VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
Taxonomie of Particles
∆++
u
uu
π+
u
d
d
us
Λ0
c
d
D+
s
u
Κ−
b
b
ϒ
d
uu
du
d
proton neutron
mesons
baryons
...
...
nucleus
He-nucleus(α-particle)
atom
matter
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
Bosons
Spin 0,1,2, …
Bose-Einstein statistic
Fermions
Spin ½, 1½, 2½, …
Fermi-Dirac statistic
Pauli exclusion principle
angular momentum
π+
u
d
He-nucleus(α-particle)
photon
γ
neutron
ud
d
proton
ud
uelectron
e-
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
composite elementary
divisible into smaller parts
π+
u
d
He-nucleus(α-particle)
photon
γneutron
ud
d
proton
ud
u
electron
e-
matteratom
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
elementary
e-
e+
Kp
p
e-
e+
K
π
it is impossible to “split” elementary particles!(i.e.: to separate and isolate the parts of an elementary particle)
if one collides elementary particles,
only elementary particles come out
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
extended Hadrons
but elementary particles can have a (sub)structure
π+
u
d
neutron
ud
d
proton
ud
u
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
fundamental ~ pointlike
leptonsτ
ντ
e
νe
µ
νµ
γvector bosons Z0W±
g
h Higgs boson (?)
b
t
s
c
d
uquarks
They appear point-like
even to our best
microscopes (which are particle accelerators)
in fundamental particles,
scientists could not find
any substructure.
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
Baryons
• are fermions:
Spin ½ and 1½
• made of 3 quarks
(or antiquarks)
Mesons
• are bosons:
Spin 0 (pseudoscalar)
Spin 1 (vector)
• quark and antiquark
Hadrons
neutron
ud
d
proton
ud
u
Spin 0Spin ½
∆++
uu
u
Υ(1s)
bb
π+
ud
Spin 1Spin 1½
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
• is a borderline case:
– large molecules behave more or less like classical objects
– small molecules, like H2 can form quantum mechanical coherent states
• H2 is a boson
• HD is a fermion
Taxonomie of Particles
molecule
macroscopic matter
• follows the laws of classical physics:the quantum mechanical description brings understanding of the properties of the material, but is not suited to classify the macroscopic object.
• There is no Bose-Einstein or Fermi-Dirac statistics, only Maxwell-Boltzman
they are neither fundamental nor elementary!
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
• the nucleus is a quantum mechanical object.• it has definite spin and parity
(can be boson or fermion)
• it is extended• it can be split into nucleons protons and neutrons (a few MeV are needed)
• the atom is a quantum mechanical object.• it has definite spin and parity
(can be boson or fermion)
• it is extended• it can be split into electrons and nucleus plasma (only a few eV are needed)
they are neither fundamental nor elementary!
atom
nucleus
Taxonomie of Particles
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
the electrone-
Thomson
the electron is fundamental and elementary!
Spin ½ FermionMass: 511 keVCharge: -1stable
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
the photonγ
Planck Einstein
Compton
e-
the photon is fundamental and elementary!
Spin 1 BosonMass: 0Charge: 0stable
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
the proton
e-
γ
Rutherford
p
the proton is not fundamental but elementary!
Spin ½ FermionMass: 938 MeVCharge: +1stable
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
Spin ½ FermionMass: 939.6 MeVCharge: 0
the neutron
e-
γ
n
p
Chadwick
the neutron is not fundamental but elementary!
τ½: 886 s “stable”
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
the muon
e-
γ
µ
pn
Who ordered that one?
• Hess• Anderson, Neddermeyer• Street, Stevenson
spark chamber
the muon is fundamental and elementary!
Spin ½ FermionMass: 105 MeVCharge: -1τ½: 2.2 μs unstable
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
the pion
e-
γ
π
pn
µ
Powell Yukawa
prediction discovery
Spin 0 BosonMass: 135 / 140 MeVCharge: 0 / ±1
the pion is not fundamental but elementary!
τ½: 8.4×10-17 s / 2.6×10-8 s unstable
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
the positron (anti-matter)
e-
γ
e+
pn
µπ
Anderson
Dirac
prediction
discovery
the electron is fundamental and elementary!
exactly like the electron!Spin ½ FermionMass: 511 keVCharge: +1stable
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
the neutrino
e-
γ
ν
pn
µπ
e+
Fermi Pauli
the neutrino is fundamental and elementary!
Spin ½ FermionMass: < 2.2 eVCharge: 0stable
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
strange particles
e-
γ
K
pn
µπ
e+
Rochester,Butler,...
ν
Σ
Λ
are Hadronsunstable
strange particles are not fundamental but elementary!
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
antiproton
e-
γp
n
µπ
e+
cosmic rays,Bevatron,PS (CERN)
ν
p_
also antiprotons!
the antiproton is not fundamental but elementary!
same as proton! Spin ½ FermionMass: 938 MeVCharge: -1stable
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
charm quark: J/Ψ
e-
γp
n
µπ
e+
Burt Richter (SLAC), Samuel Ting (BNL)1974
ν
c
all quarks are fundamental but not elementary!
Spin ½ FermionMass: 1.16 – 1.34 GeVCharge: + ⅔unstable
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
tau lepton: τ
e-
γp
n
µπ
e+Martin Perl (SLAC-LBL)1975 ν
τ
all leptons are fundamental and elementary!
Spin ½ FermionMass: 1.8 GeVCharge: -1
τ½: 2.9×10-13 s unstable
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
bottom quark
e-
γp
n
µπ
e+
ν
b
all quarks are fundamental but not elementary!
Spin ½ FermionMass: 4.13 – 4.37 GeVCharge: - ⅓unstable
E288 (Fermilab)1977
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
Gluon
e-
γp
n
µπ
e+
PETRA (DESY)1979
ν
g
the gluon is fundamental but not elementary!
Spin 1 BosonMass: 0Charge: 0stable
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
W- and Z-boson
e-
γp
n
µπ
e+
discovery: UA1, UA2 (CERN)1983
ν
W,Z
W- and Z-bosons are fundamental and elementary!
Z0-bosonSpin 1mZ = 91.2 GeVCharge: 0unstableΓZ = 2.5 GeV
W±-bosonsSpin 1mW = 80.4 GeVCharge: ±1unstableΓW = 2.14 GeV
VU Seminar – Introduction to Particle Physics Thomas Gajdosik, FI & VU
top quark
e-
γp
n
µπ
e+
ν
tCDF, D0 (Fermilab)1995
all quarks are fundamental but not elementary!
Spin ½ FermionMass: ~173 GeVCharge: + ⅔unstable