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We describe the software environment available for the APE100 parallel processor. We discuss the parallel programming language that we have defined for APE100 and its optimizing compiler. We then describe the operating system that allows to control APE100 from a host computer.

We study staggered quenched QCD at a moderate value of β on large lattices. We introduce smeared Green functions for staggered fermions, and we analyze their effectiveness. We estimate the lattice spacing, and establish that staggered fermions undergo large systematic errors at low β in the estimate of the lattice spacing from the ρ{variant}-mass. The scale ratio of the baryonic and the mesonic sector (mp/mp) is, on the contrary, consistent with the one estimated by using Wilson fermions. Owing to the use of smeared operators on large lattices (up to 243 × 32), we are able to give reliable results for the baryonic states. © 1990.

We study the behavior of the string tension in the SU(3) lattice pure-gauge theory close to the deconfining critical point. We find very large correlation lengths, increasing with the lattice size. This result is strongly suggestive of a second-order phase transition, and excludes the presence of a strong first-order transition. © 1988 The American Physical Society.

A thorough analysis is presented of the hadronic transverse energy produced in association with W± and Z0 weak bosons at p {Mathematical expression} colliders. The complete rapidity and transverse energy distributions are derived, including the perturbative annihilation and Compton terms and the resummation of soft gluons. The first non leading corrections to the corresponding Sudakov exponent are included in full and their effects are discussed. To make contact with the actual data a number of non perturbative inputs is also necessary. We extract this information from minimum bias measurements. A detailed comparison of the resulting theoretical predictions with the available experimental data is finally presented. © 1986 Springer-Verlag.

We investigate the possibility of identifying heavy quarks produced in hadron collision by detecting the multilepton final states. A new algorithm is developed for dilepton and trilepton events, which allows an efficient distinction between different primary heavy flavours. © 1982 Società Italiana di Fisica.

We report the results of a numerical computation of the pion propagator for 40 configurations on an 83 × 16 lattice using the ICL distributed array processor. We use the Wilson form for the fermion action and work in the quenched approximation which neglects dynamical fermion loops. We confirm that, for the chosen gauge coupling g2 = 1, seven or eight lattice spacings are required to see the contribution of the pion pole against the background of excited states. We estimate the critical value of the hopping parameter Kc = 0.157±0.001 and the pion decay constant ⨍ π = 130±45 MeV .

We show that a study of the processes {A figure is presented} can provide information on the pion structure functions. Using a realistic parton distribution for the pion we calculate cross sections and relevant distributions for these processes. The results show that such measurements are experimentally accessible. © 1979.

We report the results of strange and light-quark hadron masses obtained by a simulation of QCD in the zero fermion loops approximation (quenching) on a 10 3 × 20 lattice. The results are sensibly different from those obtained on smaller lattices and show a definite improvement.

A Monte Carlo computation of meson and hadron spectroscopy within lattice QCD is made. We give a detailed discussion of the statistical and systematic errors of the results and analyze the present limitations of our approach. The results are in agreement with the observed spectrum. We also estimate the values of up, down and strange quark masses. © 1982.

We compute the QCD hadronic mass spectrum in quenched lattice QCD at β=5.7 with small statistical and systematic errors by using the APE computer.

We compute the correlation length of an SU(3) gauge system in the neighbourhood of the deconfining phase transition by measuring loop-loop correlation functions. We find values that are linearly divergent with the lattice size at the critical point and fully compatible with our former estimates obtained by using a cold source method. Together with a precise determination of the location of the critical point these results make stronger the evidence for a large ξ at β close to β c .

We study the effect of mass renormalization to the behaviour of iterative methods for the computation of the quark propagator on the lattice.

Predictions on lepton pair production in meson-nucleon collisions, taking into account scale breaking, are compared with the most recent experimental data.

We measure the correlation length of Polyakov loop in the region of the deconfinement transition for a pure gauge SU(3) theory on lattices of different sizes. The correlation length is found to be of the order of lattice size, thus excluding a strong first order transition.

We study the exponential decay of the smeared plaquettes, at large distance from a cold source, close to the deconfining phase transition of N t =4 lattice QCD. We compare different lattice size results, and by using finite size scaling arguments we find a critical behavior that is in agreement with a continuous transition.

Using a Monte Carlo method to measure the correlation functions of different quantities, the mass spectrum of the glue-ball is investigated for an SU(2) gauge model in an 8 4 lattice.

