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

Modelling the measured local time evolution of strongly nonlinear heat pulses in the Large Helical Device

In some magnetically confined plasmas, an applied pulse of rapid edge cooling can trigger either a positive or negative excursion in the core electron temperature from its steady state value. We present a new model which captures the time evolution of the transient, non-diffusive local dynamics in the core plasma. We show quantitative agreement between this model and recent spatially localized measurements (Inagaki et al 2010 Plasma Phys. Control. Fusion 52 075002) of the local time-evolving temperature pulse in cold pulse propagation experiments in the Large Helical Device

Stochastic Gravitational Wave Background originating from Halo Mergers

The stochastic gravitational wave background (GWB) from halo mergers is investigated by a quasi-analytic method. The method we employ consists of two steps. The first step is to construct a merger tree by using the Extended Press-Schechter formalism or the Sheth & Tormen formalism, with Monte-Carlo realizations. This merger tree provides evolution of halo masses. From $N$-body simulation of two-halo mergers, we can estimate the amount of gravitational wave emission induced by the individual merger process. Therefore the second step is to combine this gravitaional wave emission to the merger tree and obtain the amplitude of GWB. We find $\Omega_{GW}\sim 10^{-19}$ for $f\sim 10^{-17}-10^{-16}$ Hz, where $\Omega_{GW}$ is the energy density of the GWB. It turns out that most of the contribution on the GWB comes from halos with masses below $10^{15} M_\odot$ and mergers at low redshift, i.e., $0<z<0.8$.Comment: 5 pages, 8 figures. Accepted for publication in Physical Review

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

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.

Chiral Properties of QCD Vacuum in Magnetars- A Nambu-Jona-Lasinio Model with Semi-Classical Approximation

The breaking of chiral symmetry of light quarks at zero temperature in presence of strong quantizing magnetic fiels is studied using Nambu-Jona-Lasinio (NJL) model with Thomas-Fermi type semi-classical formalism. It is found that the dynamically generated light quark mass can never become zero if the Landau levels are populated and the mass increases with the increase of magnetic field strength.Comment: REVTEX 11 Pages, One .eps figure (included

Schwinger-Dyson Analysis of Dynamical Symmetry Breaking on a Brane with Bulk Yang-Mills Theory

The dynamically generated fermion mass is investigated in the flat brane world with (4+delta)-dimensional bulk space-time, and in the Randall-Sundrum (RS) brane world. We consider the bulk Yang-Mills theory interacting with the fermion confined on a four-dimensional brane. Based on the effective theory below the reduced cutoff scale on the brane, we formulate the Schwinger-Dyson equation of the brane fermion propagator. By using the improved ladder approximation we numerically solve the Schwinger-Dyson equation and find that the dynamical fermion mass is near the reduced cutoff scale on the brane for the flat brane world with delta >= 3 and for the RS brane world. In RS brane world KK excited modes of the bulk gauge field localized around the y = pi R brane and it enhances the dynamical symmetry breaking on the brane. The decay constant of the fermion and the anti-fermion composite operator can be taken to be the order of the electroweak scale much smaller than the Planck scale. Therefore electroweak mass scale can be realized from only the Planck scale in the RS brane world due to the fermion and the anti-fermion pair condensation. That is a dynamical realization of Randall-Sundrum model which solves the weak-Planck hierarchy problem.Comment: 21 pages, 12 figures; typos corrected, references added and updated, footnotes adde

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

Symmetry structure and phase transitions

We study chiral symmetry structure at finite density and temperature in the presence of external magnetic field and gravity, a situation relevant in the early Universe and in the core of compact stars. We then investigate the dynamical evolution of phase transition in the expanding early Universe and possible formation of quark nuggets and their survival.Comment: Plenary talk given at the 4th. ICPAQGP held at Jaipur, India from Nov 26-30, 2001.laTex 2e file with 8 ps figures and 12 page