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Volume 346 - 23rd International Spin Physics Symposium (SPIN2018) - Parallel Session: Fundamental Symmetries and Spin Physics Beyond the Standard Model (D. Dutta and A. Wirzba)
Present and future prospects for lattice QCD calculations of matrix elements for nEDM
R. Gupta
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Pre-published on: 2019 August 19
Published on: 2019 August 23
A status report on the calculations of the contribution of
four CP violating operators, the $\Theta$-term, the quark chromo
EDM, the chromo EDM and the Weinberg operator to the neutron EDM are
presented. At this time, there exit precise physical results only
for the quark EDM operator by the PNDME collaboration. First results
showing signal in the contributions of the $\Theta$-term and the
connected part of the chromo EDM operator have been presented. The
challenge of divergent mixing in the chromo EDM and Weinberg
operators has motivated calculations in the gradient flow
scheme. While there is steady progress, the challenges remaining are
large. Results with $O(50\%)$ uncertainty with control over all
systematic errors can be expected for the $\Theta$-term over the
next five years. Prediction of a timeline of progress for the chromo
EDM and the Weinberg operators will depend on when the
renormalization and divergent mixing of these operators is brought
under control. The most optimistic scenario is that the gradient
flow scheme provides a solution for the signal and mixing problems
for both the gluonic and quark operators.
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