Topological charge density correlator in Lattice QCD with two flavours of unimproved Wilson fermions

Abstract

We study the two-point Topological Charge Density Correlator (TCDC) in lattice QCD with two degenerate flavours of unimproved Wilson fermions and Wilson gauge action at two values of lattice spacings and different volumes, for a range of quark masses. Configurations are generated with DDHMC algorithm and smoothed with HYP smearing. In order to shed light on the mechanisms leading to the observed suppression of topological susceptibility with respect to the decreasing quark mass and decreasing volume, in this work, we carry out a detailed study of the two-point TCDC. We have shown that, (1) the TCDC is negative beyond a positive core and radius of the core shrinks as lattice spacing decreases, (2) as the volume decreases, the magnitude of the contact term and the radius of the positive core decrease and the magnitude of the negative peak increases resulting in the suppression of the topological susceptibility as the volume decreases, (3) the contact term and radius of the positive core decrease with decreasing quark mass at a given lattice spacing and the negative peak increases with decreasing quark mass resulting in the suppression of the topological susceptibility with decreasing quark mass, (4) increasing levels of smearing suppresses the contact term and the negative peak keeping the susceptibility intact and (5) both the contact term and the negative peak diverge in nonintegrable fashion as lattice spacing decreases. It is gratifying to note that observations similar to 1 and 5 have been made using topological charge density operator based on chiral fermion. The observations 2 and 3 may be confirmed more precisely by using formulations based on chiral fermions.

arXiv commentsome qualifying remarks are added, results unchanged

References in corpus (12)

• Schwarz-preconditioned HMC algorithm for two-flavour lattice QCD
• Solution of the Dirac equation in lattice QCD using a domain decomposition method
• Topological effects in QCD and the problem of short-distance singularities
• Topological Structure in the SU(2) Vacuum
• The U_A(1) Problem on the Lattice with Ginsparg-Wilson Fermions
• Instanton Content of the SU(3) Vacuum
• Topological susceptibility in full QCD with Ginsparg-Wilson fermions
• Some more remarks on the Witten-Veneziano formula for the ${\eta }^{\prime }$ mass
• The Negativity of the Overlap-Based Topological Charge Density Correlator in Pure-Glue QCD and the Non-Integrable Nature of its Contact Part
• Topological susceptibility in full QCD: lattice results versus the prediction from the QCD partition function with granularity
• Topology of dynamical lattice configurations including results from dynamical overlap fermions
• Topological susceptibility in Lattice QCD with unimproved Wilson fermions

Cited by in corpus (5)

• Correlation and localization properties of topological charge density and the pseudoscalar glueball mass in SU(3) lattice Yang-Mills theory
• Topological susceptibility in lattice Yang-Mills theory with open boundary condition
• Lattice determination of the topological susceptibility slope ${\chi }^{\prime }$ of $2d{\mathrm{CP}}^{N-1}$ models at large $N$
• Exploring autocorrelations in two-flavour Wilson Lattice QCD using DD-HMC algorithm
• Pion and nucleon in two flavour QCD with unimproved Wilson fermions