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

Comparing different definitions of the topological charge

27 Jul 2016, 11:30
20m
Building 67 Room 1003 (Highfield Campus, University of Southampton)

Building 67 Room 1003

Highfield Campus, University of Southampton

Talk Chiral Symmetry Chiral Symmetry

Speaker

Dr Andreas Athenodorou (University of Cyprus)

Description

We perform a numerical comparison of different lattice definitions of the topological charge by investigating the correlation coefficient between different definitions as well as the topological susceptibility. We use small-volume ensembles with 2 flavours of dynamical twisted mass fermions. We investigate the following definitions of the topological charge: index of the overlap Dirac operator, spectral flow of the Hermitian Wilson-Dirac operator, spectral projectors and field theoretic extracted with the smoothing schemes of APE, stout and HYP smearing schemes as well as cooling and the recently introduced gradient flow. Furthermore, we carry out a (tree-level) perturbative comparison between the smoothing procedures of the gradient flow, cooling as well as APE and stout smearing. We demonstrate both analytically and numerically that the above smoothing schemes are equivalent if the smoothing scales (flow time, number of cooling or smearing steps) are rescaled properly. Moreover, we demonstrate that HYP smearing is numerically equivalent with all the above smoothers. We show that the generally high correlation between different definitions increases towards the continuum limit.

Primary author

Dr Andreas Athenodorou (University of Cyprus)

Co-authors

Mr Arthur Dromard (Goethe-Universität Frankfurt am Main) Prof. Carsten Urbach (Bethe Center for Theoretical Physics, Universität Bonn) Prof. Constantia Alexandrou (University of Cyprus and The Cyprus Institute) Dr Elena Garcia-Ramos (Humboldt Universität zu Berlin) Dr Falk Zimmermann (Bethe Center for Theoretical Physics, Universität Bonn) Prof. Karl Jansen (NIC, DESY) Dr Konstantin Ottnad (Bethe Center for Theoretical Physics, Universität Bonn) Dr Krzysztof Cichy (Goethe-University Frankfurt am Main) Prof. Urs Wenger (Albert Einstein Center for Fundamental Physics)

Presentation Materials