125392602
Track reconstruction in the ATLAS Muon Spectrometer with MOORE 007
13590622
A muon identification and combined reconstruction procedure for the ATLAS detector at the LHC at CERN
Muon identification (MUID) and high-momentum measurement accuracy is crucial to fully exploit the physics potential that will be accessible with the ATLAS experiment at the LHC. The muon energy of physics interest ranges in a large interval from few GeV, where the b-physics studies dominate the physics program, up to the highest values that could indicate the presence of new physics. The muon detection system of the ATLAS detector is characterized by two high-precision tracking systems, namely the inner detector (ID) and the muon spectrometer, (MS) plus a thick calorimeter that ensures a safe hadron absorption filtering with high-purity muons with energy above 3 GeV. In order to combine the muon tracks reconstructed in the ID and the MS, a MUID object-oriented software package has been developed. The purpose of the MUID procedure is to associate tracks found in the MS with the corresponding ID track and calorimeter information in order to identify muons at their production vertex with optimum parameter resolution. The performance of these two combined systems has been evaluated with Monte Carlo studies using single muons of fixed-transverse momentum and with full physics events.
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.
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.
121757543
Measurement of single spin asymmetry for direct photon production in pp collisions at 200 GeV/c
The single spin asymmetry for inclusive direct-photon production has been measured using a polarized proton beam of 200 GeV/c with an unpolarized proton target at −0.15 < xf < 0.15 and 2.5 < pt < 3.1 GeV/c at Fermilab. The data on the cross section for pp → γX at 2.5 < pt < 3.8 GeV/c are also provided. The measurement was done using lead-glass calorimeters and photon detectors which surrounded the fiducial area of the calorimeters. Background rejection has been done using these surrounding photon detectors. The cross section obtained is consistent with the results of previous measurements assuming a nuclear dependence of A1.0. The single spin asymmetry, AN, for the direct-photon production is consistent with zero within experimental uncertainty.
122179155
Comparison of spin asymmetries and cross sections in π0 production by 200 GeV polarized antiprotons and protons
55547886
Index and overlap construction for staggered fermions
Recent developments regarding index and overlap construction for staggered fermions are reviewed, highlighting the surprising and unexpected aspects.
5507561
Rooting issue for a lattice fermion formulation similar to staggered fermions but without taste mixing.
Toinvestigatetheviabilityofthe4th roottrickforthestaggered ferm ion determ inantin asim pler setting,weconsidera two taste(avor)lattice ferm ion form ulation with no tastem ixing butwith exact taste-nonsinglet chiralsym m etries analogous to the taste-nonsinglet U(1)A sym m etry of staggered ferm ions.M .Creutz’sobjectionsto therooting trick apply justasm uch in thissetting. To counter them we show thatthe form ulation has robustwould-be zero-m odes in topologically nontrivialgauge backgrounds,and that these m anifestthem selves in a viable way in the rooted ferm ion determ inantand also in the disconnected piece ofthe pseudoscalarm eson propagatoras required to solvetheU(1)problem .Also,ourrooted theory isheuristically seen to bein theright universality classforQCD ifthesam eistrueforan unrooted m ixed ferm ion action theory.
55533512
Geometric discretization scheme applied to the Abelian Chern-Simons theory
We give a detailed general description of a recent geometrical discretisation scheme and illustrate, by explicit numerical calculation, the scheme's ability to capture topological features. The scheme is applied to the Abelian Chern-Simons theory and leads, after a necessary field doubling, to an expression for the discrete partition function in terms of untwisted Reidemeister torsion and of various triangulation dependent factors. The discrete partition function is evaluated computationally for various triangulations of $S^3$ and of lens spaces. The results confirm that the discretisation scheme is triangulation independent and coincides with the continuum partition function
14334225
General bounds on the Wilson-Dirac operator
Lower bounds on the magnitude of the spectrum of the Hermitian Wilson-Dirac operator $H(m)$ have previously been derived for $0lml2$ when the lattice gauge field satisfies a certain smoothness condition. In this paper lower bounds are derived for $2p\ensuremath{-}2lml2p$ for general $p=1,2,\dots{},d$ where d is the spacetime dimension. The bounds can alternatively be viewed as localization bounds on the real spectrum of the usual Wilson-Dirac operator. They are needed for the rigorous evaluation of the classical continuum limit of the axial anomaly and the index of the overlap Dirac operator at general values of m, and provide information on the topological phase structure of overlap fermions. They are also useful for understanding the instanton size dependence of the real spectrum of the Wilson-Dirac operator in an instanton background.
6382264
Theoretical foundation for the index theorem on the lattice with staggered fermions.
A way to identify the would-be zero modes of staggered lattice fermions away from the continuum limit is presented. Our approach also identifies the chiralities of these modes, and their index is seen to be determined by gauge field topology in accordance with the index theorem. The key idea is to consider the spectral flow of a certain Hermitian version of the staggered Dirac operator. The staggered fermion index thus obtained can be used as a new way to assign the topological charge of lattice gauge fields. In a numerical study in U(1) backgrounds in two dimensions it is found to perform as well as the Wilson index while being computationally more efficient. It can also be expressed as the index of an overlap Dirac operator with a new staggered fermion kernel.