Introduction to Particle Physics I

Transcription

1 Introduction to Particle Physics I Introduction Risto Orava Spring

2 outline Lecture I: Introduction, the Standard Model Lecture II: Particle detection Lecture III: Relativistic kinematics Lectures IV: Decay rates and cross sections Lecture V: The Dirac equation Lecture VI: Particle exchange Lecture VII: Electron-positron annihilation

3 outline continued... Lecture VIII: Electron-proton elastic scattering Lecture IX: Deeply inelastic scattering Lecture X: Symmetries and the quark model

4 COURSE INFORMATION WEB-OODI WILL CONTAIN COURSE INFORMATION & LINK TO THE HOME PAGE HOME PAGE WILL HAVE (LECTURE-BY-LECTURE) PDF-VERSIONS OF THE LECTURES, REFERENCE LITERATURE & LINKS TO RELEVANT WEB SITES THE COURSE MOSTLY FOLLOWS Modern Particle Physics by Mark Thomson, OTHER RECOMMENDED TEXT BOOKS WILL BE LISTED USE THE PDG & WEB! EXERCISES WILL BE HELD FROM NEXT WEEK ON (Mikael Mieskolainen) THESE WILL CONTRIBUTE TO THE FINAL SCORE SPECIAL ASSIGNMENTS ON KEY TOPICS FOR PAIRS OF STUDENTS TO BE PREPARED AND PRESENTED ONE INTERMEDIATE AND ONE FINAL EXAM (B324) and (B322) available for consultation at Physicum appointment by , please.

5 personal background Risto Orava STUDIES: MSc in physics and theoretical physics (-74, UH), PhD (-81/Fermilab) RESEARCH: (1) At CERN, Switzerland -74, -75, , (staff scientist), (visiting scientist), 2000 on (50%); (2) Fermilab (Wilson Fellow, staff scientist) EXPERIMENTS: antiproton-proton/proton-proton/ proton-nucleus/nucleus-nucleus/k ± p/ neutrino- & antineutrino-nucleon/e + e - /astroparticle physics experiments physics analysis responsible in a number of experiments leadership positions in collaborations CEURRENT RESEARCH ACTIVITIES: ALICE/LHC: diffractive scattering MoEDAL/LHC: magnetic monopoles, dark matter, susy... LHC Ring as a detector PUBLICATIONS: 1000, h-index > 100

6 INTRODUCTION TO PARTICLE PHYSICS " BUILDING BLOCKS: LEPTONS, QUARKS, GAUGE & HIGGS BOSON(S), MESONS, BARYONS,.. " THEORY FRAMEWORK: QED, QCD, ELECTROWEAK THEORY, CONSERVATION LAWS, MIXING (QUARK/ NEUTRINO TYPES) " THE BIG PICTURE: GRAND UNIFICATION, SUPERSYMMETRY, STRING THEORY, EXTRA DIMENSIONS, BIG BANG,... " TECHNICAL TOOLS: QUANTUM MECHANICS, RELATIVISTIC KINEMATICS, MATHEMATICS, PHYSICS CONSTANTS, EXPERIMENTS & DETECTOR PHYSICS, MONTE CARLO &PHYSICS & DATA ANALYSIS TECHNIQUES, PROBABILITY & STATISTICS, ACCELERATORS

7 What do we know about matter and interactions? matter particles: quarks and leptons carriers of interactions: gluons, photon, W/Z intermediate bosons, graviton? the Standard Model (EW+QCD), gravitation theory, supersymmetry? Higgs! 7

8 are available what tools how to cover a dynamic range of m! LEP Tevatron LHC

9 the standard model ν 57 elementary particles? m top m ν > 10 12? the Standard Model flavor structure is too complicated for a theory of elementary constituents

10 small energy content matter and energy large energy content matter molecule atom nucleus proton/ quark neutron u cm 10-9 m m m m chemistry biology atom physics nuclear physics <10-19 m electron <10-19 m particle physics 10

11 fundamental forces force mediator strength depende nce on distance range [m] vahva gluoni 1 ~ r ~ sähkö fotoni 0.01 ~ 1/r 2 exp( m heikko W/Z W, Z ( ) ~ paino gravitoni? ~ 1/r 2 d dr r r) Note: Nuclear energy is based on collective interaction between large number of nucleons (protons & neutrons). The force between nucleons is a tiny remnant of the strong force at distances in excess of m.

12 atoms are > % empty electron. nucleus γ

13 protons are > % empty g proton u u d

14 but this empty space is full of potential for change: matter and energy is being created and annihilated at extremely high rate ainetta anti-ainetta VACUUM FLUCTUATIONS GROUND STATE OF ENERGY? Casimir-efekti

15 the minimum energy? vacuum fluctuations: continuous matter-energy transitions within Δt s fills the vacuum observed experimentally contradiction between cosmology and particle physics theory: the minimum energy of the universe between J/cm 3? 15

16 Aine, energia, tila ja aika nivoutuvat yhteen. supernauhat? perusvoimien yhteys inflaatioäkillinen laajentuminen perusvoimat erkaantuvat ydinhiukkaset syntyvät atomit syntyvät tähdet syntyvät tänään aika s s s 10-5 s vuotta 10 9 vuotta vuotta energia TeV TeV 1 TeV 150 MeV 1eV 4 MeV 0,7 MeV extrapolaatio hiukkaskiihdyttimet (LHC, Tevatron) 16

17 the highest energy? estimated energy that corresponds to the over-all mass of the universe: Joule? Note: With the present level of energy consumption (in * J was used), we would use during the next 14 billion years ( afe of the universe) about (=0, %) of the total in our unverse.

