556 research outputs found
Monopoles Can be Confined by 0, 1 or 2 Vortices
There are three types of monopole in gauge theories with fundamental matter
and N=2 supersymmetry broken by a superpotential. There are unconfined
0-monopoles and also 1 and 2-monopoles confined respectively by one or two
vortices transforming under distinct components of the unbroken gauge group. If
a Fayet-Iliopoulos term is added then there are only 2-monopoles. Monopoles
transform in the bifundamental representation of two components of the unbroken
gauge symmetry, and if two monopoles share a component they may form a
boundstate. Selection rules for this process are found, for example vortex
number is preserved modulo 2. We find the tensions of the vortices, which are
in general distinct, and also the conditions under which vortices are mutually
BPS. Results are derived in field theory and also in MQCD, and in quiver
theories a T-dual picture may be used in which monopoles are classified by
quiver diagrams with two colors of vertices.Comment: 46 pages, 13 figures, V2: Comment on non-BPS correction added; 1
figure adde
Retraction with face saving: Modelling conversational interaction through dynamic hypermedia
This paper describes RWFS (Retraction With Face Saving), a hypermedia application which models an interview between a lawyer and his client â a lorry driver â facing court charges of reckless driving. At one level RWFS takes the form of a sophisticated game in which different outcomes to the interview are possible according to the learner's degree of skill. At another level, RWFS is designed to encourage the language learner's awareness and understanding of the pragmatic features of conversation. RWFS runs on HyperContext, a hybrid hypertextlexpert system developed in Pavia by two of the authors, Marco Piastra and Roberto Bolognesi, and which supports dynamic hypermedia units. HyperContext's dynamic linking capacity plays a vital role in simulating significant conversational features such as the conditioning of a current move in the conversation by information acquired much earlier in the course of the interview. In this connection, the paper discusses the contribution of RMCI (Reâusable Model of Conversational Interaction), a reâusable applicationâindependent applied model of interaction on which the game is based, and which links a tactical level (the conversation) to a metalevel which provides a moveâbyâmove commentary on interactional theory. In its turn, RMCFs metalevel is linked to a strategic level which interprets the structure of the conversation in terms of a pyramidâlike hierarchy of increasingly abstract theoretical concepts
Metaphors in Dreams: Where Cognitive Linguistics meets Psychoanalysis
This article approaches the study of metaphors in dreams from an interdisciplinary perspective, which aims at bringing together the psychoanalytic tradition, and the main views that constitute what is commonly known as the contemporary cognitive theory of metaphor. Our perspective aims at showing how these approaches can (and need) to be integrated, and suggests why in this endeavour it is necessary to consider the personal background of the dreamer and her need to re-establish/confirm her identity within each metaphor.
Nonabelian Superconductors: Vortices and Confinement in SQCD
We study nonabelian vortices (flux tubes) in SU(N) gauge theories, which are
responsible for the confinement of (nonabelian) magnetic monopoles. In
particular a detailed analysis is given of SQCD with gauge group
SU(3) deformed by a small adjoint chiral multiplet mass. Tuning the bare quark
masses (which we take to be large) to a common value , we consider a
particular vacuum of this theory in which an SU(2) subgroup of the gauge group
remains unbroken. We consider flavors so that the SU(2)
sub-sector remains non asymptotically free: the vortices carrying nonabelian
fluxes may be reliably studied in a semi-classical regime. We show that the
vortices indeed acquire exact zero modes which generate global rotations of the
flux in an group. We study an effective world-sheet theory of
these orientational zero modes which reduces to an O(3) sigma
model in (1+1) dimensions. Mirror symmetry then teaches us that the dual SU(2)
group is not dynamically broken.Comment: 37 pages Latex, 6 eps figures, Typos corrected and a few sentences
added or correcte
On the time dependence of holographic complexity for charged AdS black holes with scalar hair
In the presence of a scalar hair perturbation, the Cauchy horizon of a
Reissner-Nordstr\"om black hole disappears and is replaced by the rapid
collapse of the Einstein-Rosen bridge, which leads to a Kasner singularity
[1,2]. We study the time dependence of holographic complexity, both for the
