Why is there something rather than nothing? Baryogenesis and leptogenesis

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

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

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 details of both processes depend on relatice densities of baryons and photons

5. The number WMAP+BAO+SNe after Davidson et al., 0802.2962 BBN • corresponds to 20 000 000 001 quarks vs 20 000 000 000 antiquarks – small !

7. The number WMAP+BAO+SNe after Davidson et al., 0802.2962 • too big for a fluctuation in the matter-antimatter symmetric Universe • corresponds to 20 000 000 001 quarks vs 20 000 000 000 antiquarks – small !

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

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

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

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

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

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

17. B+L=0 L B B–L=const Sphalerons 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, 0911.5291

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

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

21. L R=R NR NL=NL Neutrino masses seesaw mechanism – 2 possibilities in 1 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. generatione genation washout washout Generating L asymmetry

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 Does successful leptogenesis prefer any values of the low-energy CP phases in the neutrino sector? phase 2 phase 1

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