The Big Bang, the LHC and the God Particle

Cormac O’Raifeartaigh (WIT)

Black Holes, the LHC and the God Particle

Dr Cormac O’Raifeartaigh (WIT)

Overview

I. LHC

What, why, how

II. A brief history of particles

From the nucleus to the Standard Model

III. LHC Expectations

The God particle

Beyond the Standard Model

Cosmology at the LHC

E = mc2

The Large Hadron Collider (CERN)

No black holes

Particle accelerator

Head-on collision of protons

Huge energy density

Create short-lived particles

Detection

Why

I. Explore fundamental constituents of matter

Investigate inter-relation of forces that hold matter together

II. Study early universe

Highest energy since BB

T = 1019 K

t = 1x10-12 s

V = football

• Puzzle of antimatter• Puzzle of dark matter

Cosmology

E = kT → T =

How

Ultra-high vacuum

Low temp: 1.6 K

v = speed of light

E = 14 TeV (2.2 µJ)

LEP tunnel: 27 km Superconducting magnets

600 M collisions/sec (1.3 kW)

Particle detectors

4 main detectors

• CMS multi-purpose

•ATLAS multi-purpose

•ALICE quark-gluon plasma

•LHC-b antimatter decay

UCD group

Particle detectors

Tracking devicemeasures momentum of charged particle

Calorimeter measures energy of particle by

absorption

Identification detector measures velocity of particle by Cherenkov radiation

Matter and Energy

Matter is a form of energy

E = mc2

Energy is a form of matterm = E/c2

→ Create matter and antimatter from energy

Antimatter

Predicted by Dirac Equation

Electron of opposite charge

Detected 1932

All particles have opposites

Why is universe dominated by matter?

Black Holes

• Huge mass shrunk to tiny volume

• Extreme gravitational field

• Light, matter ‘trapped’

Huge energy required

m = E/c2

II Particle physics (1930s)

• Atoms (1909) Brownian motion

• The atomic nucleus (1911) Rutherford Backscattering

• Proton (1918)

• Neutron (1932)

Protons and the Periodic Table

• Fundamental differences in atoms

no. protons in nucleus

• Determines electron configuration

• Determines chemical properties

What holds nucleus together? What causes radioactivity?

Strong force (Yukawa, 1934)

strong force >> em

charge indep (p+, n)

short range

Heisenberg Uncertainty

massive particle

3 charge states

Yukawa pion (1947)

Yukawa

Weak force (Fermi, 1934)

Radioactivity (B decay)

Electrons from nucleus? no p+ + e- ?

But: energy, momentum missing

New particle; tiny mass, zero charge neutrino

no p+ + e- + (confirmed 1956)

Four forces of nature Force of gravityHolds cosmos togetherLong range

Electromagnetic force Holds atoms together

Strong nuclear force: holds nucleus together

Weak nuclear force: Beta decay

Walton: accelerator physics

Cockcroft and Walton: linear accelerator Protons used to split the nucleus (1932)

Nobel prize (1956)

1H1 + 3Li6.9 → 2He4 + 2He4

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

Cavendish lab, Cambridge

New particles (1950s)

Cosmic rays Particle accelerators

LINACS (Walton)synchrotronsπ+ → μ+ + ν

Particle Zoo (1950s, 1960s)

Over 100 particles

Quarks (1960s theory)

p not fundamental

new periodic table

symmetry arguments

new fundamental particles quarks

Up, down, strange

prediction of -

Gell-Mann, Zweig

Quarks (experiment, 1970s)

Stanford experiments 1969

Scattering experiments

Similar to RBS

SF = interquark force!

defining property = colour

confinement

infra-red slavery

The energy required to produce a separation far exceeds the pair production energy of a quark-antiquark pair

Quark generations (1970s –1990s)

30 years experiments

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

Six leptons (electron sisters)

(e, μ, τ, υe, υμ, υτ)

Gen I: all of ordinary matter

Gen II, III redundant?

Electro-weak force (1970s)

Electromagnetic + weak forces = e-w force

Single interaction above 100 GeV

Predictions: W+-,Z0 bosons

Detected: CERN, 1983

Mediated by new particles W, Z

Higgs mechanism to generate mass

Rubbia, Van der Meer Glashow, Salaam and Weinberg Nobel prize 1979

Nobel prize 1984

The Standard Model (1970s)

EM + weak force = electroweak

Strong force = quark force (QCD)

Force between quarks caused by colour

Matter particles: fermions

Force particles: bosons

Standard Model: 1980-1990s

• experimental success but Higgs boson outstanding

key particle: too heavy?

III LHC expectations (SM)

Higgs boson

Determines mass of other particles

Set by known mass of top quark, Z boson

120-180 GeV

Search…surprise?

Main production mechanisms of the Higgs at the LHC

Ref: A. Djouadi,hep-ph/0503172

Ref: hep-ph/0208209

Higgs search: summary

Expectations II: Beyond the SM

Unified field theory

Grand unified theory (GUT): 3 forces

Theory of everything (TOE): 4 forces

Supersymmetry

symmetry of fermions and bosons

improves GUT (circumvents no-go theorems)

gravitons: makes TOE possible

LHC

Supersymmetric particles?

Extra dimensions?

Expectations III: Cosmology

High E = photo of early U

1. Superforce:SUSY particles?

2. SUSY = dark matter? neutralinos? double whammy

3. Missing antimatter ? LHCb

LHCb (UCD)

Tangential to ringB-meson collectionDecay of b quark, antiquarkCP violation (UCD group)

• Where is antimatter?• Asymmetry in M/AM decay• CP violation

b-quarks, W,Z bosons June 2010

SummaryHiggs boson (God particle)Close chapter on SM

Supersymmetric particlesOpen chapter on unification

CosmologyMissing antimatterNature of dark matter

Surprises New dimensions - string theory?

Further reading: ANTIMATTER

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…..almost

European Organization for Nuclear Research