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The pion vector form factor from lattice QCD and NNLO chiral perturbation theory

The pion vector form factor from lattice QCD and NNLO chiral perturbation theory
The pion vector form factor from lattice QCD and NNLO chiral perturbation theory
We present a comprehensive study of the electromagnetic form factor, the decay constant and the mass of the pion computed in lattice QCD with two degenerate O(a)-improved Wilson quarks at three different lattice spacings in the range 0.05-0.08fm and pion masses between 280 and 630MeV at mπ L ≥ 4. Using partially twisted boundary conditions and stochastic estimators, we obtain a dense set of precise data points for the form factor at very small momentum transfers, allowing for a model-independent extraction of the charge radius. Chiral Perturbation Theory (ChPT) augmented by terms which model lattice artefacts is then compared to the data. At next-to-leading order the effective theory fails to produce a consistent description of the full set of pion observables but describes the data well when only the decay constant and mass are considered. By contrast, using the next-to-next-to-leading order expressions to perform global fits result in a consistent description of all data. We obtain ⟨r2π⟩ = 0.481(33)(13)fm2 as our final result for the charge radius at the physical point. Our calculation also yields estimates for the pion decay constant in the chiral limit, Fπ/F = 1.080(16)(6), the quark condensate, Σ1/3MSbar (2GeV) = 261(13)(1)MeV and several low-energy constants of SU(2) ChPT.
lattice qcd, nonperturbative effects, chiral lagrangians
1-37
Brandt, Bastian B.
519354d6-09ed-4ef9-8b3e-2cfc9f7761fb
Juttner, Andreas
a90ff7c5-ae8f-4c8e-9679-b5a95b2a6247
Wittig, Hartmut
c782e4fa-6398-4cca-96e7-7651ff8cbe69
Brandt, Bastian B.
519354d6-09ed-4ef9-8b3e-2cfc9f7761fb
Juttner, Andreas
a90ff7c5-ae8f-4c8e-9679-b5a95b2a6247
Wittig, Hartmut
c782e4fa-6398-4cca-96e7-7651ff8cbe69

Brandt, Bastian B., Juttner, Andreas and Wittig, Hartmut (2013) The pion vector form factor from lattice QCD and NNLO chiral perturbation theory. Journal of High Energy Physics, 11 (34), 1-37. (doi:10.1007/JHEP11(2013)034).

Record type: Article

Abstract

We present a comprehensive study of the electromagnetic form factor, the decay constant and the mass of the pion computed in lattice QCD with two degenerate O(a)-improved Wilson quarks at three different lattice spacings in the range 0.05-0.08fm and pion masses between 280 and 630MeV at mπ L ≥ 4. Using partially twisted boundary conditions and stochastic estimators, we obtain a dense set of precise data points for the form factor at very small momentum transfers, allowing for a model-independent extraction of the charge radius. Chiral Perturbation Theory (ChPT) augmented by terms which model lattice artefacts is then compared to the data. At next-to-leading order the effective theory fails to produce a consistent description of the full set of pion observables but describes the data well when only the decay constant and mass are considered. By contrast, using the next-to-next-to-leading order expressions to perform global fits result in a consistent description of all data. We obtain ⟨r2π⟩ = 0.481(33)(13)fm2 as our final result for the charge radius at the physical point. Our calculation also yields estimates for the pion decay constant in the chiral limit, Fπ/F = 1.080(16)(6), the quark condensate, Σ1/3MSbar (2GeV) = 261(13)(1)MeV and several low-energy constants of SU(2) ChPT.

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More information

Accepted/In Press date: 16 October 2013
Published date: 5 November 2013
Keywords: lattice qcd, nonperturbative effects, chiral lagrangians
Organisations: Theoretical Partical Physics Group

Identifiers

Local EPrints ID: 393639
URI: https://eprints.soton.ac.uk/id/eprint/393639
PURE UUID: 5677776a-c381-423f-a505-4720aeaa50a8

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Date deposited: 03 May 2016 08:07
Last modified: 01 Aug 2018 16:31

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