Transcript Recreating the Big Bang

Re-creating the Big Bang
Walton, CERN and the Large Hadron Collider
Albert Einstein
Dr Cormac O’ Raifeartaigh (WIT)
Ernest Walton
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
m
m0
1 v
2
c2
Why
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):
Dalton, Mendeleev
Einstein: (1905):
Perrin (1908):
Einstein
atomic theory of gases
chemical reactions, PT
Brownian motion due to atoms?
measurements
λ=
RT
t
3N Ar
Perrin (1908)
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
The atom
Weak nuclear force:
Beta decay
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
π+ → μ+ + ν
Particle accelerators
cyclotron
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