The Big Bang, the LHC and the Higgs Boson

Dr Cormac O’ Raifeartaigh (WIT)

Overview

I. LHC

What, How and Why

II. Particle physicsThe Standard Model

III. LHC Expectations

The Higgs boson and beyond

Big Bang Cosmology

The Large Hadron Collider

No black holes

High-energy proton beams

Opposite directions

Huge energy of collision

E = mc2 Create short-lived particles

Detection and measurement

Why

Explore fundamental constituents of matter

Investigate inter-relation of forces that hold matter together

Study early universe

Highest energy since BB

Mystery of dark matter Mystery of antimatter

Cosmology

E = kT → T =

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

Careers

Mathematics theory

Theoretical physics expected collisions

Experimental physicists experiments

Engineers detector design

Computer scientists world wide web

Software engineers GRID

Particle physics (1930s)

• atomic nucleus (1911)

• most of atom empty

• electrons outside

• strong nuclear force?

Periodic Table: determined by protons

• inside the nucleus proton (1909) neutron (1932)

Four forces of nature Force of gravityHolds cosmos togetherLong range

Electromagnetic force Holds atoms together

Strong nuclear force Holds nucleus together

Weak nuclear force: Radioactivity

The atom

Splitting the nucleus (1932)

Cockcroft and Walton: linear accelerator

Accelerator used to split the nucleus

Nobel prize (1956)

H1 + Li3 = He2 + He2

Verified mass-energy (E= mc2)Verified quantum tunnelling

Cavendish Lab, Cambridge (1928)

Nuclear fission

fission of heavy elements Meitner, Hahn

energy release

chain reaction

nuclear weapons

nuclear power

Particle physics (1950s)

Cosmic raysParticle accelerators

cyclotron π + → μ + + ν

Particle Zoo

Over 100 particles

Quarks (1960s)

new periodic tablep,n not fundamental symmetry arguments

quarks

new fundamental particlesUP and DOWNprediction of -

Gell-Mann, ZweigStanford experiments 1969

Quark model

Six different quarks(u,d,s,c,t,b)

Strong force = quark force

Six leptons

(e, μ, τ, υe, υμ, υτ)

Gen I: all of matter

Gen II, III redundant

Electro-weak unification

Unified field theory

em + w = e-w interaction

Mediated by W and Z bosons

Higgs mechanism to generate mass

Predictions• Weak neutral currents (1973)• W and Z gauge bosons (CERN, 1983)

Rubbia, Van der MeerNobel prize

The Standard Model (1970s)

Strong force = quark force (QCD)

EM + weak force = electroweak

Matter particles: fermions

Force particles: bosonsQFT: QED

Prediction: W+-,Z0 boson

Detected: CERN, 1983

Standard Model : particles

• Success of QCD, e-w many questions

Higgs boson outstanding

III. LHC expectations

Higgs boson

120-180 GeV

Set by mass of top quark, Z boson

Search

Beyond the SM: supersymmetry

Extensions of Standard ModelGrand unified theory (GUT) Theory of everything (TOE)

Supersymmetrysymmetry of bosons and fermionsimproves GUTcircumvents no-go theoremsTheory of Everything

Phenomenology Supersymmetric particles?Broken symmetry

Expectations II: cosmology

√ 1. Exotic particles

√ 2. Unification of forces

3. Nature of dark matter?neutralinos?

4. Matter/antimatter asymmetry? LHCb

High E = photo of early U

SummaryHiggs bosonClose chapter on SM

Supersymmetric particlesOpen next chapter

CosmologyNature of Dark MatterMissing antimatter

Unexpected particlesRevise theory

Epilogue: CERN and Ireland

World leader

20 member states

10 associate states

80 nations, 500 univ.

Ireland not a member

No particle physics in Ireland

European Organization for Nuclear Research