New Noise Subtraction Methods for Lattice QCD Calculations

  • Suman Baral
Part of the Springer Theses book series (Springer Theses)


Lattice QCD is a set of numerical techniques which uses a finite space-time lattice to simulate the interactions between quarks and gluons. In lattice QCD, one of the important and challenging issues is calculation of disconnected quark loops. In order to calculate them many matrix inversions are required. To tackle this problem, instead of a direct approach, we use isolated stochastic approach along with approximation techniques Wilcox, Numerical Challenges in Lattice Quantum Chromodynamics. Lecture Notes in Computer Science and Engineering, vol. 15, (Springer Berlin, 2000), p. 127. Noise theory is used to project out the loop operator expectation values and new noise subtraction methods are applied to reduce the statistical uncertainty. Perturbative subtraction Bernardson et al. (Comput Phys Commun 78:256, 1993) is a standard noise subtraction method which we will be comparing to and attempting to improve upon. This paper will be focusing on eigenspectrum subtraction (deflation), polynomial subtraction, and combination methods.



We thank the University Research Committee of Baylor University for their support of this project. We thank Abdou Abdel-Rehim and Victor Guerrero for their contribution to noise subtraction programming, and Randy Lewis for the use of his QQCD program. Also, we would like to thank Carlton DeTar and Doug Toussaint who made MILC collaboration lattices available. We would like to thank the Texas Advanced Computing Center for account support. Finally, we would like to thank Everest Institute of Science and Technology (EVIST), Kathmandu, Nepal and Neural Innovations LLC, Hewitt, Texas for assistance during research.


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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Suman Baral
    • 1
    • 2
  1. 1.Everest Institute of Science and TechnologyKathmanduNepal
  2. 2.Neural Innovations LLCLorenaUSA

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