Effects of theta on the deuteron binding energy and the triple-alpha process

TL;DR

This paper investigates how a non-zero theta parameter influences nuclear binding energies and the triple-alpha process, finding that effects are moderate, which suggests stability against small variations in fundamental parameters.

Contribution

It introduces a framework to analyze the impact of theta on nuclear forces and processes, highlighting the robustness of nuclear systems against small CP-violating effects.

Findings

Effects on binding energies are moderate

Triple-alpha process remains largely unaffected

Nuclear systems show resilience to small theta variations

Abstract

We study the effects that a non zero strong-CP-violating parameter theta would have on the deuteron and diproton binding energies and on the triple-alpha process. Both these systems exhibit fine tuning, so it is plausible that a small change in the nuclear force would produce catastrophic consequences. Such a nuclear force is here understood in the framework of an effective Lagrangian for pions and nucleons, and the strength of the interaction varies with theta. We find that the effects are not too dramatic.