Elementary particles

Introduction to elementary particles

1. ELEMENTARY PARTICLES

2. INTRODUCTION
HISTORY
DISCOVERY
CLASSIFICATION
DESCRIPTION
GLOSSARY

3. HISTORY
Idea of elementary particles first introduced by
Democritus in 460 BC
Introduced the word “atom” –indivisible particles.
Later in 1930s the protons, neutrons and
electrons were the smallest and were termed as
‘elementary particles’.
The word ‘elementary particles’ means “having no
smaller constituent parts”

5. FORCES
The elementary particle of matter interact with one another through
four distinct type of forces.
These are carriers of the basic forces
The 4 basic forces are
Gravitation
Electromagnetism
Forces from strong interactions
Forces from weak interactions

6. DISCOVERY
The first subatomic particle discovered was the
ELECTRONin 1897 by J.J. Thomson.
In 1905 photon was suggested by Einstein.
The nucleus of an tom was discovered by Ernest
Rutherfordin 1911
In 1928 P.A.M.Dirac discovered a positively charged
electron, or positron,ie antiparticle of electron.
In 1932 the neutronwas discovered by---------------?

7. In 1934 the existence of neutrino was established.
In 1947 Yukawa discovered the pi meson or pion.
By 1950s these elementary particles were observed in
laboratory through particle collisions produced by
particle accelerator.
In 1959 Antineutrino existence was announced by
Cowan and Reines

8. Two basic constituents of matter are
Leptons
Quarks
Each type of Leptons and Quarks has a corresponding
Anti particle (same mass but opposite electrical charge
and magnetic momentum)

9. Lepton
Electron
muon
tauparticle
Ele.neutrino
Muonneutrino
tauneutrino

10. Quarks
UP
DOWN
CHARM
STRANGE
TOP (TRUTH)
BOTTOM (BEAUTY)

11. The quarks found in ordinary matter are up
quarks and down quarks
Protons ----2 up quarks and a down quark
Neutrons ----2 down quarks and a
upquark

13. CLASSIFICATION
BASED ON THE STATISTICS THEY OBEY
1) Fermi-Dirac statistics
a) Fermions/Matter particles
2) Bose-Einstein statistics
a) Bosons/Force particles
BASED ON THE PARTICLE BEHAVIOR
1) Mesons/Bosonic Hadrons
2) Baryons/Fermionic Hadrons.

14. FERMIONS AND BOSONS
Fermionshalf-integral spin
only one per
state (two
fermions are not
allowed to
occupy the same
quantum state)
Examples:
electrons, protons,
neutrons, quarks,
neutrinos
Bosons integral spin
Many can
occupy the
same state
Examples:
photons,
4
He atoms,
gluons

15. FERMIONS-DEFN
Fermi-Dirac statistics apply to those particles restricted by the
Pauli’s Exclusion principle( No two “e
-”
can have same set of all 4
quantum numbers).
These particles are known as Fermions.
Two fermions are not allowed to occupy the same quantum state.
Fermions compose nuclear and atomic structure.
Leptons and Quarks are Fermions.
These are also known as matter particles.
For each matter particle there exist an anti-matter particle.

16. FERMIONS-CONTD
LEPTONS (Extra-nuclear particles)
Are fundamental particles that have no strong interactions.
Six known types of leptons and Six Anti lepton types
“Lepton” came from Greek for “small mass”.
Leptons are divided into three families.
1)The electron and its neutrino
2)The muon and its neutrino
3)The tau and its neutrino
The electron number,muon number and tau number are always
conserved when a massive lepton decays into smaller ones

17. LEPTONS-CONTD
Flavor Mass(GeV/c
2
)Electric Charge
(e)

e
electronneutrino<7x10-9 0
e
- Electron 0.000511 -1


muonneutrino <0.0003 0
 Muon(mu-minus)0.106 -1
V
T
tauneutrino <0.03 0
T
-
Tau(tau-minus) 1.7771 -1

18. FERMIONS CONTD…
QUARKS (NUCLEAR PARTICLES)
Matter particles that are constituents of neutrons and
protons and others hadrons.
Six different types of quarks.
Each type of quark has its own antiparticle (same mass but
opposite electrical charge and magnetic moment).
Each quark type is called a flavor.
Appears always in pairs/triplets.
Five quark particles called penta quarks.
Of the six the “top”/ “truth” quark is the heaviest
particle nature ever created.
Protons and Neutrons are made of the “up” and “down” quarks.

