2,689 research outputs found
Quantum and Classical Gauge Symmetries in a Modified Quantization Scheme
The use of the mass term as a gauge fixing term has been studied by
Zwanziger, Parrinello and Jona-Lasinio, which is related to the non-linear
gauge of Dirac and Nambu in the large mass limit. We have
recently shown that this modified quantization scheme is in fact identical to
the conventional {\em local} Faddeev-Popov formula {\em without} taking the
large mass limit, if one takes into account the variation of the gauge field
along the entire gauge orbit and if the Gribov complications can be ignored.
This suggests that the classical massive vector theory, for example, is
interpreted in a more flexible manner either as a gauge invariant theory with a
gauge fixing term added, or as a conventional massive non-gauge theory. As for
massive gauge particles, the Higgs mechanics, where the mass term is gauge
invariant, has a more intrinsic meaning.
It is suggested to extend the notion of quantum gauge symmetry (BRST
symmetry) not only to classical gauge theory but also to a wider class of
theories whose gauge symmetry is broken by some extra terms in the classical
action. We comment on the implications of this extended notion of quantum gauge
symmetry.Comment: 14 pages. Substantially revised and enlarged including the change of
the title. To appear in International Journal of Modern Physics
Holographic Confining Gauge theory and Response to Electric Field
We study the response of confining gauge theory to the external electric
field by using holographic Yang-Mills theories in the large limit.
Although the theories are in the confinement phase, we find a transition from
the insulator to the conductor phase when the electric field exceeds its
critical value. Then, the baryon number current is generated in the conductor
phase. At the same time, in this phase, the meson melting is observed through
the quasi-normal modes of meson spectrum. Possible ideas are given for the
string state corresponding to the melted mesons, and they lead to the idea that
the source of this current may be identified with the quarks and anti-quarks
supplied by the melted mesons. We also discuss about other possible carriers.
Furthermore, from the analysis of the massless quark, chiral symmetry
restoration is observed at the insulator-conductor transition point by studying
a confining theory in which the chiral symmetry is broken.Comment: 27 pages, 14 figure
Sexual abstinence behavior among never-married youths in a generalized HIV epidemic country: evidence from the 2005 CĂŽte d'Ivoire AIDS indicator survey
<p>Abstract</p> <p>Background</p> <p>Sexual abstinence is the best available option for preventing both pregnancy and sexually transmitted infections, including HIV/AIDS. Identifying the factors associated with sexual abstinence among youths would have meaningful implications in a generalized HIV epidemic country such as the CĂŽte d'Ivoire. Thus, we explored sexual abstinence behavior among never-married individuals aged 15 to 24 in CĂŽte d'Ivoire and assessed factors that predict sexual abstinence.</p> <p>Methods</p> <p>We obtained data from the nationally representative and population-based 2005 CĂŽte d'Ivoire AIDS Indicator Survey, conducted from September 2004 to October 2005. Our sample included 3041 never-married people aged 15 to 24. Of these, 990 reported never having sexual intercourse (primary abstinence) and 137 reported sexual experience but not in the 12 months prior to the survey (secondary abstinence). In all, 1127 youths reported sexual abstinence practice.</p> <p>Results</p> <p>Of the 3041 never-married youths, 54.4% were male and 45.6% were female. About 33.0%, 6.7%, and 37.1% of them were practicing primary, secondary, and sexual abstinence behavior, respectively. Females of higher education level were significantly 11.14 times as likely as those of no education to practice either primary or secondary abstinence. Males who were animists, had no religion, or were practicing religions other than Christianity or Muslim were significantly less likely than other male youths to practice sexual abstinence (OR = 0.53, 95% CI = 0.30â0.95). Living in the north-west region of the country significantly decreased the odds of sexual abstinence among female youths. Similarly, female youths living in rural areas were significantly 0.42 times as likely as those in the urban zones to practice sexual abstinence.</p> <p>Conclusion</p> <p>HIV/AIDS prevention program components could include media campaigns, educational intervention improvement, as well as promoting policies that shape female youth livelihoods. Likewise, youth involvement in initiatives to design appropriate messages, and activities to promote positive behaviors or to change negative perceptions could impact on youths' decision to exert abstinence behavior.</p
Generalized Ginsparg-Wilson algebra and index theorem on the lattice
Recent studies of the topological properties of a general class of lattice
Dirac operators are reported. This is based on a specific algebraic realization
of the Ginsparg-Wilson relation in the form
where stands for a non-negative integer.
