Web edition: August 27, 2010
Print edition: September 11, 2010; Vol.178 #6 (p. 4)
PRIMARY CLUE TO MATTER — The shortest lifetime of an elementary particle — only a quarter of a millionth of a billionth of a second — gives a primary clue to the structure of matter.... [S]cientists have known for about ten years of the neutral pi-meson and have been trying to pin down its lifetime. The new measurement gives theoretical physicists a new universal constant and now they must figure out why it exists or relate it to another constant. When the neutral pi-meson breaks up or decays, two photons of light are produced. These high energy photons, or gamma rays, are purely electromagnetic in character. Thus the new measurement links mesons and the electromagnetic field for the first time.