A lattice calculation of the hadronic vacuum polarization contribution to (g – 2)_µ

Abstract

We present results of calculations of the hadronic vacuum polarisation contribution to the muon anomalous magnetic moment. Specifically, we focus on controlling the infrared regime of the vacuum polarisation function. Our results are corrected for finite-size effects by combining the Gounaris-Sakurai parameterisation of the timelike pion form factor with the Lüscher formalism. The impact of quark-disconnected diagrams and the precision of the scale determination is discussed and included in our final result in two-flavour QCD, which carries an overall uncertainty of 6%. We present preliminary results computed on ensembles with Nf = 2 + 1 dynamical flavours and discuss how the long-distance contribution can be accurately constrained by a dedicated spectrum calculation in the iso-vector channel.

Lorentz-covariant coordinate-space representation of the leading hadronic contribution to the anomalous magnetic moment of the muon

“…One important consideration is the control over finite-volume effects. The nature of these corrections are by now quite well understood in the TMR method [18], although more direct numerical studies (involving several volumes, all other parameters being held fixed) are desirable. It remains to be studied how large the finite-size effects are in the CCS method.…”

“…While the phenomenologa e-mail: meyerh@uni-mainz.de ical determination of a hvp μ via its dispersive representation is still the most accurate approach [5,6], a purely theoretical prediction is both conceptually desirable and provides for an independent check. Since the vacuum polarization is inserted into an integral which is strongly weighted to the low-energy domain, calculating the hadronic vacuum polarization has become an important goal for several lattice QCD collaborations [7][8][9][10][11][12][13][14][15][16][17][18].…”

A precise determination of the HVP contribution to the muon anomalous magnetic moment from lattice QCD

“…As was observed recently in Ref. [3] such high precision on the lattice spacing is important for a high-precision calculation of a µ .…”

Mellin-Barnes approach to hadronic vacuum polarization and gμ−2

“…[10][11][12][13][14][15][16][17][18][19]), or on new dedicated experiments as proposed in ref. [20].…”

“…The natural question which then arises is: What is the best way to help LQCD (see e.g., Refs. [10][11][12][13][14][15][16][17][18][19]), or dedicated experiments [20], to evaluate this integral when only limited information about ΠðQ 2 Þ at low Q 2 values is available? The answer that we propose follows the way initiated in Ref.…”