134 research outputs found
Flavour Tagging at CLIC
We present the performance of the LCFI flavour tagging package in a realistic
CLIC environment. The application is demonstrated on the examples of the
measurement of the cross section times branching ratio of light Higgs decays to
b and c quarks at 3 TeV, a study of heavy Higgs decays at 3 TeV and of top pair
production at 500 GeV. All studies are based on full detector simulation with a
realistic account of the machine- induced background at CLIC.Comment: LCWS 2011 proceeding
Light Higgs Studies for the CLIC CDR
The Higgs boson is the most anticipated discovery at the LHC, which can only
partially explore its true nature. Thus one of the most compelling arguments to
build a future linear collider is to investigate properties of the Higgs boson,
especially to test the predicted linear dependence of the branching ratios on
the mass of the final state. At a 3TeV CLIC machine the Higgs boson production
cross section is relatively large and allows for a precision measurement of the
Higgs branching ratio to pairs of b and c quarks, and even to muons. The cross
section times branching ratio of the decays ,
and can be measured with
a statistical uncertainty of approximately 0.22%, 3.2% and 15%, respectively
Performance of Julia for High Energy Physics Analyses
We argue that the Julia programming language is a compelling alternative to
implementations in Python and C++ for common data analysis workflows in high
energy physics. We compare the speed of implementations of different workflows
in Julia with those in Python and C++. Our studies show that the Julia
implementations are competitive for tasks that are dominated by computational
load rather than data access. For work that is dominated by data access, we
demonstrate an application with concurrent file reading and parallel data
processing.Comment: 16 pages, 4 pages, 1 table, 3 code listing
Measurement of the Cross Section Times Branching Ratio of Light Higgs Decays at CLIC
The investigation of the properties of a Higgs boson, especially a test of
the predicted linear dependence of the branching ratios on the mass of the
final state, is currently one of the most compelling arguments for building a
linear collider. We demonstrate that the large Higgs boson production cross
section at a 3 TeV CLIC machine allows for a precision measurement of the Higgs
branching ratios. The cross section times branching ratio of the decays H
\rightarrow b^{-}b, H \rightarrow cc^{-} and H \rightarrow {\mu}{\mu} can be
measured with a statistical uncertainty of 0.22%, 3.2% and 15%, respectively.Comment: LCWS 2011 Proceeding
A Study of the Impact of High Cross Section ILC Processes on the SiD Detector Design
The SiD concept is one of two proposed detectors to be mounted at the
interaction region of the International Linear Collider (ILC). A substantial
ILC background arises from low transverse momentum
pairs created by the interaction of the
colliding beams' electromagnetic fields. In order to provide hermeticity and
sensitivity to beam targeting parameters, a forward Beamline Calorimeter
(BeamCal) is being designed that will provide coverage down to 5 mrad from the
outgoing beam trajectory, and intercept the majority of this pair background.
Using the SiD simulation framework, the effect of this pair background on the
SiD detector components, especially the vertex detector (VXD) and forward
electromagnetic calorimeter (FCAL), is explored. In the case of the FCAL,
backgrounds from Bhabha and two-photon processes are also considered. The
consequence of several variants of the BeamCal geometry and ILC interaction
region configuration are considered for both the vertex detector and BeamCal
performance
Comparative study of a continuous train of theta-burst stimulation for a duration of 20 s (cTBS 300) versus a duration of 40 s (cTBS 600) in a pre-stimulation relaxed condition in healthy volunteers
As variable after effects have been observed following phasic muscle contraction prior to continuous theta-burst stimulation (cTBS), we here investigated two cTBS protocols (cTBS300 and cTBS600) in 20 healthy participants employing a pre-relaxed muscle condition including visual feedback on idle peripheral surface EMG activity. Furthermore, we assessed corticospinal excitability measures also from a pre-relaxed state to better understand the potential impact of these proposed contributors to TBS. Motor-evoked potential (MEP) magnitude changes were assessed for 30 min. The linear model computed across both experimental paradigms (cTBS300 and cTBS600) revealed a main effect of TIME COURSE (p = 0.044). Separate exploratory analysis for cTBS300 revealed a main effect of TIME COURSE (p = 0.031), which did not maintain significance after GreenhouseâGeisser correction (p = 0.073). For cTBS600, no main effects were observed. An exploratory analysis revealed a correlation between relative SICF at 2.0 ms (p = 0.006) and after effects (relative mean change) of cTBS600, which did not survive correction for multiple testing. Our findings thereby do not support the hypothesis of a specific excitability modulating effect of cTBS applied to the human motor-cortex in setups with pre-relaxed muscle conditions
Comparative study of motor cortical excitability changes following anodal tDCS or highâfrequency tRNS in relation to stimulation duration
Background
In this study, we investigate the capacity of two different nonâinvasive brain stimulation (NIBS) techniques (anodal transcranial direct current stimulation (anodal tDCS) and highâfrequency transcranial random noise stimulation (hfâtRNS)) regarding the relationship between stimulation duration and their efficacy in inducing longâlasting changes in motor cortical excitability.
Methods
Fifteen healthy subjects attended six experimental sessions (90 experiments in total) and underwent both anodal tDCS of 7, 13, and 20 min duration, as well as highâfrequency 1mAâtRNS of 7, 13, and 20 min stimulation duration. Sessions were performed in a randomized order and subjects were blinded to the applied methods.
Results
For anodal tDCS, no significant stable increases of motor cortical excitability were observed for either stimulation duration. In contrast, for hf âtRNS a stimulation duration of 7 min resulted in a significant increase of motor cortical excitability lasting from 20 to 60 min poststimulation. While an intermediate duration of 13 min hfâtRNS failed to induce lasting changes in motor cortical excitability, a longer stimulation duration of 20 min hfâtRNS led only to significant increases at 50 min poststimulation which did not outlast until 60 min poststimulation.
Conclusion
HfâtRNS for a duration of 7 min induced robust increases of motor cortical excitability, suggesting an indirect proportional relationship between stimulation duration and efficacy. While hfâtRNS appeared superior to anodal tDCS in this study, further systematic and randomized experiments are necessary to evaluate the generalizability of our observations and to address current intensity as a further modifiable contributor to the variability of transcranial brain stimulation
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