Searcharxiv⌕ Search

arXiv subjects

A. Galli

Publications and source records attributed to A. Galli.

47 records · Page 3Linked to original sources
arXiv1996

Suppression of the negative sign problem in quantum Monte Carlo

We present a new Monte Carlo algorithm for simulating quantum spin systems which is able to suppress the negative sign problem. This algorithm has only a linear complexity in the lattice size used for the simulation. A general description and a rigorous proof of its correctness is given. Its efficiency is tested on a simple 2-dimensional fermionic model. For this model we show that our algorithm eliminates the sign problem.

hep-lat↗
arXiv1996

Exact Local Bosonic Algorithm for Full QCD

We present an exact local bosonic algorithm for the simulation of dynamical fermions in lattice QCD. It is based on a non-hermitian polynomial approximation of the inverse of the quark matrix and a global Metropolis accept/reject correction of the systematic errors. We show that this algorithm is a real alternative to the Hybrid Monte Carlo algorithm.

hep-lat↗
arXiv1996

Non-hermitian Exact Local Bosonic Algorithm for Dynamical Quarks

We present an exact version of the local bosonic algorithm for the simulation of dynamical quarks in lattice QCD. This version is based on a non-hermitian polynomial approximation of the inverse of the quark matrix. A Metropolis test corrects the systematic errors. Two variants of this test are presented. For both of them, a formal proof is given that this Monte Carlo algorithm converges to the right distribution. Simulation data are presented for different lattice parameters. The dynamics of the algorithm and its scaling in lattice volume and quark mass are investigated.

hep-lat↗
arXiv1995

Generalized Hyper-Systolic Algorithm

We generalize the hyper-systolic algorithm proposed in [1] for abstract data structures on massive parallel computers with $n_p$ processors. For a problem of size $V$ the communication complexity of the hyper-systolic algorithm is proportional to $\sqrt{n_p}V$, to be compared with $n_pV$ for the systolic case. The implementation technique is explained in detail and the example of the parallel matrix-matrix multiplication is tested on the Cray-T3D.

hep-lat↗
arXiv1995

Full QCD with the Lüscher local bosonic action

We investigate Lüscher's method of including dynamical Wilson fermions in a lattice simulation of QCD with two quark flavours. We measure the accuracy of the approximation by comparing it with Hybrid Monte Carlo results for gauge plaquette and Wilson loops. We also introduce an additional global Metropolis step in the update. We show that the complexity of Lüscher's algorithm compares favourably with that of the Hybrid Monte Carlo.

hep-lat↗
arXiv1994

Composite Weak Bosons: a Lattice Analysis

We present a lattice analysis of a confining Yang-Mills theory without Goldstone boson. We have analytically investigated the model by a strong coupling expansion and by an intensive lattice Monte Carlo simulation using standard lattice QCD methods. We show that this theory is an interesting candidate for describing weak bosons as composite particles.

hep-lat↗
arXiv1994

Composite Weak Bosons: a Lattice Monte Carlo Analysis

We present a lattice Monte Carlo simulation for the evaluation of the spectrum of a confining Yang-Mills theory without Goldstone boson. We show that this theory is a very good candidate for describing composite weak bosons. In order to perform the spectrum analysis we have used standard lattice QCD Monte Carlo methods. We have also developed an efficient method to evaluate the mass of the pseudoscalar isosinglet which is present in our theory.

hep-lat↗
arXiv1994

Composite Weak Bosons in a Confining Gauge Theory without Goldstone Bosons: a Strong Coupling Expansion Analysis

We consider a confining Yang-Mills theory without Goldstone Bosons which could describe the bosonic sector of the weak interactions. This model can be gauge invariantly regularized on a lattice. A strong coupling analysis of the low lying bound state spectrum indicates that the vector isotriplet bound state (the right quantum number to represent the W-boson) could be the lightest state if the mass of the pseudoscalar isosinglet is raised sufficiently by the effect of the chiral anomaly (in analogy to the $η'$ mechanism of QCD). This work is a preliminary study in support to an intensive lattice Monte Carlo analysis of the model.

hep-lat↗