# Are microcanonical algorithms still used in lattice QCD?

1. Apr 3, 2015

### Arsenic&Lace

I stumbled across a paper which stated that the relation between statistical mechanics and field theory is exploited to recast lattice QCD in terms of a "microcanonical ensemble" of sorts. I was curious to know if this was still a commonly used technique.

The paper in question:
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.49.613

2. Apr 3, 2015

### The_Duck

The standard way of doing lattice QCD calculations is to exploit the relation between statistical mechanics to express QCD expectation values as expectation values in a canonical ensemble. The paper is modifying this to use a microcanonical ensemble instead of a canonical one. AFAIK the modified technique described in the paper has never been widely used. I suspect it has some disadvantages compared to the usual method. For example the canonical ensemble technique is tolerant to the fact that errors in the numerical integration of the equations of motion produce small violations of energy conservation. But these errors seem harder to deal with in a microcanonical approach.

3. Apr 5, 2015