Abstract
Variations of fundamental physical constants have been sought for many years using various astronomical objects because their discovery can be key to developing beyond-standard physics. In particular, nuclear reaction rates are sensitive to fundamental constants, so nucleosynthetic processes can be used as a probe. We calculate the evolution and nucleosynthesis of massive Population III stars with the time-dependent nucleon–nucleon interaction δ NN , which may have left traces in elemental abundances in extremely metal-poor stars. The results are compared with the abundances in the most iron-poor star that has ever been discovered, namely, SMSS J031300.36-670839.3. It is found that calcium production in Population III stars is very sensitive to variations of the triple- α reaction rate and hence δ NN . We conclude that variations of the nucleon–nucleon interaction are constrained as − 0.002 < δ NN < 0.002 at the redshift z ∼ 20 , assuming that calcium in SMSS J031300.36-670839.3 originates from hydrogen burning in a massive Population III star.
Highlights
Since the large number hypothesis was proposed by Dirac [1], a lot of laboratory experiments and astronomical observations have been performed to detect variations of fundamental constants [2,3,4].The discovery of such variations, which are predicted by some beyond-standard theories, would be a breakthrough for new physics
Massive Population III stars with >20M are supported by the CNO cycle during the main sequence because the CNO cycle is more sensitive to temperature than the pp-chain [33,34,35,36,37]
It is seen that the initial contraction stops earlier in models with larger δNN because larger triple-α reaction rates create 12 C, which is necessary to start the CNO cycle with lower temperatures
Summary
Since the large number hypothesis was proposed by Dirac [1], a lot of laboratory experiments and astronomical observations have been performed to detect variations of fundamental constants [2,3,4]. The discovery of such variations, which are predicted by some beyond-standard theories, would be a breakthrough for new physics. It has been reported that the evolution of Population III stars is sensitive to the variation of the nucleon–nucleon (N–N) interaction through the effects on the triple-α reaction [7]. Ref. [7] constrained the variation of the N–N interaction from the composition of a CO core, showing that the production of carbon and/or oxygen becomes extreme with a different N–N interaction
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