MORNING EDITION Date: SEPTEMBER 01, 1997 Time: 10:00
BOB EDWARDS, HOST: Scientists say they may have tracked down a sub-atomic particle that researchers have been seeking for more than a decade. A recent study suggests that quarks, the fundamental building blocks of matter, can combine in exotic new ways.
The findings published today in the issue of Physical Review Letters could help confirm the quark theory of matter. But the claim is controversial. Some of the leading scientists who helped with the research don't believe the reported result.
NPR's Richard Harris reports.
RICHARD HARRIS, NPR REPORTER: Over the past several decades, scientists using atom smashers have come to realize that the protons and neutrons inside the atom are actually made up of smaller particles called quarks. In nature, quarks always come in sets of three. Atom smashers can also produce them in pairs. But Neal Cason, at Notre Dame, says in theory they should be found in other, more exotic combinations, too.
NEAL CASON, NOTRE DAME RESEARCHER: There have been hints for a number of years now. And in fact it's because of some of these hints and theoretical expectations that set us on the journey of trying to definitely identify one of these particles.
HARRIS: So Cason, along with more than 60 other scientists from seven institutions, set up an experiment at the Brookhaven National Laboratory on Long Island to look for particles containing odd assortments of quarks. They smashed a beam of sub-atomic particles into some hydrogen atoms to create a shower of other particles, and they sifted through those searching for signs of something new.
They now report that they did indeed find something they say is evidence for a new kind of particle. Cason says the new particle could either be made up of four quarks bound together, instead of the usual three, or two quarks plus another particle called a gluon.
JASON: And our present level of experimental understanding is not sufficient to distinguish between these two possibilities.
HARRIS: Either way, he says, it would be a particle new to science. Cason is called it an exotic meson named pi 1-1400. Michael Chanowitz at the Lawrence Berkeley National Lab says the discovery of a particle like this doesn't topple any theories of physics, but it would help scientists understand the strong force which holds atomic particles together.
MICHAEL CHANOWITZ, LAWRENCE BERKELEY NATIONAL LAB: It gives us a window into a dramatically different kind of matter which -- you know, different than the kind of matter that you and I and tables and chairs are made out of. That is this theory, quantum chromodynamics, the theory of the strong nuclear force, says that there are these other kinds of objects there. And it would be interesting to find them, to make sure that they are there, as the theory predicts, because it will then -- that gives us even more confidence that the theory is correct. I mean, if we could prove that they weren't there, we would, we would probably have to think hard again, either about the theory itself or about our understanding of it.
HARRIS: But there's a serious question about whether a new particle really has been found. In fact, some of the scientists who conducted the research are highly skeptical.
Alex Dzierba at Indiana University was one of the experiment's lead organizers.
ALEX DZIERBA, SCIENTIST, INDIANA UNIVERSITY: At best, this is a confirmation of a result that was published by a group from Russia about three or four years ago.
HARRIS: At worst, Dzierba says, the result is simply an error. He says it's easy to be fooled by the elaborate machinery in the experiment. In fact, other groups have made the same claims using similar data, only to retract their results. And he says the evidence from Brook Haven is flimsy at best. So, Zerba says he and about a dozen other collaborators withdrew their names from the paper.
DZIERBA: We also felt that, since we have, oh, perhaps a factor of between seven and 10 times more data in hand, that those data should have been included in the analysis of this result.
HARRIS: Dzierba says his group is still analyzing that material to figure out whether there really is a new particle in the mix.
Other experts are cautious, too. Nathan Isgur at the Thomas Jefferson Lab in Newport News, Virginia, says he's not convinced they found a new particle.
NATHAN ISGUR, THOMAS JEFFERSON LAB: I think their result is very suggestive, but I'm not yet ready to crack open my bottle of champagne.
HARRIS: Isgur says he'd like to see the particle produced through some other reaction in an atom smasher, and as it happens, he says such an experiment is planned at the Jefferson Lab where he works.
ISGUR: If we can observe the same thing that they've observed there, I would consider the effect confirmed and we'll open that champagne.
HARRIS: That experiment is supposed to begin about 18 months from now, so the controversy over this result isn't likely to be resolved soon.
I'm Richard Harris, NPR News, Washington.