CMS joins the hunt for leptoquarks

Particle collisions that look like this are used to search for leptoquarks. This figure is specifically for (electron + up/down quark) type collisions.

Leptoquarks are theoretical particles. While there are theories that suggest these particles are real, we live in a world full of leptons (the electron is the most familiar example) and quarks (which are generally found in the nucleus of an atom.) We don’t understand why there are two types of particles (quarks and leptons) and we have a long history of realizing that sometimes two things that seem different are really the same. The classic example is when Newton realized that the force that makes my scale groan is exactly the same force that governs the motions of the planets. These ideas have led some to hypothesize that perhaps there is a kind of a particle called a leptoquark with properties of both leptons and quarks. An earlier Fermilab Today article described these objects.

An additional reason leptoquarks are an attractive idea is that some theories that merge all of the forces (also called grand unification theories or GUTs) only work if leptoquarks exist. So, observation of leptoquarks would be a substantial advance in our understanding of GUTs.

To help further our understanding, my CMS colleagues combed through our data, looking for leptoquarks. Before we took the measurement, we were unsure whether it would be competitive. For the measurements announced here, CMS recorded only about 3 percent of the total recorded beam compared to leading Tevatron measurements, but did so at three and a half times the Tevatron’s energy.

It turns out that in the two different kinds of leptoquark searches attempted here and here, CMS has ruled out possible leptoquark masses between 20-25 percent higher than was announced by DZero. The extra beam energy matters much more in this kind of analysis than the relatively modest amount of delivered beam.

As CMS resumes proton operations in 2011 and the amount of recorded data increases dramatically, we will be able to make huge improvements in this effort. If leptoquarks exist, there is a very good chance that CMS could see them in the next year or two.

— Don Lincoln

These physicists are working two different leptoquark analyses, (electron + up/down quarks, University of Maryland) & (muon + charm/strange quarks, Northeastern University).
These technicians are just some of those who contributed to the CMS experiment’s unparalleled silicon-based tracking detectors.