671 research outputs found
Higgs Production via Gluon-Induced Weak Boson Fusion
We present a calculation that allows for an estimation of the NNLO
contributions to the Higgs production in the weak boson fusion channel. A
possible deterioration of this important channel for the Higgs discoveries at
the LHC can be ruled out by this calculation due to the small remaining cross
section after the weak boson cuts.Comment: 4 pages, 3 figures. To appear in the proceedings of the 14th
International QCD Conference (QCD 08), Montpellier, France, 7-12 July 200
The Underlying Event and the Total Cross Section from Tevatron to the LHC
Multiple partonic interactions are widely used to simulate the hadronic final
state in high energy hadronic collisions, and successfully describe many
features of the data. It is important to make maximum use of the available
physical constraints on such models, particularly given the large extrapolation
from current high energy data to LHC energies. In eikonal models, the rate of
multiparton interactions is coupled to the energy dependence of the total cross
section. Using a Monte Carlo implementation of such a model, we study the
connection between the total cross section, the jet cross section, and the
underlying event. By imposing internal consistency on the model, we derive
constraints on its parameters at the LHC. By imposing internal consistency on
the model and comparing to current data we constrain the allowed range of its
parameters. We show that measurements of the total proton-proton cross-section
at the LHC are likely to break this internal consistency, and thus to require
an extension of the model. Likely such extensions are that hard scatters probe
a denser matter distribution inside the proton in impact parameter space than
soft scatters, a conclusion also supported by Tevatron data on double-parton
scattering, and/or that the basic parameters of the model are energy dependent.Comment: 17 pages, 6 figures, version accepted by JHE
The H1 Forward Proton Spectrometer at HERA
The forward proton spectrometer is part of the H1 detector at the HERA
collider. Protons with energies above 500 GeV and polar angles below 1 mrad can
be detected by this spectrometer. The main detector components are
scintillating fiber detectors read out by position-sensitive photo-multipliers.
These detectors are housed in so-called Roman Pots which allow them to be moved
close to the circulating proton beam. Four Roman Pot stations are located at
distances between 60 m and 90 m from the interaction point.Comment: 20 pages, 10 figures, submitted to Nucl.Instr.and Method
Design criteria for multi-layered scintillating fibre arrays with inclined columns
Multi-layered scintillating fibre arrays read-out are commonly used as high
resolution charged particle hodoscopes. Fibres of a column along the
geometrical trajectory of incident particles are typically grouped to one pixel
of a multi-channel read-out device. In some applications the incident particles
will cross the detection plane with large angles w.r.t. the normal to the
layers. Then, the packing of the fibres needs to be adapted to the incident
particles and the columns need to be inclined. In this paper possible fibre
array geometries are shown, relevant design criteria for detectors are
discussed, and the effect of diverging particles incident on fibre arrays was
studied using a Monte Carlo simulation.Comment: submitted to Nucl. Instrum. Meth.
Prototype design of a timing and fast control system in the CBM experiment
The Compressed Baryonic Matter (CBM) experiment is designed to handle interaction rates of up to 10 MHz and up to 1 TB/s of raw data generated. With triggerless streaming data acquisition in the experiment and beam intensity fluctuations, it is expected that occasional data bursts will surpass bandwidth capabilities of the Data Acquisition System (DAQ) system. In order to preserve integrity of event data, the bandwidth of DAQ must be throttled in an organised way with minimum information loss. The Timing and Fast Control (TFC) system provides a latency-optimised datapath for throttling commands and distributes a system clock together with a global timestamp. This paper describes a prototype design of the system with focus on synchronisation and its evaluation
T1 Mapping Quantifies Spinal Cord Compression in Patients With Various Degrees of Cervical Spinal Canal Stenosis
Age-related degeneration of the cervical spinal column is the most common cause of spinal cord lesions. T1 mapping has been shown to indicate the grade and site of spinal cord compression in low grade spinal canal stenosis (SCS). Aim of our study was to further investigate the diagnostic potential of a novel T1 mapping method at 0.75 mm resolution and 4 s acquisition time in 31 patients with various grades of degenerative cervical SCS. T1 mapping was performed in axial sections of the stenosis as well as above and below. Included subjects received standard T2-weighted MRI of the cervical spine (including SCS-grading 0-III), electrophysiological, and clinical examination. We found that patients with cervical SCS showed a significant difference in T1 relaxation times within the stenosis (727 ± 66 ms, mean ± standard deviation) in comparison to non-stenotic segments above (854 ± 104 ms, p < 0.001) and below (893 ± 137 ms, p < 0.001). There was no difference in mean T1 in non-stenotic segments in patients (p = 0.232) or between segments in controls (p = 0.272). Mean difference of the T1 relaxation times was significantly higher in grade III stenosis (234 ± 45) vs. in grade II stenosis (176 ± 45, p = 0.037) vs. in grade I stenosis (90 ± 87 ms, p = 0.010). A higher difference in T1 relaxation time was associated with a central efferent conduction deficit. In conclusion, T1 mapping may be useful as a tool for SCS quantification in all grades of SCS, including high-grade stenosis with myelopathy signal in conventional T2-weighted imaging
Prototype design of a timing and fast control system in the CBM experiment
The Compressed Baryonic Matter (CBM) experiment is designed to handle interaction rates of up to 10 MHz and up to 1 TB/s of raw data generated. With triggerless streaming data acquisition in the experiment and beam intensity fluctuations, it is expected that occasional data bursts will surpass bandwidth capabilities of the Data Acquisition System (DAQ) system. In order to preserve integrity of event data, the bandwidth of DAQ must be throttled in an organised way with minimum information loss. The Timing and Fast Control (TFC) system provides a latency-optimised datapath for throttling commands and distributes a system clock together with a global timestamp. This paper describes a prototype design of the system with focus on synchronisation and its evaluation
Colour reconnections in Herwig++
We describe the implementation details of the colour reconnection model in
the event generator Herwig++. We study the impact on final-state observables in
detail and confirm the model idea from colour preconfinement on the basis of
studies within the cluster hadronization model. Moreover, we show that the
description of minimum bias and underlying event data at the LHC is improved
with this model and present results of a tune to available data.Comment: 19 pages, 21 figures, 2 tables. Matches with published versio
A 3D track finder for the Belle II CDC L1 trigger
Machine learning methods are integrated into the pipelined first level (L1) track trigger of the upgraded flavor physics experiment Belle II at KEK in Tsukuba, Japan. The novel triggering techniques cope with the severe background from events outside the small collision region provided by the new SuperKEKB asymmetric-energy electron-positron collider. Using the precise drift-time information of the central drift chamber which provides axial and stereo wire layers, a neural network L1 trigger estimates the 3D track parameters of tracks, based on input from the axial wire planes provided by a 2D track finder. An extension of this 2D Hough track finder to a 3D finder is proposed, where the single hit representations in the Hough plane are trained using Monte Carlo. This 3D finder improves the track finding efficiency by including the stereo sense wires as input. The estimated polar track angle allows a specialization of the subsequent neural networks to sectors in the polar angle
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