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Published on: November 15, 2013
Susceptibility of the QCD vacuum to CP-odd electromagnetic background fields
Massimo D'Elia1, Marco Mariti, Francesco Negro
1Dipartimento di Fisica, dell'Università di Pisa and INFN-Sezione di Pisa, Largo Pontecorvo 3, I-56127 Pisa, Italy. delia@df.unipi.it
Abstract:
We investigate two flavor quantum chromodynamics (QCD) in the presence of CP-odd electromagnetic background fields and determine, by means of lattice QCD simulations, the induced effective θ term to first order in E[over →] · B[over →]. We employ a rooted staggered discretization and study lattice spacings down to 0.1 fm and Goldstone pion masses around 480 MeV. In order to deal with a positive measure, we consider purely imaginary electric fields and real magnetic fields, and then exploit the analytic continuation. Our results are relevant to a description of the effective pseudoscalar quantum electrodynamics-QCD interactions.
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