121239422
Accurate intensity measurements for proton beams with a 201 MHz structure
A counting system which measures the absolute beam intensity accurately (< 1%) at intermediate energies with a beam microstructure of 201.25 MHz or lower is described in this paper. The number of beam micropulses containing one or more beam particles are counted and time-sequenced coincidences between micropulses correct this number to obtain the actual number of beam particles using formulas based on Poisson statistics. The counting system, both the experimental setup and the correction method, was examined fully with two different beam microstructures. 10 MHz and 201.25 MHz, the two main beam microstructures at LAMPF. Maximum beam intensities, below which the system is accurate within a few tenths of a percent, were determined to be ∼ 0/4 pA and ∼ 0.1 pA average beam currents for the 5 ns and 100 ns beam microstructures, respectively.
10735130
DIAL: Distributed Interactive Analysis of Large Datasets
DIAL will enable users to analyze very large, event-based datasets using an application that is natural to the data format. Both the dataset and the processing may be distributed over a farm, a site (collection of farms) or a grid (collection of sites). Here we describe the goals of the project, the current design and implementation, and plans for future development. DIAL is being developed within PPDG to understand the requirements that interactive analysis places on the grid and within ATLAS to enable distributed interactive analysis of event data.
13375438
ATLAS Distributed Analysis
The distributed analysis system for the ATLAS experiment is described. Although the system is under construction and the design is still evolving, the major components have been identified. A generic analysis service interface provides the connection between a choice of user environments and a selection of engines capable of carrying out the distributed processing. Other services provide access to catalogs, files and software.
14339689
Fermionic topological charge of families of lattice gauge fields
Abstract Topological charge of families of lattice gauge fields is defined fermionically via families index theory for the overlap Dirac operator. Certain obstructions to gauge invariance of the overlap chiral fermion determinant, as well as the lattice analogues of certain obstructions to gauge fixings without the Gribov problem have natural descriptions in this context.
14724506
Perturbative expansion in gauge theories on compact manifolds
A geometric formal method for perturbatively expanding functional integrals arising in quantum gauge theories is described when the spacetime is a compact riemannian manifold without boundary. This involves a refined version of the Faddeev-Popov procedure using the covariant background field gauge-fixing condition with background gauge field chosen to be a general critical point for the action functional (i.e. a classical solution). The refinement takes into account the gauge-fixing ambiguities coming from gauge transformations which leave the critical point unchanged, resulting in the absence of infrared divergences when the critical point is isolated modulo gauge transformations. The procedure can be carried out using only the subgroup of gauge transformations which are topologically trivial, possibly avoiding the usual problems which arise due to gauge-fixing ambiguities. For Chern-Simons gauge theory the method enables the partition function to be perturbatively expanded for a number of simple spacetime manifolds such as $S^3$ and lens spaces, and the expansions are shown to be formally independent of the metric used in the gauge-fixing.
94177258
Pairs of chiral quarks on the lattice from staggered fermions
A new formulation of chiral fermions on the lattice is presented. It is a version of overlap fermions, but built from the computationally efficient staggered fermions rather than the previously used Wilson fermions. The construction reduces the four quark flavors described by the staggered fermion to two quark flavors; this pair can be taken as the up and down quarks in Lattice QCD. A domain wall formulation giving a truncation of this overlap construction is also outlined.
2672535
The semiclassical approximation for the Chern–Simons partition function
Abstract The semiclassical approximation for the partition function in Chern–Simons gauge theory is derived using the invariant integration method. Volume and scale factors which were undetermined and had to be fixed by hand in previous derivations are automatically taken account of in this framework. Agreement with Witten's exact expressions for the partition function in the weak coupling (large k ) limit is verified for gauge group SU (2) and spacetimes S 3 , S 2 ×S 1 , S 1 × S 1 × S 1 and L ( p , q ).
15521983
Structure of logarithmically divergent one-loop lattice Feynman integrals
For logarithmically divergent one-loop lattice Feynman integrals I(p, a), subject to mild general conditions, we prove the following expected and crucial structural result: I(p, a) = f(p)log(aM) g(p) + h(p, M) up to terms which vanish for lattice spacing a→0. Here p denotes collectively the external momenta and M is a mass scale which may be chosen arbitrarily. The f(p) and h(p,,M) are shown to be universal and coincide with analogous quantities in the corresponding continuum integral when the latter is regularized either by momentum cutoff or dimensional regularization. The nonuniversal term g(p) is shown to be a homogeneous polynomial in p of the same degree as f(p). This structure is essential for consistency between renormalized lattice and continuum formulations of QCD at one loop.