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HENEVER Star Trekneeded a dramatic cri-sis, the show knewthey could count on

anti-matter.

Anti-matter fuelled the warpdrive that propelled those star-

ships. It was dangerous stuff.Just a small glitch in the con-tainment field and, kaboom,goodbye Enterprise or Voya-geur and all who sailed in her.

And that's what most peopleknow about anti-matter: Itstricky but strictly sci-ence-fiction stuff.

An elite group of Canadianphysicists, however, know thatanti-matter is not only trickybut quite real as well. It's also

confounding, exasperating andmostlymissing inthe universe:The Canadi-ans are partof a massiveinternationalresearch ef-fort tryingto get to thebottom ofone of themost fun-

damentalmysteries:why nature

is lopsided, seemingly favour-ing matter over anti-matter.

"There really is a fundamentaldifference in how matter andanti-matter react," says Christo-

pher Hearty, a research scientistwith the Institute of ParticlePhysics at the University ofBritish Columbia.

Hearty is Canada's representa-tive on the executive board thatruns BaBar, an extremely sensi-

tive detector hooked up to aflow of fleeting subatomic par-ticles called B mesons producedin the linear accelerator at Cali-fornia's Stanford University.

One of the five measuring de-vices at the heart of BaBar is acat's cradle Of 29,000 ultrafinewires, called a drift chamber,which was designed and con-structed under trying circum-stances at TRIUMF, Canada'snational laboratory for particle

and nuclear physics in Vancou-ver.

BaBar embodies the high-stakes game of what's calledNew Physics. It's a collaborationamong 600 scientists and engi-neers from 73 institutions innine countries, including UBC,the University of Victoria, the

University of Montreal andMcGill University. The com-bined price tag for the detectorand what's called the B factoryis roughly $300 million.

This huge investment and twoyears of intense research pro-

duced new evidence earlier thismonth that some processes innature really are lopsided. Byrecording the almost instanta-neous disintegrations of 32Million pairs of B mesons andanti-B mesons, BaBar con-firmed that the matter andanti-matter versions of the par-ticles decay at different rates.

Physicists call this differencethe charge-parity violation CPviolation sounds incredibly ar-

cane but it may lie at the heartof why our universe exists.

If the universe was indeed cre-ated by a Big Bang, then thatmassive of energy (E=mc2)should also have created equalamounts of matter andanti-matter. They would then

REALLY WIRED: A scientist at TRIUMF, Canadas national laboratory for

particle and nuclear physics in Vancouver, replaced 19 of the 29,000 wires in

the Canadian-built detector used to probe the nature of anti-matter.

!SCIENCE

Anti-matter hunt pays offCanadian physicistsfind evidence naturereally is lopsidedin certain processes

BY PETER CALAMAI SCIENCE REPORTER

It would be likehaving twoarmies on thefield, one with abillion soldiersand the otherwith a billionand one. Theyslaughter eachother evenlyuntil just theone extrasoldier is left

STEW SMITH

TEAM LEADER

WW

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have cancelled one another andwe wouldn't be here today.

An alternate explanationmuch favoured by sci-fi writersis that the original matter andanti-matter divided creating amirror universe of anti-mattersomewhere.

Since any cosmic anti-matterwould be annihilated by colli-sions with matter before reach-ing the Earth's surface, scientistshave been looking above theplanet for traces of anti-matter.

A high-energy particle detec-tor on the space shuttle in 1998didn't spot a single anti-nucleusamong three million nuclei. Amore sensitive version of thedetector is planned for the

space station in 2004.But a mirror universe isn't

necessary if matter andanti-matter behave differently.Even a minute difference in de-cay rates, for instance, couldhave been enough to give mat-ter the crucial edge in the BigBang.

It would be like having twoarmies on the field, one with abillion soldiers and the otherwith a billion and one. They

slaughter each other evenly un-til just the one extra soldier isleft, says Stew Smith, teamleader and spokesman for Ba-Bar

Actually a difference of onein 10 billion might have beenenough, according to measure-ments of the cosmic back-ground radiation. But the the-ory at the core of modern parti-cle physics the so-calledStandard Model can onlyexplain a billionth of even that

minute difference. There isn'tanywhere near enough lopsid-edness in the Standard Modelfor matter to triumph as it did.

That's why at least some BaBarexperimenters were hoping tofind a bigger decay differencefor B mesons than allowed by

the Standard Model. But theactual measurement agreedclosely with the model's pre-dicted difference.

The Standard Model winsagain, says a laughing Smith.

Yet the quest to explain lop-sidedness is far from over. Ba-Bar will continue with more andmore precise measurements ofvarious characteristics of Bmesons over the next severalyears.

And the world's most powerfulaccelerator the $6 billionLarge Hadron Collider isscheduled to begin operating in2006 at Europe's particle phys-ics laboratory (CERN) near Ge-neva.

Physicists believe that this newaccelerator will bash togetherenough protons with highenough energies to produce anever-before-seen subatomicparticle known as the Higgsboson, considered the doorwayto the future of physics.

If the Higgs boson exists andif its mass is relatively smallthen the theoretical prospectsfor a mirror universe brighten.If the Higgs boson is middle

weight, then the StandardModel can probably be re-jigged to accommodate it. Butif is heavy, then entirely newmodels will be needed to de-scribe the particle universe.

For physicists, matters don'tget much more exciting thanthis. But getting in on theground floor of BaBar in themid1990s proved difficult forCanadians because the federalgovernment had just slashedfunding for scientific research.

Originally Canadian physicistsproposed taking full responsi-bility for BaBar's drift chamber,which would have cost $4 mil-lion. But when the federalgranting council could come upwith only $500,000, the re-searchers had to scramble.

Eventually the chamber wasbuilt in Vancouver with morethan $2 million donated byFrance and Italy and another$500,000 of in-kind supportfrom TRIUMF. But the fundinghassle in Canada so frustrated

McGill physicist DavidMacFarlane that he snapped upan attractive job offer from theUniversity of California at SanDiego.

MacFarlane was part of agroup of about 15 Canadianphysicists who helped blaze thetrail for this month's BaBar suc-cess during an international ex-periment called ARGUS atGermany's national acceleratorfacility near Hamburg between1983 and 1993.

We wanted to evolve Cana-dian participation in ARGUSinto participation in one of theB factories when they got built.But the timing was unfortu-nate, he says.

So now MacFarlane heads theU.S. group responsible for thekey analysis behind the BaBarresults. And he's not the onlyexpatriate Canadian scientistplaying a key role in the BaBareffort.

Stanford University physicistPatricia Burchat, a University ofToronto graduate, has coordi-nated analysis from the experi-ment's physics results. And StewSmith, the Princeton Universityresearcher who is the publicface of BaBar, is originallyfrom Victoria and studiedphysics at UBC.

Smith got to go home tempo-rarily when construction of thedrift chamber began at TRI-

UMF in March, 1997.A year later, we put it in the

truck to leave for Stanford andI cried, he says.