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22-28 July 2018
Kellogg Hotel and Conference Center
EST timezone

Nucleon-pion-state contamination in the lattice determination of the axial form factors of the nucleon

Jul 25, 2018, 2:00 PM
20m
105 (Kellogg Hotel and Conference Center)

105

Kellogg Hotel and Conference Center

219 S Harrison Rd, East Lansing, MI 48824
Hadron Spectroscopy and Interactions Hadron Spectroscopy and Interactions

Speaker

Dr Oliver Baer (Humboldt University Berlin)

Description

The nucleon-pion-state ($N\pi$) contribution to QCD two- and three-point functions used in the calculation of the axial form factors of the nucleon are studied in chiral perturbation theory. For physical quark masses the $N\pi$ states are expected to dominate the excited-state contamination at large euclidean time separations. To leading order in chiral perturbation theory the results depend on two experimentally well-known low-energy constants only and the $N\pi$-state contamination can be reliably estimated. In the axial form factor $G_A(Q^2)$ it amounts to a 5 percent overestimation for source-sink separations of about 2 fm and shows essentially no dependence on the momentum transfer $Q^2$. In contrast, for the induced pseudo-scalar form factor $G_P(Q^2)$ the $N\pi$-state contamination shows a much stronger dependence on $Q^2$ and leads to a 20-40 percent underestimation of $G_P(Q^2)$ at small momentum transfers.

Primary author

Dr Oliver Baer (Humboldt University Berlin)

Presentation Materials