Slide1 : Particle Physics
(experimentalists view) 2004/2005 Particle and Astroparticle Physics Master
Overview : Overview Aim:
To make current experimental frontline research in particle physics accessible to you. I.e. publications, seminars, conference talks, etc.
To get an idea: look at recent conference talks, e.g. on http://www.ichep02.nl
Program:
The theoretical framework:
Quantum Electro Dynamics (QED): electro-magnetic interaction
Quantum Flavor Dynamics (QFD): weak interaction
Quantum Color Dynamics (QCD): strong interaction
The experiments:
History
Large-Electron/Positron-Project (LEP): “standard” electro-weak interaction physics
Probing the proton: “standard” strong interaction physics
K0-K0, B0-B0 and neutrino oscillations: CP violation (origin of matter!)
Large-Hadron-Collider (LHC): electro-weak symmetry breaking (origin of mass!)
Fantasy land (order TeV ee and colliders, neutrino factories, …)
Administration : Administration Literature:
“Introduction to Elementary Particles” D. Griffiths
“Quarks & Leptons” F. Halzen & A. Martin
“The Experimental Foundations of Particle Physics” R. Cahn & G. Goldhaber
“Gauge Theories in Particle Physics” I.J.R. Aitchison & A.J.G. Hey
“Introduction to High Energy Phyics” D.H. Perkins
“Facts and Mysteries in Elementary Particle Physics” (M. Veltman)
“Review of Particle Properties” http://pdg.lbl.gov
Exam:
Course participation & exercises
Written exam (probably one at each semester’s end)
Our coordinates:
F. Linde, Tel. 020-5925134 (NIKHEF-H250), f.linde@nikhef.nl
S. Bentvelsen, Tel. 020-5925140 (NIKHEF-H241), s.bentvelsen@nikhef.nl
G. Raven, Tel. 020-5925107 (NIKHEF-N327), g.raven@nikhef.nl
Your coordinates:
Room H222b at NIKHEF
Slide4 : The social side: Friday’s between 17:00 and 18:00
“happy hour” at few locations at NIKHEF Biertje?
Slide5 :
Particle Physics II
Quantum Flavour Dynamics: QFD (4)
Low q2 weak interaction
High q2 weak interaction
Electro-weak interaction
Experimental highlights: LEP
Origin of mass? (2)
Symmetry breaking
Higgs particle: in ee and in pp
Origin of matter? (6)
K0-K0, oscillations
B0-B0 oscillations
Neutrino oscillations
Fantasy land (2)
Particle Physics I
Introduction, history & overview (1)
Concepts (3):
Units (h=c=1)
Symmetries (quark model, …)
Relativistic kinematics
Cross section, lifetime, decay width, …
Quantum Electro Dynamics: QED (6-7)
Spin 0 electrodynamics (Klein-Gordon)
Spin ½ electrodynamics (Dirac)
Experimental highlights: “g-2”, ee, …
Quantum Chromo Dynamics: QCD (3-4)
Colour concept and partons
High q2 strong interaction
Structure functions
Experimental highlights: s, ep, … I. Introduction, history & overview Lecturers: Thomas Peitzmann
Stan Bentvelsen
Paul Kooijman
Marcel Merk
Slide6 : Introduction
Particle physics: particles & forces : Particle physics: particles & forces
Slide8 : e electron p proton n qelectron = 1.61019 C 1 neutron
Slide9 : Particles: masses & history
Forces: masses & history : Forces: masses & history
How do we get particles? I. From outer space: cosmic rays : How do we get particles? I. From outer space: cosmic rays
How do we get particles? II. Nuclear reactions: powerplants & sun : How do we get particles? II. Nuclear reactions: powerplants & sun
How do we get particles? III. Particle accelerators : How do we get particles? III. Particle accelerators
Particle accelerator: example : Particle accelerator: example
Experiment at particle accelerator: schematic : Experiment at particle accelerator: schematic
What do we measure? I. Bound state energy levels : What do we measure? I. Bound state energy levels
What do we measure? II. Particle mass, lifetime and decay width : What do we measure? II. Particle mass, lifetime and decay width
What do we measure? III. Particle scattering : What do we measure? III. Particle scattering
How do we observe particles? I. Tracking : How do we observe particles? I. Tracking
Track reconstruction: an example : Track reconstruction: an example time measurement
space measurement Real life: in magnetic field B; curvature gives particle momentum p; p/p p (you check!)
