109957260
The ATLAS computing model & distributed computing evolution
Despite only a brief availability of beam-related data, the typical usage patterns and operational requirements of the ATLAS computing model have been exercised, and the model as originally constructed remains remarkably unchanged. Resource requirements have been revised, and cosmic ray running has exercised much of the model in both duration and volume. The operational model has been adapted in several ways to increase performance and meet the asdelivered functionality of 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; the key tools developed in the operational system are outlined, with an emphasis on those under recent development.
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.
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.
126069786
Physics and detector performance measurements with the decays B0(s) ---> J/Psi Phi and B0(d) ---> J/Psi K0* with early data
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.
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.
20354147
Possible Phase Loop for the Global Decoupling
The two eigentunes Q<inf>I</inf>and Q<inf>II</inf>, two eigenmode amplitude ratios R<inf>I</inf>and R<inf>II</inf>, and two eignmode phase differences Δφ<inf>I</inf>and Δφ<inf>II</inf>, are defined as the coupling observables for the linear weak difference betatron coupling. Simulations were carried out to investigate their behaviors in global decoupling scans. It was found that the amplitude ratios R<inf>I</inf>,<inf>II</inf>are more sensitive than the tune split when the decoupling scan is approaching the global uncoupled point, and that the phase differences Δφ<inf>I</inf>,<inf>II</inf>tell the right global decoupling direction, the right strength combination of the skew quadrupoles or families. The analytical solution to these six coupling observables is calculated through both the strict matrix approach and the perturbation Hamiltonian approach. The constant phase differences in the right decoupling direction hint a possible global decoupling phase loop. Dedicated beam experiments were carried out at the Relativistic Heavy Ion Collider (RHIC). The preliminary results from the beam experiments are presented. These six parameters can be used for the global decoupling in feedback mode, especially on the non-stop energy ramp.
17515691
The classical action for a Bianchi VI_h model
An estimate for the classical action for a Bianchi VI_h homogeneous spatially closed cosmology is presented as a function of b, a parameter of the model that is proportional to the relative rotation of the average inertial frame and the bulk of matter in the universe. It is assumed (through the equation of state) that a relativistic early universe is followed by a matter-dominated late universe. The action is used in a saddlepoint approximation to a semiclassical estimate for the wave function in quantum cosmology to explain why our inertial frame seems not to rotate relative to the stars. The saddlepoint is at b=0, as would be expected. Application of the saddlepoint approximation leads to the result that only those classical geometries whose action differs from the saddlepoint value for the action by an amount less than Planck's constant contribute significantly to the integration to give the present value of the wave function. Using estimates for our universe implies that only those classical geometries for which the present relative rotation rate of inertial frames and matter are less than about 10^(-130) radians per year contribute significantly to the integration. This is well below the limit set by experiment. The result depends on the ratio of the Hubble distance to the Planck length, but does not depend on the details of the theory of quantum gravity.