CERN, 8 February, 2001 Egil Lillestøl, CERN & Univ. of Bergen Lectures recorded at :

CERN, 8 CERN, 8 February, 2001February, 2001Egil Lillestøl, CERN & Univ. of BergenEgil Lillestøl, CERN & Univ. of Bergen

Lectures recorded at :

http://www.cern.ch/wlap



Can not use light microscopes to study atoms !!!

Quantum mechanics tells us thatparticles behave like waves and visa versa:

h/p

Use electron microscopes

LEP the world’s biggestelectron microscope

electron


electron

quark

New Stuff from E = Mc2

New, unstable particles, can NOT be explainedas made of up and down quarks only.

High Energy electron-proton scattering

Jet ofParticles


electron(energy U)

U= 1 eV= 1.6x10-19J(speed at positive plate18 000 km/s)

1 keV = 103 eV1 MeV = 106 eV1 GeV = 109 eV1 TeV = 1012 eV

LEP = 209 GeVLHC = 14 TeV

Practical Units

- +

1 Volt


Einstein: E = Mc2

pc

use units such that c =1 E (GeV or MeV)p (GeV/c or MeV/c)M (GeV/c2 or MeV/c2)

M0c2Mproton = 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)

E

Special Relativity:( E2= (pc)2 + (M0c2)2 )


Creating New Matter with LEP

fully described by the Standard Model :


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 Leptons

charges: 2/3 -1/3 0 -1 up down e electron (e) charm strange muon ()

top bottom tau

Two different sorts of Matter particles:-composite particles made up of quarks (called HADRONS)-non composite particles like electrons and neutrinos (LEPTONS)


u

d

c

s

t

b

e

e

Charge

+2/3

-1/3

0

-1

quarks (q)

leptons

“Fundamental” Matter Particles

heavier


q q q

Composite Matter Particles (hadrons)made out of quarks ( q ) and anti quarks ( q )

Baryons Mesons

q q q q q

Anti BaryonsHundreds of possible

combinations or particles

hadrons


Forces of Nature

name of field (wave) force carrier (particle)

gravitational field graviton (?) electromagnetic field (a) (photon) weak field Z0, W+, W-

strong (color) field 8 gluons, g

higgs field (*) h0, H0, H+, H-..

(*)Unifying the weak and the electromagnetic fieldsgiving 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 ?

(*)


the Strong Field (gluons) couple to Quarksthe Weak field (W’s and Z) couple to Leptonsthe 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 Particlesgive us the explanation why we have three families ofquarks and leptons, and why they have such enormousmass differences ??

How the forces work

LHC will tell us !


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 !


How does a point in empty space know exactlythe variety of particles it can produceand all their properties and their forces .... ???

Back to Heisenberg and Faraday:Particles and Forces are Quantum Fields fillingevery point of “Empty” Space (or the “Vacuum”).

The Fields materialize as Particles whenEnergy is fed into this Vacuum.


Heisenberg’s Uncertainty Relation:

(x)(p) ≈ h/(2) or (t)(E) ≈ h/(2)

(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.(x) means uncertainty in position, etc


Structures are temporary, the Pattern lasts for ever !

In every Point of “Empty” Space there is full Information on all possible particles andall the fundamental forces !

Particles are produced when energy is fed into the Vacuum.Particles appear and disappear, but the “memory” remains


With LEP Blowing into the Vacuum producing the Z0 particle

Energy (e+ + e-)

Collision Probability

Z0-mass

resonance curve

resonance width (E)


e- e+

e- e+

lepton

anti lepton

3 jetsZ0 Decays :


1989-1995: The 4 LEP experimentscollected 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 tracksneutrino-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


Z0 resonance (line shape):

E (or M) = 91.2 GeV

E (or M) = 2.5 GeV

Heisenberg: (E) (t) = h/2 (h = 4x10-24 GeVs)

(t) is the lifetime and (E) the resonance widthgiving = 10-25 s corresponding to

Only three light neutrino species, i.e.only three lepton generations,and three quark generations.


Z0

Lifetime of Z0 like water in a leaking bucket:

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


How many “Holes” ?

Quark pairs: charge numberd-d, s-s, b-b 1/3 3 (x3)u-u, c-c 2/3 2 (x3)

Lepton pairs: charge numbere--e+, -- +, -- +, 1 3e- e, - , ? 0 2+?

Autumn 1989:Perfect match with 3 different neutrino species.


LEP, the Top and the Higgs

H

t tg

b b

jets

The “tune” of the bb-note has anearly imperceptible “overtone” due to the presence of thehiggs and the top quarks

This overtone can be measured and calculatedfrom the Standard Model with the higgs massand the top mass as free parameters

Predictions: top mass ≈ 175 GeV and higgs mass < 1000 GeV


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 !


Is the Higgs Idea falsified ?


Higgs Hunting with LEP (Total energy 206.6 GeV)

e- e+H (115 GeV)

Z (91 GeV)

two Higgs jetscontainingB-particles

two Z jets

2.5 effect for a Higgs Particle at 115 GeV

(e- + e+) -----> (Z0 + H) -----> 4 jets


ALEPH DELPHI


B - Particles in DELPHI


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 !

Documents

CERN, 8 February, 2001 Egil Lillestøl, CERN & Univ. of Bergen Lectures recorded at :