We have computed the proton and neutron magnetic moments on the lattice by a Monte Carlo simulation of QCD in the quenched approximation. The results are in remarkable agreement with the experimental values. © 1982.

The string tension has been measured at β =6 in the quenched approximation using a new technique for minimizing the statistical errors.

The production of large-angle real photons from the reactions (p, p ,π − )+p→γ+X is analysed in the framework of QCD with scaling violations also taken into account. Estimates of the ratios γ π 0 are discussed in view of future possible experiments.

A relevant contribution to the large fluctuations of hadron masses present in lattice calculations with periodic boundary conditions is due to unphysical quark paths which are absent in the infinite volume limit. We show that these contributions can be eliminated by averaging over possible rotations of the boundary links by the elements of the Z(3) subgroup. In this way the “effective” volume for these paths is triplicated.

We study glueball masses in lattice QCD. We present the first numerical determination of the mass of the lowest spin 2 state in the scaling region, and find that it is close to the lowest spin 0 state. We present very precise results for the string tension and for the spin 0 state, obtained by analyzing a large set of operators. We find that finite size effects are significant. © 1987.

We study the scaling behaviour of lattice quantum chromodynamics by comparing the β dependence of the string tension and the 0 ++ glueball mass. We use a source method at β =5.7, β =5.9 and β =6.1, on lattices from 9 3 · 24 to 16 3 · 32. Assuming a string tension of about (420 MeV) 2 , the lattice spacing ranges from 0.16 to 0.08 fm. In order to separate finite volume from scaling violation effects we have compared data from lattices having approximately the same overall physical size at the different values of β. We find deviations from scaling to be very small.

We study the hadronic mass spectrum in quenched lattice QCD. We present the results of numerical simulations done at β = 5.7 and β = 6.0. B and A1 meson masses get much closer to the physical values at β = 6.0, and so do the baryonic splittings. The mass ratio m p m p in the chiral limit tends to be from 10 to 20% higher than the experimental value. We estimate the nucleon σ term from the proton mass slope.

The APE computer is a high performance processor designed to provide massive computational power for intrinsically parallel and homogeneous applications. APE is a linear array of processing elements and memory boards that execute in parallel in SIMD mode under the control of a CERN/SLAC 3081/E. Processing elements and memory boards are connected by a ‘circular’ switchnet. The hardware and software architecture of APE, as well as its implementation are discussed in this paper. Some physics results obtained in the simulation of lattice gauge theories are also presented.

We briefly describe the APE processor, a parallel computer currently used in lattice gauge simulations. We also present in greater details the architecture and the implementation of APE-100, a fine grained SIMD processors for lattice gauge theory simulations, similar in structure to APE and designed to provide floating-point performance in the 100 Gflops range.

We present a high statistics study of the D- and B-meson decay constants. The results were obtained by using the Clover and Wilson lattice actions at two different values of the lattice spacing $a$, corresponding to $\beta=6.0$ and 6.2. After a careful analysis of the systematic errors present in the extraction of the physical results, by assuming quite conservative discretization errors, we find $f_{D_s}=237 \pm 16$ MeV, $f_{D} = 221 \pm 17$ MeV ($f_{D_s}/f_D=1.07(4)$), $f_{B_s} = 205 \pm 35$ MeV, $f_{B} = 180 \pm 32$ MeV ($f_{B_s}/f_B=1.14(8)$), in good agreement with previous estimates., Comment: 15 pages, Latex with one postscript figure

By using a source method and improved measuring techniques, we study the decay of the Polyakov loop in SU(3) lattice gauge theory at finite temperature. Our aim is to measure the correlation length of the system in the neighbourhood of the critical point. We work with lattices of size up to 162×64×4. We found that the maximum correlation length is only bounded by the spatial dimension of the lattice. This result is the one expected in a second order phase transition and appears to be incompatible with the presence of the strong first order transition claimed in the literature.

We determine the quark masses and the chiral condensate in the MSbar scheme at NNLO from Lattice QCD in the quenched approximation at beta=6.0, beta=6.2 and beta=6.4 using both the Wilson and the tree-level improved SW-Clover fermion action. We extract these quantities using the Vector and the Axial Ward Identities and non-perturbative values of the renormalization constants. We compare the results obtained with the two methods and we study the O(a) dependence of the quark masses for both actions., LATTICE98(spectrum), 3 pages, 1 figure, Edinburgh 98/17