Saturday, July 21, 2012:
Thousands of scientists, decades of research, billions of dollars—if all of this culminates in a super-duper discovery, and you get a chance to be in the same room as the man who began the quest half a century ago, what would you do but forget yourself and cheer as if in a football match or a rock concert. Well, we are talking about an auditorium packed with some of the world’s best researchers—at CERN, the European Organization for Nuclear Research, headquartered in Geneva, Switzerland. The scene was replicated in almost all of the planet’s best research institutions… as CERN quickly passed on news of having discovered what looks like the so-far elusive Higgs-boson, the magic particle that gives mass to all things bright and beautiful, all creatures great and small. Scientists cheered. Peter Higgs shed a happy tear. The world watched.
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The Higgs-boson
When asked questions like why there is life on Earth, why is there so much diversity, why do creatures come in so many sizes and shapes, some would say, “God,” while others would say, “The God Particle.” God Particle was the nickname given to the Higgs-boson by Nobel prize winner Leon Lederman in one of his writings (he is known to have admitted later than he actually wanted to call it the god-damned particle, as it was sending so many physicists on a sleepless chase).
The Higgs-boson is the missing link in the Standard Model that is one of the basic underlying principles of modern particle physics. Physicists believe that there are only four forces in nature – electromagnetic, strong, weak and gravitational. The Standard Model is a unified theory that explains the strong, weak and electromagnetic interactions in nature; the gravitational field being too weak in comparison. In the 1960s, in a paper describing the weak and electromagnetic field interactions, Peter Higgs mentioned that there ought to be a heavy particle which breaks up to give the other paticles their mass. It is this mass that then combines with gravity to give objects what we call as weight. Other physicists called it the Higgs particle to acknowledge Peter Higgs’ contribution.
The Higgs is a particle with zero spin, making it a boson. Bosons are particles that are governed by the Bose-Einstein Statistics first discovered by Indian physicist Satyendranath Bose. Combined, the particle became the Higgs-boson, which later acquired the notorious God Particle nomer.
While the theory about the existence of a heavy particle seemed perfectly logical, it sent physicists on a hunt that lasted around fifty years!
July’s discovery
In the course of the five decades since the Higgs-boson was proposed, particle physicists across the world have devised several high-energy proton collision experiments in which they expected to see this particle. But, with little success. Most of these experiments closed down in the past decade.
CERN too has been doing its share of experiments. Its $10-billion Large Hadron Collider (LHC) on the Swiss-French border, has been creating high-energy collisions of protons—for years together—to investigate dark matter, anti-matter and the creation of the universe through the Big Bang. Of the many teams working with the LHC, two claimed in July to have noted a new subatomic particle, which is a boson for sure, supposedly a Higgs-boson, and hopefully the Higgs-boson defined in the Standard Model.
The two teams that observed the particle were: the 2100-scientist CMS (Compact Muon Solenoid) headed by Joe Incandela, and the 3000-scientist ATLAS (A Toroidal LHC Apparatus) headed by Fabiola Gianotti. Both have strong evidence concerning the new particle. The particle has a mass 125 giga-electron-volts, and is one of the heaviest bosons identified till date.
What does this mean?
In short, it means more research. “We have now found the missing cornerstone of particle physics,” Rolf Heuer, director of the European Centre for Nuclear Research (CERN), told scientists on July 4th, 2012. He worded their success very carefully: “As a layman, I think we did it,” he said. “We’ve a discovery. We’ve observed a new particle that is consistent with a Higgs-boson.” What they have discovered is a Higgs-boson. And, they are quite sure about this, claiming five-sigma statistical significance, a 1 in 3.5 million chance of error.
The team now has to delve further into the properties of the new particle by studying how it transforms, decays, and so on, to confirm whether it is the Higgs-boson that fits perfectly into the Standard Model. One physicist has already raised doubts concerning a deviation of the new particle’s decay path from what is expected of the Higgs-boson.
If the particle is the highly sought after Higgs-boson, it would help solve many puzzles about the formation of this Universe and biodiversity. According to a wonderful explanation by the BBC, the matter we see in the world today is just 4 per cent of the Universe. The remaining is composed of dark and anti-matter. If the Higgs-boson were found, it would help unravel this 96 per cent of the Universe that has eluded scientists all along. But, while a majority of the world’s physicists cried and hugged and cheered, a few shrugged their shoulders thinking it to be no big deal. According to them, there are other questions beyond what is explained by the Standard Model, and they believe in alternative theories (e.g., Technicolor) that claim the Standard Model to be insufficient or even wrong.
Well, let us wait and see what transpires! The LHC will continue to run its experiments and try to revalidate the results before it shuts down for maintenance at the end of this year. “The LHC has the highest beam energy in the world now. The experiment was designed to yield quick results. With its high luminosity, it quickly narrowed down the energy-ranges. I’m sure that by the end of the year, we will have a definite word on the Higgs-boson’s properties,” said Dr. Rahul Sinha, a participant of the Belle Collaboration in Japan.
The LHC
o Situated on the Swiss-French border, 100 metres below the ground, in a 27 kilometre long tunnel
o It is a particle-accelerator that helps study the smallest known particles
o Hopes to throw more light on how the Universe was formed, and on the Standard Model that helps explain the forces of nature
o Two beams of subatomic particles called ‘hadrons’ – either protons or lead ions – travel in opposite directions inside the circular accelerator
o The particles gain energy with every lap
o The goal is to recreate the conditions just after the Big Bang, by colliding the two beams head-on at very high energy
o Physicists around the world then analyse the particles created in the collisions using various special equipment.
Indian connections
Here are some of the Indian contributions to this new discovery…
o The Higgs-boson is governed by the Bose-Einstein Statistics first discovered by Indian physicist Satyendranath Bose
o Indian physicists have also played a key role in validating, or furthering, the Standard Model theory since the 1960s
o Archana Sharma, the only permanent Indian staff at the CERN facility has contributed at various levels to the discovery of the new particle. She worked on designing and prototyping the present generation of muon-detectors currently operational. These are crucial for the gold-plated discovery channel for the Higgs-boson. Her main job is to develop radiation hard detectors for CMS for sustained operation at LHC upgrades in this decade and the next
o Prof. Prafulla Kumar Behera worked with CERN before resigning in March 2012 to work on the India-based Neutrino Oberservatory (INO) in Theni, Tamilnadu. In a talk at IIT-Madras this July, he recollected various experiences including how his team once redesigned a detector at ATLAS, due to a technical glitch, within a short span of three months
o Research institutes in Kolkata, Allahabad, Mumbai and Bhubaneswar were involved in the experiment at CERN
o The INO hopes to go beyond the Standard Model, to try and overcome its limitations and truly explain the formation of this Universe.
Pic courtesy: CERN
- Janani Gopalakrishnan Vikram
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