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Lectures recorded at :
http://www.cern.ch/wlap
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
Can not use light microscopes to study atoms !!!
Quantum mechanics tells us that
particles behave like waves and visa versa:
electron
l = h/p
Use electron microscopes
LEP the world’s biggest
electron microscope
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
High Energy electron-proton scattering
quark
electron
New Stuff from
Jet of
Particles
E = Mc2
New, unstable particles, can NOT be explained
as made of up and down quarks only.
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
Practical Units
electron
(energy U)
-
U= 1 eV
= 1.6x10-19J
(speed at positive plate
18 000 km/s)
+
1 Volt
Egil Lillestøl, CERN & Univ. of Bergen
1 keV =
1 MeV =
1 GeV =
1 TeV =
103 eV
106 eV
109 eV
1012 eV
LEP = 209 GeV
LHC = 14 TeV
CERN, 8 February, 2001
Einstein: E = Mc2
Special Relativity:
( E2= (pc)2 + (M0c2)2 )
pc
E
M0c2
use units such that c =1
E (GeV or MeV)
p (GeV/c or MeV/c)
M (GeV/c2 or MeV/c2)
Mproton = 0.931 GeV/c2 ≈ 1 GeV/c2
Melectron = 0.5 MeV/c2
( Mtop = 170 GeV/c2 )
proton diameter = length scale:
10-15 m = 1 fermi (femtometer)
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
Creating New Matter with LEP
fully described by the Standard Model :
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
Ingredients of the Standard Model
To explain all matter we need three generations of quarks
We also have three generations of leptons.
THE COMPLETE PICTURE:
Quarks
charges: 2/3
up
charm
top
-1/3
down
strange
bottom
Leptons
0
ne
nm
nt
-1
electron (e)
muon (m)
tau (t)
Two different sorts of Matter particles:
-composite particles made up of quarks (called HADRONS)
-non composite particles like electrons and neutrinos (LEPTONS)
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
“Fundamental” Matter Particles
heavier
Charge
+2/3
-1/3
0
-1
u
c
t
d
s
b
ne
nm
nt
e
m
t
Egil Lillestøl, CERN & Univ. of Bergen
quarks (q)
leptons
CERN, 8 February, 2001
Composite Matter Particles (hadrons)
made out of quarks ( q ) and anti quarks ( q )
hadrons
Baryons
Mesons
q q q
q q
Anti Baryons
q q q
Egil Lillestøl, CERN & Univ. of Bergen
Hundreds of possible
combinations or particles
CERN, 8 February, 2001
Forces of Nature
name of field (wave)
(*)
force carrier (particle)
gravitational field
electromagnetic field (a)
weak field
strong (color) field
graviton (?)
g (photon)
Z0, W+, W8 gluons, g
higgs field (*)
h0, H0, H+, H-.
(*)Unifying the weak and the electromagnetic fields
giving mass to the Z and the W’s - all other particles !!!
(a) Electric and Magnetic Fields Unified by Maxwell (1864)
Big Question: Can all Force Fields be unified ?
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
How the forces work
the Strong Field (gluons) couple to Quarks
the Weak field (W’s and Z) couple to Leptons
the Electromagnetic field couple to Charge
(classical: F = qE)
the Gravitational field couple to Mass
(Newton: F = mg)
the Higgs field couple to Mass ! ! !
In fact the Higgs field is responsible for the mass !
Can detailed studies of large number of Higgs Particles
give us the explanation why we have three families of
quarks and leptons, and why they have such enormous
mass differences ??
LHC will tell us !
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
The Forces and Particles as Fields
Newton and Gravity
Faraday and Fields
Forces as “Exchange” Particles
Particles as Fields
Forces and Particles as Quantum Fields
Quantum Fields are part of Space itself !
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
How does a point in empty space know exactly
the variety of particles it can produce
and all their properties and their forces .... ???
Back to Heisenberg and Faraday:
Particles and Forces are Quantum Fields filling
every point of “Empty” Space (or the “Vacuum”).
The Fields materialize as Particles when
Energy is fed into this Vacuum.
