Evidence increases for new elementary particle

There may very well be a new elementary particle to add to our current understanding of particle physics.

Anomalies in measurements taken at the Tevatron in Ill. were previously thought to have been little more than events that occurred by chance in experiments looking for top quarks. However, more evidence is mounting that this may be more than a freak event.

“In the last two weeks, two very puzzling measurements at the Tevatron particle collider have been revealed. Both measurements show a ‘strange behavior’ that we cannot explain with our current Standard Model,” Markus Schulze, theoretical physicist at the Department of Physics and Astronomy here at Hopkins, wrote in an e-mail to The News-Letter.

Although the signals seem convincing, Schulze says that thus far the signal is too weak and that more will need to be done to lead to an official discovery. “There is still some (small) chance that it is just a statistical fluctuation or some error in the measurement,” he wrote. “So, to be really sure we have to wait a little for a refinement of the analysis or the LHC to take over.”

These measurements at the Tevatron were taken from an experiment that collided proton beams in the search for top quarks, the heaviest of the six quarks predicted by the Standard Model.

Measurements collected from this experiment found that there were particles that were flying off in one direction much more frequently than the other, a behavior contrary to the particle predicted by the Standard Model.

“If a new particle is responsible for this strange behavior then this new particle must have special interactions with the top quark and interact very differently with the other elementary particles,” Schulze wrote. “We have no clue yet, what kind of new particle this is — if it exists.”

One other particle that has been long sought after, the Higgs Boson, has already been ruled out as the identity of this mystery particle. As no other particle in the Standard Model remains to explain this new arrival, a new model for elementary particles may very well be needed.

“This would be very exciting because one cannot just add a single new particle to the Standard Model without violating its mathematical consistency,” Schulze wrote. “What would be needed is a whole new framework, like for example a new force or new symmetry principles or a rethinking of space-time. This is what we are actually looking for. This would probably give us some hints about unsolved problems like dark matter, dark energy or the matter-antimatter asymmetry in the universe.”

With the power to address some of these questions, the Large Hadron Collider (LHC) may give some further insight into the existence of this mystery particle. Running under the border between Switzerland and France, the LHC at CERN is the world’s largest particle collider, and provides massive amounts of data annually for physicists worldwide to analyze.

As Schulze noted, the LHC has the power to address some of the peculiarities of the unusual event at the Tevatron. “The anomalies in the two measurements at the Tevatron show up in a rather indirect and delicate way,” he wrote. “The LHC with its much higher energy and intensity can directly produce these particles and make them detect much easier.” With some luck, results from the LHC will yield the results within a year or two.

Schulze himself is not involved in any of the data from the Tevatron, a task that experimental physicists undertake. While at Hopkins, Schulze’s work, providing predictions to compare against experimental data, has involved providing calculations for particles in a vacuum that have interactions with top quarks.

He notes that the potential discovery of this new elementary particle may help address other unsolved questions. “Finding a new particle can lead to the discovery of a whole new theory which also contains many other particles. Finally, we hope to explain some of the unsolved big questions in physics.”