1. Why is there something rather than nothing
Why is there something rather than nothing? Baryogenesis and leptogenesis
Krzysztof Turzyński Institute of Theoretical Physics Faculty of Physics, University of Warsaw

2. Early natural philosophy
Leibniz, 1697
Nothingness is spontaneous, while an existing Universe must have required work to form.
Swinburne
Nothingness is uniquely natural, because simpler than anything else.

3. Outline Rudiments Electroweak baryogenesis
Baryogenesis through leptogenesis
Leptogenesis vs neutrino and other experiments
M. Olechowski, S. Pokorski, K. Turzyński, J.D. Wells, “Reheating Temperature in Gauge Mediated Models of Supersymmetry Breaking”, JHEP 0912 (2009)

4. The paradigm observations consistent with hot Biga Bang
• nucleosynthesis (T1MeV) ligt element abundances
• decoupling of radiation (T1eV) power spectrum of the cosmic microwave background
BBN: im mniej barionów, tym później fotony nie są w stanie efektywnie rozbijać jąder deuteru, tym później rozpoczyna się cykl reakcji jądrowych, ale do tego czasu rozpadnie się więcej neutronów -> mniej He
CMB: Im więcej barionów, tym większy potencjał grawitacyjny nakłada się na zaburzenia DM I przeciwdziała rozrzedzaniu zaburzeń w płynie barionowo-fotonowym -> niski drugi pik w CMB
details of both processes depend on relatice densities of baryons and photons

5. The number WMAP+BAO+SNe BBN
after Davidson et al.,
WMAP+BAO+SNe
BBN
• corresponds to quarks vs antiquarks – small !
Mozna tez wyznaczac z CMB przy zalozeniu LambdaCDM i spektrum HZ

7. The number WMAP+BAO+SNe
after Davidson et al.,
WMAP+BAO+SNe
• corresponds to quarks vs antiquarks – small !
• too big for a fluctuation in the matter-antimatter symmetric Universe

8. A few equations metrics of the Universe Friedmann equation
continuity equation
input from particle physics
equation of state

9. History of a particle species
Photons of avg energy T cannot create efficiently create particles of mass >T
Universe too rarefied for the massive particles to meet at all 1

10. interaction rate > expansion rate

11. Sakharov conditions
Conditions necessary for dynamical generation of a nonzero baryon number in the initially matter-antimatter symmetric Universe. 1
B violation 2
C and CP violation 3
departure from thermal equilibrium

12. Sakharov conditions Remark 1. Any quantum number will do
L, B – L, B + L ...
Remark 2. If B violating interactions are even back to equilibrium, they completely wash out previously generated asymmetry.

13. CP in the Standard Model
daL
ubL W+
ig2Vab
daL
ubL W– C
daR
ubR W–
ig2Vab*
daR
ubR W–
ig2Vab CP 

14. Sphaleron field configurations locally maximizing energy
Sphalerons
Sphaleron field configurations locally maximizing energy V 
DB=3 DL=3
B – L conserved
B + L violated
Tunelling between vacua in equilibrium for 1012GeV > T > Tew 

15. Electroweak phase transistion
T>>Tc
T<<Tc  V
T<<Tc
T>>Tc V   

16. Bubble wall allows more quarks than antiquarks inside
A bubble of broken phase forms. It expands rapidly, coallescing with other bubbles. Eventually the entire Universe sits inside a bubble of broken phase.
Bubble wall allows more quarks than antiquarks inside
You are here
phase of broken symmetry
Remaining antiquarks are destroyed in sphaleron transitions
phase of unbroken symmetry

17. Sphalerons B+L=0 L Sphaleron transitions • conserve B–L • wash B+L out
B–L=const
Sphaleron transitions • conserve B–L • wash B+L out
L asymmetry is reprocessed into B asymmetry

18. Neutrino masses 1. Oscillations 2. Tritium decay
3. Cosmology (CMB vs LSS)
WMAP
WMAP+BAO+SNe
WMAP+BAO+Sne+HST+MegaZ
after Thomas et al,

19. Fermion interacting with a spinless particle changes helicity.
Neutrino masses L R
Fermion interacting with a spinless particle changes helicity.
Interactions with a constant vacuum expectation value of a scalar field => mass: Higgs mechanism

20. Neutrino masses L R R= R L two possibilities Dirac particle
R – new state – sterile neutrino (not interacting with W,Z0)
only SM states – but lepton number broken (so what?)
Dirac particle
Majorana particle

21. Neutrino masses L R= R NR NL= NL
seesaw mechanism – 2 possibilities in 1 L
R= R NR
NL= NL
N: singlet of SU(2), fermion (Type I) triplet of SU(2), skalar (Type II) triplet of SU(2), fermion (Type III)
m= (MEW)2 / MBig
MN = MBig

22. Generating L asymmetry
genation
washout
generatione
washout

23. Generating L asymmetry
CP violation

24. Generating L asymmetry
Equilibrium (in N production)
>
Fast production processes => equilibrium distribution for RH neutrinos
Strong washout:

25. Generating L asymmetry
Out of equlibrium (N decay)

26. Generowanie asymetrii w L

27. Summary I
The origin of the baryon asymmetry of the Universe remains a mystery. Different options are still possible, but some have already been ruled out.
Leptogenesis appears a reasonably natural option

28. Leptogenesis vs low-energy CP violation
CP asymmetry relevant for leptogenesis
Neutrino Yukawa couplings ?
CP asymmetry potentially observable in terrestrial experiments

29. CP violation: from low to high energies
There are only low-energy (Dirac and Majorana) phases
Branco, Gonzalez Felipe & Joaquim, 2006

30. CP violation: from low to high energies
SUSY enters the game: in mSUGRA models additional constraints from LFV processes and electron EDM
Joaquim, Masina & Riotto, 2006

31. CP violation: from high to low energies
Davidson, Garayoa, Palorini & Rius, 2008
Markov chain Monte Carlo analysis
phase 1
phase 2
Does successful leptogenesis prefer any values of the low-energy CP phases in the neutrino sector?

32. Summary II
The origin of the baryon asymmetry of the Universe remains a mystery. Different options are still possible, but some have already been ruled out.
Leptogenesis appears a reasonably natural option
Alas, not testable!
Generically requires T>109 GeV. In SUSY models this leads to overproduction of gravitinos, ruining nucleosynthesis