Viability of carbon-based life as a function of the light quark mass
  The Hoyle state plays a crucial role in the helium burning of stars that have reached the red giant stage. The close proximity of this state to the triple-alpha threshold is needed for the production of carbon, oxygen, and other elements necessary for life. We investigate whether this life-essential condition is robust or delicately fine-tuned by measuring its dependence on the fundamental constants of nature, specifically the light quark mass and the strength of the electromagnetic interaction. We show that there exist strong correlations between the alpha-particle binding energy and the various energies relevant to the triple-alpha process. We derive limits on the variation of these fundamental parameters from the requirement that sufficient amounts of carbon and oxygen be generated in stars. We also discuss the implications of these results for an anthropic view of the universe. 
Evgeny Epelbaum, Hermann Krebs, Timo A. L\"ahde, Dean Lee, Ulf-G.   Mei{\ss}ner
nucl-th hep-lat hep-ph