1. Ab Initio Calculation of the Hoyle State
Presentation by John Bromell
Ab Initio Calculation of the Hoyle State
Evgeny Epelbaum, Hermann Krebs, Dean Lee, and Ulf-G. Meißner
Phys. Rev. Lett. 106, – Published 9 May 2011

2. Overarching Purpose
What is the excitation energy of the Hoyle state, and how was it calculated from first principles?

3. Background (History and Physics)
The Hoyle State was predicted by Fred Hoyle in 1954.
F. Hoyle, Astrophys. J. Suppl. Ser. 1, 121 (1954).
It is a zero-spin excited state of 12C.
This state was observed experimentally three years later.
C. Cook, W. A. Fowler, C. C. Lauritsen, and T. Lauritsen, Phys. Rev. 107, 508 (1957).
Without this state, 12C would not form in stars. There would be no carbon-based life, and no CNO cycle.

4. How is 12C formed in stars Alpha particles fuse to form 8Be.
Rarely, a third alpha particle will fuse to make the Hoyle State.
Rarely, the Hoyle state will decay by gamma de-excitation to the ground state of 12C.

5. Methods Chiral Effective Field Theory
Incorporated into Monte Carlo lattice simulations

6. Chiral Effective Field Theory
Series expansion about particle momentum
Scale: Q = the mass of the pion times the speed of light
Separate out Isospin symmetry breaking and electromagnetic effects.

7. Monte Carlo Lattice Simulations
Discretized cubic lattice
Updated every time step
Nucleons interact on this lattice and are updated every time step.

8. Results
Ground state, spin-2 excited state, and zero-spin excited state (Hoyle state) were identified.
The calculated energy of the Hoyle state of 85 MeV was in close agreement with the experimental value of MeV.

9. Conclusion and Further Research
Hoyle State has been successfully calculated from first principles
Meaningful insight into our origins
Check on our understanding of nuclear physics
Structure of the Hoyle State
Structure and Rotations of the Hoyle State. Evgeny Epelbaum, Hermann Krebs, Timo A. Lähde, Dean Lee, and Ulf-G. Meißner. Phys. Rev. Lett. 109,
Improving accuracy of theoretical predictions and experimental measurements