Through a peephole tantalizingly.

Through a peephole tantalizingly 

The flood of data that comes out of the type of physics experiment in which two subatomic particles collide at high energy is often so copious that physicists need some time to notice and interpret some of the strange new things that appear. This is especially true if the strange new things are of a sort that nobody was looking for.

Thus, some anomalous events that occurred at the PETRA colliding beam apparatus of the German Electron Synchrotron Laboratory (DESY) in Hamburg back in 1984 are now being interpreted as what Harald Fritzsch of DESY calls "a peephole' into a possible new domain of physics (quoted in the September CERN COURIER). If it is such an opening, the recently completed and more energetic TRISTAN collider at Tsukuba, Japan, and the Stanford Linear Collider (SLC) of the Stanford Linear Accelerator Center in Menlo Park, Calif., could enlarge the window.

In 1984 PETRA provided the most energetic collisions of electrons and positrons in the world with a total of 47 billion electron-volts (47 GeV) in each collision. In that run PETRA's Mark J detector saw seven instances of something unanticipated: the simultaneous production of a gang of hadrons (protons and related particles) with a wide spread of energies along with a single isolated muon. None of the other detectors working at PETRA at the time appeared to see such things, so the matter was dropped.

Later on, a reexamination of the data from the JADE detector that searched specifically for isolated muons found five more such events. That made the question interesting again, and by this year theorists were proposing that these events might come from the decay of varieties of quarks or leptons (particles related to muons) of a sort whose existence is not now contemplated by theory. Such a thing could represent an entirely new development for particle physics.

Interested physicists are hoping that TRISTAN (with up to 50 GeV per collision), which just began experiments, or SLC (up to 100 GeV per collision), which is complete and undergoing tests, may be able to cross a threshold that PETRA seems to have just bumped.