Higgs boson

The Higgs boson is the last particle in the Standard Model of particle physics to be observed, announced in a seminar July 4, 2012. Its existence was first proposed by Professor Peter Higgs of Edinburgh University in 1964 as a means to explain the origin of the masses of the elementary particles by the introduction of an fundamental scalar field. This gives all the fundamental particles mass via a process of spontaneous symmetry breaking called the Higgs Mechanism. The Higgs boson was popularised as the "God particle" by the Nobel Prize-winning physicist Leon M. Lederman in his 1993 popular science book The God Particle: If the Universe Is the Answer, What is the Question? co-written with science writer Dick Teresi.

The Higgs Mechanism

The Higgs Mechanism is vital in explaining the masses of the electroweak W and Z bosons. To understand the problem in giving mass to the vector bosons let us first consider the QED sector of the Standard Model Lagrangian.

${\mathcal {L}}_{QED}={\overline {\psi }}(i\gamma ^{\mu }\partial _{\mu }-m)\psi -j_{em}^{\mu }A_{\mu }-{\frac {1}{4}}F_{\mu \nu }F^{\mu \nu }$

Now consider how things will change if we perform a local phase rotation such that:

$\psi (x)\rightarrow \psi '(x)=e^{i\alpha (x)}\psi (x)$

We would expect the Langrangian to remain invariant under such a rotation since to do otherwise would mean that if I chose a different phase than someone else where we could get different physics results.

Search for the Higgs Boson

Studies using the Fermilab's Tevatron collider suggest a range for the mass of the Higgs boson between 115-150 GeV (gigaelectronvolts), assuming the correctness of the Standard Model of particle physics. See review of the experiments:

The Higg’s particle may be too heavy to be made in the Tevatron collider, but the high energies of the Large Hadron Collider in Geneva should enable it to be produced and detected, and this is an early goal of this major international project.