openQCD Hadron Spectrum Computation Program

openqcd-hadspec provides functionality for computing the hadron spectrum using existing gauge configurations. The program currently computes the following particles:

• 2 flavour meson
• 2 flavour J=1/2 baryons, positive parity projection
• 1 flavour J=3/2 baryons, positive parity projection
• 2 flavour J=3/2 baryons, positive parity projection

The sources are set in the same way as in openqcd-propagator, and we therefore support two different source types:

• Point sources
• Gaussian smeared sources

The code builds on top of openqcd-fastsum, and one can therefore use the Dirac operator as provided by that code:

• Order a improved Wilson fermions
• Optional anisotropic actions
• Stout smeared gauge links

Building

To compile the project simply cd into the build directory and run make. See the Readme file inside of the build directory for more details.

Requirements

• v1.1 of openqcd-fastsum
• v1.0 of openqcd-propagator
• an implementation of MPI

Usage

The main output of the program is the openqcd-hadspec executable which runs through pre-existing lattice gauge configurations and computes hadronic correlation functions with parameters as set by the input file. The program has the following usage:

``` usage: openqcd-hadspec -i [-a] [-seed ]

Program Parameters: -i Name of the input file from which the simulation parameters are read

Optional parameters: -a Run in append mode to continue a previously started run from the last successful computation -seed Set the simulation RNG seed, overriding the infile seed and old seeds in continuation runs ```

The program infile is has many of the same sections as openqcd, and an example of a complete infile can be found at main/examples/hadspec.in. The input parameters are similar to those in openqcd-propagator with the addition of the following hadspec section

``` [Hadspec] quarks 0 0 1 2 names u d s c

[Quark 0] im0 0 isolv 0 smear 1

[Quark 1] im0 1 isolv 0 smear 1

[Quark 2] im0 2 isolv 0 smear 1 ani 1.078 4.3 1.3545694350 0.7939900651 ```

This section tells the program that we have 4 quark flavours with labels u, d, s, and c. In this case the u and d are degenerate something the program takes into account when constructing valid particles. In the case of the charm quark we have supplied a different set of anisotropy parameters.

It also supports the following definition of the deflation subspace parameters:

[Deflation subspace] bs 4 4 4 4 Ns 28 retries 100

where retries tells the program how many times to attempt to make a deflation subspace before it gives up. This is necessary due to a bug in openqcd-fastsum, and should not be necessary once this has been fixed.

Authors

This code was written by Jonas Rylund Glesaaen while a post-doc in the lattice group at Swansea University.

License

The software may be used under the terms of the GNU General Public Licence (GPL).