Transcript Bariogeneza – wstęp

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
Nothingness is spontaneous, while
an existing Universe must have
required work to form.
Swinburne
Nothingness is uniquely natural,
because simpler than anything else.
Outline
1.
2.
3.
4.
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)
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
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 !
The number
WMAP+BAO+SNe
after Davidson et al., 0802.2962
• corresponds to 20 000 000 001
quarks vs 20 000 000 000
antiquarks – small !
• too big for a fluctuation in
the matter-antimatter
symmetric Universe
A few equations
metrics 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 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.
CP in the Standard Model
daL
W+
daR
ubL
daL
C
W–
ig2Vab
CP
ubR
W– ig2Vab*
ubL
daR
ubR
W– ig2Vab

Sphalerons
1
Sphaleron
field configurations
locally maximizing
energy
V
V
f
1
5
-
5
f
DB=3
DL=3
B – L conserved
B + L violated
Tunelling between vacua in
equilibrium for
1012GeV > T > Tew

Electroweak phase transistion
V
V
T>>Tc
T>>Tc
f
f
T<<Tc
T<<Tc


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
Sphalerons
B+L=0
L
Sphaleron transitions
• conserve B–L
• wash B+L out
B
B–L=const
L asymmetry is
reprocessed into B
asymmetry
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
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
Neutrino masses
two possibilities
L
R
L
R= R
R – new state – sterile neutrino
(not interacting with W,Z0)
only SM states –
but lepton number broken
(so what?)
Dirac particle
Majorana particle
Neutrino masses
seesaw mechanism – 2 possibilities in 1
L
R= R
NR
m= (MEW)2 / MBig
MN = MBig
N L= N L
N:
singlet of SU(2), fermion (Type I)
triplet of SU(2), skalar (Type II)
triplet of SU(2), fermion (Type III)
Generating L asymmetry
generatione
washout
genation
washout
Generating L asymmetry
CP violation
Generating L asymmetry
Equilibrium (in N production)
>
Fast production processes => equilibrium distribution
for RH neutrinos
Strong washout:
Generating L asymmetry
Out of equlibrium (N decay)
Generowanie asymetrii w L
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
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
There are only low-energy (Dirac and Majorana) phases
Branco, Gonzalez Felipe & Joaquim, 2006
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
CP violation:
from high to low energies
Does successful
leptogenesis prefer any
values of the low-energy CP
phases in the neutrino
sector?
phase 2
Davidson, Garayoa, Palorini & Rius, 2008
Markov chain Monte Carlo analysis
phase 1
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