Chinese Physicists Found Particle After Years of Speculation

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Chinese Physicists Found Particle After Years of Speculation

Chinese scientists have discovered a new particle predicted decades ago but never observed before, they announced on Wednesday.

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Chinese scientists have discovered a new particle predicted decades ago but never observed before, they announced on Wednesday.

It could be what was once called the "multi-quark state,'' tiny elementary particles with a strong interaction or force that serves as the source of nuclear energy.

The discovery, made recently at the Beijing Electron Positron Collider (BEPC), was published in the science journal Physical Review Letters in mid-July.

It challenges existing theories in high energy physics and has attracted international attention as a first in the field.

The discovery was made by a team known as BES International Collaboration, which consists of physicists from the Institute of High Energy Physics (IHEP) under the Chinese Academy of Sciences, some other Chinese institutes as well as researchers from the University of Hawaii in the United States.

The mass of the newly discovered particle is about 1.859 billion Electron Volts (about twice that of the Proton, a subatomic particle) and its width is less than 30 million Electron Volts, according to the researchers.

Earlier studies under the BES international collaboration in 1990s provided some clues to the existence of this particle. However, due to limited statistics, it was not identified as a new particle at that time, researchers from the IHEP noted.

A detailed study on the unnamed, short-lived particle shows that it cannot be explained by any known particles, convincing scientists it is a previously unknown particle. They said the important feature of this new particle is its narrow width, which is very different from that of a conventional meson (the composite of quark and anti-quark). A quark is the smallest known elementary particle with strong interaction and the new particle could be a multi-quark state. The search for multi-quark states has been one of the focal points for many experiments including those by the BES. The discovery of this particle, together with other recent discoveries of possible multi-quark states, suggests that so-called Quantum Chromodynamics, our basic understanding of strong interactions, is incomplete.

Strong interaction is the force between sub-particles that is much more powerful than the electro-magnetic force between charged particles or gravitational force. This force is the source of nuclear energy.

John Ellis, a famous theorist with the European Organization for Nuclear Research, spoke highly of the recent breakthrough and its significance to developing strong interaction theory. This new observation at BES marksa milestone in the study of the short-lived particles, he said.

Based on the observation, physicists both at home and abroad are now trying to understand the particle's nature theoretically and experimentally.

Researchers at the IHEP said this discovery is based on continued experimentation by the BES collaboration since 1999 and is one of the most significant results achieved so far.

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