دانلود رایگان مقاله یک الگوریتم بلوک موثر برای همبسته های باریون - باریون

Abstract

We describe an approach for the efficient calculation of a large number of four-point correlation functions for various baryon–baryon (BB) channels, which are the primary quantities for studying the nuclear and hyperonic nuclear forces from lattice quantum chromodynamics. Using the four-point correlation function of a proton-Λ system as a specific example, we discuss how an effective block algorithm significantly reduces the number of iterations. The effective block algorithm is applied to calculate 52 channels of the four-point correlation functions from nucleon–nucleon to Ξ–Ξ, in order to study the complete set of isospin symmetric BB interactions. The elapsed times measured for hybrid parallel computation on BlueGene/Q demonstrate that the performance of the present algorithm is reasonable for various combinations of the number of OpenMP threads and the number of MPI nodes. The numerical results are compared with the results obtained using the unified contraction algorithm for all computed sites of the 52 four-point correlators.

7. Summary

In this paper, we present an approach for the efficient simultaneous calculation of a large number of four-point correlation functions, which are the primary quantities for studying the nuclear and hyperonic nuclear forces from lattice QCD. The effective block algorithm significantly reduces the number of iterations required for the Wick contraction, and is applied to calculate the 52 channels of fourpoint correlation functions in order to study the complete set of BB interactions in the isospin symmetric limit. The elapsed time is measured for hybrid parallel computation on the BlueGene/Q supercomputer. The hybrid parallel executions of the 163 × 32 lattice show reasonable performances for various combinations of the number of MPI processes and the number of threads. The numerical values of the calculated 52 four-point correlation functions are compared with the results obtained using the unified contraction algorithm. We find that all numerical results are in good agreement and the two different algorithms give virtually identical results. This is advantageous for performing the large scale computation of various BB potentials at the physical quark mass point.