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Why is there something rather than nothing? Baryogenesis and leptogenesis. Krzysztof Turzyński Institute of Theoretical Physics Faculty of Physics, University of Warsaw. Early natural philosophy. Leibniz, 1697. - PowerPoint PPT Presentation
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Why is there something rather than nothing?
Baryogenesis and leptogenesis
Krzysztof TurzyńskiInstitute of Theoretical Physics
Faculty of Physics, University of Warsaw
Early natural philosophy
Leibniz, 1697
Swinburne
Nothingness is spontaneous, while an existing Universe must have required work to form.
Nothingness is uniquely natural, because simpler than anything else.
Outline1. Rudiments2. Electroweak baryogenesis3. Baryogenesis through leptogenesis4. 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)
The paradigmobservations consistent with hot Biga Bang
• nucleosynthesis (T1MeV)ligt element abundances
• decoupling of radiation (T1eV) power spectrum of the cosmic microwave background
details of both processes depend on relatice densities of baryons and photons
The number
• corresponds to 20 000 000 001 quarks vs 20 000 000 000 antiquarks – small !
after Davidson et al., 0802.2962
WMAP+BAO+SNe
BBN
The number
• too big for a fluctuation in the matter-antimatter symmetric Universe
after Davidson et al., 0802.2962
WMAP+BAO+SNe
• corresponds to 20 000 000 001 quarks vs 20 000 000 000 antiquarks – small !
A few equationsmetrics of the Universe
Friedmann equation
continuity equation
equation of state
input from particle physics
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
interaction rate > expansion rate
expansion rate
interaction rate
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
Sakharov conditionsRemark 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.
CP in the Standard Model
daL
ubL
W–
C
CP
daL
ubL
W+ ig2Vab
daR
ubR
W– ig2Vab
daR
ubR
W– ig2Vab*
Sphalerons
Tunelling between vacua in equilibrium for 1012GeV > T > Tew
-1
1
-5 5
V
Sphaleron field configurations locally maximizing
energy
B=3L=3
B – L conserved
B + L violated
V
Electroweak phase transistion
T<<Tc
T>>TcV
T>>Tc
T<<Tc
V
A bubble of broken phase forms. It expands rapidly, coallescing with other bubbles.
Eventually the entire Universe sits inside a bubble of broken phase.
Remaining antiquarks are destroyed in
sphaleron transitions
Bubble wall allows more quarks than antiquarks inside
phase of broken symmetry
phase of unbroken symmetry
You are here
B
LB+L=0
B–L=const
Sphalerons
Sphaleron transitions • conserve B–L• wash B+L out
L asymmetry is reprocessed into B asymmetry
Neutrino masses1. Oscillations
2. Tritium decay
3. Cosmology (CMB vs LSS)
WMAP
WMAP+BAO+SNe
WMAP+BAO+Sne+HST+MegaZ
after Thomas et al, 0911.5291
Neutrino massesFermion interacting with a spinless particle changes
helicity. L R
Interactions with a constant vacuum expectation value of a scalar field => mass: Higgs mechanism
Neutrino massestwo possibilities
L R R= RL
R – new state – sterile neutrino (not interacting with W,Z0)
Dirac particle
only SM states – but lepton number broken
(so what?)
Majorana particle
Neutrino massesseesaw mechanism – 2 possibilities in 1
L R= R
NR NL= NL
m= (MEW)2 / MBig
MN = MBig
N: singlet of SU(2), fermion (Type I)triplet of SU(2), skalar (Type II)triplet of SU(2), fermion (Type III)
Generating L asymmetrygeneratione
washout
genation
washout
Generating L asymmetryCP violation
Generating L asymmetryEquilibrium (in N production)
>
Fast production processes => equilibrium distribution for RH neutrinos
Strong washout:
Generating L asymmetryOut of equlibrium (N decay)
Generowanie asymetrii w L
Summary IThe 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
Leptogenesis vs low-energy CP violation
Neutrino Yukawa couplings
CP asymmetry relevant for leptogenesis
CP asymmetry potentially observable in terrestrial experiments
?
CP violation:from low to high energies
Branco, Gonzalez Felipe & Joaquim, 2006
There are only low-energy (Dirac and Majorana) phases
CP violation:from low to high energies
Joaquim, Masina & Riotto, 2006
SUSY enters the game:in mSUGRA models additional constraints from LFV processes and electron EDM
CP violation:from high to low energies
Davidson, Garayoa, Palorini & Rius, 2008Markov chain Monte Carlo analysis
Does successful leptogenesis prefer any values of the low-energy CP phases in the neutrino sector?
phase 1
phas
e 2
Summary IIThe 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