INTRODUCTION TO PARTICLE PHYSICS Maltese Teacher Programme 2019 KATE SHAW UNIVERSITY OF SUSSEX THE ATLAS EXPERIMENT INTRODUCTION TO PARTICLE PHYSCIS THE LARGE HADRON COLLIDER Collides protons ~ 1 Billion times a second! At the highest ever energy (13 TeV!) INTRODUCTION TO PARTICLE PHYSCIS THE LARGE HADRON COLLIDER The LHC accelerates some of the smallest objects in the universe up to almost the fastest speeds possible in the universe (speed of light) Using magnets 1.9 K (-271.3°C), colder than outer space! INTRODUCTION TO PARTICLE PHYSCIS THE LARGE HADRON COLLIDER The LHC is a particle accelerator 27 KM (almost 17 miles) in circumference Up to 100 m underground! INTRODUCTION TO PARTICLE PHYSCIS THE LARGE HADRON COLLIDER WHAT DOES A PARTICLE PHYSICIST DO? Questions we might ask: ▸Where did everything come from? ▸What is everything made out of? ▸How does it work (interact)? Physicists are ambitious! Particle Physicists want to understand what the fundamental particles of matter are and the fundamental forces between them. What do we mean by ‘Fundamental’? INTRODUCTION TO PARTICLE PHYSCIS THE BEGINNING… BIG BANG 13.8 Billion years ago INTRODUCTION TO PARTICLE PHYSCIS WHERE DID EVERYTHING COME FROM? Edwin Hubble, American Astronomer, first to prove there are galaxies outside of the Milky Way (1924) INTRODUCTION TO PARTICLE PHYSCIS WHERE DID EVERYTHING COME FROM? Hubble showed that the further away a galaxy is from us (or any point in space), the faster it appears to move (1929) INTRODUCTION TO PARTICLE PHYSCIS WHERE DID EVERYTHING COME FROM? Space is stretching at a constant rate! Hubble constant: 42 miles/second/3 million light year steps INTRODUCTION TO PARTICLE PHYSCIS WHERE DID EVERYTHING COME FROM? INTRODUCTION TO PARTICLE PHYSCIS WHAT IS EVERYTHING MADE OF? “The universe is composed of two elements: the atoms and the void in which they exist and move.” ‘All matter consists of invisible particles called ‘atoms’ Democritus , Ancient Greek philosopher, ~5 BC The word atom comes from atomos, an ancient Greek word meaning indivisible ‘Atoms are indestructible, solid but invisible, homogenous, and differ in size, Leucippus , Ancient Greek shape, mass, position and arrangement’ philosopher, ~5 BC INTRODUCTION TO PARTICLE PHYSCIS WHAT IS EVERYTHING MADE OF? In 1869 Russian chemist Dimitri Mendeleev published the periodic table, arranging chemical elements by atomic mass. ~ 80 elements – WHY SO MANY? Is there a simpler structure? INTRODUCTION TO PARTICLE PHYSCIS WHAT IS EVERYTHING MADE OF? Particle Physics seeks to understand fundamental particle and forces Proton Neutron Electron • 1897 electron discovered by J.J. Thompson • 1911 nucleus of the atom discovered by Ernest Rutherford, and nucleus of hydrogen a proton • 1932 neutron discovered by James Chadwick INTRODUCTION TO PARTICLE PHYSCIS WHAT IS EVERYTHING MADE OF? Particle Physics seeks to understand fundamental particle and forces • Photon – particle of the electromagnetic force suggested by Einstein in 1905 • Electromagnetic waves could only exist as discrete wave packets –light quantum or photon INTRODUCTION TO PARTICLE PHYSCIS WHAT IS EVERYTHING MADE OF? However other particles not part of the atom seemed to appear! • 1932 positron detected (predicted by Dirac in 1928) • 1934 neutrinos established in theory – detected in 1956 Cosmic rays • 1937 muons were discovered in cosmic rays Who ordered that? • 1947 pions ( a type of meson) were also discovered!! Things were getting out of hand! What were all these particles? INTRODUCTION TO PARTICLE PHYSCIS WHAT IS EVERYTHING MADE OF? Atom smashers (1950s) Plethora of NEW particles started coming out of these atom smashes! Sigma particles, rho particles, Delta particles, kaons, The Brookhaven Cosmotron, at Lambda… 1.3 – 3.3 GeV accelerator INTRODUCTION TO PARTICLE PHYSCIS WHAT IS EVERYTHING MADE OF? BREAK THROUGH 1960s Murray Gell-Mann of Caltech said hadrons are composed