329 research outputs found
Relating branes and matrices
We construct a general map between a Dp-brane with magnetic flux and a matrix
configuration of D0-branes, by showing how one can rewrite the boundary state
of the Dp-brane in terms of its D0-brane constituents. This map gives a simple
prescription for constructing the matrices of fuzzy spaces corresponding to
branes of arbitrary shape and topology. Since we explicitly identify the
D0-brane degrees of freedom on the brane, we also derive the D0-brane charge of
the brane in a very direct way including the A-genus term. As a check on our
formalism, we use our map to derive the abelian-Born-Infeld equations of motion
from the action of the D0-brane matrices.Comment: 28 pages, Late
Non-BPS Dyons and Branes in the Dirac-Born-Infeld Theory
Non-BPS dyon solutions to D3-brane actions are constructed when one or more
scalar fields describing transverse fluctuations of the brane, are considered.
The picture emerging from such non-BPS configurations is analysed, in
particular the response of the D-brane-string system to small perturbations.Comment: 16 pages, 4 figures, Revtex fil
Shimura curve computations via K3 surfaces of Neron-Severi rank at least 19
It is known that K3 surfaces S whose Picard number rho (= rank of the
Neron-Severi group of S) is at least 19 are parametrized by modular curves X,
and these modular curves X include various Shimura modular curves associated
with congruence subgroups of quaternion algebras over Q. In a family of such K3
surfaces, a surface has rho=20 if and only if it corresponds to a CM point on
X. We use this to compute equations for Shimura curves, natural maps between
them, and CM coordinates well beyond what could be done by working with the
curves directly as we did in ``Shimura Curve Computations'' (1998) =
Comment: 16 pages (1 figure drawn with the LaTeX picture environment); To
appear in the proceedings of ANTS-VIII, Banff, May 200
Spins, charges and currents at Domain Walls in a Quantum Hall Ising Ferromagnet
We study spin textures in a quantum Hall Ising ferromagnet. Domain walls
between ferro and unpolarized states at are analyzed with a functional
theory supported by a microscopic calculation. In a neutral wall, Hartree
repulsion prevents the appearance of a fan phase provoked by a negative
stiffness. For a charged system, electrons become trapped as solitons at the
domain wall. The size and energy of the solitons are determined by both Hartree
and spin-orbit interactions. Finally, we discuss how electrical transport takes
place through the domain wall.Comment: 4 pages, 3 figures include
Gravity duals of half-BPS Wilson loops
We explicitly construct the fully back-reacted half-BPS solutions in Type IIB
supergravity which are dual to Wilson loops with 16 supersymmetries in
super Yang-Mills. In a first part, we use the methods of a
companion paper to derive the exact general solution of the half-BPS equations
on the space , with isometry group
in terms of two locally harmonic functions
on a Riemann surface with boundary. These solutions, generally, have
varying dilaton and axion, and non-vanishing 3-form fluxes. In a second part,
we impose regularity and topology conditions. These non-singular solutions may
be parametrized by a genus hyperelliptic surface , all of
whose branch points lie on the real line. Each genus solution has only a
single asymptotic region, but exhibits homology
3-spheres, and an extra homology 5-spheres, carrying respectively RR 3-form
and RR 5-form charges. For genus 0, we recover with 3 free
parameters, while for genus , the solution has free
parameters. The genus 1 case is studied in detail. Numerical analysis is used
to show that the solutions are regular throughout the parameter space.
Collapse of a branch cut on subtending either a homology 3-sphere or a
homology 5-sphere is non-singular and yields the genus solution. This
behavior is precisely expected of a proper dual to a Wilson loop in gauge
theory.Comment: 62 pages, LaTeX, 6 figures, v2: minor change
Application of heavy-quark effective theory to lattice QCD: III. Radiative corrections to heavy-heavy currents
We apply heavy-quark effective theory (HQET) to separate long- and
short-distance effects of heavy quarks in lattice gauge theory. In this paper
we focus on flavor-changing currents that mediate transitions from one heavy
flavor to another. We stress differences in the formalism for heavy-light
currents, which are discussed in a companion paper, showing how HQET provides a
systematic matching procedure. We obtain one-loop results for the matching
factors of lattice currents, needed for heavy-quark phenomenology, such as the
calculation of zero-recoil form factors for the semileptonic decays . Results for the Brodsky-Lepage-Mackenzie scale are also
given.Comment: 35 pages, 17 figures. Program LatHQ2QCD to compute matching one-loop
coefficients available at http://theory.fnal.gov/people/kronfeld/LatHQ2QCD
Nucleon-nucleon coincidence measurement in the non-mesonic weak decay of 5_Lambda-He and 12_Lambda-C hypernuclei
We have measured both yields of neutron-proton and neutron-neutron pairs
emitted from the non-mesonic weak decay process of 5_Lambda-He and 12_Lambda-C
hypernuclei produced via the (pi^+,K^+) reaction for the first time. We
observed clean back-to-back correlation of the np- and nn-pairs in the
coincidence spectra for both hypernuclei. The ratio of those back-to-back pair
yields, Nnn / Nnp, must be close to the ratio of neutron- and proton-induced
decay widths of the decay, Gn(Lambda n -> nn)/Gp(Lambda p -> np). The obtained
ratios for each hypernuclei support recent calculations based on short-range
interactions.Comment: 4 pages, 1 figure, International Nuclear Physics Conference (INPC
2004), Goteborg, Sweden, June 27 - July 2, 2004, to appear in Nuclear Physics
Ghost D-brane, Supersymmetry and Matrix Model
In this note we study the world volume theory of pairs of D-brane and ghost
D-brane, which is shown to have 16 linear supersymmetries and 16 nonlinear
supersymmetries. In particular we study a matrix model based on the pairs of
D(-1)-brane and ghost D(-1)-brane. Since such pairs are supposed to be
equivalent to the closed string vacuum, we expect all 32 supersymmetries should
be unbroken. We show that the world volume theory of the pairs of D-brane and
ghost D-brane has unbroken 32 supersymmetries even though a half of them are
nonlinearly realized.Comment: 12 pages, references adde
Electromagnetic vertex function of the pion at T > 0
The matrix element of the electromagnetic current between pion states is
calculated in quenched lattice QCD at a temperature of . The
nonperturbatively improved Sheikholeslami-Wohlert action is used together with
the corresponding improved vector current. The electromagnetic
vertex function is extracted for pion masses down to and
momentum transfers .Comment: 17 pages, 8 figure
Exact Solutions of Open Bosonic String Field Theory
In this paper we present two solutions of open bosonic string field theory
defined on D0-brane background that correspond to the change of the D0-brane
position in the transverse space.Comment: 18 page
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