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The relation between center vortices and fractional topological charge has been studied in this work. Specifically, we investigate a vortex configuration with fractional topological charge analyzing the lowest modes of the adjoint Dirac operator in both overlap and staggered formulations. We discuss the effects leading to chiral symmetry breaking.

We argue that due to isospin and U-spin invariance of strong low-energy interactions the S-wave scattering lengths a^0_0 and a^1_0 of bar-KN scattering with isospin I=0 and I = 1 satisfy the low-energy theorem a^0_0 + 3 a^1_0 = 0 valid to leading order in chiral expansion. In the model of strong low-energy bar-KN interactions at threshold (EPJA 21,11 (2004)) we revisit the contribution of the Sigma(1750) resonance, which does not saturate the low-energy theorem a^0_0 + 3 a^1_0 = 0, and replace it by the baryon background with properties of an SU(3) octet. We calculate the S-wave scattering amplitudes of K^-N and K^-d scattering at threshold. We calculate the energy level displacements of the ground states of kaonic hydrogen and kaonic deuterium. The result obtained for kaonic hydrogen agrees well with recent experimental data by the DEAR Collaboration. We analyse the cross sections for elastic and inelastic K^-p scattering for laboratory momenta of the incident K^- meson from the domain 70 MeV/c < p_K < 150 MeV/c. The theoretical results agree with the available experimental data within two standard deviations., 20 pages, Latex, We have slightly corrected the contribution of the double scattering. This changes the S-wave scattering length of K^-d scattering by 17%, which is commensurable with the theoretical uncertainty

The energy level displacements of the excited nl states of pionic hydrogen and the contribution of the ns -> 1s transitions and the (pi^-p)_Coul -> 1s transitions of the pi^-p pair, coupled by the attractive Coulomb field in the S-wave state with a continuous energy spectrum, to the shift of the energy level of the ground state of pionic hydrogen, caused by strong low-energy interactions, are calculated within a quantum field theoretic, relativistic covariant and model-independent approach developed in nucl-th/0306047., 18 pages, no figures, latex, text is revised, references are added

We investigate the equivalence between Thirring model and sine-Gordon model in the chirally broken phase of the Thirring model. This is unlike all other available approaches where the fermion fields of the Thirring model were quantized in the chiral symmetric phase. In the path integral approach we show that the bosonized version of the massless Thirring model is described by a quantum field theory of a massless scalar field and exactly solvable, and the massive Thirring model bosonizes to the sine-Gordon model with a new relation between coupling constants. We show that the non-perturbative vacuum of the chirally broken phase in the massless Thirring model can be described in complete analogy with the BCS ground state of superconductivity. The Mermin-Wagner theorem and Coleman's statement concerning the absence of Goldstone bosons in the 1+1-dimensional quantum field theories are discussed. We investigate the current algebra in the massless Thirring model and give a new value of the Schwinger term. We show that the topological current in the sine-Gordon model coincides with the Noether current responsible for the conservation of the fermion number in the Thirring model. This allows to identify the topological charge in the sine-Gordon model with the fermion number., Comment: 62 pages, 3 figures,misprints are corrected, the chiral Jacobian is recalculated and a few references are added

The Nambu–Jona–Lasinio model of the deuteron suggested by Nambu and Jona–Lasinio (Phys. Rev. 124 (1961) 246) is formulated from the first principles of QCD. The deuteron appears as a neutron–proton collective excitation, i.e. a Cooper np–pair, induced by a phenomenological local four–nucleon interaction in the nuclear phase of QCD. The model describes the deuteron coupled to itself, nucleons and other particles through one–nucleon loop exchanges providing a minimal transfer of nucleon flavours from initial to final nuclear states and accounting for contributions of nucleon–loop anomalies which are completely determined by one–nucleon loop diagrams. The dominance of contributions of nucleon–loop anomalies to effective Lagrangians of low–energy nuclear interactions is justified in the large NC expansion, where NC is the number of quark colours.

