Transverse Asymmetry in Nucleon Deuteron Scattering in Pionless Effective Field Theory

TL;DR

This paper uses pionless effective field theory to calculate neutron-deuteron scattering observables, especially the transverse asymmetry $A_y$, and suggests that higher-order terms can resolve the longstanding $A_y$-puzzle.

Contribution

The study introduces two-body P-wave interactions at NN3LO in pionless EFT, successfully addressing the $A_y$-puzzle and improving agreement with experimental data.

Findings

Calculated polarization observables at NN3LO

Found that P-wave interactions resolve the $A_y$-puzzle

Achieved good agreement with experimental data

Abstract

In this dissertation we apply the pionless effective field theory to low energy neutron deuteron elastic scattering process. We calculated some of the polarization observables in neutron deuteron scattering to next-to-next-to-next-to-leading-order, in particular the transverse asymmetry $A_y$. All of the previous calculations have the same characteristic feature of under-predicting this observable, this is known as the $A_y$-puzzle. At this order of the pionless EFT new two-body $P$-wave interaction terms enter into the Lagrangian. This interaction terms give crucial contributions to the $A_y$ observable. By varying the interaction coefficients within the allowed error estimates of the pionless EFT we find results that at this order are consistent with the experimental data. Our conclusion is that the $A_y$-puzzle is likely to be solved within the next few orders of the \EFT. Other observables in neutron-deuteron scattering process are also calculated and are in good agreement with the experimental data.