The canonical approach, which was developed for solving the sign problem, may suffer from a new type of sign problem. In the canonical approach, the grand partition function is written as a fugacity expansion: $Z_G(μ,T) = \sum_n Z_C(n,T) ξ^n$, where $ξ=\exp(μ/T)$ is the fugacity, and $Z_C(n,T)$ are given as averages over a Monte Carlo update, $\langle z_n\rangle$. We show that the complex phase of $z_n$ is proportional to $n$ at each Monte Carlo step. Although $\langle z_n\rangle$ take real positive values, the values of $z_n$ fluctuate rapidly when $n$ is large, especially in the confinement phase, which gives a limit on $n$. We discuss possible remedies for this problem.
QCDLAB is a set of programs, written in GNU Octave, for lattice QCD computations. Version 2.0 includes the generation of configurations for the SU(3) theory, computation of rectangle Wilson loops as well as the low lying meson spectrum with Wilson fermions. Version 2.1 includes also the computation of the low lying meson spectrum using minimally doubled chiral fermions. In this paper, we give a brief tutorial on lattice QCD computations using QCDLAB.
This document is one of a series of whitepapers from the USQCD collaboration. Here, we outline the opportunities for, prospects of and challenges to the lattice QCD calculations relevant for the understanding of the phases and properties of hot-dense QCD matter. This program of lattice QCD calculations is relevant to current and upcoming heavy-ion experimental programs at RHIC and LHC.
This is an introductory review of lattice QCD with external fields. The study of external magnetic fields is one of the greatest achievements in modern lattice QCD. Large-scale simulations and detailed analyses have revealed intriguing properties of QCD in the magnetic fields. The study of external electric fields is more challenging because of a technical difficulty. We overview the successes and challenges of the lattice simulations with the electromagnetic fields. We also introduce a newly developing field, the lattice simulation of rotating QCD matters.
In this work we present an efficient construction of baryon interpolating fields for lattice QCD computations of two and three point functions. These are essential building blocks of computations of nucleon parton distribution functions (PDFs), generalized parton distribution functions (GPDs) and transverse momentum dependent distributions functions (TMDs). Lattice QCD computations of these quantities can provide additional input to assist with the global fits on experimental data for determining TMDs, GPDs and PDFs.
QCDOC: A 10-teraflops scale computer for lattice QCD
本文描述了一种新的用于格点量子色动力学计算的计算机体系结构。单个节点基于单个集成电路，该集成电路包含PowerPC 32位整数处理器、1 Gflops 64位IEEE浮点单元、4 Mbyte存储器、8 Gbit/sec最近邻通信以及附加控制和诊断电路。这台机器的名字QCDOC来自于“QCD On a Chip”。
