The God Particle for Atheists and Agnostics
The God Particle for Atheists and Agnostics
Vikram Vyas
18 November 2013
The God Particle for Atheists and Agnostics
Outline
1 Caveat
2 The Standard Model
3 The Electro-Weak Interactions
4 The Beauty of the Local Symmetry
5 Problem in the Paradise
6 Higgs is Hiding the Symmetry
7 Higgs Particle: Making Waves in Vacuum
8 More Things Under the Heaven
The God Particle for Atheists and Agnostics
Caveat
Caveat
However, this does not mean that I have tried to write an easybook ... I picture the reader as a smart old attorney who doesnot speak my language, but who expects none the less to hearsome convincing arguments before he makes up his mind.Steven Weinberg (Introduction to First Three Minutes)The complement of truth is clarity. Truth and clarity arecomplementary.Neils Bohr
The God Particle for Atheists and Agnostics
The Standard Model
Inward Bound
The God Particle for Atheists and Agnostics
The Standard Model
The Standard Model
The God Particle for Atheists and Agnostics
The Electro-Weak Interactions
Light: The Electromagnetic Interaction
The way we see the world.Long range - we can see almost to the edge of the universe.Mirror world is a possible world.The force carrier is the photon: A massless particle
The God Particle for Atheists and Agnostics
The Electro-Weak Interactions
Weak Interaction
It is short range - relevant only when particles are at distanceof the order of nuclear sizes.It is responsible for radioactivity.Mirror world is NOT A POSSIBLE WORLD.The force carrier are massive particles.
The God Particle for Atheists and Agnostics
The Electro-Weak Interactions
Some examples of weak interaction
Scattering of neutrinos from proton
νe + p → νe + p
Scattering of electron from proton
e + p → νe + n
Decay of neutronn → p + e + ν̄e
Nuclear Fusion
The God Particle for Atheists and Agnostics
The Beauty of the Local Symmetry
The Photon
A particle with zero mass.It has two helicity or polarization.
The God Particle for Atheists and Agnostics
The Beauty of the Local Symmetry
Quantum Field Theory
Mathematical language to describe creation and annihilation ofidentical particles.With each fundamental particle we associate a set of numbersat each point in space which change with timeAll these numbers together called a field.
The God Particle for Atheists and Agnostics
The Beauty of the Local Symmetry
QED: The Quantum Theory Photons
What is the Quantum Field For Photons?
We need two numbers at each point for describing two typesof photons.But such a theory would lead to a description which wouldgive different laws of nature for differs observers.We add two redundant numbers so at each point of space wehave four numbers describing photons.
The God Particle for Atheists and Agnostics
The Beauty of the Local Symmetry
Redundancy is Symmetry
Symmetry
By symmetry we mean that there is some thing we can do to anobject such that after having done that the object still looks thesame.
The God Particle for Atheists and Agnostics
The Beauty of the Local Symmetry
Local Symmetry of QED
In QED the symmetry is that we can add redundant numbersto a given field and still the corresponding field would describethe same situation as the one described by the original field.Further these number can be different at different points ofspace and time, and so we say that the symmetry is local.
The God Particle for Atheists and Agnostics
The Beauty of the Local Symmetry
Gauge Symmetry = Massless Particle
Theorem
A quantum field theory which has local gauge symmetry describesmassless particles like photons.
The God Particle for Atheists and Agnostics
The Beauty of the Local Symmetry
The Beauty of the Local Symmetry
In 1950-60s many physicist realized that one can extend theidea of local symmetry from photon field to other fields.Such theories are called Yang-Mills theory.One of the simplest such extension would describe four photonlike particles, in that they are massless and have twopolarizations.
The God Particle for Atheists and Agnostics
The Beauty of the Local Symmetry
The Electro-Weak Unification
One of the particle behaves just like photon.It turns out that the way other three particles interacted withelectron and quarks could precisely describe the weakinteractions between them and these, then hypotheticalparticles, were called Z0, W+, W−.This was the electro-weak unification!
The God Particle for Atheists and Agnostics
Problem in the Paradise
Massless Particles = Long Range Force
Faraday’s Field Lines
Force goes as inverse square law - never becomeszero!
The God Particle for Atheists and Agnostics
Problem in the Paradise
Problem in the Paradise - 1
We have a problem!
If the weak interaction is described by Yang-Mills theory then weakinteraction cannot be a short range force.
The God Particle for Atheists and Agnostics
Problem in the Paradise
Weak World is not a Mirror World
If electron is massless then it comes in two varieties
Left Hand of Weak Interaction
Weak interaction requires eL carries weak charge and er has noweak charge.
The God Particle for Atheists and Agnostics
Problem in the Paradise
Problem in the Paradise - 2
We have a problem!
If weak interaction is described by Yang-Mills theory then electronand quarks must be massless.
The God Particle for Atheists and Agnostics
Higgs is Hiding the Symmetry
Vacuum is Not Nothing: Mexican Hat
Weinberg-Salam Model
Electromagnetic and weak interactions are described by aYang-Mills theory in which there is an additional field, the Higgsfield, which has two important properties
It carries weak charge.It has non-zero value in the ground state of the theory.
The God Particle for Atheists and Agnostics
Higgs is Hiding the Symmetry
Symmetric Theory Asymmetric Vacuum
Hiding the Symmetry
The universe is immersed in a field that carries weak charge - this isthe Higgs field.
The God Particle for Atheists and Agnostics
Higgs is Hiding the Symmetry
Curious Properties of Quantum Vacuum
Electro-Weak Vacuum
The vacuum has indefinite amount of weak charge.It has no electric charge.The weak charges (and field lines) can disappear into thevacuum.
The God Particle for Atheists and Agnostics
Higgs is Hiding the Symmetry
Higgs+Faraday:Massive Gauge Bosons
Since the vacuum caries weak charge, the field-lines of weakcharge can disappear in vacuum.Weak-force can become zero - has finite range - thecorresponding particle is massive!
The God Particle for Atheists and Agnostics
Higgs is Hiding the Symmetry
Dirac:Massive Electrons
Dirac Electron
A massive electron oscillates between left-handed electron andright-handed electron.
The God Particle for Atheists and Agnostics
Higgs is Hiding the Symmetry
Dirac+Higgs: Massive Electron from Massless Electron
A massless left handed electron can interact with the Higgsfield and get converted into a massless right handed electronwithout violating conservation of charge and becomes amassive particle.
The God Particle for Atheists and Agnostics
Higgs Particle: Making Waves in Vacuum
The Higgs Particle: That God Damm Particle
If the universe is immersed in Higgs field then we should beable to create waves in this medium.The quanta of this wave should be a particle - the Higgsparticle.
The God Particle for Atheists and Agnostics
Higgs Particle: Making Waves in Vacuum
Producing and Detecting Higgs Particle: The TheoristCartoon
The God Particle for Atheists and Agnostics
Higgs Particle: Making Waves in Vacuum
Higgs in LHC
The God Particle for Atheists and Agnostics
More Things Under the Heaven
Why these Masses?
The God Particle for Atheists and Agnostics
More Things Under the Heaven
Where is the Dark Matter?
The Unfinished Journey
The motion of stars in galaxies tell us that the our Universemust contain other types of particles which interact throughgravity but are not part of the standard model. This is the socalled “dark matter.”Therefore we know that the standard-model is incomplete.What are those new particles and interactions? We hope LHCwill provide us the with clues to them, and so we wait for LHCto start again!