2,672 research outputs found
On The Problem of the Quantum Heterotic Vortex
We address the problem of non-Abelian super-QCD, with a Fayet-Iliopoulos
term, as seen from the vortex worldsheet perspective. Together with the FI term
, also a mass for the adjoint superfield enters in the game.
This mass allows the interpolation between and super-QCD. While
the phenomenology of the case () is pretty much understood, much
remains to be clarified for the finite- case. We distinguish, inside the
parameter space spanned by the FI term and the mass , four different
corners where some quantitative statements can be made. These are the regions
where the strong dynamics can, in some approximation, be quantitatively
analyzed. We focus in particular on two questions: 1) Is the quantum vortex BPS
or non-BPS? 2) What is the phase of the internal non-Abelian moduli? We find
that the answer to these questions strongly depends upon the choice of the
linear term in the superpotential. We also try to explain what happens in the
most unexplored, and controversial, region of parameters, that of the quantum
heterotic vortex, where .Comment: 47 pp; v2: typo
Strings Inside Walls in N=1 Super Yang-Mills
We conjecture the existence of strings bounded inside walls in SU
Super Yang-Mills theory. These strings carry quantum number, where
is the greatest common divisor between , the charge of the wall, and
. We provide field-theoretical arguments and string-theoretical evidences,
both from MQCD and from gauge-gravity correspondence. We interpret this result
from the point of view of the low-energy effective action living on the
-wall.Comment: 25 pp. Major changes. In particular, following the recent work
arXiv:0807.1908 we have been able to give a field theoretical proof of the
statement. We have also corrected an important erroneous interpretation in
the previous version regarding the 2+1 effective action; Typo
Stable vs Unstable Vortices in SQCD
We give a topological classification of stable and unconfined massive
particles and strings (and some instantons) in worldvolume theories of
M5-branes and their dimensional reductions, generalizing Witten's
classification of strings in SYM. In particular 4d N=2 SQCD softly broken to
N=1 contains torsion (Douglas-Shenker) Z_N-strings and nontorsion (Hanany-Tong)
Z-strings. Some of the former are stable when the flavor symmetry is gauged,
while those that are not stable confine quarks and in some vacua even dyons
into baryons. The nontorsion strings are stable if and only if all colors are
locked to flavors, which is weaker than the BPS condition. As a byproduct
unstable string decay modes and approximate lifetimes are found. Cascading
theories have no vortices stabilized by the topological charges treated here
and in particular Gubser-Herzog-Klebanov axionic strings do not carry such a
charge.Comment: 32 pages, 6 figure
Compositional Performance Modelling with the TIPPtool
Stochastic process algebras have been proposed as compositional specification formalisms for performance models. In this paper, we describe a tool which aims at realising all beneficial aspects of compositional performance modelling, the TIPPtool. It incorporates methods for compositional specification as well as solution, based on state-of-the-art techniques, and wrapped in a user-friendly graphical front end. Apart from highlighting the general benefits of the tool, we also discuss some lessons learned during development and application of the TIPPtool. A non-trivial model of a real life communication system serves as a case study to illustrate benefits and limitations
The Quantum Dynamics of Heterotic Vortex Strings
We study the quantum dynamics of vortex strings in N=1 SQCD with U(N_c) gauge
group and N_f=N_c quarks. The classical worldsheet of the string has N=(0,2)
supersymmetry, but this is broken by quantum effects. We show how the pattern
of supersymmetry breaking and restoration on the worldsheet captures the
quantum dynamics of the underlying 4d theory. We also find qualitative matching
of the meson spectrum in 4d and the spectrum on the worldsheet.Comment: 13 page
Heterotic Vortex Strings
We determine the low-energy N=(0,2) worldsheet dynamics of vortex strings in
a large class of non-Abelian N=1 supersymmetric gauge theories.Comment: 44 pages, 3 figures. v2: typos corrected, reference adde
Monopoles and Holography
We present a holographic theory in AdS_4 whose zero temperature ground state
develops a crystal structure, spontaneously breaking translational symmetry.
The crystal is induced by a background magnetic field, but requires no chemical
potential. This lattice arises from the existence of 't Hooft-Polyakov monopole
solitons in the bulk which condense to form a classical object known as a
monopole wall. In the infra-red, the magnetic field is screened and there is an
emergent SU(2) global symmetry.Comment: 33 pages, 16 figures; v2: ref adde
Magnetic Catalysis in AdS4
We study the formation of fermion condensates in Anti de Sitter space. In
particular, we describe a novel version of magnetic catalysis that arises for
fermions in asymptotically AdS4 geometries which cap off in the infra-red with
a hard wall. We show that the presence of a magnetic field induces a fermion
condensate in the bulk that spontaneously breaks CP symmetry. From the
perspective of the dual boundary theory, this corresponds to a strongly coupled
version of magnetic catalysis in d=2+1.Comment: 22 pages, 4 figures. v2: References added, factors of 2 corrected,
extra comments added in appendix. v3: extra comments about fermion modes in a
hard wall background. v4: A final factor of
Geometry and Dynamics of a Coupled 4D-2D Quantum Field Theory
Geometric and dynamical aspects of a coupled 4D-2D interacting quantum field
theory - the gauged nonAbelian vortex - are investigated. The fluctuations of
the internal 2D nonAbelian vortex zeromodes excite the massless 4D Yang-Mills
modes and in general give rise to divergent energies. This means that the
well-known 2D CP(N-1) zeromodes associated with a nonAbelian vortex become
nonnormalizable. Moreover, all sorts of global, topological 4D effects such as
the nonAbelian Aharonov-Bohm effect come into play. These topological global
features and the dynamical properties associated with the fluctuation of the 2D
vortex moduli modes are intimately correlated, as shown concretely here in a
U(1) x SU(N) x SU(N) model with scalar fields in a bifundamental representation
of the two SU(N) factor gauge groups.Comment: Latex, 39 pages, 5 figure
The Hopf Skyrmion in QCD with Adjoint Quarks
We consider a modification of QCD in which conventional fundamental quarks
are replaced by Weyl fermions in the adjoint representation of the color SU(N).
In the case of two flavors the low-energy chiral Lagrangian is that of the
Skyrme-Faddeev model. The latter supports topologically stable solitons with
mass scaling as N^2. Topological stability is due to the existence of a
nontrivial Hopf invariant in the Skyrme-Faddeev model. Our task is to identify,
at the level of the fundamental theory, adjoint QCD, an underlying reason
responsible for the stability of the corresponding hadrons. We argue that all
"normal" mesons and baryons, with mass O(N^0), are characterized by (-1)^Q
(-1)^F =1, where Q is a conserved charge corresponding to the unbroken U(1)
surviving in the process of the chiral symmetry breaking (SU(2) \to U(1) for
two adjoint flavors). Moreover, F is the fermion number (defined mod 2 in the
case at hand). We argue that there exist exotic hadrons with mass O(N^2) and
(-1)^Q (-1)^F = -1. They are in one-to-one correspondence with the Hopf
Skyrmions. The transition from nonexotic to exotic hadrons is due to a shift in
F, namely F \to F - {\cal H} where {\cal H} is the Hopf invariant. To detect
this phenomenon we have to extend the Skyrme-Faddeev model by introducing
fermions.Comment: 18 pages, 3 figures; v.2: a reference and a comment added; v.3: two
comments added, figures improve
- âŠ