494 research outputs found
The HERA challenges for LHC
Over the last two decades, the HERA collider has provided a large amount of
new information about QCD dynamics at high energy. While the most appreciated
are the measurements of the proton structure functions in a wide range of
parton momentum x and virtuality Q^2, it is hard to believe that some of the
observations at HERA which do not fit the simple picture of DGLAP dynamics
would not get amplified at the LHC, possibly rendering certain approaches to
searches beyond the Standard Model inadequate.Comment: 19 pages, 15 figures, Talk presented at the 2009 Epiphany meeting,
Cracow, Jan 5-7, 2009, dedicated to the memory of Jan Kwiecinsk
The Pomeron structure and diffractive parton distributions
Measurements of the diffractive structure function, , of the proton at
HERA are used to extract the partonic structure of the Pomeron. Regge
Factorization is tested and is found to describe well the existing data within
the selected kinematic range. The analysis is based on the next to leading
order QCD evolution equations. The results obtained from various data sets are
compared. An analysis of the uncertainties in determining the parton
distributions is provided. The probability of diffraction is calculated using
the obtained results.Comment: Talk presented at DIS05, Madison, Wisconsi
Neural Network based Electron Identification in the ZEUS Calorimeter
We present an electron identification algorithm based on a neural network
approach applied to the ZEUS uranium calorimeter. The study is motivated by the
need to select deep inelastic, neutral current, electron proton interactions
characterized by the presence of a scattered electron in the final state. The
performance of the algorithm is compared to an electron identification method
based on a classical probabilistic approach. By means of a principle component
analysis the improvement in the performance is traced back to the number of
variables used in the neural network approach.Comment: 20 pages, latex, 16 figures appended as uuencoded fil
An Orientation Selective Neural Network and its Application to Cosmic Muon Identification
We propose a novel method for identification of a linear pattern of pixels on
a two-dimensional grid. Following principles employed by the visual cortex, we
employ orientation selective neurons in a neural network which performs this
task. The method is then applied to a sample of data collected with the ZEUS
detector at HERA in order to identify cosmic muons which leave a linear pattern
of signals in the segmented uranium-scintillator calorimeter. A two dimensional
representation of the relevant part of the detector is used. The results
compared with a visual scan point to a very satisfactory cosmic muon
identification. The algorithm performs well in the presence of noise and pixels
with limited efficiency. Given its architecture, this system becomes a good
candidate for fast pattern recognition in parallel processing devices.Comment: 19 pages, 10 Postrcipt figure
Diffraction and the Pomeron
Recent experimental results on inclusive diffractive scattering and on
exclusive vector meson production are reviewed. The dynamical picture of hard
diffraction emerging in perturbative QCD is highlighted.Comment: 25 pages, 21 postscript figures, contribution to the XIX
International Symposium on Lepton and Photon Interactions at High Energies,
Stanford University, August 9-14, 199
Production of Z0 bosons in elastic and quasi-elastic ep collisions at HERA
Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMThe production of Z0 bosons in the reaction ep →eZ0 p(∗), where p(∗) stands for a proton or a lowmass nucleon resonance, has been studied in ep collisions at HERA using the ZEUS detector. The analysis is based on a data sample collected between 1996 and 2007, amounting to 496 pb−1 of integrated luminosity. The Z0 was measured in the hadronic decay mode. The elasticity of the events was ensured by a cut on ηmax < 3.0, where ηmax is the maximum pseudorapidity of energy deposits in the calorimeter defined with respect to the proton beam direction. A signal was observed at the Z0 mass. The cross section of the reaction ep → eZ0 p(∗) was measured to be σ(ep → eZ0 p(∗)) =0.13 ± 0.06(stat.) ± 0.01(syst.) pb, in agreement with the Standard Model prediction of 0.16 pb. This is the first measurement of Z0 production in ep collisionsWe appreciate the contributions to the construction and maintenance of the ZEUS detector of many people who are not listed as authors. The HERA machine group and the DESY computing staff are especially acknowledged for their success in providing excellent operation of the collider and the data-analysis environment. We thank the DESY directorate for their strong support and encouragemen
International Large Detector: Interim Design Report
The ILD detector is proposed for an electron-positron collider with collision centre-of-mass energies from 90~\GeV~to about 1~\TeV. It has been developed over the last 10 years by an international team of scientists with the goal to design and eventually propose a fully integrated detector, primarily for the International Linear Collider, ILC. In this report the fundamental ideas and concepts behind the ILD detector are discussed and the technologies needed for the realisation of the detector are reviewed. The document starts with a short review of the science goals of the ILC, and how the goals can be achieved today with the detector technologies at hand. After a discussion of the ILC and the environment in which the experiment will take place, the detector is described in more detail, including the status of the development of the technologies foreseen for each subdetector. The integration of the different sub-systems into an integrated detector is discussed, as is the interface between the detector and the collider. This is followed by a concise summary of the benchmarking which has been performed in order to find an optimal balance between performance and cost. To the end the costing methodology used by ILD is presented, and an updated cost estimate for the detector is presented. The report closes with a summary of the current status and of planned future actions.Available at arXiv.org: [https://arxiv.org/abs/2003.01116
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