Sunday, February 26, 2012

Higgs Boson is Running Out of Hiding Places

Via Science News (Feb 23, 2012) -

Even as physicists in Europe close in on their most-wanted quarry — a particle known as the Higgs boson — scientists in Illinois are helping narrow the hunt. New measurements of a different particle, one called the W boson, confirm the Higgs is in the mass range that most physicists had thought.

Theory suggests that the Higgs particle must exist in order to imbue many other particles with mass. Experiments at the Large Hadron Collider, at the CERN laboratory near Geneva, have shown that the Higgs’ own mass must be less than 127 billion electron volts. (Though it sounds like a unit of electricity, the electron volt is particle physicists’ fundamental unit of mass. A proton’s mass is about 1 billion electron volts.)

The new W boson findings confirm that the Higgs must be less than 145 billion electron volts. At the bottom end scientists have long known the Higgs, if it exists, must be at least 114 billion electron volts.

Narrowing the Higgs mass range with different methods helps scientists cross-check and thus have more confidence in their results. The W boson comes into play because it, the Higgs, and a third particle called the top quark are all interrelated. Determine the mass of any two of those, and you can calculate the mass of the third.

The new measurement is the most precise ever of the W boson mass: 80,387 million electron volts, according to scientists with the CDF collaboration at the Fermi National Accelerator Laboratory in Batavia, Ill., who announced the findings February 23 at a lab seminar.

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