Higgs Boson Discovery

In 1913, Danish physicist Niels Bohr revealed the inner world of the atom: a positively charged nucleus orbited by negatively charged electrons. This only led to more questions, like what was in those particles, and why did they behave the way they did?

New subatomic particle discoveries, such as the neutron (1932), added pieces to the puzzle. By the early-Sixties, the hot game in town was devising a maths-based theory to explain how it all fitted together. But leading theories tripped on a basic question: where does mass come from?

In 1964, three separate groups of physicists arrived at the same answer: particles gain mass by moving through an invisible field, formed less than a second after the Big Bang. In a 1966 follow-up paper, one of the crowd – Scottish physicist Peter Higgs – elaborated on how it all might work. In the Higgs mechanism, the invisible Higgs field imparts mass to particles by way of force-carrying particles called Higgs bosons.

The Higgs mechanism is a cornerstone of the Standard Model, a theory of how fundamental forces work on the subatomic level. To validate the model, physicists needed evidence of the Higgs field – clear detection of a Higgs boson.

Higgs-hunting means rapidly colliding particles together to reproduce the immense amounts of energy that followed the Big Bang. The energy of these collisions transforms into subatomic particles. A Higgs particle is especially tricky to identify as, if it exists, it immediately decays into other particles. The search requires computers to pore over trillions of collisions looking for decay patterns that match the theoretical profile of the Higgs.

CERN's Large Electron-Positron ColliderIn the Nineties, high-energy collisions in CERN’s Large Electron-Positron Collider (LEP) yielded proof of Z and Y bosons – also predicted in the Standard Model – but no conclusive evidence of a Higgs. CERN dismantled the LEP in 2000, and in 2008 replaced it with the more powerful Large Hadron Collider (LHC). On 4 July 2012, physicists reported that the LHC had detected a previously unknown boson that matches the predicted mass and behaviour of the elusive Higgs.

The future of Higgs?

Physicists have no specific applications or objectives in mind for the Higgs. Their only goal has been to understand the universe better. The Higgs may usher in a new era of discovery, however. Future observations could help scientists identify or predict additional particles and phenomena, including extra dimensions and the nature of dark matter. In 2013, the LHC will shut down for a major equipment upgrade, nearly doubling the energy of its collisions… and possibly showing us something completely unexpected.

Read also Higgs boson continues to be maddeningly well-behaved

Higgs Boson facts

1. ESSENTIAL TO EVERYTHING – Without the Higgs boson (or an equivalent mechanism), particles would be energy without mass, making it impossible for them to form atoms. Consequently, the universe would be entirely devoid of matter.

Higgs Boson2. HIGGS IS BIG – Big by subatomic standards, anyway. CERN scientists reported the suspected Higgs boson was 125.3 gigaelectronvolts (GeV), which is about 133 times heavier than a proton.

3. HOW SURE IS ‘PRETTY SURE’? – Particle physicists report certainty in terms of sigma – the likelihood of random chance yielding the same results. CERN scientists put the chance that this was not a new particle at 1 in 550 million, a 5.9-sigma certainty.

4. GONE IN A ZEPTOSECOND – One of the trickiest qualities of the Higgs (if it exists) is that it decays almost immediately. Within a zeptosecond (that’s a thousandth of a billionth of a billionth of a second) of appearing, it’s gone.

5. DATA OVERLOAD – A single second of LHC activity yields 1,000 terabytes of data – more than all the books in all the world’s libraries. The July discovery entailed analysis of more than 300 trillion collisions.