Re-creating the Big Bang Walton, CERN and the Large Hadron Collider Albert Einstein Ernest Walton Dr Cormac O’ Raifeartaigh (WIT)

Overview I. LHC What, why, how II. A brief history of particles From the atom to the Standard Model III. LHC Expectations The Higgs boson Beyond the Standard Model

CERN European Organization for Nuclear Research World leader 20 member states 10 associate states 80 nations, 500 univ. Ireland not a member No particle physics in Ireland

The Large Hadron Collider High-energy proton beams Opposite directions Huge energy of collision E = mc2 Create short-lived particles Detection and measurement No black holes

How E = 14 TeV λ =1 x 10-19 m Ultra high vacuum Low temp: 1.6 K LEP tunnel: 27 km Superconducting magnets

Particle detectors

Why t = 1x10-12 s Explore fundamental constituents of matter Investigate inter-relation of forces that hold matter together Glimpse of early universe Answer cosmological questions t = 1x10-12 s V = football Highest energy since BB

Cosmology E = kT → T =

Particle cosmology

LHCb Where is antimatter? Asymmetry in M/AM decay CP violation Tangential to ring B-meson collection Decay of b quark, antiquark CP violation (UCD group) Quantum loops

Discovery of electron Crooke’s tube cathode rays Perrin’s paddle wheel mass and momentum Thompson’s B-field e/m Milikan’s oil drop electron charge Result: me = 9.1 x 10-31 kg: TINY

Atoms: centenary Maxwell (19th ct): atomic theory of gases Dalton, Mendeleev chemical reactions, PT Einstein: (1905): Brownian motion due to atoms? Perrin (1908): measurements λ = λ = Perrin (1908) Einstein

The atomic nucleus (1911) Most projectiles through A few deflected backwards Most of atom empty Atom has nucleus (+ve) Electrons outside Rutherford (1911)

Nuclear atom +ve nucleus 1911 proton (1909) Periodic Table: determined by protons neutron (1932) strong nuclear force?

Four forces of nature Force of gravity Holds cosmos together Long range Electromagnetic force Holds atoms together Strong nuclear force: holds nucleus together Weak nuclear force: Beta decay The atom

Splitting the nucleus Cockcroft and Walton: linear accelerator Protons used to split the nucleus (1932) H + Li = He + He Verified mass-energy (E= mc2) Verified quantum tunnelling Nobel prize (1956)

Ernest Walton (1903-95) Born in Dungarvan Early years Limerick, Monagahan, Tyrone Methodist College, Belfast Trinity College Dublin (1922) Cavendish Lab, Cambridge (1928) Split the nucleus (1932) Trinity College Dublin (1934) Erasmus Smith Professor (1934-88)

Nuclear fission fission of heavy elements Meitner, Hahn energy release chain reaction nuclear weapons nuclear power

Strong force SF >> em protons, neutrons charge indep short range HUP massive particle Yukawa pion 3 charge states

New particles (1950s) Cosmic rays Particle accelerators cyclotron π + → μ + + ν

Particle Zoo Over 100 particles

Quarks (1960s) new periodic table p+,n not fundamental isospin symmetry arguments (SU3 gauge group) prediction of - SU3 → quarks new fundamental particles UP and DOWN Stanford experiments 1969 Gell-Mann, Zweig

Quantum chromodynamics scattering experiments colour chromodynamics asymptotic freedom confinement infra-red slavery The energy required to produce a separation far exceeds the pair production energy of a quark-antiquark pair,

Quark generations Six different quarks (u,d,s,c,t,b) Six leptons (e, μ, τ, υe, υμ, υτ) Gen I: all of matter Gen II, III redundant

Gauge theory of e-w interaction Unified field theory of e and w interaction Salaam, Weinberg, Glashow Above 100 GeV Interactions of leptons by exchange of W,Z bosons and photons Higgs mechanism to generate mass Predictions Weak neutral currents (1973) W and Z gauge bosons (CERN, 1983)

The Standard Model (1970s) Matter: fermions quarks and leptons Force particles: bosons QFT: QED Strong force = quark force (QCD) EM + weak = electroweak Prediction: W+-,Z0 boson Detected: CERN, 1983

Standard Model (1970s) Success of QCD, e-w Higgs boson outstanding many questions

Today: LHC expectations Higgs boson 120-180 GeV Set by mass of top quark, Z boson Search

Main production mechanisms of the Higgs at the LHC Ref: A. Djouadi, hep-ph/0503172

Decay channels depend on the Higgs mass: Ref: A. Djouadi, hep-ph/0503172

For low Higgs mass mh  150 GeV, the Higgs mostly decays to two b-quarks, two tau leptons, two gluons and etc. In hadron colliders these modes are difficult to extract because of the large QCD jet background. The silver detection mode in this mass range is the two photons mode: h   , which like the gluon fusion is a loop-induced process.

A summary plot: Ref: hep-ph/0208209

Beyond the SM: supersymmetry Super gauge symmetry symmetry of bosons and fermions removes infinities in GUT solves hierachy problem Grand unified theory Circumvents no-go theorems Gravitons ? Theory of everything Phenomenology Supersymmetric particles? Broken symmetry

Expectations III: cosmology √ 1. Exotic particles √ 2. Unification of forces 3. Missing antimatter? LHCb 4. Nature of dark matter? neutralinos? High E = photo of early U

Summary Higgs boson Close chapter on SM Supersymmetric particles Open chapter on unification Cosmology Missing antimatter Nature of Dark Matter Unexpected particles Revise theory

Epilogue: CERN and Ireland European Organization for Nuclear Research World leader 20 member states 10 associate states 80 nations, 500 univ. Ireland not a member No particle physics in Ireland