19. QUARKS-CONTD
Flavor
Mass (GeV/c2)Electric
Charge (e)
u up 0.004 +2/3
d Down 0.008 -1/3
c Charm 1.5 +2/3
s Strange0.15 -1/3
t top 176 +2/3
b bottom4.7 -1/3

20. BOSON-DEF
Bose-Einstein statistics apply to all the other particles those are not
covered by the exclusion principle.
Those particles are called as bosons.
The bosons are the particles that mediate forces.
The number of bosons in a given quantum state is not restricted.
Bosons act to transmit energy between fermions.
5 categories; photon, gluon, W+,W-, Z.

21. BOSON
Particle Context Mass Charge Spin
Graviton Gravity 0 0 2
Photon Electromagn
etism
0 0 1
Gluon Strong force0 0 1
WEAK GAUGE BOSONS
W+ weak force80,000 1 1
W- weak force80,000 -1 1
Z+ weak force91,000 0 1
Higgsboson weak force>78,000 0 0

22. HADRONS
Are particles made from quarks and gluons bound together by
strong interactions.
Are nuclear particles.
Have no net strong charge.
There are two classes of hadrons: mesons and baryons.

23. MESONS
Mesons (Yukawa,1947)
Color –neutral particle with a basic nature of one quark and
one anti quark.
Electriccharge:-1 (same as an electron)
Mass:
1
/
7
of a proton (or 273 electron-masses)
Composition:One "down" quark + one "up" antiquark
Have mass in between protons and neutrons.
There are no stable mesons

24. MESONS
Mesons have integer (or zero) units of spin.
They do not obey Pauli’s exclusion principle rules.
Mesons are having a mass in between proton and neutron.
Also known as resonances or resonance states
Average lifetime is 26 billionths of a second
Decays into: Ina vacuum, usually a negative muon, and
antineutrino.
The antimatter in a pion makes it very unstable

25. MESONS p i + k - r h o + D + e t a - c p i + k - r h o + D + e t a - c
Bosonic Hadrons
Mesons
Name Electric
Charge
Mass (GeV/c
2
)Spin
pion +1 0.140 0
kaon -1 0.494 0
rho +1 0.770 1
D+ +1 1.869 0
eta-c 0 2.979 0

26. BARYONS
Are particles made from a basic structure of 3 quarks.
Carry an odd half quantum unit of angular momentum.
They obey pauli’s exclusion principle.
Proton is the only baryon that is stable in isolation
neutron is also baryon but are not stable in isolation

27. BARYONS p p - b a r n
Fermionic Hadrons
Baryons
Name Electric
Charge
Mass
(GeV/c
2
)
Spin
proton 1 0.938 1/2
anti-proton -1 0.938 1/2
neutron 0 0.940 1/2
lambda 0 1.116 1/2
omega -1 1.672 3/2

28. NEUTRINO AND GLUE BALLS
Are one of the fundamental particles which make up the universe.
Are similar to electron but carry no charge.
Three neutrinos are known.
Glueballsare additional types of hadrons made of gluons.
They do not contain virtual quark-antiquarkpairs so it is difficult to
distinguish from an ordinary meson.

29. GLOSSARY
Annihilation
Attenuation
Bound state
Bubble chamber
Conservation laws
Collimation
Higgs boson.
Jet
The standard model plus gravity.
S particles
Storage Ring
THE CURRENT CONCERN IN THE RESEARCH OF ELEMENTARY PARTICLES
IS THE INTERFACE BETWEEN THAT DISCIPLINE
AND COSMOLOGY

30. As you think so you become
As your thoughts must be your life
Improve your thoughts
Better thoughts bring better action