The choice corresponds to the commonly discussed Ginsparg-Wilson relation
and thus to the overlap operator. It is shown that local chiral anomaly and the
instanton-related index of all these operators are identical. The locality of
all these Dirac operators for vanishing gauge fields is proved on the basis of
explicit construction, but the locality with dynamical gauge fields has not
been established yet. We suggest that the Wilsonian effective action is
essential to avoid infrared singularities encountered in general perturbative
analyses.Comment: 11 pages. Talk given at APCTP-Nankai Joint Symposium on Lattice
Statistics and Mathematical Physics, Tianjin, China, 8-11 October, 2001. To
be published in the Proceedings and in Int. Jour. Mod. Phys.
Parity-broken ground state for the spin-1 pyrochlore antiferromagnet
The ground-state properties of the spin-1 pyrochlore antiferromagnet are
studied by applying the VBS-like tetrahedron-unit decomposition to the original
spin system. The symmetrization required on every vertex is taken into account
by introducing a ferromagnetic coupling. The pairwise effective Hamiltonian
between the adjacent tetrahedrons is obtained by considering the next nearest
neighbor and the third neighbor exchange interactions. We find that the
transverse component of the spin chirality exhibits a long-range order,
breaking the parity symmetry of the tetrahedral group, while the chirality
itself is not broken.Comment: 4 pages, 3 figures, REVTeX(ver.3.1
Detection of Excess Hard X-ray Emission from the Group of Galaxies HCG62
From the group of galaxies HCG62, we detected an excess hard X-ray emission
in energies above keV with \A SCA. The excess emission is spatially
extended up to from the group center, and somewhat enhanced toward
north. Its spectrum can be represented by either a power-law of photon index
0.8-2.7, or a Bremsstrahlung of temperature keV. In the 2-10 keV range,
the observed hard X-ray flux, erg cm
s, implies a luminosity of erg s for a
Hubble constant of 50 km s Mpc. The emission is thus too luminous
to be attributed to X-ray binaries in the memb er galaxies. We discuss possible
origin of the hard X-ray emission.Comment: 6 pages, 3 Postscript figures, uses emulateapj.sty. Accepted for
publication in the Astrophysical Journal Letter
N=2 Liouville Theory with Boundary
We study N=2 Liouville theory with arbitrary central charge in the presence
of boundaries. After reviewing the theory on the sphere and deriving some
important structure constants, we investigate the boundary states of the theory
from two approaches, one using the modular transformation property of annulus
amplitudes and the other using the bootstrap of disc two-point functions
containing degenerate bulk operators. The boundary interactions describing the
boundary states are also proposed, based on which the precise correspondence
between boundary states and boundary interactions is obtained. The open string
spectrum between D-branes is studied from the modular bootstrap approach and
also from the reflection relation of boundary operators, providing a
consistency check for the proposal.Comment: 1+48 pages, no figure. typos corrected and references added. the
version to appear in JHE
Boundary operators in the O(n) and RSOS matrix models
We study the new boundary condition of the O(n) model proposed by Jacobsen
and Saleur using the matrix model. The spectrum of boundary operators and their
conformal weights are obtained by solving the loop equations. Using the
diagrammatic expansion of the matrix model as well as the loop equations, we
make an explicit correspondence between the new boundary condition of the O(n)
model and the "alternating height" boundary conditions in RSOS model.Comment: 29 pages, 4 figures; version to appear in JHE
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