Histoire de l’univers

infinite,

G8

H30k

20

c

finite,c

1k

infinite,c

1k

c

Early universe: photons + ultra-relativistic particles radiation era

42rad Tc

2

22

radt

G32/c3c

2/1tT 2/1tRR1

T

Grand and super unification of all interactions

Thermal equilibrium: interaction rate> volume expansion

interaction rate per unit time (one particle): (n=density)

volume expansion:

relative expansion per unit time:

0Hvn

dt)x(H3)x()dtH1(x)x( 30

330

3 nvN

0H

relativistic particles loose energy between interactions because of expansion

hc

hE

E'

hc'h'E

uud

p

p

duu

ud

ud

uud

p

ud

p

duu

ud

if

2pcm2E

annihilatenn,ppGeV2cm2kT 2p

p

p

p

p

2pcm2E

as soon as

When kt<2mc2= 280 MeV, t=10-4 s, the last hadrons annihilate ,

except for a few non relativistic protons and neutrons, surviving thanks to a small asymmetry between matter and antimatter ( ). This is today’s matter!

This requires

1) small B non conservation, not included in the SM GUT

2) CP non conservation

CKM q mixing contributes, but may not be sufficient

neutrino mixing matrix also has a CP non conservation phase, which may do the job

3) Non equilibrium

910

pn

np

W W

s1t,MeV3kTfordecouple

kTEEm

g: cm

2cm4

W

4

e e

e e

W

e

e e

e e

e

e

e

,

onlyeofsurplussmallleaving

s'boosting,annihilatee,e

s10t

MeV1cm2kTwhenends 2e

t<1 s:

Neutrino freeze out at kT=0.8 MeV :

t> 10 s: primordial nucleosynthesis

remain photons, and a few electrons and non relativistic p, n in thermal equilibrium

Deuterium 2H is then the start of other fusion reactions, leading to light nuclei

s887epn

nep

pen

ne

e

e

MeV293.1c)mm(mckTmc

expN

N 2pn

22

p

n

20.0N

N

p

n

npH

MeV2.2QQHpn

epn

2

2

e

ends when MeV05.0kT

LiHeH

LieBe

BeHeHe

ppHeHeHe

HHn

HeHp

Hnp

743

e77

743

433

32

32

2

Nucleosynthesis

No stable nuclei with A=5, 8, primordial nucleosynthesis ends here!

N

NB 10104

005.0044.0

mkg10)4.00.4(

B

328B

After that the universe is filled with photons, electrons and light nuclei in thermal equilibrium

e-+p H(atom)+

slows down when ends for kT 0.3 eV, t=105 yr

,eV6.13IkT

t>105 yr matter (neutral atoms) and radiation decouple

no more Compton interaction with charged particles:

Universe becomes transparent to radiation (photons) relic photons

now cooled down to Cosmic Microwave Background (CMB)

e

e

BIG BANG

10-43 sec

10-32 sec

10-11 sec

10-4 sec

100 sec

300’000 yr109 yr

15x109 yr

gravity separates

EW Weak+Elec

inflation ends

quarks p, n

p, n He

formation of atoms

galaxy formationtoday

normal expansion

COBE

COBE

T=2.735 K

waves/cm

inte

nsity

, 10

-4er

g/cm

2 sr

sec

cm-1

3cm5410n

d

1e

h

c

8d)T,(ukTh3

2

black body, Planck

Relic of the early universe

WMAP (NASA)

WMAP

CMB