32,628 research outputs found
A Parity Invariant Regularization in 3-D Quantum Electrodynamics
We regularize the 3-D quantum electrodynamics by a parity invariant
Pauli-Villars regularization method. We find that in the perturbation theory
the Chern-Simons term is not induced in the massless fermion case and induced
in the massive fermion case.Comment: 7 pages, CHIBA-EP-76, LaTe
Influence of QED Corrections on the Orientation of Chiral Symmetry Breaking in the NJL model
We study QED corrections to chiral symmetry breaking in the
Nambu--Jona-Lasinio (NJL) model with two flavors of quarks. In this model, the
isospin symmetry is broken by the differences between the current quark masses
and the electromagnetic charges of the up and down quarks. To leading order in
the 1/N expansion, we calculate the effective potential of the model with
one-loop QED corrections at finite temperature.
Evaluating the effective potential, we study the influence of the isospin
symmetry breaking on the orientation of chiral symmetry breaking.
The current quark mass plays an essential role in maintaining the orientation
of the chiral symmetry breaking.
If the average of the up and down quark masses is small enough, we find a
phase in which the pion field has non-vanishing expectation value and dynamical
CP violation takes place.Comment: 22 pages, 13 figures; added discussion about pion mass differenc
Structure and decay pattern of linear-chain state in 14C
The linear-chain states of C are theoretically investigated by using
the antisymmetrized molecular dynamics. The calculated excitation energies and
the decay widths of the linear-chain states were compared with the
observed data reported by the recent experiments. The properties of the
positive-parity linear-chain states reasonably agree with the observation, that
convinces us of the linear-chain formation in the positive-parity states. On
the other hand, in the negative-parity states, it is found that the
linear-chain configuration is fragmented into many states and do not form a
single rotational band. As a further evidence of the linear-chain formation, we
focus on the decay pattern. It is shown that the linear-chain states
decay to the excited states of daughter nucleus as well as to
the ground state, while other cluster states dominantly decay into the ground
state. Hence, we regard that this characteristic decay pattern is a strong
signature of the linear-chain formation
Canonical Quantization of SU(3) Skyrme Model in a General Representation
A complete canonical quantization of the SU(3) Skyrme model performed in the
collective coordinate formalism in general irreducible representations. In the
case of SU(3) the model differs qualitatively in different representations. The
Wess-Zumino-Witten term vanishes in all self-adjoint representations in the
collective coordinate method for separation of space and time variables. The
canonical quantization generates representation dependent quantum mass
corrections, which can stabilize the soliton solution. The standard symmetry
breaking mass term, which in general leads to representation mixing,
degenerates to the SU(2) form in all self-adjoint representations.Comment: 24 RevTex4 pages, no figure
Infrared spectroscopy under multi-extreme conditions: Direct observation of pseudo gap formation and collapse in CeSb
Infrared reflectivity measurements of CeSb under multi-extreme conditions
(low temperatures, high pressures and high magnetic fields) were performed. A
pseudo gap structure, which originates from the magnetic band folding effect,
responsible for the large enhancement in the electrical resistivity in the
single-layered antiferromagnetic structure (AF-1 phase) was found at a pressure
of 4 GPa and at temperatures of 35 - 50 K. The optical spectrum of the pseudo
gap changes to that of a metallic structure with increasing magnetic field
strength and increasing temperature. This change is the result of the magnetic
phase transition from the AF-1 phase to other phases as a function of the
magnetic field strength and temperature. This result is the first optical
observation of the formation and collapse of a pseudo gap under multi-extreme
conditions.Comment: 5 pages, 3 figures, accepted for publication in Phys. Rev.
Anisotropic Electronic Structure of the Kondo Semiconductor CeFe2Al10 Studied by Optical Conductivity
We report temperature-dependent polarized optical conductivity
[] spectra of CeFeAl, which is a reference material
for CeRuAl and CeOsAl with an anomalous magnetic
transition at 28 K. The spectrum along the b-axis differs
greatly from that in the -plane, indicating that this material has an
anisotropic electronic structure. At low temperatures, in all axes, a shoulder
structure due to the optical transition across the hybridization gap between
the conduction band and the localized states, namely -
hybridization, appears at 55 meV. However, the gap opening temperature and the
temperature of appearance of the quasiparticle Drude weight are strongly
anisotropic indicating the anisotropic Kondo temperature. The strong
anisotropic nature in both electronic structure and Kondo temperature is
considered to be relevant the anomalous magnetic phase transition in
CeRuAl and CeOsAl.Comment: 5 pages, 4 figure
Spontaneous Z2 Symmetry Breaking in the Orbifold Daughter of N=1 Super Yang-Mills Theory, Fractional Domain Walls and Vacuum Structure
We discuss the fate of the Z2 symmetry and the vacuum structure in an
SU(N)xSU(N) gauge theory with one bifundamental Dirac fermion. This theory can
be obtained from SU(2N) supersymmetric Yang--Mills (SYM) theory by virtue of Z2
orbifolding. We analyze dynamics of domain walls and argue that the Z2 symmetry
is spontaneously broken. Since unbroken Z2 is a necessary condition for
nonperturbative planar equivalence we conclude that the orbifold daughter is
nonperturbatively nonequivalent to its supersymmetric parent. En route, our
investigation reveals the existence of fractional domain walls, similar to
fractional D-branes of string theory on orbifolds. We conjecture on the fate of
these domain walls in the true solution of the Z2-broken orbifold theory. We
also comment on relation with nonsupersymmetric string theories and
closed-string tachyon condensation.Comment: 37 pages, 7 figures. v2: various significant changes; revisions
explained in the introduction. Final version to appear in Phys.Rev.
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