Bi-local baryon interpolating fields with two flavors

We construct bi-local interpolating field operators for baryons consisting of three quarks with two flavors, assuming good isospin symmetry. We use the restrictions following from the Pauli principle to derive relations/identities among the baryon operators with identical quantum numbers. Such relations that follow from the combined spatial, Dirac, color, and isospin Fierz transformations may be called the (total/complete) Fierz identities. These relations reduce the number of independent baryon operators with any given spin and isospin. We also study the Abelian and non-Abelian chiral transformation properties of these fields and place them into baryon chiral multiplets. Thus we derive the independent baryon interpolating fields with given values of spin (Lorentz group representation), chiral symmetry (U _L (2)×U _R (2) group representation) and isospin appropriate for the first angular excited states of the nucleon.     

A class of nontrivial weakly local massive wightman fields with interpolating properties

It is shown that in a quantum field theory satisfying Wightman's axioms with locality replaced by weak locality and cyclicity by a weak irreducibility, every unitary Poincaré invariant and CPT-invariant operator is a scattering operator (in the LSZ-sense). The proof is given by explicit construction of a corresponding class of nontrivial weakly local massive Wightman fields. This result implies Jost's conjecture that only locality leads to nontrivial restrictions for the scattering operator and extends corresponding results of Schneider.     

Chiral symmetry restoration in baryon rich environments

Chiral symmetry restoration in an environment rich in baryons is studied by computer simulation methods in SU(2) and SU(3) gauge theories in the quenched approximation. The basic theory of symmetry restoration as a function of chemical potential is illusstrated and the implementation of the ideas on a lattice is made explicit. A simple mean field model is presented to guide one's expectations. The second order conjugate-gradient iterative method and the pseudo-fermion Monte Carlo procedure are convergent methods of calculating the fermion propagator in an environment rich in baryons. Computer simulations of SU(3) gauge theory show an abrupt chiral symmetry restoring transition and the critical chemical potential and induced baryon density are estimated crudely. A smoother transition is observed for the color group SU(2).     

Structure of the gauge fields inside baryon

We present the results of lattice calculations of the distributions of the gauge fields inside a baryon constructed from three heavy quarks. It turns out that the chromoelectric flux tube has a Y shape. At nonzero temperature, we observe the breaking of the confining string below the deconfining temperature and the disappearance of the string above the critical temperature.     

Pseudoscalar glueball in terms of composite interpolating fields

The pseudoscalar (PS) glueball is described with an account of the quark-gluon mixing and strict observation of the QCD local gauge and renormalization invariance. The lower limits on the mass and total width are established. The partial radiative decay widths and the PS-glueball production inJ/gY radiative decays are calculated. The consistency of the results with the η- and η′-meson data onJ/Ψ→PV decays is verified. On the basis of the results, the lower PS-glueball state may be identified with the upper iota state η(1490).     

Chiral dynamics of baryon resonances and hadrons in a nuclear medium

In these lectures I make an introduction to chiral unitary theory applied to the meson-baryon interaction and show how several well-known resonances are dynamically generated, and others are predicted. Two very recent experiments are analyzed, one of them showing the existence of two Λ(1405) states and the other one providing support for the Λ(1520) resonance as a quasi-bound state of Σ(1385)π. The use of chiral Lagrangians to account for the hadronic interaction at the elementary level introduces a new approach to deal with the modification of meson and baryon properties in a nuclear medium. Examples of it for $\bar K$ andø modification in the nuclear medium are presented     

Selected problems of baryon spectroscopy: Chiral soliton versus quark models

The inconsistency between the rigid rotator and bound state models at an arbitrary number of colors, the rigid rotator—soft rotator dilemma, and some other problems of baryon spectroscopy are discussed in the framework of the chiral soliton approach (CSA). Consequences of the comparison of CSA results with simple quark models are considered and the 1/N _c expansion for the effective strange antiquark mass is presented, as it follows from the CSA. Strong dependence of the effective strange antiquark mass on the SU(3) multiplet is required to fit the CSA predictions. The difference between “good” and “bad” diquark masses, which is about 100 MeV, is in reasonable agreement with other estimates. Multibaryons (hypernuclei) with strangeness are described and some states of interest are also predicted within the CSA. The article is published in the original.     

