39 research outputs found
Supersymmetric Non-Abelian Born-Infeld Theory
Using the natural curvature invariants as building blocks in a superfield
construction, we show that the use of a symmetric trace is mandatory if one is
to reproduce the square root structure of the non-Abelian Dirac-Born-Infeld
Lagrangian in the bosonic sector. We also discuss the BPS relations in
connection with our supersymmetry construction.Comment: 13 pages, Latex, no figure
Bogomol'nyi Bounds and the Supersymmetric Born-Infeld Theory
We study N=2 supersymmetric Born-Infeld-Higgs theory in 3 dimensions and derive Bogomol'nyi relations in its bosonic sector. A peculiar coupling between the Higgs and the gauge field (with dynamics determined by the Born-Infeld action) is forced by supersymmetry. The resulting equations coincide with those arising in the Maxwell-Higgs model. Concerning Bogomol'nyi bounds for the vortex energy, they are derived from the N=2 supersymmetry algebra.Facultad de Ciencias Exacta
Bogomol'nyi Bounds and the Supersymmetric Born-Infeld Theory
We study N=2 supersymmetric Born-Infeld-Higgs theory in 3 dimensions and
derive Bogomol'nyi relations in its bosonic sector. A peculiar coupling between
the Higgs and the gauge field (with dynamics determined by the Born-Infeld
action) is forced by supersymmetry. The resulting equations coincide with those
arising in the Maxwell-Higgs model. Concerning Bogomol'nyi bounds for the
vortex energy, they are derived from the N=2 supersymmetry algebra.Comment: 24 pages, Latex fil
Stabilization of the Yang-Mills chaos in non-Abelian Born-Infeld theory
We investigate dynamics of the homogeneous time-dependent SU(2) Yang-Mills
fields governed by the non-Abelian Born-Infeld lagrangian which arises in
superstring theory as a result of summation of all orders in the string slope
parameter . It is shown that generically the Born-Infeld dynamics is
less chaotic than that in the ordinary Yang-Mills theory, and at high enough
field strength the Yang-Mills chaos is stabilized. More generally, a smothering
effect of the string non-locality on behavior of classical fields is
conjectured.Comment: 7 pages, 5 figure
Dynamics of BPS States in the Dirac-Born-Infeld Theory
The Dirac-Born-Infeld action with transverse scalar fields is considered to
study the dynamics of various BPS states. We first describe the characteristic
properties of the so-called 1/2 and 1/4 BPS states on the D3 brane, which can
be interpreted as F/D-strings ending on a D3-brane in Type IIB string theory
picture. We then study the response of the BPS states to low energy excitations
of massless fields on the brane, the scalar fields representing the shape
fluctuation of the brane and U(1) gauge fields describing the open string
excitations on the D-brane. This leads to an identification of interactions
between BPS states including the static potentials and the kinetic
interactions.Comment: 19 pages, 4 figures References added, Typographical errors are
correcte
Non-Linear/Non-Commutative Non-Abelian Monopoles
Using recently proposed non-linearly realized supersymmetry in non-Abelian
gauge theory corrected to the order (alpha')^2, we derive the non-linear BPS
equations in the background B-field for the U(2) monopoles and instantons. We
show that these non-Abelian non-linear BPS equations coincide with the
non-commutative anti-self-dual equations via the Seiberg-Witten map.Comment: 9 pages, LaTe
Primordial fluctuations from nonlinear couplings
We study the spectrum of primordial fluctuations in theories where the
inflaton field is coupled to massless fields and/or to itself. Conformally
invariant theories generically predict a scale invariant spectrum. Scales
entering the theory through infrared divergences cause logarithmic corrections
to the spectrum, tiltilng it towards the blue. We discuss in some detail
whether these fluctuations are quantum or classical in nature.Comment: 12 pages, Revtex, we added an appendix clarifying our assumptions
about the initial conditions at the beggining of inflatio
Dyonic BIon black hole in string inspired model
We construct static and spherically symmetric particle-like and black hole
solutions with magnetic and/or electric charge in the
Einstein-Born-Infeld-dilaton-axion system, which is a generalization of the
Einstein-Maxwell-dilaton-axion (EMDA) system and of the Einstein-Born-Infeld
(EBI) system. They have remarkable properties which are not seen for the
corresponding solutions in the EMDA and the EBI system.Comment: 13 pages, 15 figures, Final version in PR
Dihydropyridine receptor (DHPR, CACNA1S) congenital myopathy
Muscle contraction upon nerve stimulation relies on excitationâcontraction coupling (ECC) to promote the rapid and generalized release of calcium within myofibers. In skeletal muscle, ECC is performed by the direct coupling of a voltage-gated L-type Ca2+ channel (dihydropyridine receptor; DHPR) located on the T-tubule with a Ca2+ release channel (ryanodine receptor; RYR1) on the sarcoplasmic reticulum (SR) component of the triad. Here, we characterize a novel class of congenital myopathy at the morphological, molecular, and functional levels. We describe a cohort of 11 patients from 7 families presenting with perinatal hypotonia, severe axial and generalized weakness. Ophthalmoplegia is present in four patients. The analysis of muscle biopsies demonstrated a characteristic intermyofibrillar network due to SR dilatation, internal nuclei, and areas of myofibrillar disorganization in some samples. Exome sequencing revealed ten recessive or dominant mutations in CACNA1S (Cav1.1), the pore-forming subunit of DHPR in skeletal muscle. Both recessive and dominant mutations correlated with a consistent phenotype, a decrease in protein level, and with a major impairment of Ca2+ release induced by depolarization in cultured myotubes. While dominant CACNA1S mutations were previously linked to malignant hyperthermia susceptibility or hypokalemic periodic paralysis, our findings strengthen the importance of DHPR for perinatal muscle function in human. These data also highlight CACNA1S and ECC as therapeutic targets for the development of treatments that may be facilitated by the previous knowledge accumulated on DHPR
Improving genetic diagnosis in Mendelian disease with transcriptome sequencing
Exome and whole-genome sequencing are becoming increasingly routine approaches in Mendelian disease diagnosis. Despite their success, the current diagnostic rate for genomic analyses across a variety of rare diseases is approximately 25 to 50%. We explore the utility of transcriptome sequencing [RNA sequencing (RNA-seq)] as a complementary diagnostic tool in a cohort of 50 patients with genetically undiagnosed rare muscle disorders. We describe an integrated approach to analyze patient muscle RNA-seq, leveraging an analysis framework focused on the detection of transcript-level changes that are unique to the patient compared to more than 180 control skeletal muscle samples. We demonstrate the power of RNA-seq to validate candidate splice-disrupting mutations and to identify splice-altering variants in both exonic and deep intronic regions, yielding an overall diagnosis rate of 35%. We also report the discovery of a highly recurrent de novo intronic mutation in COL6A1 that results in a dominantly acting splice-gain event, disrupting the critical glycine repeat motif of the triple helical domain. We identify this pathogenic variant in a total of 27 genetically unsolved patients in an external collagen VIâlike dystrophy cohort, thus explaining approximately 25% of patients clinically suggestive of having collagen VI dystrophy in whom prior genetic analysis is negative. Overall, this study represents a large systematic application of transcriptome sequencing to rare disease diagnosis and highlights its utility for the detection and interpretation of variants missed by current standard diagnostic approaches