Radiative Symmetry Breaking and Dynamical Origin of Cosmological Constant in ϕ4\phi^4 Theory with Non-Linear Curvature Coupling

A scalar self-interacting theory non-linearly coupled with some power of the curvature have a possibility to explain the current smallness of the cosmological constant. Here one concentrate on a massless scalar field in the four-dimensional Fridmann-Robertson-Walker (FRW) spacetime with flat spatial part. One show the phase structure of radiative symmetry breaking and review a dynamical resolution of the cosmological constant problem.Comment: 9 pages. To appear in the proceedings of 7th Workshop on Quantum Field Theory Under the Influence of External Conditions (QFEXT 05), Barcelona, Catalonia, Spain, 5-9 Sep 200

Aharonov-Bohm Effect at liquid-nitrogen temperature: Frohlich superconducting quantum device

The Aharonov-Bohm (AB) effect has been accepted and has promoted interdisciplinary scientific activities in modern physics. To observe the AB effect in condensed matter physics, the whole system needs to maintain phase coherence, in a tiny ring of the diameter 1 micrometer and at low temperatures below 1 K. We report that AB oscillations have been measured at high temperature 79 K by use of charge-density wave (CDW) loops in TaS3 ring crystals. CDW condensate maintained macroscopic quantum coherence, which extended over the ring circumference 85 micrometer. The periodicity of the oscillations is h/2e in accuracy within a 10 percent range. The observation of the CDW AB effect implies Frohlich superconductivity in terms of macroscopic coherence and will provide a novel quantum interference device running at room temperature.Comment: 11 pages, 4 figure

Inhomogeneous Quasi-stationary States in a Mean-field Model with Repulsive Cosine Interactions

The system of N particles moving on a circle and interacting via a global repulsive cosine interaction is well known to display spatially inhomogeneous structures of extraordinary stability starting from certain low energy initial conditions. The object of this paper is to show in a detailed manner how these structures arise and to explain their stability. By a convenient canonical transformation we rewrite the Hamiltonian in such a way that fast and slow variables are singled out and the canonical coordinates of a collective mode are naturally introduced. If, initially, enough energy is put in this mode, its decay can be extremely slow. However, both analytical arguments and numerical simulations suggest that these structures eventually decay to the spatially uniform equilibrium state, although this can happen on impressively long time scales. Finally, we heuristically introduce a one-particle time dependent Hamiltonian that well reproduces most of the observed phenomenology.Comment: to be published in J. Phys.

π\pi and σ\sigma mesons at finite temperature and density in the NJL model with dimensional regularization

Dynamical Symmetry breaking and meson masses are studied in the Nambu-Jona-Lasinio (NJL) model at finite temperature and chemical potential using the dimensional regularization. Since the model is not renormalizable in four space-time dimensions, physical results and parameters depend on the regularization method. Following the imaginary time formalism, we introduce the temperature, $T$ and the chemical potential, $\mu$. The parameters in the model are fixed by calculating the pion mass and decay constant in the dimensional regularization at $T=\mu=0$.Comment: 28 pages, 9 figures, v2: a few points corrected and references adde

Space-time evolution induced by spinor fields with canonical and non-canonical kinetic terms

We study spinor field theories as an origin to induce space-time evolution. Self-interacting spinor fields with canonical and non-canonical kinetic terms are considered in a Friedman-Robertson-Walker universe. The deceleration parameter is calculated by solving the equation of motion and the Friedman equation, simultaneously. It is shown that the spinor fields can accelerate and decelerate the universe expansion. To construct realistic models we discuss the contributions from the dynamical symmetry breaking.Comment: 16 pages, 19 figure

Phase Structure of a Four- and Eight-Fermion Interaction Model at Finite Temperature and Chemical Potential in Arbitrary Dimensions

The phase structure of a four- and eight-fermion interaction model is investigated at finite temperature and chemical potential in arbitrary space-time dimensions, $2\leq D<4$. The effective potential and the gap equation are calculated in the leading order of the 1/N expansion. If the first order phase transition takes place, the phase boundary dividing the symmetric and the broken phase is modified by the eight-fermion interaction.Comment: 20 pages, 26 figures; revised argument and added reference for section

