60501245
The Evolution of the ATLAS Computing Model
Despite the all too brief availability of beam-related data, much has been learned about the usage patterns and operational requirements of the ATLAS computing model since Autumn 2007. Bottom-up estimates are now more detailed, and cosmic ray running has exercised much of the model in both duration and volume. Significant revisions have been made in the resource estimates, and in the usage of those resources. In some cases, this represents an optimization while in others it attempts to counter lack of functionality in the available middleware. There are also changes reflecting the emerging roles of the different data formats. The model continues to evolve with a heightened focus on end-user performance, and the state of the art after a major review process over winter 08/09 is presented.
65296691
ATLAS computing: Technical design report.
9457823
Ganga user interface for job definition and management
Ganga is a frontend for job definition and management in a distributed environment. It is being developed in the context of two high-energy physics experiments, ATLAS and LHCb, but is a component-based system that can readily be extended to meet the needs of other user communities. Ganga allows the user to specify the software to run, which may include user code, to set values for any configurable parameters, to select data for processing, and to submit jobs to a variety of local batch queues and Grid-based systems, hiding Grid technicalities. After jobs are submitted, ganga monitors their status, and takes care of saving any output. Ganga offers a Command-Line Interface in Python (CLIP), possibilities for scripting, and a Graphical User Interface (GUI), which significantly simplifies basic tasks. This paper describes the job model and architecture of ganga, and illustrates ganga’s main features as a user interface.
121691932
W mass measurements at LEP and the Tevatron
The prospects for precise tests of the standard model by measuring the mass of the W boson at LEP II and the Tevatron are considered. The limiting systematic effects are discussed.
120991534
B-physics in the p-p collisions at the LHC
The LHC provides an excellent opportunity for B-physics studies, providing both high statistics and a wide range of kinematic conditions. This paper summarises the prospects for the ATLAS, CMS and LHCb experiments, with an emphasis on the QCD aspects. The rather different programme of the heavy-ions experiment ALICE is not addressed. The experiments will probe both the production and decay of B-hadrons. The various trigger strategies are presented, after which the production measurements are considersed and are shown to provide stringent test of QCD, as well as providing vital information of the backgrounds to searches. After this, the studies of B-decays are presented. The measurements of CP-violation are shown to have a good potential for discovering signatures of new physics. B s mixing will also open a window on new physics, and Δ| Gamma s will be measurable. Finally, the prospects for rare deacys are considered, especially for the decays to muons.
122721907
Into the mix
The challenge to measure the quantum-mechanical mixing between particle and antiparticle states for a particular type of meson is at last being met — but as yet, alas, reveals no exotic physics.
17352400
The criteria for a solution of the field equations to be a classical limit of a quantum cosmology
If the gravitational field is quantized, then a solution of Einstein's field equations is a valid cosmological model only if it corresponds to a classical limit of a quantum cosmology. To determine which solutions are valid requires looking at quantum cosmology in a particular way. Because we infer the geometry by measurements on matter, we can represent the amplitude for any measurement in terms of the amplitude for the matter fields, allowing us to integrate out the gravitational degrees of freedom. Combining that result with a path-integral representation for quantum cosmology leads to an integration over 4-geometries. Even when a semiclassical approximation for the propagator is valid, the amplitude for any measurement includes an integral over the gravitational degrees of freedom. The conditions for a solution of the field equations to be a classical limit of a quantum cosmology are: (1) The effect of the classical action dominates the integration, (2) the action is stationary with respect to variation of the gravitational degrees of freedom, and (3) only one saddlepoint contributes significantly to each integration.
14899076
On star formation in primordial protoglobular clouds.
Using a new physical model for star formation (Padoan 1995) we have tested the possibility that globular clusters (GCs) are formed from primordial mass fluctuations, whose mass scale (10 8 - 10 9 M⊙) is selected out of a CDM spectrum by the mechanism of non-equilibrium formation of H2.