README

This software computes the quantization determinant involving
the box matrix B and the Ktilde matrix which relates two-particle
interaction energies in finite volume to the scattering matrix.
An overview of this software is given in the paper below:


@article{Morningstar:2017spu,
      author         = {Morningstar, Colin and Bulava, John and Singha, Bijit and
                        Brett, Ruair\'i and Fallica, Jacob and Hanlon, Andrew and
                        H\"orz, Ben},
      title          = {Estimating the two-particle $K$-matrix 
                        for multiple partial waves and decay channels 
                        from finite-volume energies},
      journal        = "Nucl. Phys. B",
      volume         = "924",
      year           = "2017",
      pages          = "477--507",
      doi            = "10.1016/j.nuclphysb.2017.09.014"
}


See comments in the header files for information on each class
and required XML forms.

   File           Important classes
   ----           -----------------
box_quant.h       BoxQuantization, DecayChannelInfo
box_matrix.h      BoxMatrix
K_matrix_info.h   KElementInfo, KIndex, KFitParamInfo
K_matrix_calc.h   KtildeMatrixCalculator, KtildeInverseCalculator
fit_forms.h       FitForm, Polynomial, SumOfPoles, SumOfPolesPlusPolynomial


There are two sample driver programs "driver1.cc" and "driver2.cc".
"driver1.cc" creates the needed objects from XML input given in
"input1.xml".  "driver2.cc" creates the objects in the code itself.

Tables of the block diagonal basis states and explicit expressions
for the box matrix elements are given in the file "box_matrix.pdf".



The software may be used under the terms of the GNU General Public 
Licence (GPL).  If you use this code, please cite the reference
mentioned at the top of this file.

Please report bugs/comments to colin_morningstar@cmu.edu


Colin Morningstar
Dept of Physics
Carnegie Mellon University
July 2017