52 research outputs found
Shadows and Twisted Variables
We explain how a new type of fields called shadows and the use of twisted
variables allow for a better description of Yang-Mills supersymmetric theories.
(Based on lectures given in Cargese, June 2006.)Comment: Cargese Jun 200
Twisted Superspace
We formulate the ten-dimensional super-Yang-Mills theory in a twisted
superspace with 8+1 supercharges. Its constraints do not imply the equations of
motion and we solve them. As a preliminary step for a complete formulation in a
twisted superspace, we give a superspace path-integral formulation of the N=2,
d=4 super-Yang-Mills theory without matter. The action is the sum of a
Chern--Simons term depending on a super-connection plus a BF-like term. The
integration over the superfield B implements the twisted superspace constraints
on the super-gauge field, and the Chern-Simons action reduces to the known
action in components
Shadow Fields and Local Supersymmetric Gauges
To control supersymmetry and gauge invariance in super-Yang-Mills theories we
introduce new fields, called shadow fields, which enable us to enlarge the
conventional Faddeev-Popov framework and write down a set of useful
Slavnov-Taylor identities. These identities allow us to address and answer the
issue of the supersymmetric Yang-Mills anomalies, and to perform the
conventional renormalization programme in a fully regularization-independent
way.Comment: 2
Supersymmetric renormalization prescription in N = 4 super-Yang--Mills theory
Using the shadow dependent decoupled Slavnov-Taylor identities associated to
gauge invariance and supersymmetry, we discuss the renormalization of the N=4
super-Yang-Mills theory and of its coupling to gauge-invariant operators. We
specify the method for the determination of non-supersymmetric counterterms
that are needed to maintain supersymmetry
Topological Vector Symmetry of BRSTQFT and Construction of Maximal Supersymmetry
The scalar and vector topological Yang-Mills symmetries determine a closed
and consistent sector of Yang-Mills supersymmetry. We provide a geometrical
construction of these symmetries, based on a horizontality condition on
reducible manifolds. This yields globally well-defined scalar and vector
topological BRST operators. These operators generate a subalgebra of maximally
supersymmetric Yang-Mills theory, which is small enough to be closed off-shell
with a finite set of auxiliary fields and large enough to determine the
Yang-Mills supersymmetric theory. Poincar\'e supersymmetry is reached in the
limit of flat manifolds. The arbitrariness of the gauge functions in BRSTQFTs
is thus removed by the requirement of scalar and vector topological symmetry,
which also determines the complete supersymmetry transformations in a twisted
way. Provided additional Killing vectors exist on the manifold, an equivariant
extension of our geometrical framework is provided, and the resulting
"equivariant topological field theory" corresponds to the twist of super
Yang-Mills theory on Omega backgrounds.Comment: 50 page
Molecular Imaging of Microglial Activation in Amyotrophic Lateral Sclerosis
There is growing evidence of activated microglia and inflammatory processes in the cerebral cortex in amyotrophic lateral sclerosis (ALS). Activated microglia is characterized by increased expression of the 18 kDa translocator protein (TSPO) in the brain and may be a useful biomarker of inflammation. In this study, we evaluated neuroinflammation in ALS patients using a radioligand of TSPO, 18F-DPA-714. Ten patients with probable or definite ALS (all right-handed, without dementia, and untreated by riluzole or other medication that might bias the binding on the TSPO), were enrolled prospectively and eight healthy controls matched for age underwent a PET study. Comparison of the distribution volume ratios between both groups were performed using a Mann-Whitney’s test. Significant increase of distribution of volume ratios values corresponding to microglial activation was found in the ALS sample in primary motor, supplementary motor and temporal cortex (p = 0.009, p = 0.001 and p = 0.004, respectively). These results suggested that the cortical uptake of 18F-DPA-714 was increased in ALS patients during the ‘‘time of diagnosis’’ phase of the disease. This finding might improve our understanding of the pathophysiology of ALS and might be a surrogate marker of efficacy of treatment on microglial activation
Procedure for the fine delay adjustment of the CMS tracker
One of the crucial aspects of the commissioning of the CMS silicon tracker will be the absolute timing adjustment of each module, to accommodate both delays introduced by the hardware configuration and effects due to the time of flight of particles. The objective is to be optimally synchronized with the bunch-crossing to maximize the efficiency while minimizing the number of remnant hits from the adjacent bunch-crossings. In the present note, a procedure to reach that goal is studied. Monte Carlo studies as well as the analysis of data from the commissioning of the detector are used to assess the time needed and the resolution that can be achieved. Critical aspects are discussed, and results from the first implementation are presented
Charged Particle Tracking in Real-Time Using a Full-Mesh Data Delivery Architecture and Associative Memory Techniques
We present a flexible and scalable approach to address the challenges of
charged particle track reconstruction in real-time event filters (Level-1
triggers) in collider physics experiments. The method described here is based
on a full-mesh architecture for data distribution and relies on the Associative
Memory approach to implement a pattern recognition algorithm that quickly
identifies and organizes hits associated to trajectories of particles
originating from particle collisions. We describe a successful implementation
of a demonstration system composed of several innovative hardware and
algorithmic elements. The implementation of a full-size system relies on the
assumption that an Associative Memory device with the sufficient pattern
density becomes available in the future, either through a dedicated ASIC or a
modern FPGA. We demonstrate excellent performance in terms of track
reconstruction efficiency, purity, momentum resolution, and processing time
measured with data from a simulated LHC-like tracking detector
Reception Test of Petals for the End Cap TEC+ of the CMS Silicon Strip Tracker
The silicon strip tracker of the CMS experiment has been completed and was inserted into the CMS detector in late 2007. The largest sub system of the tracker are its end caps, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted onto the TEC support structures. Each end cap consists of 144 such petals, which were built and fully qualified by several institutes across Europe. Fro
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