Introduction

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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 ee 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

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The social side: Friday’s between 17:00 and 18:00 “happy hour” at few locations at NIKHEF Biertje?

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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 ee 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”, ee, … Quantum Chromo Dynamics: QCD (3-4) Colour concept and partons High q2 strong interaction Structure functions Experimental highlights: s, ep, … I. Introduction, history & overview Lecturers: Thomas Peitzmann Stan Bentvelsen Paul Kooijman Marcel Merk

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Introduction

Particle physics: particles & forces: 

Particle physics: particles & forces

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e electron p proton n qelectron = 1.61019 C  1 neutron

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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

Particleaccelerator: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: ee with: E’=1/2E ee 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

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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?

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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?

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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)  106

QED: ee  cross-section “calculation”: 

QED: ee  cross-section “calculation”

The running QED coupling constant: em(q2) : 

Each electron is surrounded by a “cloud” of ee 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

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”Asymptotic freedom” The running QCD coupling constant: S(q2)

Running of s : 

Running of s S(MZ) =0.1190.004

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?