of more fundamental particles which he called quarks. The word comes from a line in Finnegans Wake, a book written by James Joyce. INTRODUCTION TO PARTICLE PHYSCIS WHAT IS EVERYTHING MADE OF? INTRODUCTION TO PARTICLE PHYSCIS WHAT IS EVERYTHING MADE OF? Quarks lived together in twos or threes, making up hadrons like the proton INTRODUCTION TO PARTICLE PHYSCIS HOW DOES EVERYTHING INTERACT? INTRODUCTION TO PARTICLE PHYSICS HOW DOES MATTER INTERACT? INTRODUCTION TO PARTICLE PHYSICS HOW DOES MATTER INTERACT? INTRODUCTION TO PARTICLE PHYSICS THE STANDARD MODEL OF PARTICLE PHYSICS The Higgs boson was the last of the fundamental particles predicted by the Standard Model to be observed. Fundamental particles interact with the Higgs and acquire mass! INTRODUCTION TO PARTICLE PHYSICS THE STANDARD MODEL OF PARTICLE PHYSICS INTRODUCTION TO PARTICLE PHYSICS THE STANDARD MODEL OF PARTICLE PHYSICS INTRODUCTION TO PARTICLE PHYSICS THE STANDARD MODEL OF PARTICLE PHYSICSThe interaction of gauge bosons with fermions is very well described by the standard model INTRODUCTION TO PARTICLE PHYSCIS THE STANDARD MODEL OF PARTICLE PHYSICS First line provides information about force carrying particles and how they interact Second line shows how fermion matter particles interact via by the force carriers Third line shows how the matter particles couple to the Higgs field f , Notice the Yukawa matrix yij which represents the coupling parameter to the Higgs field, and is directly proportional to the mass of a particle Last line shows how vector bosons couple to the Higgs field , and the Higgs field potential INTRODUCTION TO PARTICLE PHYSCIS WHAT IS EVERYTHING MADE OF? INTRODUCTION TO PARTICLE PHYSCIS HOW DO WE STUDY PARTICLE PHYSICS? INTRODUCTION TO PARTICLE PHYSCIS HOW DO WE STUDY PARTICLE PHYSICS? E = mc2 INTRODUCTION TO PARTICLE PHYSCIS HOW DO WE STUDY PARTICLE PHYSICS? INTRODUCTION TO PARTICLE PHYSCIS HOW DO WE STUDY PARTICLE PHYSICS? Particle Physics INTRODUCTION TO PARTICLE PHYSCIS THE ATLAS EXPERIMENT INTRODUCTION TO PARTICLE PHYSCIS THE ATLAS EXPERIMENT INTRODUCTION TO PARTICLE PHYSCIS THE ATLAS EXPERIMENT INTRODUCTION TO PARTICLE PHYSCIS THE ATLAS EXPERIMENT ATLAS comprises 5000 scientists from about 180 institutions around the world, representing 38 countries INTRODUCTION TO PARTICLE PHYSCIS THE ATLAS EXPERIMENT INTRODUCTION TO PARTICLE PHYSCIS THE ATLAS EXPERIMENT Standard Model Production Cross Section Measurements Status: August 2016 ] total (x2) b 11 ATLAS Preliminary 10 inelastic Theory p [ √ Run 1,2 s =7, 8,13 TeV √ nj ≥ 1 LHC pp =7 σ 6 s TeV 10 0.1 < pT < 2 TeV Data 4.5 − 4.9fb−1 nj ≥ 2 0.3 < mjj < 5TeV 105 √ LHC pp s =8TeV pT > 25 GeV −1 4 Data 20.3fb 10 nj ≥ 0 √ LHC pp s =13 TeV 3 nj ≥ 0 n ≥ 1 10 j nj ≥ 0 Data 0.08 − 14.8fb−1 total WW pT > 100 GeV nj ≥ 2nj ≥ 1 t -chan 2 nj ≥ 1 WW 10 WW total nj ≥ 2 nj ≥ 3 Wt WZ nj ≥ 2 WZ ggF 1 nj ≥ 3 ZZ WZ 10 nj ≥ 4 H→WW nj ≥ 3 nj ≥ 4 W γ ZZ ZZ nj ≥ 4 nj ≥ 5 s-chan Z γ nj ≥ 5 nj ≥ 4 H→ττ 1 nj ≥ 6 nj ≥ 5 Zγ nj ≥ 6 nj ≥ 7 nj ≥ 5 VBF −1 nj ≥ 6 H→WW 10 nj ≥ 8 nj ≥ 6 nj ≥ 7 H→γγ −2 nj ≥ 7 10 nj ≥ 7 H→ZZ→4ℓ W ± W ± 10−3 WZ pp Jet s γ W Z t¯t t VV γγ H Vγ t¯tWt¯tZ t¯t γ Zjj WW Zγγ Wγγ VVjj R= 0.4 EWK Excl. EWK fid. fid. fid. fid. tot. tot. fid. fid. fid. tot. tot. fid. fid. tot. fid. fid. fid. INTRODUCTION TO PARTICLE PHYSCIS THE ATLAS EXPERIMENT INTRODUCTION TO PARTICLE PHYSCIS THE ATLAS EXPERIMENT The observed signal strengths and uncertainties for different Higgs boson decay channels and their combination for mH=125.36 GeV Signal strength μ = σ/σSM Deviation from μ =1 could indicate new physics! INTRODUCTION TO PARTICLE PHYSCIS THE ATLAS EXPERIMENT INTRODUCTION TO PARTICLE PHYSCIS SEARCHES FOR NEW PHYSICS!! STANDARD MODEL PHYSICS HIGGS PHYSICS TOP QUARK PHYSICS BEYOND STANDARD MODEL PHYSICS SUPERSYMMETRY EXOTICS DARK MATTER EXTRA DIMENSIONS/ STRING THEORY… INTRODUCTION TO PARTICLE PHYSCIS VISIT HTTP://WWW.ATLAS.CERN/ FOR ALL YOUR PHYSICS NEEDS .