Transcript The Big Bang, the LHC and the God Particle

Black Holes, the LHC and the God Particle
Dr Cormac O’Raifeartaigh (WIT)
The Big Bang, the LHC and the God
Particle
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)
Particle accelerator
Head-on collision of protons
Huge energy density
Create short-lived particles
Detection
No black holes
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 device
measures 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 matter
m = 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 gravity
Holds cosmos together
Long 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)
1H
3Li
2He + 2He
+
→
1
6.9
4
4
Verified mass-energy (E= mc2)
Verified quantum tunnelling
Nobel prize (1956)
Cavendish lab, Cambridge
New particles (1950s)
Cosmic rays
π+ → μ+ + ν
Particle accelerators
LINACS (Walton)
synchrotrons
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
Mediated by new particles W, Z
Higgs mechanism to generate mass
Predictions:
Detected:
W+-,Z0 bosons
CERN, 1983
Rubbia, Van der Meer
Nobel prize 1984
Glashow, Salaam and Weinberg
Nobel prize 1979
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
Higgs search: summary
Ref: hep-ph/0208209
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
1.
Superforce:
SUSY particles?
2. SUSY = dark matter?
neutralinos?
double whammy
3. Missing antimatter ?
LHCb
High E = photo of early U
LHCb (UCD)
• 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)
b-quarks, W,Z bosons June 2010
Summary
Higgs boson (God particle)
Close chapter on SM
Supersymmetric particles
Open chapter on unification
Cosmology
Missing antimatter
Nature of dark matter
Surprises
New dimensions - string theory?
Further reading: ANTIMATTER
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…..almost