How do we observe particles? II. Calorimetry : How do we observe particles? II. Calorimetry Simple Model:
ee with: E’=1/2E
ee with: E’=1/2E
Interactions after a
“radiation length (XRL) Characteristics:
After X radiation lengths:
Multiplicity: N(X)=2X
Energy/particle: E(X)=E0/2X
Charged track length: T(X)XRL2X
Particle energy equal Emin:
Xmin = ln(E0/Emin) / ln(2)
T(Xmin) XRL E0/Emin E0
Energy reconstruction: an example : Energy reconstruction: an example This gives you:
shower center coordinates (X0,Y0)
observed energy fraction tot (i;X0,Y0) 1 Efit Ei /tot Eseen /tot
quality of fit (figure of merit)
possibility to correct for dead channels
Real detectors: many sub-systems : Real detectors: many sub-systems
LEP I events: e+e- Z ff : LEP I events: e+e- Z ff
LEP I results : LEP I results cross sections asymmetries
LEP II events: e+e- W+W- …. : LEP II events: e+e- W+W- …. How best to determine W-boson mass from these events?
LEP II results : LEP II results cross sections W-boson mass
Fit all available data to the “Standard Model” : Fit all available data to the “Standard Model”
Real life: resolution, inefficiency, breakdown, … : Real life: resolution, inefficiency, breakdown, … Solution, simulate your data sample in great detail i.e.:
the underlying physics of interests (event generator e.g. e+e- Z +-)
detector response (GEANT; software package for particle passage through material)
specific detector reconstruction software and your own event selection/analysis code
Monte Carlo integration technique : Monte Carlo integration technique
Slide32 : History
Historical overview : Historical overview Periodic system of elements (Mendeleev)
Electron discovery (Thomson 1897)
Photon as a particle (Einstein, Compton, …: 1900-1924)
Atomic structure (Rutherford 1911)
Positron discovery (First anti-particle, Anderson 1931)
Anti-proton discovery (1955)
Cosmic rays muon, pion, … (1937, 1946, …)
Strange particles (1946, 1951, …)
Neutrino’s “observed” (1958)
Charmed particles (1974)
Gluon discovery (1979)
W and Z bosons (1983)
t-quark discovery (1995)
Neutrino oscillations (atmospheric (1998) and solar (2000))
-neutrino discovery (2000)
XVI. Higgs boson discovery?
Mendeleev: periodic system of elements : Mendeleev: periodic system of elements Chaos
order
better understanding
predictions (new elements)
new insights
Thompson (1897): electron : Thompson (1897): electron
Joseph Thomson (1856-1940) : Joseph Thomson (1856-1940) Nobel Prize 1906
In recognition of the great merits of his theoretical and experimental investigations on the conduction of electricity by gases
Rutherford (1911): 4He-Au scattering experiment : Rutherford (1911): 4He-Au scattering experiment
Cross section calculation : Cross section calculation
Earnest Rutherford (1871-1937) : Earnest Rutherford (1871-1937) Nobel Prize 1908 (Chemistry!)
