## 19.07.10 16:15

# Parity violation, nd spin rotation, and the predictive power of EFT without pions

## Harald W. Grießhammer (George Washington U.)

One of the least-explored sectors of the Standard Model is the weak part of the nuclear force. Experiments on hadronic parity-violation (PV) at low energies require one comprehensive theoretical framework with reliable error-estimates to: check data consisteny; subtract binding effects; and extract the PV interaction strengths. "Pion-less" Effective Field Theory is such a method with minimal theoretical bias. At next-to-leading order, we find that the PV neutron spin-rotation in deuterium is increased by a factor of about 10 relative to that in hydrogen and numerically confirm that the result is regulator-independent. We show that PV 3-nucleon interactions are suppressed in the nd-system, despite the non-perturbative renormalisation of parity-conserving 3-nucleon interactions. This finding is based on naïve dimensional analysis and the observation that Wigner’s SU(4) spin-isospin symmetry is approximately realised in 2-nucleon scattering even when effective-range corrections are included. Therefore, few-nucleon experiments can disentangle PV 2-nucleon interactions at the 10%-level without introducing new unknowns. [arXiv:1007.0734 [nucl-th] and in preparation]

(Seminarraum II)