The world of physics has had its share of truly euphoric
moments before but none were as much awaited as the one that took place at the
Large Hadron Collider at CERN on 4th July, 2012. Two completely
independent experiments, ATLAS and CMS carried out in two different Higgs decay
modes confirmed that a new resonance has been found that proves the existence
of the last missing piece of the standard model, ‘The Higgs Boson’.
The Standard Model of particle physics that helps us in
understanding the dynamics of all the known sub atomic particles and their
interactions could not predict the exact mass of the particle named ‘Higgs
Boson’ and so it has been extremely difficult for the experimentalists to find
out simply because they just didn’t know where to look for! It is the particle
that is formed during the Higgs mechanism which is a very crucial part of our
understanding of how different particles while flowing through space-time
acquire mass and with its discovery mankind has been able to take a significant
step towards understanding and appreciating nature and her mysteries.
The discovery of the Higgs boson has its own story held
deep within. During the 1960s when it was realized that gauge symmetry was a
fundamental aspect of understanding sub atomic interactions in particle
physics, the emergence of weak interactions posed a great problem to the
physicists of that time. The newly found weak interaction were so short ranged
that the mathematics required the exchange of bosons of considerable mass
between particles unlike the exchange of the massless photons in
electromagnetism. Gauge symmetry completely fell apart because of it and people
started looking for ways to develop a mass generation mechanism that is
consistent with gauge symmetry.
By that time a mass generation mechanism was developed by
Condense matter physicist Phillip Anderson for his own field in 1962. Finding
it on a condensed matter journal two groups of particle physicists Robert Brout
, Francois Englert and Gerald Guralnik, C.R Hagen, Tom Kibble developed the
corresponding relativistic model. This idea was finally applied in the weak
interaction problem by Peter Higgs in 1964. These physicists were able to show
that when a gauge theory is combined with an additional scalar field with 0
spin, the gauge symmetry can eventually break itself down spontaneously to give
the gauge bosons finite mass. And in the process a new particle is created
called the Higgs boson.
Ironically it so happened that after Higgs’ paper was
rejected by ‘Physics Letters’ (a leading journal of that time) while he was
revising it to send it this time to ‘Physical Review’ he added a line at the
end mentioning that his analysis implied the existence of one or more new
massive spin-less bosons… which eventually came to be known as Higgs Bosons.
Later it was realized that these bosons and the same Higgs mechanism is
responsible for giving mass to all known particles. That missing term in Higgs
calculations that occurred in 1964 turned alive in LHC on 4th July
2012 after a long wait of 50 years ending the age old mystery of how things in
nature acquire mass… why they have to…
P.S – I hope I have been able to create the same
excitement in readers as much as Prof. Ravishankar created in me while telling
the story of Higgs Boson. It has only been possible because of him.
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