Compton scattering from ${}^4$He at the TUNL HI$\gamma$S facility

Differential cross sections for elastic Compton scattering from ${}^4$He have been measured with high statistical precision at the High Intensity $\gamma$-ray Source at laboratory scattering angles of ${55}^{\circ }$, ${90}^{\circ }$, and ${125}^{\circ }$ using a quasi-monoenergetic photon beam with a weighted mean energy value of $81.3$ MeV. The results are compared to previous measurements and similar fore-aft asymmetry in the angular distribution of the differential cross sections is observed. This experimental work is expected to strongly motivate the development of effective-field-theory calculations of Compton scattering from ${}^4$He to fully interpret the data.