Dynamical symmetry breaking in the external gravitational and constant magnetic fields

We investigate the effects of the external gravitational and constant magnetic fields to the dynamical symmetrybreaking. As simple models of the dynamical symmetry breaking we consider the Nambu-Jona-Lasinio (NJL) model and the supersymmetric Nambu-Jona-Lasinio (SUSY NJL) model non-minimally interacting with the external gravitational field and minimally interacting with constant magnetic field. The explicit expressions for the scalar and spinor Green functions are found up to the linear terms on the spacetime curvature and exactly for a constant magnetic field. We obtain the effective potential of the above models from the Green functions in the magnetic field in curved spacetime. Calculating the effective potential numerically with the varying curvature and/or magnetic fields we show the effects of the external gravitational and magnetic fields to the phase structure of the theories. In particular, increase of the curvature in the spontaneously broken chiral symmetry phase due to the fixed magnetic field makes this phase to be less broken. On the same time strong magnetic field quickly induces chiral symmetry breaking even at the presence of fixed gravitational field within nonbroken phase.Comment: 23 pages, Latex, epic.sty and eepic.sty are use

Superconducting Fluctuations in a Multi-Band 1D Hubbard Model

A renormalization-group and bosonization approach for a multi-band Hubbard Hamiltonian in one dimension is described. Based on the limit of many bands, it is argued that this Hamiltonian with bare repulsive electron-electron interactions is scaled under specific conditions to a model in which superconducting fluctuations dominate.Comment: 12 pages + 1 fig, Revtex, Preprint - Los Alamo

Phase diagram of Nambu-Jona-Lasinio model with dimensional regularization

We investigate the phase diagram on temperature-chemical potential plane in the Nambu-Jona-Lasinio model with the dimensional regularization. While the structure of the resulting diagram shows resemblance to the one in the frequently used cutoff regularization, some results of our study indicate striking difference between these regularizations. The diagram in the dimensional regularization exhibits strong tendency of the first order phase transition.Comment: 9 pages, 9 figure

Attitudes toward depression among Japanese non-psychiatric medical doctors: A cross-sectional study

Abstract Background: Under-recognition of depression is common in many countries. Education of medical staff, focusing on their attitudes towards depression, may be necessary to change their behavior and enhance recognition of depression. Several studies have previously reported on attitudes toward depression among general physicians. However, little is known about attitudes of non-psychiatric doctors in Japan. In the present study, we surveyed nonpsychiatric doctors’ attitude toward depression. Methods: The inclusion criteria of participants in the present study were as follows: 1) Japanese non-psychiatric doctors and 2) attendees in educational opportunities regarding depression care. We conveniently approached two populations: 1) a workshop to depression care for non-psychiatric doctors and 2) a general physician-psychiatrist (GP)network group. We contacted 367 subjects. Attitudes toward depression were measured using the Depression Attitude Questionnaire (DAQ), a 20-item self-report questionnaire developed for general physicians. We report scores of each DAQ item and factors derived from exploratory factor analysis. Results: We received responses from 230 subjects, and we used DAQ data from 187 non-psychiatric doctors who met the inclusion criteria. All non-psychiatric doctors (n = 187) disagreed with "I feel comfortable in dealing with depressed patients' needs," while 60 % (n = 112) agreed with "Working with depressed patients is heavy going." Factor analysis indicated these items comprised a factor termed "Depression should be treated by psychiatrists" - to which 54 % of doctors (n = 101) agreed. Meanwhile, 67 % of doctors (n = 126) thought that nurses could be useful in depressed patient support. The three factors derived from the Japanese DAQ differed from models previously derived from British GP samples. The attitude of Japanese non-psychiatric doctors concerning whether depression should be treated by psychiatrists was markedly different to that of British GPs. Conclusions: Japanese non-psychiatric doctors believe that depression care is beyond the scope of their duties. It is suggested that educational programs or guidelines for depression care developed in other countries such as the UK are not directly adaptable for Japanese non-psychiatric doctors. Developing a focused educational program that motivates non-psychiatric doctors to play a role in depression care is necessary to enhance recognition and treatment of depression in Japan