@edgarblythe,
October 21, 1999
What exactly is the Higgs boson? Have physicists proved that it really exists?
Stephen Reucroft in the Elementary Particle Physics group at Northeastern University gives this introductory reply:
"Over the past few decades, particle physicists have developed an elegant theoretical model (the Standard Model) that gives a framework for our current understanding of the fundamental particles and forces of nature. One major ingredient in this model is a hypothetical, ubiquitous quantum field that is supposed to be responsible for giving particles their masses (this field would answer the basic question of why particles have the masses they do--or indeed, why they have any mass at all). This field is called the Higgs field. As a consequence of wave-particle duality, all quantum fields have a fundamental particle associated with them. The particle associated with the Higgs field is called the Higgs boson.
"Because the Higgs field would be responsible for mass, the very fact that the fundamental particles do have mass is regarded by many physicists as an indication of the existence of the Higgs field. We can even take all our data on particle physics data and interpret them in terms of the mass of a hypothetical Higgs boson. In other words, if we assume that the Higgs boson exists, we can infer its mass based on the effect it would have on the properties of other particles and fields. We have not yet truly proved that the Higgs boson exists, however. One of the main aims of particle physics over the next couple of decades is to prove once and for all the existence or nonexistence of the Higgs boson."
Another, more extensive response comes from Howard Haber and Michael Dine, both of whom are professors of physics at the Santa Cruz Institute for Particle Physics at the University of California at Santa Cruz:
"Much of today's research in elementary particle physics focuses on the search for a particle called the Higgs boson. This particle is the one missing piece of our present understanding of the laws of nature, known as the Standard Model. This model describes three types of forces: electromagnetic interactions, which cause all phenomena associated with electric and magnetic fields and the spectrum of electromagnetic radiation; strong interactions, which bind atomic nuclei; and the weak nuclear force, which governs beta decay--a form of natural radioactivity--and hydrogen fusion, the source of the sun's energy. (The Standard Model does not describe the fourth force, gravity.)
"In our daily lives, electromagnetism is the most familiar of these forces. Until relatively recently, it was the only one which we understood well. Since the 1970s, however, scientists have come to understand the strong and weak forces almost equally well. In the past few years, in high-energy experiments at CERN, the European laboratory for particle physics, near Geneva and at the Stanford Linear Accelerator Center (SLAC), physicists have made precision tests of the Standard Model. It seems to provide a complete description of the natural world down to scales on the order of one- thousandth the size of an atomic nucleus.
"The Higgs particle is connected with the weak force. Electromagnetism describes particles interacting with photons, the basic units of the electromagnetic field. In a parallel way, the modern theory of weak interactions describes particles (the W and Z particles) interacting with electrons, neutrinos, quarks and other particles. In many respects, these particles are similar to photons. But they are also strikingly different. The photon probably has no mass at all. From experiments, we know that a photon can be no more massive than a thousand-billion-billion-billionth (10 -30) the mass of an electron, and for theoretical reasons, we believe it has exactly zero mass. The W and Z particles, however, have enormous masses: more than 80 times the mass of a proton, one of the constituents of an atomic nucleus.
TO READ THE COMPLETE ARTICLE:
http://www.scientificamerican.com/article.cfm?id=what-exactly-is-the-higgs
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