http://dailynews.yahoo.com/h/nm/20010707/sc/science_universe_dc.html

Saturday July 7 6:13 PM ET

Antimatter Not As Tough As Matter -- Thus We Exist

By Peter Henderson

SAN FRANCISCO (Reuters) - Looks like antimatter is not all it's cracked up to be, a group of international physicists have announced in a finding which proves there is a good reason for our universe, made of matter, to exist.

The experiments set the stage for another debate, however.

After bashing a stream of antimatter particles against a stream of matter particles in mile-long tubes near Silicon Valley, scientists found themselves with some left over matter that the uninitiated would not have expected.

Matter and antimatter blow each other up when they meet, as any Star Trek fan knows, which has left physicists working hard to explain how our universe, made up of matter, could exist, since around the Big Bang which started things there apparently were equal amounts of matter and antimatter.

The answer is that matter is a bit tougher than antimatter, at least as far as the recent experiments on a particle called a B meson are concerned, the team working at the Stanford Linear Accelerator Center in Palo Alto, California, announced.

That confirmed results of another experiment on a similar particle that has haunted physicists for decades.

``For 37 years people have looked and they haven't found anything beyond the original one,'' said Princeton University physicist Stewart Smith, a spokesman for the group.

``Physicists now know that there are at least two types of subatomic particles that exhibit this puzzling phenomenon, thought to be responsible for the great preponderance of matter in the universe.''

The physicists drove electrons against positrons, a type of antimatter, in a 1.3 mile particle accelerator. A 1,200-ton detector, called BABAR, recorded how B mesons and their antimatter equivalents, anti-B mesons, were born and how they decayed, leaving a bit more matter than antimatter.

STANDARD MODEL OF THE UNIVERSE

The work fits nicely with the current view of the universe, the Standard Model, which accurately predicted that B mesons and anti-B mesons would be slightly different, or asymmetrical.

``We don't have to invent new physics to explain our results,'' Smith.

Russian physicist and dissident Andrei Sakharov came up with the idea in 1967 that the universe of matter could exist because of the slight difference, also called charge-parity violation, or CP violation.

Sakharov in turn was explaining results of experiments with another particle, the K meson, which in 1964 showed the same behavior as particles in the Stanford-based experiment.

But in settling one debate physicists set the stage for another.

The Standard Model is missing something, even if it is correct as far as it goes. The amount of matter it predicts is only about one billionth as much as exists, Smith said.

``There is something major out there that we don't know,'' he said.

``Either there is some new set of ghostly particles, maybe they are just too massive to have been produced in accelerators... or there is some completely new phenomenon that we have not been able to see that is there to have catalyzed the evolution of the universe.''

A top candidate for a bit of asymmetry might be neutrinos, another fundamental particle that has not been studied much in this regard, Smith said, but those experiments await.

The Stanford-based tests were conducted by more than 600 scientists from 75 institutions in Canada, China, France, Germany, Great Britain, Italy, Norway, Russia and the United States, and the results have been submitted for publication in the Physical Review Letters journal.

-- Tidbit (of@the.day), July 08, 2001