This year’s Nobel Prize in physics was awarded for the confirmation of the existence of Higgs Boson aka God Particle and the Higgs scalar field; first of its kind. The prediction to discovery time of this research was more than 50 years, making it very special. So it seemed quite reasonable to discuss and signify this discovery which is now being hailed the greatest find in particle physics and what took it so long!
The Higgs mechanism was proposed in 1964 by Peter Higgs, Francis and few other physicists separately. The idea was to find a mechanism that would explain anomalies and dissimilarities between fundamental forces such as electromagnetic and weak nuclear force etc and to answer one of the most fundamental questions of all time:
How does matter acquire mass?
Grand Unification and theories of Everything (TOEs)
Since beginning physicists have tried to unite the three fundamental forces of nature into one force. Many mechanisms have been put forward. The most famous of them was the 1979 Nobel Prize winning electroweak model of Glashow, Weinberg and Abdul Salam. This model united two of the fundamental forces namely electromagnetic and weak force into one electroweak force and left us with 3 instead of 4 forces to handle. This model explained that at high energies and mass densities both forces’ carries particles behave the same way. So we now know that in the beginning of time all forces were one and they separated from one another as the universe cooled. Many of you would have an idea of messenger/carrier particles. These are the entities that carry force from one particle to another in the quantum regime. According to Quantum field theories (QFTs), every force field is quantized and its unit i.e. a quantum is the messenger particle of that force. So uniting forces is the game of understanding and uniting carrier particles of forces.
Why a new particle?
All QFTs are based on mathematical concepts of gauge theories. What it means in reference to our discussion is that every such field is symmetric and the underlying symmetry remains in it in all circumstances. If that is true then we would be in a world with only one force i.e. “The Force” as in grand unification theories. But we live in a world of three fundamental forces and as I mentioned above, “The Force” may have broken down into the forces of today. So this breaking creates an asymmetry or discontinuity violating gauge concepts. Hence there should be some way to account for this symmetry breakdown and that’s where the Higgs boson comes in! It is a boson, which means it belongs to a class of carrier particles, specifically the ones with an integer spin.
How it works?
The Higgs field is present everywhere but it is a scalar field so it cannot be detected or felt as ordinary force fields. But it is felt by carrier particles when they interact with it. The interaction in a field is characterized by degrees of freedom of that field. To clearly understand this, a lot of math is required making it very boring and complex. In simple words Higgs field is a 4 tier field with 4 parts for particles to interact. Different particles interact with it differently giving them properties such as mass. So in this way particles move in a sea of Higgs Bosons and there is the inertia and friction that gives particles their mass.
A good analog to our case is when an object travels in a fluid, it experiences drag. The same is the drag of a particle in a Higgs field which gives it inertial mass. So in this way we find a way to explain the difference in behavior or electromagnetic and weak nuclear force i.e. the carrier particles of weak force interact with the Higgs field and acquire mass while photons don’t making electromagnetic field different and long ranging compared to weak force.
Searching for Higgs Boson
Higgs Boson is a heavy particle and to find it a lot of energy is needed in a particle collision process. This process is carried in particle accelerators. Many of you would be familiar with CERN and Fermi labs. These are the top notch accelerators. CERN holds the Large Hadron Collider (LHC). It can accelerate hadrons to 99 percent speed of light. Earlier colliders tried to locate the particle but their energies were far too less. The first extensive search at CERN could only narrow the range of energies to 114 GeV/c2. In July 2012, LHC started analyzing collision. It had the ability to accelerate protons to 7 TeV. This is some energy! With the energy in hand still it was a very difficult job. Searching for a particle in a catastrophic collision is like a needle in a haystack, a statistical anomaly. The probabilities were like one in millions. For many months LHC collected tons of data in billions of collisions looking for little shifts in readings. They found that there is an anomaly in the range of 115-130 GeV/c2, close to theoretically predicted energy, and that was the Higgs Boson. Then a series of confirming experiments revealed its properties and they matched the proposed Higgs Boson properties.
Our knowledge of the Universe
For centuries human kind has tried to understand the cosmos. The Higgs Boson has takes us further and familiarized us with a whole new world of particles and fields. Higgs field has become a candidate for the rapid expansion of our universe during the first few moments of the Big Bang known as the “Inflation Epoch”.
Around 96 percent of all the matter energy content of the universe is invisible or undetectable to us. The visible universe accounts for just 4 percent. 73 percent of it is named as Dark Energy. It is responsible for the never-ending expansion of our universe. This vacuum energy is a lot being pinned to a scalar field and Higgs is a candidate. The state of the universe and its fate has always been a hot topic among physicist and philosophers alike. To find whether our home is in a stable state or it will bring its wrath and shift into a more stable vacuum state depends on the properties of the fundamental particles specifically their mass. For this we need more accurate calculations of the masses of the Higgs Boson and the quarks to get a better idea.
We are in a very rich time where our eyes and ears are towards heavens searching for clues of where we are, what is around us and what lies beyond the limits of our existence to better understand and praise our home and the endless stretches of space and time…………