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The Higgs
- Theory
The Higgs
Martin Bauer
Arthur H. Compton Lecture
th
Martin
Oct. 26
2013Bauer
Arthur H. Compton
Lectures
Oct 26th 2013
Theory
Outline
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The Higgs: A new interaction
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How the Higgs field gives particles their masses
●
How the Higgs mechanism breaks symmetries
What are the fundamental forces?
●
The most well known fundamental force is
gravity.
Newton 1686
Gravity acts on all masses!
What are the fundamental forces?
●
The most well known fundamental force is
gravity.
Einstein 1916
Gravity acts on all masses!
Forms of energy!
What are the fundamental forces?
●
●
Electromagnetism acts on charges. It is the
force that holds atoms together.
It is much stronger than
gravity …
take a guess !
-
+
..about a million times
large than the visible
universe
What are the fundamental forces?
●
●
Electromagnetism acts on charges. It is the force
that holds atoms together.
It is
1 000 000 000 000
000 000 000 000 000
000 000 000 000 times
stronger than gravity!
What are the fundamental forces?
●
●
●
The strong nuclear Force acts on different charges
(aca color charges). It holds the nucleus together
It also holds the quarks in the Proton and Neutrons
together
It is 100 times stronger than
the electromagnetic force
●
And we make use of this...
Fermi 1942
Why are there no
macroscopic objects
bound by the strong
force?
Politzer, Gross, Wilczek 1973
… it is short ranged.
What are the fundamental forces?
●
●
The weak nuclear Force acts on the weak
charge
It is hard to picture, because there are
no bound systems
What are the fundamental forces?
●
●
The “Higgs Force” acts on masses
In contrast to gravity its really only couples to
masses and not to other kinds of energy
What are the fundamental forces?
Name
Acts on...
Strength
Range
Spin
Character
Gravity
Energy
Extremely
weak
infinite
2
Always
attractive
Electromagnetic
Force
Electric
charge
strong
infinite
1
Strong Nuclear
Force
Color
charge
Very strong
10⁻¹⁵ m 1
Weak Nuclear
Force
Weak
charge
weak
10⁻¹⁸ m 1
depends
10⁻¹⁸ m 0 !
Higgs Interaction Masses
Attractive or
repulsive
Always
attractive
What is a Field?
●
Everything is a field! The best description of
nature we have today is Quantum Field Theory.
particle
What is a Quantum Field?
●
Quantum field theory tells us that there is a
smallest possible excitation of a field, the
quanta of this field or a particle.
What is a Quantum Field?
●
●
Quantum field theory tells us that there is a
smallest possible excitation of a field, the
quanta of this field or a particle.
When we say “particles interact”,
what we really mean is: One field
quantum excites another field.
B
A
B
The Spin of a Field
●
A good example for a
scalar field (spin 0) is
temperature
The Spin of a Field
●
A good example for a vector
field (spin 1) is a wind map
The Spin of a Field
Every
fundamental field
In nature ...
0
The Spin of a Field
vev
0
The Higgs
Masses from the Higgs Field
●
●
For some particles the Higgs field is
transparent. They are massless and move with
the speed of light.
Other particles slow
down in the Higgs field,
for example matter
fields (quarks and
leptons), but also the
weak force carriers.
This is the reason why
the weak force is
short-ranged!
The Higgs Mechanism
●
The process of generating masses for the
elementary particles and “clouding” the weak
force is called Higgs Mechanism.
The Phase of the Universe
●
The underlying physics are the same as in
phase transitions in thermodynamic systems.
H2O
The Universe
Symmetry Breaking
●
When water freezes it looses its spherical
symmetry. In the same way breaks the Higgs
mechanism the electroweak symmetry.
Dictionary
Higgs
Mechanism
Higgs Field
Higgs Boson
Thank you for your attention!