24-30 July 2016
Highfield Campus, University of Southampton
Europe/London timezone

Algorithms for disconnected diagrams.

27 Jul 2016, 11:50
Building 67 Room 1007 (Highfield Campus, University of Southampton)

Building 67 Room 1007

Highfield Campus, University of Southampton

Talk Algorithms and Machines Algorithms and Machines


Mr Arjun Gambhir (College of William and Mary/JLab)


Computing disconnected diagrams on the lattice involves taking the trace of the inverse of the Dirac operator. This is a computationally challenging problem, however recent algorithmic improvements such as low mode averaging and hierarchical probing have increased the efficiency of this trace estimation. We detail an algorithm that builds upon hierarchical probing by deflating the near null space of the Dirac matrix. An additional order of magnitude of variance reduction is achieved by combining these two methods and we explore this synergy both theoretically and experimentally. Finally, we apply this algorithm to calculate contributions to the Pauli and Dirac form factors of the nucleon, and present initial results.

Primary author

Mr Arjun Gambhir (College of William and Mary/JLab)


Prof. Kostas Orginos (College of William and Mary/JLAB) Prof. Stathopoulos Andreas (College of William and Mary)

Presentation Materials

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