Chiral quarks,chiral limit,nonanalytic terms and baryon spectroscopy

It is shown that the principal pattern in baryon spectroscopy, which is associated with the flavor-spin hyperfine interactions, is due to the spontaneous breaking of chiral symmetry in QCD and persists in the chiral limit. All corrections, which are associated with a finite quark (Goldstone boson) mass are suppressed by the factor (μ/Λ_χ)² and higher.     

Oscillations of the static meson fields at finite baryon density

The spatial dependence of static meson correlation functions at finite baryon density is studied in the Nambu-Jona-Lasinio model. In contrast to the finite-temperature case, we find that the correlation functions at finite density are not screened but exhibit long-range oscillations. The observed phenomenon is analogous to the Friedel oscillations in a degenerate electron gas.     

Chiral magnetic wave at finite baryon density and the electric quadrupole moment of the quark-gluon plasma

The chiral magnetic wave is a gapless collective excitation of quark-gluon plasma in the presence of an external magnetic field that stems from the interplay of chiral magnetic and chiral separation effects; it is composed of the waves of the electric and chiral charge densities coupled by the axial anomaly. We consider a chiral magnetic wave at finite baryon density and find that it induces the electric quadrupole moment of the quark-gluon plasma produced in heavy ion collisions: the "poles" of the produced fireball (pointing outside of the reaction plane) acquire additional positive electric charge, and the "equator" acquires additional negative charge. We point out that this electric quadrupole deformation lifts the degeneracy between the elliptic flows of positive and negative pions leading to v(2)(π(+))相似文献   

Static baryon properties in a relativistic quark model with centre-of-mass correction

The static properties such as magnetic moments, charge radii and axial vector coupling constant ratios of the quark core of baryons in the nucleon octet have been calculated in an independent-quark model based on the Dirac equation with equally mixed scalar-vector potential in linear form in the current quark mass limit. The results obtained with appropriate corrections due to centre-of-mass motion are in reasonable agreement with experimental data. The magnetic moments of the quark core of baryons in the charmed andb-flavoured sectors have also been calculated with this model and the overall predictions so obtained compare very well with other model predictions.     

Photoproduction of pions and properties of baryon resonances from a Bonn-Gatchina partial-wave analysis

Masses, widths and photocouplings of baryon resonances are determined in a coupled-channel partial-wave analysis of a large variety of data. The Bonn-Gatchina partial-wave formalism is extended to include a decomposition of t and u exchange amplitudes into individual partial waves. The multipole transition amplitudes for $ \gamma$ p $ \rightarrow$ p $ \pi^{0}_{}$ and $ \gamma$ p $ \rightarrow$ n $ \pi^{+}_{}$ are given and compared to results from other analyses.     

Spontaneous violation of chiral symmetry in QCD vacuum is the origin of baryon masses and determines baryon magnetic moments and their other static properties

A short review is presented of the spontaneous violation of chiral symmetry in QCD vacuum. It is demonstrated that this phenomenon is the origin of baryon masses in QCD. The value of nucleon mass is calculated, as well as the masses of hyperons and some baryonic resonances, and expressed mainly through the values of quark condensates—, q = u, d, s,—the vacuum expectation values (v.e.v.) of quark field. The concept of v.e.v. induced by external fields is introduced. It is demonstrated that such v.e.v. induced by static electromagnetic field results in quark condensate magnetic susceptibility, which plays the main role in determination of baryon magnetic moments. The magnetic moments of proton, neutron, and hyperons are calculated. The results of calculation of baryon octet β-decay constants are also presented. The text was submitted by the author in English.