Interquark confinement potential is calculated in the dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings as a functional of a dual Dirac string length. The calculation is carried out by the explicit integration over quantum fluctuations of a dual-vector field (monopole-antimonopole collective excitation) around the Abrikosov flux line and string shape fluctuations. The contribution of the scalar field (monopole-antimonopole collective excitation) exchange is taken into account in the tree approximation due to the London limit regime., 10 pages, Latex, no figures

The magnetic monopole condensate is calculated in the dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings suggested in Refs.[1,2] as a functional of the dual Dirac string shape. The calculation is carried out in the tree approximation in the scalar monopole-antimonopole collective excitation field. The integration over quantum fluctuations of the dual-vector monopole-antimonopole collective excitation field around the Abrikosov flux line and string shape fluctuations are performed explicitly. We claim that there are important contributions of quantum and string shape fluctuations to the magnetic monopole condensate., Comment: 19 pages, Latex, 2 figures

The present status of the nuclear reaction rates determining the solar neutrino flux is discussed. This includes the reaction rates for the two branching ratios of the three pp-chains involving the reactions 3He(3He,2p)4He and 3He(4He,γ)7Be for the first branching, and 7Be(e−, νe)7Li and 7Be(p, γ)8B for the second branching. Mainly we will concentrate on the basic nuclear reaction p + p → D + e+ + νe of the pp-chains. This reaction rate can only be determined using the theoretical methods. The present status of the application of the relativistic field theory model of the deuteron for this reaction will be discussed.

We investigate the polarization cloud around static electric charges in the framework of compact lattice QED. We calculate the correlations of Polyakov loops with the electric charge densityψ†ψ normalized to the chiral condensate. It turns out that virtual anticharges screen static charges as expected from continuum QED. Charge polarization is more pronounced at strong couplings and extends to a longer range on the lattice in the weak coupling phase. In both phases the correlations decrease with larger fermion mass.

We explore the diquark-quark picture of the octet and the decuplet of low-lying baryons in QCD with a linear confinement potential. The mass spectra of scalar, pseudoscalar, vector and axial-vector diquarks, transforming like\((\underline {\widetilde3} _f ,\underline {\widetilde3} _c )\) and\((\underline 6 _f ,\underline {\widetilde3} _c )\), are analysed. For scalar, pseudoscalar and vector diquarks we find bound states with massesMS≃MP=1.95 GeV, andMV=2.40 GeV, whereas for axial-vector diquarks no bound states exist. We conclude that low-lying baryons cannot be described by the diquark-quark picture. Our results confirm the three-body structure of low-lying baryons, and lead to an unambiguously fixed spinor structure of three-quark currents of low-lying baryons as proposed by Ioffe, Pascual and Tarrach.

Chiral symmetry breaking is explored within QCD with linearly rising confinement potential at the Nambu-Jona-Lasinio (NJL) prescription. The dynamical quark mass is obtained from the gap equation in terms of the string tension σ, σ,i.e.m=2蜰σ/π=0.33 GeV at σ=0.27 GeV2. The phenomenological constants of the NJL local four-quark interactionsG1 andG2 are found equal and expressed in terms of the string tension and the confinement radius. It is shown that the spectra of low-lying quark-antiquark collective excitations coincide with those predicted by the NJL model.

We study the dependence of the center-projected string tension on both the lattice size, and the number of gauge copies used for maximal center gauge fixing. We show that a recent finding of Bornyakov, Komarov, Polikarpov, and Veselov (hep-lat/0002017), indicating a substantial breakdown of center dominance in maximal center gauge, is only obtained for rather small lattice volumes, and is not found in numerical simulations on larger lattices. It is shown that center-projected Creutz ratios approach the full asymptotic string tension as lattice size increases, and that the P-vortex density is consistent, at moderately weak couplings, with 2-loop scaling behavior., Comment: 15 pages, 9 figures, Latex

We consider projections of SU(2) lattice link variables onto Z(2) center and U(1) subgroups, with and without gauge-fixing. It is shown that in the absence of gauge-fixing, and up to an additive constant, the static quark potential extracted from projected variables agrees exactly with the static quark potential taken from the full link variables; this is an extension of recent arguments by Ambjorn and Greensite, and by Ogilvie. Abelian and center dominance is essentially trivial in this case, and seems of no physical relevance. The situation changes drastically upon gauge fixing. In the case of center projection, there are a series of tests one can carry out, to check if vortices identified in the projected configurations are physical objects. All these criteria are satisfied in maximal center gauge, and we show here that they all fail in the absence of gauge fixing. The non-triviality of center projection is due entirely to the maximal center gauge-fixing, which pumps information about the location of extended physical objects into local Z(2) observables., Comment: 18 pages, 6 figures, Latex2e

A contribution of the tensor force to the phenomenological spin-orbit (SO) potential in the single-particle Hamiltonian is studied for spherical and deformed rare-earth and actinide nuclei. It is found that the deformation dependence of the SO coupling constant, suggested by the second order tensor force contribution, enables to explain the observed single particle (s.p.) states in the second minimum of237Pu and239Pu using a SO strength weaker than usually applied. Consequences of the tensor contributions for the stability of theZ=114 superheavy nucleus are studied.