesons in the final state are also accessible because the DSEs provide a description of light-quark propagation characteristics and light-meson structure. A description of B-meson decays is straightforward, however, the study of decays involving the D-meson indicates that c-quark mass-corrections are quantitatively important.
Semileptonic heavy -> heavy and heavy -> light meson transitions are studied as a phenomenological application of a heavy-quark limit of Dyson-Schwinger equations. Employing two parameters: E, the difference between the mass of the heavy meson and the effective-mass of the heavy quark; and Lambda, the width of the heavy-meson Bethe-Salpeter amplitude, we calculate f_+(t) for all decays on their entire kinematically accessible t-domain. Our study favours f_B in the range 0.135-0.17 GeV and with E=0.44 GeV and 1/Lambda = 0.14 fm we obtain f_+^{B pi}(0) = 0.46. As a result of neglecting 1/m_c-corrections, we estimate that our calculated values of ρ^2 = 0.87 and f_+^{DK}(0)=0.62 are too low by approximately 15%. However, the bulk of these corrections should cancel in our calculated values of Br(D -> πl nu)/Br(D -> K l nu)=0.13 and f_+^{D pi}(0)/f_+^{DK}(0) = 1.16.
A heavy-quark limit of the Dyson-Schwinger equations is introduced and used in an exploratory study of leptonic and semileptonic decays of heavy mesons. The application of this framework to heavy-to-light semileptonic decays, which require a good knowledge of light-quark propagation characteristics and light-meson bound state amplitudes, is illustrated.
We investigate possible consequences of resonant scalar interactions for dilepton production from a quark plasma at the chiral phase transition. It is found that this production mechanism is strongly suppressed compared to the Born process and has no significance for present experiments.
At the Mott transition of a quark/meson plasma, mesons become unbound. This leads to the effect of critical scattering, which is studied by investigating photon pair production due to the process $q\bar q\toγγ$. This process can proceed either via direct annihilation or via the formation of a mesonic resonance. It is shown that the latter channel leads to an enhancement of photon pairs with invariant mass equal to the thermal pion mass. The size of this effect measures the time the temperature stays near the Mott temperature during the evolution. It is particularly pronounced for a first order phase transition. The $π^0\toγγ$ decay gives a strong background contribution and may make the observation of critical scattering in two-photon spectra of present day heavy ion collision experiments difficult.
The semileptonic and leptonic decays of heavy mesons are studied as a phenomenological application and exploration of a heavy-quark limit of Dyson-Schwinger equations. The single form factor, $ξ(w)$, which characterises the semileptonic decay in this limit, is calculated and compares well with recent experimental extractions. We obtain a lower bound of 1/3 on the slope-parameter $ρ^2 \equiv -ξ^\prime(1)$, which, in calculations with realistic input, is exceeded by a great deal: agreement with experimental data requiring $ρ^2 \sim 1.2 - 1.6$. The flavour and momentum dependence of the light-quark propagators has observable consequences.
Previously the quark and meson properties in a many quark system at finite temperature have been studied within effective QCD approaches in the Hartree approximation. In the present paper we consider the influence of the mesonic correlations on the quark self-energy and on the quark propagator within a systematic $1/N_c$- expansion. Using a general separable ansatz for the nonlocal interaction, we derive a selfconsistent equation for the $1/N_c$ correction to the quark propagator. For a separable model with cut-off formfactor, we obtain a decrease of the condensate of the order of 20\% at zero temperature. A lowering the critical temperature for the onset of the chiral restoration transition due to the inclusion of mesonic correlations is obtained what seems to be closer to the results from lattice calculations.
Heavy--light mesons are described in an effective quark theory with a two--body vector--type interaction. The bilocal interaction is taken to be instantaneous in the rest frame of the bound state, but formulated covariantly through the use of a boost vector. The chiral symmetry of the light flavor is broken spontaneously at mean field level. The framework for our discussion of bound states is the effective bilocal meson action obtained by bosonization of the quark theory. Mesons are described by 3--dimensional wave functions satisfying Salpeter equations, which exhibit both Goldstone solutions in the chiral limit and heavy--quark symmetry for $m_Q\rightarrow\infty$. We present numerical solutions for pseudoscalar $D$-- and $B$--mesons. Heavy--light meson spectra and decay constants are seen to be sensitive to the description of chiral symmetry breaking (dynamically generated vs.\ constant quark mass).
In this paper we consider the bilocal field approach for $QCD$. We obtain a bilocal effective meson action with a potential kernel given in relativistic covariant form. The corresponding Schwinger--Dyson and Bethe--Salpeter equations are investigated in detail. By introducing weak interactions into the theory we study heavy meson properties as decay constants and semileptonic decay amplitudes. Thereby, the transition from the bilocal field description to the heavy quark effective theory is discussed. Considering as example the semileptonic decay of a pseudoscalar $B$--meson into a pseudoscalar $D$--meson we obtain an integral expression for the corresponding Isgur--Wise function in terms of meson wave functions.