# Spin polarization observables of the deuteron photodisintegration at low energies in pionless effective field theory

## TL;DR

This study uses pionless effective field theory up to NNLO to analyze spin polarization observables in low-energy deuteron photodisintegration, providing detailed calculations of cross sections and analyzing powers.

## Contribution

It presents the first NNLO calculations of polarization observables in deuteron photodisintegration within pionless EFT, highlighting the importance of higher-order corrections.

## Key findings

- NNLO corrections converge well for cross sections and neutron polarization
- Tensor analyzing powers $T_{20}$ and $T_{22}$ are significantly affected by NNLO contributions
- Discrepancy between theory and experiment in neutron polarization $P_{y'}$ persists

## Abstract

Spin polarization observables of the deuteron photodisintegration at low energies are studied in a pionless effective field theory up to next-to-next-to-leading order (NNLO). The total and differential cross sections, induced neutron polarization $P_{y'}$, and tensor analyzing powers $T_{20}$ and $T_{22}$ of the process are calculated at photon energies from the breakup threshold to 20~MeV. We find that the NNLO corrections in the cross sections and $P_{y'}$ converge well whereas they turn out to be important contributions in $T_{20}$ and $T_{22}$. We discuss the discrepancy between theory and experiment in $P_{y'}$ still persisting as well as an implication of our result to the first measurement of $T_{20}$ at low energies in the HIGS facility.