For his investigations into the disintegration of the elements and the chemistry of radioactive substances
Bohr (1914): energy levels in atoms : Bohr (1914): energy levels in atoms Experiment showed emission (absorption) of specific, element dependent, wavelengths! Discreteness of energy levels hard to reconcile with the classical atomic model
Niels Bohr (1885-1962) : Niels Bohr (1885-1962) Nobel prize 1922
For his services in the investigation of the structure of atoms and of the radiation emanating from them"
Chadwick (1932): the neutron discovery : Chadwick (1932): the neutron discovery 14C nucleus:
14 protons
7 electrons
spin ½
experiment: spin 1
James Chadwick 1891 - 1974 : James Chadwick 1891 - 1974 Nobel Prize 1935
For the discovery of the neutron
The photon (1900-1924) as a particle : The photon (1900-1924) as a particle
Max Planck (1858-1947) : Max Planck (1858-1947) Nobel prize 1918
In recognition of the services he rendered to the advancement of Physics by his discovery of energy quanta In 1916 Millikan stated on the foto-electric effect:
“Einstein’s photo electric equation … appears in every case to predict exactly the observed results…. Yet the semi-corpuscular theory by which Einstein arrived at this equation seems at present wholly untenable”
Albert Einstein (1879-1955) : Albert Einstein (1879-1955) Nobel prize 1921
For his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect
Robert Andres Millikan (1868-1953) : Robert Andres Millikan (1868-1953) Nobel price 1923
For his work on the elementary charge of electricity and on the photo-electric effect
Arthur Holly Compton (1892-1962) Charles Thomson Rees Wilson (1969-1959) : Arthur Holly Compton (1892-1962) Charles Thomson Rees Wilson (1969-1959) Nobel prize 1927
"for his discovery of the effect named after him"
"for his method of making the paths of electrically charged particles visible by condensation of vapour" In de quantum-velden theorie is een interactie (of kracht) het gevolg van uitwisseling van veld-quanta
Anti-matter : Anti-matter How do you avoid that all particles tumble into the negative energy levels?
The anti-particles: e and p : The anti-particles: e and p anti-particles: predicted to exist by Dirac
Werner Schrodinger (1887 – 1961) Paul Dirac (1902 – 1984) : Werner Schrodinger (1887 – 1961) Paul Dirac (1902 – 1984) Nobel Prize 1933
For the discovery of new productive forms of atomic theory
Anderson (1905 – 1991) : Anderson (1905 – 1991) Nobel Prize 1936
For his discovery of the positron
Sin-Itiro Tomonaga (1906 – 1979) Julian Schwinger (1918 – 1994) Richard Feynman (1918 – 1988) : Sin-Itiro Tomonaga (1906 – 1979) Julian Schwinger (1918 – 1994) Richard Feynman (1918 – 1988) Nobel prize 1965
For their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles
Mathematische consistente theorie voor electro-magnetische kracht: Quantum-Electro-Dynamica (QED)
The pion () and the muon () : The pion () and the muon ()
Strange particles : Strange particles
Murray Gell-Mann (1929) : Murray Gell-Mann (1929) Nobel prize 1969
For his fundamental contributions to our knowledge of mesons and baryons and their interactions
Also for having developed new algebraic methods which have led to a far-reaching classification of these particles according to their symmetry properties. The methods introduced by you are among the most powerful tools for further research in particle physics.
Neutrino’s : Neutrino’s existence of the neutrino postulated by Pauli:
Martin Perl (1927) Frederick Reines (1918 – 1998) (Cowan had died) : Martin Perl (1927) Frederick Reines (1918 – 1998) (Cowan had died) Nobel Prize 1995
For pioneering experimental contributions to lepton physics:
for the discovery of the tau lepton
for the detection of the neutrino
Leptongetal : Leptongetal 1962: Experiment shows that there exists something like “conservation of lepton number”
Leon M. Lederman (1922) Melvin Schwartz (1932) Jack Steinberger (1921) : Leon M. Lederman (1922) Melvin Schwartz (1932) Jack Steinberger (1921) Nobel Prize 1988
For the neutrino beam method and the demonstration of the doublet structure of the leptons through the discovery of the muon neutrino
Charmed particles (1974) : Charmed particles (1974)
Burton Richter (1931) Samuel Ting (1936) : Burton Richter (1931) Samuel Ting (1936) Nobel Prize 1976
For their pioneering work in the discovery of a heavy elementary particle of a new kind
And many many more particles ……… : And many many more particles ………
Sheldon Lee Glashow (1932) Abdus Salam (1926 – 1996) Steven Weinberg (1933) : Sheldon Lee Glashow (1932) Abdus Salam (1926 – 1996) Steven Weinberg (1933) Nobel Prize 1979
For their contributions to the theory of the unified weak and electromagnetic interaction between elementary particles, including, inter alia, the prediction of the weak neutral current
Gerardus 't Hooft (1946) Martinus Veltman (1931) : Gerardus 't Hooft (1946) Martinus Veltman (1931) Nobel Prize 1999
For elucidating the quantum structure of electroweak interactions in physics
The W and Z bosons: SppS collider : The W and Z bosons: SppS collider
Carlo Rubbia (1934) Simon van der Meer (1925) : Carlo Rubbia (1934) Simon van der Meer (1925) Nobel Prize 1984
For their decisive contributions to the large project, which led to the discovery of the field particles W and Z, communicators of weak interaction
Gluon discovery : Gluon discovery
The t-quark: Tevatron collider : The t-quark: Tevatron collider
Higgs discovered @ LEP? : Higgs discovered @ LEP?
