Baryogenesis Astrophysical Seminar 2004/2005 Ben Koch

Outline Baryon assymmetry Three conditions for baryogenesis Baryon number - what is it? Sphalerons Other candidates baryon number violation

Matter- antimater asymmetrie: Solar system: Separation of matter antimatter regions: Define number densities for baryons

Expansion of Universe dilutes densities, for relative change look at Taking - Boltzmann distribution of photon densities - Hubble expansion of the Universe - measured primordial deuterium and hydrogen abundances

Different way of looking at baryon asymmetry via entropy with (compare ) g * is counting the effective degrees of freedom of all particles. This gives in an analogous way:

Three conditions for baryogenesis 1. There must be baryon number non conserving interactions in nature. clear but not observed in nature for example proton decay...

2. there must be C- and CP violating interactions in nature. Consider: If C exact symmetry: So in total: -from bar: -from anti bar: with (*): = (*)

3. the baryon-number non-conserving process occurs when the universe is not in thermal equilibrium Consider Particle X with B X not equal 0 at T<<m X in thermal equilibrium: Antiparticle: A baryon number non-conserving process in thermal eqilibrium requires

BN what is it? & Sphalerons Tooooooo many formulas, go to black board

Other candidates for baryon number violation Generally: The decay of heavy particles X with B X =0 into baryonic particles in the early universe can produce a baryon number violating effect Such particles and interactions are provided by several GUT´s (great unification)

1. SU(5) Some states of Higgs multiplet can decay into baryons. 2. SO(10) Similar decays like SU(5) 3. In SM Sphalerons are nice 4. In MSSM can in principle cure CP problem of SM 3. Other Susy with Affleck-Dine baryogenesis Using generic features of Susy excluded by experiment only possible with fine tuned choice of GUT scale not enough CP violation only with highly finetuned parameters don´t know - looks involved

Conclusion: Interesting and vital field of physics, for which it is too early to make more than preliminary conclusions.

Appendix - Bailin and Love, Cosmolgy in gauge field and string theory (2004) - Rubakov, Lecture in summer school cosmology and astroparticle physics, ICTP Trieste (2004)