10,492 research outputs found
A Note on Chern-Simons Solitons - a type III vortex from the wall vortex
We study some properties of topological Chern-Simons vortices in 2 + 1
dimensions. As has already been understood in the past, in the large magnetic
flux limit, they are well described by a Chern-Simons domain wall, which has
been compactified on a circle with the symmetric phase inside and the
asymmetric phase on the outside. Our goal is two-fold. First we want to explore
how the tension depends on the magnetic flux discretized by the integer n. The
BPS case is already known, but not much has been explored about the non-BPS
potentials. A generic renormalizable potential has two dimensionless parameters
that can be varied. Variation of only one of them lead to a type I and type II
vortex, very similar to the Abrikosov-Nielsen-Olesen (ANO) case. Variation of
both the parameters leads to a much richer structure. In particular we have
found a new type of vortex, which is type I-like for small flux and then turns
type II-like for larger flux. We could tentatively denote it a type III vortex.
This results in a stable vortex with number of fluxes which can be greater than
one. Our second objective is to study the Maxwell-Chern-Simons theory and and
understand how the large n limit of the CS vortex is smoothly connected with
the large n limit of the ANO vortex.Comment: 27 pages, 17 figures; v2.: references added, subsection 3.2 added,
explanation added in section 2.
Skyrmions in Orientifold and Adjoint QCD
This is a review of recent developments regarding the Skyrmion sector of
higher representation QCD. Ordinary QCD is a SU(n) gauge theory with n_f Dirac
quarks in the fundamental representation. Changing the representation of quarks
leads to different and interesting theories, which are not as well studied as
ordinary QCD. In order to be able to have a consistent asymptotically free
large n limit, we must limit ourselves to three cases: two-index representation
(symmetric or anti-symmetric) and adjoint representation. Skyrmions of the
low-energy effective Lagrangian shall be the main subject of this review. There
are puzzling aspects, both in orientifold and adjoint QCD, regarding the
identification of the Skyrmion and its quantum stability, that have not yet
been understood. We shall explain these problems and the solution we proposed
for them. The first part is dedicated to the two-index representation. Here the
challenge is to identify the correct particle in the spectrum that has to be
identified with the Skyrmion. It turns out not to be the simplest baryon (as in
ordinary QCD) but a baryonic state with higher charge, precisely composed by
n(n\pm 1)/2 quarks. Although not the simplest among the baryons, it is the one
that minimizes the mass per unit of baryonic charge and thus is the most stable
among them. The second part is devoted to the quarks in the adjoint
representation. The task here assume a different perspective. We do not have a
baryon charge, like in ordinary QCD. An important role is now played by a
massive fermion that must be considered in the low-energy effective Lagrangian.
Through this fermion, the Skyrmion acquires an anomalous fermionic number
(-1)^F and, as a consequence, an odd relationship between the latter and its
spin/statistic. This implies a Z_2 stability of the Skyrmion.Comment: 38 pages; 15 figures. v2: ref adde
Magnetic Bags and Black Holes
We discuss gravitational magnetic bags, i.e. clusters of large number of
monopoles in presence of gravitational effects. Physics depends on the
dimensionless ratio between the vev of the Higgs field at infinity and the
Planck mass. We solve the equations for the gravitational bags, and study the
transition from monopole to black hole. The critical coupling for this
transition is , and it is larger than that of
a single 't Hooft-Polyakov monopole. We investigate in detail the black-hole
limit.Comment: 20 pages, 12 figures; v2 small change
Born Reciprocity and Cosmic Accelerations
The trans-Planckian theory is a model that realizes concretely the Born
reciprocity idea, which is the postulate of absolute equivalence between
coordinate and momenta . This model is intrinsically global, and thus it
is naturally implemented in a cosmological setting. Cosmology and Born
reciprocity are made for each other. Inflation provides the essential mechanism
to suppress the terms coming from the dual part of the action. The
trans-Planckian theory provides an explanation for the present acceleration of
the universe scale factor. This is possible just considering a simple model
that contains gravity, one gauge field plus one matter field (to be identified
with dark matter), together with the reciprocity principle.Comment: 22 pages, 5 figures. v2: minor corrections. v3: book chapter of
"Advances in Dark Energy Research". v4: some correction
Forgetful linear systems on the projective space and rational normal curves over \cM_{0,2n}^{GIT}
Let \cM_{0,n} the moduli space of -pointed rational curves. The aim of
this note is to give a new, geometric construction of \cM_{0,2n}^{GIT}, the
GIT compacification of \cM_{0,2n}, in terms of linear systems on \PP^{2n-2}
that contract all the rational normal curves passing by the points of a
projective base. These linear systems are a projective analogue of the
forgetful maps between \bar{\cM}_{0,2n+1} and \bar{\cM}_{0,2n}. The
construction is performed via a study of the so-called
maps from the Knudsen-Mumford compactification \bar{\cM}_{0,2n} to
\cM_{0,2n}^{GIT} and of the canonical forgetful maps. As a side result we
also find a linear system on \bar{\cM}_{0,2n} whose associated map is the
contraction map .Comment: New version: corrected typos, added contextualization and relations
with previous GIT constructions and with linear systems on the Knudsen
compactificatio
Instanton Bags, High Density Holographic QCD and Chiral Symmetry Restoration
We describe the simplest example of an instanton bag in Euclidean space. It
consists of a monopole wall and a Kaluza-Klein monopole wall, lifted to one
higher dimension, trapping the instanton charge in the middle. This object has
finite instanton density in a three-dimensional volume.
Baryon physics in holographic QCD models gets translated into a
multi-instanton problem in the bulk, and a state with a high density baryonic
charge consists of a non-diluted multi-instanton solution. The instanton bag is
a good candidate for this high-density state. We compute its parameters via
moduli stabilization. Chiral symmetry restoration is exhibited by this state,
and it is a direct consequence of its non-diluted features.Comment: 32 pages, 11 figures; v2: revised version, accepted on pr
A conic bundle degenerating on the Kummer surface
Let be a genus 2 curve and \su the moduli space of semi-stable rank 2
vector bundles on with trivial determinant. In \cite{bol:wed} we described
the parameter space of non stable extension classes (invariant with respect to
the hyperelliptic involution) of the canonical sheaf of with
. In this paper we study the classifying rational map \phi: \pr
Ext^1(\omega,\omega^{-1})\cong \pr^4 \dashrightarrow \su\cong \pr^3 that sends
an extension class on the corresponding rank two vector bundle. Moreover we
prove that, if we blow up \pr^4 along a certain cubic surface and \su
at the point corresponding to the bundle \OO \oplus \OO, then the induced
morphism \tilde{\phi}: Bl_S \ra Bl_p\su defines a conic bundle that
degenerates on the blow up (at ) of the Kummer surface naturally contained
in \su. Furthermore we construct the \pr^2-bundle that contains the conic
bundle and we discuss the stability and deformations of one of its components.Comment: 29 page
W/Z and diboson production at hadron colliders
A general review of the latest results about single and double vector boson
production in the multipurpose experiments at LHC (ATLAS and CMS) and at
Tevatron (CDF and D0) will be presented. The review will focus on boson
production, while a more detailed report about W and Z properties can be found
elsewhere. Only leptonic decays into electrons and muons will be considered.Comment: 7 pages, 6 figures, proceedings of XXXI PHYSICS IN COLLISION,
Vancouver, BC Canada, August 28 - September 1, 201
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