122429057
Existence of the sigma meson below 1-GeV and f0(1500) glueball
On the basis of a simultaneous description of the isoscalar s-wave channel of the $\pi\pi$ scattering (from the threshold up to 1.9 GeV) and of the $\pi\pi\to K\bar{K}$ process (from the threshold to $\sim$ 1.4 GeV) in the model-independent approach, a confirmation of the $\sigma$-meson at $\sim$ 665 MeV and an indication for the glueball nature of the $f_0(1500)$ state are obtained. It is shown that the large $\pi\pi$-background, usually obtained, combines, in reality, the influence of the left-hand branch-point and the contribution of a very wide resonance at $\sim$ 665 MeV. The coupling constants of the observed states with the $\pi\pi$ and $K\bar{K}$ systems and lengths of the $\pi\pi$ and $K\bar{K}$ scattering are obtained.
120703177
IS THE CRONIN’S REPRESENTATION CORRECT FOR THE PENGUIN OPERATOR?
It is shown that the Cronin’s operator, being used for a phenomenological description of non-loptonic K-meson decays within the effective chiral Lagrangian approach with non-linear realization of chiral SU(3)×SU(3) symmetry (so-called, chiral perturbation theory at the hadronic level), cannot be applied to the determination of the Penguin-operator (O5-operator) at the hadronic level. The affirmation is based on the proof of the violation of the low-energy theorem $\lim _{P + \to 0} \left\langle {\pi ^ + \left( {p_ + } \right)\pi ^ - \left( {p_ - } \right)\left| {O_5 } \right|K^0 \left( p \right)} \right\rangle = \frac{i}{{F_\pi }}\left\langle {\pi ^0 \left( p \right)\left| {O_5 } \right|K^0 \left( p \right)} \right\rangle $ which is valid within the framework of the Cronin’s representation. The violation of this low-energy theorem is obtained at the quark level and connected with the account of the low-energy interactions of pions caused by the overlap of wave functions of pions in the |π+π−> state in the...
121038747
EFFECTIVE CHIRAL LAGRANGIANS, THE QUARK MODEL OF SUPERCONDUCTIVITY TYPE AND THE PROBLEM OF P-A DIAGONALIZATION
The vertices appearing after the inclusion of P-A transitions and a subsequent diagonalization of the chiral Lagrangian are analyzed in the quark model of superconductivity type. These vertices can conditionally be divided into physical and nonphysical ones. It is shown that if the Pauli-Villars regularization is used, the contribution of the latter can be eliminated from the description of the physical processes. This is in full agreement with the experimental data.
15150236
Effective quark model with chiral U(3) x U(3) symmetry for baryon octet and decuplet
We suggest an effective quark model for low-lying baryon octet and decuplet motivated by QCD with a linearly rising confinement potential incorporating the extended Nambu--Jona-Lasinio (ENJL) model with linear realization of chiral $U(3)\ifmmode\times\else\texttimes\fi{}U(3)$ symmetry. Baryons are considered as external heavy states coupled to local three-quark currents with fixed spinorial structure and to low-lying mesons through quark-meson interactions defined in the ENJL model. In the constituent quark loop representation we have calculated the coupling constants of the $\ensuremath{\pi}NN, \ensuremath{\pi}N\ensuremath{\Delta},$ and $\ensuremath{\gamma}N\ensuremath{\Delta}$ interactions and the ${\ensuremath{\sigma}}_{\ensuremath{\pi}N}$ term. The obtained results are in reasonable agreement with experimental data and other effective field theory approaches.
122493642
On the problem of D-meson leptonic and semileptonic decays
Abstract The infinite mass effective theory, when a heavy quark mass goes to infinity, and chiral perturbation theory at the quark level, based on the extended Nambu-Jona-Lasinio model, are applied for the description of form factors of semileptonic decay D→ K e + ν e and leptonic constant FD of D-mesons. The relation is derived connecting the form factor f+(0) with the ratio F D F π , which gives the estimate F D F π =1.21±0.17 . The slope parameter of the f+ form factor is calculated in agreement with experimental data.
121077448
Quark model of superconducting type and nondiagonal P-A transitions
ConclusionsWe discuss the obtained results. We note that the solution to the problem of the elimination of the unphysical interactions that arise through the P-A diagnonalization has been obtained at the prescriptional level. We have found that to eliminate the unphysical vertices due to the P-A diagnonalization, it is sufficient to replace the effective Lagrangian (22) by the Pauli-Villars regularized Lagrangian (33). The regularization is needed because of the nonuniqueness of the calculation of the individual quark diagrams that describe the new interaction vertices. The Pauli-Villars regularization corresponds to subtraction from the quark diagram of a quantity determined by the same diagram but in which all the masses of the virtual quarks are replaced by the masses of the fermions — the regularizers M. Application of the regularization for the complete effective Lagrangian has the consequence that an appropriate contribution of the regularizers is subtracted from any vertex that arises as a result of shift of the axial fields (4). This is sufficient for the correct description of the interaction vertices that arise from the P-A diagonalization.
118390158
QCD EoS, initial conditions and final state from relativistic hydrodynamics in heavy-ion collisions
Some recent developments in exact results in relativistic hydrodynamics is reviewed. We discuss phenomenological applications in high-energy collisions and theoretical features of the solutions. We compare the method of numerical modelling to the strategy based on exact solutions. We argue that the efforts made and progress achieved in this seemingly purely theoretical topic is of interest for phenomenology.
118401873
New simple explicit solutions of perfect-fluid hydrodynamics and phase-space evolution
New exact solutions of relativistic perfect-fluid hydrodynamics are presented, including the first family of exact rotating solutions. The method used to search for them is a simultaneous investigation of the relativistic hydrodynamical equations and the collisionless Boltzmann equation. Possible connections to the evolution of hot and dense partonic matter in heavy-ion collisions is discussed.