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
Heisenberg’s Uncertainty Relation:
(Dx)(Dp) ≈ h/(2p)
or
(Dt)(DE) ≈ h/(2p)
(valid for the Fields as well as the Vacuum)
h is Planck’s constant - a very small number, (6.6x10-34Js)
x is position, p is momentum,
t is time, and E is energy.
(Dx) means uncertainty in position, etc
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
In every Point of “Empty” Space there is full Information
on all possible particles and
all the fundamental forces !
Particles are produced when energy is fed into the Vacuum.
Particles appear and disappear, but the “memory” remains
Structures are temporary, the Pattern lasts for ever !
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
With LEP Blowing into the Vacuum
producing the Z0 particle
Collision Probability
resonance curve
resonance width (DE)
Z0-mass
Egil Lillestøl, CERN & Univ. of Bergen
Energy (e+ + e-)
CERN, 8 February, 2001
Z0 Decays :
3 jets
e-
e+
anti lepton
e-
e+
lepton
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
1989-1995: The 4 LEP experiments
collected and studied 17 million Z particles
Z particles decays “democratically” into all possible
quark-anti quark pairs (sometimes accompanied by one or more gluons
and all possible lepton-anti lepton pairs.
Quarks and gluons seen as jets, and charged leptons as single tracks
neutrino-anti neutrino pairs are NOT observed
However, the number of different neutrino species can
be found from the resonance width (or lifetime) of the
Z particle
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
Z0 resonance (line shape):
E (or M)
= 91.2 GeV
DE (or DM)
= 2.5 GeV
Heisenberg:
(DE) (Dt) = h/2p
GeVs)
(h = 4x10-24
(Dt) is the lifetime t and (DE) the resonance width
giving t = 10-25 s corresponding to
Only three light neutrino species, i.e.
only three lepton generations,
and three quark generations.
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
Lifetime of Z0 like water in a leaking bucket:
Z
0
the more and bigger the holes - the shorter the lifetime
a hole = a decay channel;
Sizes of the holes can be calculated using the Standard Model
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
How many “Holes” ?
Quark pairs:
d-d, s-s, b-b
u-u, c-c
Lepton pairs:
e--e+, m-- m +, t-- t+,
n e- n e, n m- n m , ?
charge
1/3
2/3
charge
1
0
number
3 (x3)
2 (x3)
number
3
2+?
Autumn 1989:
Perfect match with 3 different neutrino species.
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
LEP, the Top and the Higgs
H
g
b b
jets
t t
The “tune” of the bb-note has a
nearly imperceptible “overtone”
due to the presence of the
higgs and the top quarks
This overtone can be measured and calculated
from the Standard Model with the higgs mass
and the top mass as free parameters
Predictions: top mass ≈ 175 GeV and higgs mass < 1000 GeV
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
LEP and the Higgs
Fermilab found the top with mass as predicted from LEP:
Standard Model Higgs: MH < 1000 GeV
Lightest Super Symmetric Higgs Mh < 200 GeV
Best fit : Mh ≈ 100 GeV
Within reach of LEP200 !
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
Is the Higgs Idea falsified ?
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
Higgs Hunting with LEP (Total energy 206.6 GeV)
(e- + e+) -----> (Z0 + H) -----> 4 jets
two Higgs jets
containing
B-particles
e-
two Z jets
H (115 GeV)
Z (91 GeV)
e+
2.5 s effect for a Higgs Particle at 115 GeV
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
ALEPH
Egil Lillestøl, CERN & Univ. of Bergen
DELPHI
CERN, 8 February, 2001
B - Particles in DELPHI
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001
Questions for the LHC
- Does Higgs Particles exist ?
- Can all the Forces and Particles be unified ? (Super Symmetry
- Is Dark Matter made of Super Symmetric Particles ?
- What happened to the Antimatter in the Universe ?
- Did the Universe go through a Phase of Quark-Gluon Plasma ?
- Are the Fundamental Particles two-dimensional Strings ?
- Does the Universe have more than three Spatial Dimensions ?
- Are there more Forces and Particles to be discovered ?
- Accelerating Expansion of the Universe and Dark Matter
- Could everything be just wrong ?
The LHC Experiments will be very Exciting !
Egil Lillestøl, CERN & Univ. of Bergen
CERN, 8 February, 2001