Effective chiral hadron lagrangian with anomalies and skyrme terms from quark flavour dynamics

By bosonization of an extended Nambu-Jona-Lasinio type of quark model with explicit breaking of chiral U(n) × U(n) symmetry we derive a effective low-energy lagrangian of composite scalar, pseudoscalar, vector and axial-vector mesons. This lagrangian contains the gauged Wess-Zumino term as well as higher order derivative terms of the Skyrme type, the coefficients of which agree with recent phenomenological estimates. In particular, the value predicted for the strength of the standard fourth-order Skyrme term is in satisfactory agreement with the results obtained by fitting the nucleon and delta masses. Our effective chiral lagrangian reproduces the wealth of the results of successful phenomenological lagrangians as, e.g. soft-pion theorems, Goldberger-Treiman relations, PCAC, the KSFR relation, the (approximate) Weinberg relation, etc. Moreover, the predicted mass spectra and decay constants of composite mesons are in qualitative agreement with the experimental findings. Furthermore, when electroweak interactions are included the lagrangian contains vector (axial-vector) dominance based on field-current identities.     

Effective chiral meson lagrangian with Weinberg and KSFR relations from microscopic four-quark interactions

An effective chiral meson lagrangian is derived from a microscopic quark lagrangian. It contains a partial Higgs mechanism for ϱ-A₁ mass splitting reproducing Weinberg and KSFR relations, and includes quartic derivative “Skyrme” terms and the gauges Wess-Zumino term. The connection to previous approaches deriving the effective lagrangian exclusively from the chiral anomaly including “normal-parity” terms is established.     

Union of chiral and heavy quark symmetries

We describe the chiral symmetric couplings of pions to heavy mesons (B or D), valid in the portion of phase space where the pions have low momentum. In order to include consistently all low energy excitations, the vector mesons (B^* or D^*) must appear explicitly in the effective lagrangian. The result is then invariant under both the chiral and heavy quark symmetries. We include matrix elements relevant for various weak decays.     

Asymmetries in heavy meson production from light quark fragmentation

We discuss the possibility of the asymmetry in production from beams, being a direct consequence of the properties of the light quark fragmentation function into heavy mesons. The main features of the asymmetry, as a function of , are easily described. An integrated sum rule for the multiplicity difference is presented. Predictions for the asymmetry in meson production are given. Received: 5 August 1999 / Published online: 17 March 2000     

Charm diffusion in a pion gas implementing unitarity, chiral and heavy quark symmetries

We compute the charm drag and diffusion coefficients in a hot pion gas, such as is formed in a heavy ion collision after the system cools sufficiently to transit into the hadron phase. We fully exploit heavy quark effective theory (with both D and D^∗ mesons as elementary degrees of freedom during the collision) and chiral perturbation theory, and employ standard unitarization to reach higher temperatures. We find that a certain friction and shear diffusion coefficients are almost p²-independent at a fixed temperature which simplifies phenomenological analysis.At the higher end of reliability of our calculation, , we report a charm relaxation length , in agreement with the model estimate of He, Fries and Rapp.The momentum of a 1 GeV charm quark decreases about 50 MeV per fermi when crossing the hadron phase.     

Hierarchical chiral symmetries and the quark mass matrix

A hierarchical pattern of chiral symmetries is introduced, whose breaking is supposed to lead to the observed hierarchical pattern of the quark mass spectrum. Specific consequences for the interplay between the quark masses and the weak interaction mixing parameters are derived, in accordance with the observational constraints. They can be regarded as stringent constraints for any realistic dynamical theory of the quark mass spectrum. CP violation is absent in the limit m_u=m_d=0. A specific way to describe the weak interaction mixing emerges.     

Ratios ofB andD meson decay constants with heavy quark symmetry

SU(3) flavor symmetry allows the decay constantsf _{D 1} andf _{D 2} as well asf _{B 1} andf _{B 1} to be equal. But due toSU(3) flavor symmetry breaking the ratiosf _{B 1}/f _{B 2} andf _{D 1}/f _{D 2} are deviated from unity. We have estimated these ratios in the heavy quark effective theory and obtainedf _{B 1}/f _{B 2}=0.93,f _{D 1}/f _{D 2}=0.94 and the double ratio (f _{B 1}/f _{B 2})/(f _{D 1}/f _{D 2})=0.99.     

In-medium modification of meson properties in a chiral quark model

Two-photon decays of vector mesons and dilepton decays of scalar mesons which are forbidden in a vacuum and can occur in dense baryonic matter due to the explicit violation of Lorentz symmetry are described within a quark model of the Nambu-Jona-Lasinio type. The temperature and chemical potential dependence of these processes is investigated. Talk at the Helmoltz International Summer School “Dense Matter in Heavy Ion Collision and Astrophysics,” JINR, Dubna, August 21–September 1, 2006. The text was submitted by the authors in English.     

Heavy quark spin symmetry and heavy flavor hadronic molecules

We argue that the heavy quark spin symmetry can lead to important consequences for heavy flavor hadronic molecules.It can be used to predict new heavy flavor hadronic molecules and hence provides a method to identify the nature of some newly observed exotic hadrons.For example,if the Y（4660） were an S-wave ψ f 0 （980） shallow bound state,then the mass,width and line shape of its spin partner are predicted.     

Heavy quark spin symmetry and heavy flavor hadronic molecules

We argue that the heavy quark spin symmetry can lead to important consequences for heavy flavor hadronic molecules.It can be used to predict new heavy flavor hadronic molecules and hence provides a method to identify the nature of some newly observed exotic hadrons.For example,if the Y(4660) were an S-wave ψ f 0 (980) shallow bound state,then the mass,width and line shape of its spin partner are predicted.     

Heavy meson spectra for heavy quark potential in quantum chromodynamics with dilaton

For heavy meson systems, we study the heavy quark potential, which emerges from the effective dilaton－gluon coupling inspired from the superstring theory. We put emphasis on the new confinement generating mechanism of this potential through the investigation of the spin-averaged energy levels of the heavy meson systems. By using a unified approach to the solutions of the Schr?dinger and the spinless Salpeter equations, we can examine in a realistic way the effects of using a relativistic kinetic energy. The obtained results agree favourably with other predictions, and the relativistic equation can better account for the observed energy levels.     

Effective quark masses in the chiral limit

The behavior of effective, scale dependent quark masses in the chiral limit is studied using the operator product expansion. Their relation to current and constituent quark masses is clarified. Current correlation functions are examined as an example of separating effects of spontaneous and explicit chiral symmetry breaking.