Daily Activities and Social Association of the Bongando in Central Zaire

Daily activities and association patterns of the Bongando, a Bantu speaking people in central Zaire, were studied, using a systematic "self-focal sampling" method. The time spent on the subsistence activities was unexpectedly short, whereas leisure time was abundant. The Bongando are engaged more frequently in non-agricultural activities such as hunting, fishing, and gathering than in agriculture. So they can be described as a "multi-subsistence people" rather than just "farmers." Men tended to concentrate their work on one activity at a time, and women tended to perform two or more activities simultaneously. In the social associations, men and wome rarely associated with each other. Men associated infrequently but evenly with many persons, while women associated more frequently but with only a few specific persons. Although the Bongando have a patrilineal lineage system, they do not clearly segregate the members of their own lineage from the non-members in the association behavior. In daliy life, they do not need to rely on the lineage coalition, probably because their subsistence activities tend to be conducted individually

NJL Model at Finite Chemical Potential in a Constant Magnetic Field

We investigate the influence of an external magnetic field on chiral symmetry breaking in the Nambu-Jona-Lasinio (NJL) model at finite temperature and chemical potential. According to the Fock-Schwinger proper-time method, we calculate the effective potential in the leading order of the $1/N_c$ expansion. The phase boundary dividing the symmetric phase and the broken phase is illustrated numerically. A complex behavior of the phase boundary is found for large chemical potential.Comment: 6 pages, 2 figures, Poster talk presented at the Workshop on Finite Density QCD at Nara, Japan, 10-12 July 2003; replaced two reference

Phase structure of NJL model with finite quark mass and QED correction

We study QED corrections to the chiral symmetry breaking in Nambu-Jona-Lasinio (NJL) model with two flavors of quarks. In the model the isospin symmetry is broken by differences of the current quark masses and the electromagnetic charges between up and down quarks. In the leading order of the 1/N expansion we calculate the effective potential of the model with one-loop QED corrections. Evaluating the effective potential, we study an influence of the isospin symmetry breaking on the orientation of chiral symmetry breaking. The current quark mass has an important contribution for the orientation of chiral symmetry breaking.Comment: 7 pages, 8 figures, To appear in the proceedings of the Workshop on Origin of Mass and Strong Coupling Gauge Theories, Nagoya, Japan, 21-24 November 200

Four-fermion Interaction Model in a Constant Magnetic Field at Finite Temperature and Chemical Potential

We investigate an influence of an external magnetic field on chiral symmetry breaking in a four-fermion interaction model at finite temperature and chemical potential. By using the Fock-Schwinger proper-time method, we calculate the effective potential for the four-fermion interaction model at the leading order of the $1/N_c$ expansion. A phase structure of the chiral symmetry breaking is shown on $T$-$\mu$, $H$-$T$ and $\mu$-$H$ planes. The external magnetic field modifies the phase structure. It is found that a new phase appears for a large chemical potential.Comment: 16 pages, 10 figure

CP violation of Extended Higgs sector and Its impact on D^0 -> mu^+ mu^- decay

We study the impact of the CP violation of the extra Higgs sector on $D^0$ decay. The CP even and CP odd neutral Higgs mixing of the two Higgs doublet model is studied and we show how the CP violating effect of the mixing may lead to the longitudinal muon polarization asymmetry of $D^0 \to \mu^+ \mu^-$. The asymmetry of the short-distance contribution is sensitive to the CP violating phase of the extended Higgs sector.Comment: 7 pages, 2 figures, presented as a poster in GUT2012 (YITP,Kyoto,15-17 March2012

Super Restoration of Chiral Symmetry in Massive Four-Fermion Interaction Models

The chiral symmetry is explicitly and spontaneously broken in a strongly interacting massive fermionic system. We study the chiral symmetry restoration in massive four-fermion interaction models with increasing temperature and chemical potential. At high temperature and large chemical potential, we find the boundaries where the spontaneously broken chiral symmetry can be fully restored in the massive Gross--Neveu model. We call the phenomenon super restoration. The phase boundary is obtained analytically and numerically. In the massive Nambu--Jona-Lasinio model, it was found that whether super restoration occurs depends on regularizations. We also evaluate the behavior of the dynamical mass and show the super restoration boundaries on the ordinary phase diagrams.Comment: 11 pages, 13 figure