Slide72 : outstanding issues (only a selection!):
Why 3 families?
Neutrino masses?
Why matter/anti-matter balanced distorted?
How to incorporate mass? Higgs?
Dark matter in universe?
Further unification of interactions?
Gravity?
Slide73 : Overview
Quantum-Electro-Dynamics (QED) The theory of electrons, positrons and photons : Quantum-Electro-Dynamics (QED) The theory of electrons, positrons and photons First and most successful Quantum Field Theory (1948: Feynman, Tomonaga, Schwinger) electric charge
based on a local U(1) gauge symmetry
field quantum: photon
QED: coupling constant em & perturbation series : QED: coupling constant em & perturbation series Feynman diagrams do not represent particle trajectories; they are just a symbolic notation to facilitate the calculation of physics quantities like cross-sections, lifetimes, … e.g.: (ge-2)/2 1159.6521869 (41) 106
QED: ee cross-section “calculation” : QED: ee cross-section “calculation”
The running QED coupling constant: em(q2) : Each electron is surrounded by a “cloud” of ee pairs!
Through polarisation this cloud (partial) shields the bare electron charge. The “effective” charge (I.e. interaction strength) you experience depends on how close you get! The running QED coupling constant: em(q2)
Running of em : Running of em em(0) =1/137.0359895(61)
Quantum-Chromo-Dynamics (QCD) The theory of quarks and gluons : Quantum-Chromo-Dynamics (QCD) The theory of quarks and gluons color charge
based on a local SU(3) gauge symmetry
field quanta: eight gluons g
QCD: color interaction : QCD: color interaction Quarks carry color; anti-quarks carry anti-color
Gluons carry a color and anti-color charge; eight (not nine!) possible combinations
The size of the strong coupling constant: s : The size of the strong coupling constant: s
Slide82 : ”Asymptotic freedom” The running QCD coupling constant: S(q2)
Running of s : Running of s S(MZ) =0.1190.004
QCD confinement and jets : QCD confinement and jets Within a proton the quarks rattle around and behave as almost free particles because at such distances the strong coupling constant s is small.
This we call asymptotic freedom.
Once the distances between individual quarks becomes large; the coupling constant gets large and in the region in between the quarks new
particle/anti-particle pairs can be created.
This we call confinement.
QCD jets in e+e annihilation : QCD jets in e+e annihilation
Weak interaction: introduction : Weak interaction: introduction The lifetime of the ++ particle, 10-23 s, corresponds to the time it takes the decay products (p+) to separate by about 1 fm, which in turn corresponds to about the proton diameter. This is typical for the strong interaction.
Quantum-Flavor-Dynamics (QFD) The weak interaction theory : Quantum-Flavor-Dynamics (QFD) The weak interaction theory which charge?
based on a local SU(2) gauge symmetry
field quanta: W+, W and Z0 bosons Note:
Later we will see that the weakness of the weak interaction is not due to a small coupling constant, but finds its origin in the heaviness of the W and Z0 field quanta.
Weak interaction vertices & diagrams : Weak interaction vertices & diagrams
The “skewed” weak interaction : The “skewed” weak interaction
Interaction summary : Interaction summary
The “Standard model” : The “Standard model” Gauge symmetry based on SU(3)xSU(2)xU(1) groups
Open question: are these interactions unified at a (very) high energy scale?