volume and for the action proposals, in a class of models with hairy black
holes. Volume complexity can only probe a portion of the black hole interior
that remains far away from the Kasner singularity. We provide numerical
evidence that the Lloyd bound is satisfied by the volume complexity rate in all
the parameter space. Action complexity can instead probe a portion of the
spacetime closer to the singularity. In particular, the complexity rate
diverges at the critical time for which the Wheeler-DeWitt patch touches
the singularity. After the critical time the action complexity rate approaches
a constant. We find that the Kasner exponent does not directly affect the
details of the divergence of the complexity rate at and the late-time
behaviour of the complexity. The Lloyd bound is violated by action complexity
at finite time, because the complexity rate diverges at .We find that
the Lloyd bound is satisfied by the asymptotic action complexity rate in all
the parameter space that we explored.Comment: 57 pages, 26 figure
Biotechnological production of galactooligosaccharides (GOS) using porungo cheese whey
The bioconversion of porungo cheese whey into galactooligosaccharides (GOS) was investigated using immobilized ÎČ-galactosidase in batch system. Two enzymatic immobilization strategies were tested for optima pH and temperature and the best immobilization strategy was used to evaluate the GOS production in two steps. First, different lactose sources (substrates) were tested, and subsequently, different concentrations of porungo cheese whey (200 g L-1 and 400 g L-1) and temperatures (37 °C to 46 °C) were evaluated. Immobilization of ÎČ-galactosidase increased the range of operational pH (7.0-7.5) when immobilized in calciumalginate support. However, the pH range decreased when the immobilization was conducted using calcium-Concanavalin A support. Batch reactions using the calcium-alginate immobilized biocatalyst produced the highest yields of GOS (63.2%) from porungo cheese whey, compared to the control substrate of lactose solution at concentration of 50 g L-1 (41.1%). The temperature of 46 °C and 400 g L-1 of substrate shown the better condition to GOS production, with lactose conversion of 61.4%. These results suggest the possible use of porungo cheese whey as substrate in the biotechnological production of GOS
Almost Conformal Vacua and Confinement
Dynamics of confining vacua which appear as deformed superconformal theory
with a non-Abelian gauge symmetry, is studied by taking a concrete example of
the sextet vacua of , SU(3) gauge theory with , with equal
quark masses. We show that the low-energy "matter" degrees of freedom of this
theory consist of four magnetic monopole doublets of the low-energy effective
SU(2) gauge group, one dyon doublet, and one electric doublet. We find a
mechanism of cancellation of the beta function, which naturally but
nontrivially generalizes that of Argyres-Douglas. Study of our SCFT theory as a
limit of six colliding vacua, suggests that the confinement in the
present theory occurs in an essentially different manner from those vacua with
dynamical Abelianization, and involves strongly interacting non-Abelian
magnetic monopoles.Comment: 27 pages, 11 figures, LaTex fil
Type I Non-Abelian Superconductors in Supersymmetric Gauge Theories
Non-BPS non-Abelian vortices with CP^1 internal moduli space are studied in
an N=2 supersymmetric U(1) x SU(2) gauge theory with softly breaking adjoint
mass terms. For generic internal orientations the classical force between two
vortices can be attractive or repulsive. On the other hand, the mass of the
scalars in the theory is always less than that of the vector bosons; also, the
force between two vortices with the same CP^1 orientation is always attractive:
for these reasons we interpret our model as a non-Abelian generalization of
type I superconductors. We compute the effective potential in the limit of two
well separated vortices. It is a function of the distance and of the relative
colour-flavour orientation of the two vortices; in this limit we find an
effective description in terms of two interacting CP^1 sigma models. In the
limit of two coincident vortices we find two different solutions with the same
topological winding and, for generic values of the parameters, different
tensions. One of the two solutions is described by a CP^1 effective sigma
model, while the other is just an Abelian vortex without internal degrees of
freedom. For generic values of the parameters, one of the two solutions is
metastable, while there are evidences that the other one is truly stable.Comment: 35 pages, 8 figures. v2: fixed typos and added small comments, v3
removed an unecessary figur
- âŠ