124531134
Measurement of analyzing power and spin correlations in np elastic scattering at 0.744 and 0.794 GeV using a deuteron polarized beam
Abstract The np and the pp analyzing powers A oono d and spin correlations A oonn d and A oosk d were measured simultaneously using the SATURNE II polarized deuteron beam at 0.744 and 0.794 GeV/nucleon. The results for the pp observables coincide with the free pp elastic scattering data. We thus can assume that also the np analyzing power A oono d and spin correlations A oonn d and A oosk d are equal to those for scattering of free polarized neutrons. The np data cover the angular region 95°⩽ θ CM ⩽122°. Our results for A oono d (np) confirm the phase-shift analysis predictions but spin correlations A oonn d (np) and A oosk d (np) have never been measured in this energy region and will considerably affect the PSA solution. Present results allow conclusions about the angular dependence near the minimum of A oono (np) and A oonn (np) in the vicinity of 0.8 GeV.
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.
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.
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.
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.
122179155
Comparison of spin asymmetries and cross sections in π0 production by 200 GeV polarized antiprotons and protons
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 ).
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.
118986549
Chiral limit of strongly coupled lattice gauge theories
Abstract We construct a new and efficient cluster algorithm for updating strongly coupled U ( N ) lattice gauge theories with staggered fermions in the chiral limit. The algorithm uses the constrained monomer–dimer representation of the theory and should also be of interest to researchers working on other models with similar constraints. Using the new algorithm we address questions related to the chiral limit of strongly coupled U ( N ) gauge theories beyond the mean field approximation. We show that the infinite volume chiral condensate is non-zero in three and four dimensions. However, on a square lattice of size L we find ∑ x 〈 ψ ψ(x) ψ ψ(0)〉∼L 2−η for large L where η =0.420(3)/ N +0.078(4)/ N 2 . These results differ from an earlier conclusion obtained using a different algorithm. Here we argue that the earlier calculations were misleading due to uncontrolled autocorrelation times encountered by the previous algorithm.
2864130
A Remark on Schwarz's Topological Field Theory
The standard evaluation of the partition function Z of Schwarz's topological field theory results in the Ray–Singer analytic torsion. Here we present an alternative evaluation which results in Z=1. Mathematically, this amounts to a novel perspective on analytic torsion: it can be formally written as a ratio of volumes of spaces of differential forms which is formally equal to 1 by Hodge duality. An analogous result for Reidemeister combinatorial torsion is also obtained.
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.