Some peculiarities in response on filling up the Fermi sphere by quarks

Considering quarks as the quasi-particles of the model Hamiltonian with four-fermion interaction we study response on the process of filling up the Fermi sphere by quarks.Comment: 11 pages, 5 figures, minor language improvemen

Background Configurations, Confinement and Deconfinement on a Lattice with BPS Monopole Boundary Conditions

Finite temperature SU(2) lattice gauge theory is investigated in a 3D cubic box with fixed boundary conditions provided by a discretized, static BPS monopole solution with varying core scale $\mu$. Using heating and cooling techniques we establish that for discrete $\mu$-values stable classical solutions either of self-dual or of pure magnetic type exist inside the box. Having switched on quantum fluctuations we compute the Polyakov line and other local operators. For different $\mu$ and at varying temperatures near the deconfinement transition we study the influence of the boundary condition on the vacuum inside the box. In contrast to the pure magnetic background field case, for the self-dual one we observe confinement even for temperatures quite far above the critical one.Comment: to appear in EPJ

Phonon surface mapping of graphite: disentangling quasi--degenerate phonon dispersions

The two-dimensional mapping of the phonon dispersions around the $K$ point of graphite by inelastic x-ray scattering is provided. The present work resolves the longstanding issue related to the correct assignment of transverse and longitudinal phonon branches at $K$. We observe an almost degeneracy of the three TO, LA and LO derived phonon branches and a strong phonon trigonal warping. Correlation effects renormalize the Kohn anomaly of the TO mode, which exhibits a trigonal warping effect opposite to that of the electronic band structure. We determined the electron--phonon coupling constant to be 166$\rm(eV/\AA)^2$ in excellent agreement to $GW$ calculations. These results are fundamental for understanding angle-resolved photoemission, double--resonance Raman and transport measurements of graphene based systems