Baryogenesis by hedongchenchen

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									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 BX not equal 0 at T<<mX
 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 BX=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) excluded by experiment
       Some states of Higgs multiplet can
       decay into baryons.

2. SO(10) only possible with fine tuned choice of GUT scale
       Similar decays like SU(5)

3. In SM not enough CP violation
       Sphalerons are nice

4. In MSSM only with highly finetuned parameters
       can in principle cure CP problem of SM
                            don´t know - looks involved
3. Other Susy with Affleck-Dine baryogenesis
       Using generic features of Susy
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)

								
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