The Sundaytimes Sri Lanka

Is this the Higgs boson?

The discovery of this new particle will be one of the greatest finds of the modern era

On July 4, at a news conference at CERN (European Organization for Nuclear Research) in Zurich, Switzerland, the two main experiments at the Large Hadron Collider (LHC) reported independently the discovery of a new particle, a boson with mass 123.3 +/- 0.6 GeV 4.9 sigma confidence (CMS) and 126.5 GeV with 5 sigma confidence (ATLAS).

A 5 sigma confidence implies a result which has less than 1 in a million chance of being spurious.
It is still not confirmed that this particle with a weight about that of 133 protons is indeed the Higgs boson which was the primary aim of building the LHC particle accelerator. If and when after further investigations, physicists are able to confirm that this particle is the Higgs boson, it will clearly be one of the greatest discoveries of modern era.

CERN established in 1954 has 20 member states. The Large Hadron Collider (LHC) is built in a circular tunnel, 27 km in circumference which is located 100 metres underground, in the region between the Geneva International Airport and the nearby Jura mountains. It became operational in 2010 at a cost of US$ 10 billion.

Scientists understand the structure of the Universe by building mathematical models to fit observations. When observations are made which are inconsistent with current models, they are refined. The power of mathematical models is that it may not only fit the known observations but also predict the existence of something which is still unobserved. When such an observation is made we get more confidence in the validity of the mathematical model to describe reality.

Dimitri Mendeleev’s periodic table of elements 1869, for example, was initially an empirical arrangement based on the properties of atoms that led to the prediction of 8 elements which had not yet been observed. The subsequent discovery of these elements led to our deep understanding of the chemistry of the Universe.

A century later in 1960, the Standard Model is a theory concerning the electromagnetic, weak, and strong nuclear forces, which mediate the dynamics of the known subatomic particles.

The Higgs particle is a massive scalar elementary particle theorized by Peter Higgs and others in 1964 and is a key building block in the Standard Model. It has no intrinsic spin, and for that reason is classified as a boson. It is the last of the particles of the Standard Model, the existence of which remains to be confirmed. Because the Higgs boson is a very massive particle and also decays almost immediately when created, only a very high energy particle accelerator can observe and record it via the trajectories of its decay products.

The Higgs boson plays a unique role in the Standard Model, by explaining why the other elementary particles, except the photon and gluon, are massive. In particular, the Higgs boson would explain why the photon has no mass, while the W and Z bosons are very heavy.
Elementary particle masses, and the differences between electromagnetism (mediated by the photon) and the weak force (mediated by the W and Z bosons), are critical to many aspects of the structure of matter. In electroweak theory, the Higgs boson generates the masses of the leptons (electron, muon, and tau) and quarks.

In USA, Superconducting Super Collider (SSC) was planned to be built in Texas with a much larger ring circumference of 87 km, and although work started in 1991, the project was cancelled in 1993 after spending US$2 billion due to budget problems.
(The writer is an astrophycist)

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