Parity-violating photon circular polarization in $nd\rightarrow$ $^3H\gamma$ with effective field theory at thermal energy

TL;DR

This paper calculates the parity-violating photon circular polarization in neutron-deuteron radiative capture using pionless effective field theory, providing a leading-order theoretical prediction and comparison with previous models.

Contribution

The study applies pionless EFT to compute $P_ ext{gamma}$ in $nd ightarrow ^3H ext{gamma}$, introducing a systematic EFT framework for parity violation at thermal energies.

Findings

Calculated $P_ ext{gamma}$ at leading order in EFT.

Identified five LECs needed to describe parity violation.

Compared EFT results with previous DDH model calculations.

Abstract

We study the parity-violating effects in $nd\rightarrow$ $^3H\gamma$ process using pionless effective field theory (EFT($//!/!/!/pi$)) at thermal energy. For the weak $NN$ interaction the parity-violating Lagrangian contains five independent low-energy coupling constants (LECs). One can fix the coupling constants by comparison of the calculated observables with a sufficient number of experimental data. So, we need five observables to obtain LECs. One of the five parity-violating observables is the photon circular polarization ($P_\gamma$) in $nd\rightarrow$ $^3H\gamma$ process. We calculate $P_\gamma$ at the leading order in terms of LECs. We compare our results with the previous $P_\gamma$ calculation based on the model of Desplanques, Donoghue, and Holstein.