The pion mass dependence of the nucleon form-factors of the energy momentum tensor in the chiral quark-soliton model

The nucleon form factors of the energy-momentum tensor are studied in the large-Nc limit in the framework of the chiral quark-soliton model for model parameters that simulate physical situations in which pions are heavy. This allows for a direct comparison to lattice QCD results.Comment: 17 pages, 12 figure

Collective coordinates of the Skyrme model coupled with fermions

The problem of construction of fiber bundle over the moduli space of the Skyrme model is considered. We analyse an extension of the original Skyrme model which includes the minimal interaction with fermions. An analogy with modili space of the fermion-monopole system is used to construct a fiber bundle structure over the skyrmion moduli space. The possibility of the non-trivial holonomy appearance is considered. It is shown that the effect of the fermion interaction turns the $n$-skyrmion moduli space into a real vector bundle with natural $SO(2n+1)$ connection.Comment: 10 page

QCD Instantons in Vacuum and Matter

The singlet coupling to the topological charge density in the instanton vacuum, causes the instantons and antiinstantons to be screened over distances of the order of 1/2 fm. Dilute instanton systems behave as a free gas, while dense instanton systems behave as a plasma. The free gas behaviour is favored by a density of 1 fm$^{-4}$. Owing to the Higgs mechanism, the $\eta$' mass is heavy (1100 MeV). The vacuum topological susceptibility is small (0.07 fm$^{-4}$) and consistent with the QCD Ward identity. In the chiral limit, the singlet screening vanishes, leading to a four dimensional plasma state with a temperature given by the nonet decay constant $f$ (90 MeV). The phase is Debye screened. In the presence of matter, the screening is quenched, and a Kosterlitz-Thouless transition may occur signaling the restoration of the $U_A(1)$ symmetry. We suggest to use the spatial asymptotics of the static topological charge correlator together with the topological susceptibility to probe the interplay between the $U_A(1)$ restoration and the chiral restoration in finite temperature QCD. The relevance of these results to the bulk thermodynamics in the instanton vacuum is discussed.Comment: 18 Page

Scattering Through QCD Sphalerons

Diffractive parton-parton scattering in the soft pomeron regime can be explained by the production of a QCD sphaleron. Sphaleron production results into the emission of $3+2N_F$ gluons and quarks. At RHIC we expect many sphalerons to be released thereby affecting most prompt processes.Comment: Contribution to quark matter 200

Spin-dependent twist-4 matrix elements from the instanton vacuum: Flavor-singlet and nonsinglet

We estimate the twist-4 spin-1 nucleon matrix element f_2 in an instanton-based description of the QCD vacuum. In addition to the flavor-nonsinglet we compute also the flavor-singlet matrix element, which appears in next-to-leading order of the (1/N_c)-expansion. The corresponding twist-3 spin-2 matrix elements d_2 are suppressed in the packing fraction of the instanton medium, (\bar \rho)/(\bar R) << 1. We use our results to estimate the leading (1/Q^2) power corrections to the first moment of the proton and neutron spin structure functions G_1, as well as the intrinsic charm contribution to the nucleon spin.Comment: 17 pages, 4 eps figures include

On Topological Susceptibility, Vacuum Energy and Theta Dependence in Gluodynamics

We suggest that the topological susceptibility in gluodynamics can be found in terms of the gluon condensate using renormalizability and heavy fermion representation of the anomaly. Analogous relations can be also obtained for other zero momentum correlation functions involving the topological density operator. Using these relations, we find the theta dependence of the condensates , and of the partition function for small theta and an arbitrary number of colors.Comment: Details of the derivation are clarified, changes in discussions, new references are adde