18 u u-quark -68 c c -74 t -94 g(-79) d s b -77 d-quark γ e electron 1897 µ -37 τ -75 W/Z(-83) ν e electron neutrino-56 ν µ -68 ν τ -00 I II III Higgs! 18

19 fundamental forces and Big Bang E (GeV) Theories of everything? Time after Big Bang (seconds) Grand Unified Theories? Theories Standard Model Higgs boson 10-9 Gravity Strong Weak Relative strength EM Experimental reality - LEP et al. 19

20 open questions? (1) number of fundamental families & their hierarchies? (2) the Standard Model how far does it work? (3) QCD Colour confinement of quarks and gluons? (4) origin of masses Higgs boson? (5) The Big Picture hints of physics beyond the SM? How to find answers to these questions? - what tools are needed? 12

21 e + e - scattering What is being measured? g 2 g 2 time Μ g 2 Μ 2 = ΜΜ* g 4 α em = g 2 = e 2 4πε 0!c

22 Standard Model interactions... forces mediated by gauge bosons g Z e g s g W

23 e - e - è e - e - scattering Μ γ 2 α 2 α = g 2 = e 2 4πε 0!c Μ γγ 2 α 4

24 particle decays g W g W

25 ρ 0 resonance decay g s Μ γ 2 α 2 g s Μ g 2 αs 2 g W g W Μ W 2 α W 2

26 Large Hadron Collider proton-proton collider 14TeV L3 PARTICLE PHYSICS EVOLVES THROUGH FRONTIER EXPERIMENTS! 6

27 World Colliders FNAL HH RICH SLAC e + e - B-Factory pp Tevatron 2TeV BNL e - p HERA DESY CERN pp LHC 14 TeV KEK e + e - B-Factory IHEP e - e+ t Factory BINP e - e+ t Factory IHEP e - p HERA What Next? * e + e - Linear Collider * ν Factory * µ Collider * Very Big Accelerator 27

28 Big Bang level energy densities in laboratory environment! 28

29 CMS-experiment tons 21,5m long 4Tesla magnetic field 40 nationalities 200 institutes 3000 researchers 29

30 big bang at the LHC collider in 2010 matter and energy created for nothing vacuum fluctuations

31 THE BASIC PRINCIPLE OF A COLLIDER EXPERIMENT 1011 E = mc

32 e + e - Z o - number of families N ν = 3. within << 1% 32

33 higgs searches -the Bjorken process Z o l + l -,qq,νν - - Higgs boson decays to the heaviest fermions possible. H o - bb,τ + τ -,gg,cc- 75% 33

34 e + e - hadrons Colour coherence! Quarks & Gluons are confined inside the hadrons- -How to tell where the quarks & gluons are? 42

35 52

36 A MULTIMUON COSMIC EVENT IN ALICE 36

37 Coupling to ordinary matter? Masses of the susy particles? Fermion-Boson Symmetric 37

38

39 supersymmetry? tunnettu aine unifies matter and energy every know particle has its supersymmetric sparticle unifies fundamental forces unified theory of matter & energy? explains dark matter/energy? voimakkuus supersymmetrinen peili-aine perusvoimien yhteys? sähkö heikko energia GeV-yksiköissä

40 extra dimensions?

41 what is the physics that hides extra dimensions? if extra spatial dimensions exist, they are difficult to probe experimentally several possible explanations the extra spatial dimensions are compact and small Nordstrom, Kaluza, and Klein, circa 1920

42 particles from strings a microscopic wiggling - string looks like a particle, its dimensions and wigglings are are too small to be seen the momentum of the string vibrations, and the energy of the string stretching, produce the mass of the particle in the rest frame of the cm of the string, this is m 2 = E 2 stretch p 2 x p 2 y p 2 z

43 three more reasons to take extra dimensions seriously cosmology the Standard Model of particle physics string theory

44 classical general relativity already tells us that spacetime is dynamical the three spatial dimensions that are observed are changing expanding and the process is not understood what is the dark energy driving the expansion?

45 ..in fact, little is understood! it is not understood what drove cosmic inflation in the early universe it is not understood what this is

46 ..extra dimensions may help extra dimensions may explain the dynamical evolution of the 3 spatial dimensions that we observe

47 the shape, content, and dynamics of extra dimensions may account for complexities of particle physics slice of a 6 dimensional Calabi-Yau manifold

48 the basic matter/energy entities as unknown today % dark energy 80% 60% 40% dark matter 20% 0% dark matter neutrinos! matter stars 48 61

49 SOME COSMOLOGICAL PARAMETERS THE ENERGY DENSITY BUDGET Ω B BARYONS Ω CDM COLD DARK MATTER Ω ν Ω DE NEUTRINOS DARK ENERGY Ω TO T = Ω B + Ω CD M + Ω ν + Ω D E

50 E = mc 2 64 TIME AND ENERGY ARE BORN TOGETHER

51 NEXT: Lecture II Particle detection CERN Summer Student program: 65