Is There a Sign of New Physics in Beryllium Transitions?

Abstract

We discuss the current status of the anomaly in beryllium-8 nuclear transitions recently reported in the angular distribution of internal conversion electron-positron pairs. We present a phenomenological analysis of the signal and review the models proposed to explain it, focusing on those involving a new light protophobic vector gauge boson. We also elaborate on the prospects of verifying the anomaly in present and future experiments.

Comments: 19 pages + references, 10 figures; Invited talk given at the American Physical Society April Meeting 2017, Washington, DC, January 28, 2017; based mainly on arXiv:1604.07411 [hep-ph] and arXiv:1608.03591 [hep-ph]