725 research outputs found
Domain Wall Fermions and Chiral Gauge Theories
We review the status of the domain wall fermion approach to construct chiral
gauge theories on the lattice. In this model an extra, fifth dimension is added
and our 4-dimensional world lives on a domainwall induced by a soliton shaped
mass defect that depends on the extra dimension only. We demonstrate that the
domain wall model gives the correct anomaly structure when external gauge
fields are used. We discuss two ways of adding dynamical gauge fields aiming at
a lattice regularized chiral gauge theory. An approach is presented to keep the
lattice infinite by regarding the fifth direction as the time-axis of a
4-dimensional Hamiltonian. Finally, a prospect to use domain wall fermions for
simulating QCD is given.Comment: 62pages, DESY-94-18
Zero-modes in the random hopping model
If the number of lattice sites is odd, a quantum particle hopping on a
bipartite lattice with random hopping between the two sublattices only is
guaranteed to have an eigenstate at zero energy. We show that the localization
length of this eigenstate depends strongly on the boundaries of the lattice,
and can take values anywhere between the mean free path and infinity. The same
dependence on boundary conditions is seen in the conductance of such a lattice
if it is connected to electron reservoirs via narrow leads. For any nonzero
energy, the dependence on boundary conditions is removed for sufficiently large
system sizes.Comment: 12 pages, 11 figure
Localized Gravitons, Gauge Bosons and Chiral Fermions in Smooth Spaces Generated by a Bounce
We study five-dimensional solutions to Einstein equations coupled to a scalar
field. Bounce-type solutions for the scalar field are associated with AdS_5
spaces with smooth warp functions. Gravitons are dynamically localized in this
framework in analogy to the Randall-Sundrum solution whereas, a bulk fermion
gives rise to a single chiral zero mode localized at the bounce. Additional
bulk scalar fields are incorporated in this picture. The dilaton, as a bulk
scalar leads, through its coupling, to localized gauge boson fields, something
that holds also in the case that the bounce system is replaced by a brane.Comment: latex, 14 page
Dynamics of a string coupled to gravitational waves - Gravitational wave scattering by a Nambu-Goto straight string
We study the perturbative dynamics of an infinite gravitating Nambu-Goto
string within the general-relativistic perturbation framework. We develop the
gauge invariant metric perturbation on a spacetime containing a
self-gravitating straight string with a finite thickness and solve the
linearized Einstein equation. In the thin string case, we show that the string
does not emit gravitational waves by its free oscillation in the first order
with respect to its oscillation amplitude, nevertheless the string actually
bends when the incidental gravitational waves go through it.Comment: Published in Physical Review D. Some explanations are changed to
clarify our point
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