When Protons Collide, the Answers May Lie in the Wreckage

By Amar ('19/SAS/HC)
Illustration of proton-proton collision
Amar ('19/SAS/HC)

For the last two years, I have been working as part of a research group, led by Professor Stephen Schnetzer, in the High-Energy Experimental section of the physics department here at Rutgers. The focus of our research has been the search for a hypothesized new subatomic particle, known as a vector-like quark (VLQ). Belonging to a class of elementary particles, quarks comprise part of the building blocks of the universe, coming together to form such particles as protons and neutrons, which in turn constitute atomic nuclei. Thus far, 3 generations of quarks have been discovered, with VLQs being a potential next generation. In particular, VLQs have been proposed as a possible explanation for what is arguably the greatest problem in particle physics today: why is the Higgs boson so light? Hailed by pundits as the “god particle”, a moniker which makes most physicists quiver with rage, the Higgs boson essentially filled one of the biggest theoretical gaps in quantum mechanics, essentially explaining why and how particles have mass. However, when it was discovered in 2012, the Higgs was observed to have a mass of only 125 GeV/c2, about 200,000 times heavier than an electron. While this may seem huge, it pales in comparison to its theoretical predicted mass of 1019 GeV/c2, or about 20 trillion times the mass of the electron. This obscene discrepancy puzzled physicists, who responded by churning out prospective theories to explain it. The most vaunted such theory is known as “supersymmetry” (SUSY), but thus far there has been no experimental evidence to support it. VLQs are a consequence of a different theoretical model and, given SUSY’s issues, they have recently gained significant traction as a possible alternative solution to this Higgs problem. 

The research itself consists mainly of analyzing copious amounts of data output by the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) in Switzerland. This data is essentially the result of crashing protons together at 99.99% the speed of light and seeing what falls out. We then have to comb through the wreckage to attempt to find events where the VLQ we hope to find may have appeared. We are aided in this effort by sophisticated computer simulations, software packages, and statistical techniques. My personal role in the project has been to perform nearly the entirety of this data analysis, in conjunction with other team members who have been working in ancillary roles. In this capacity, I have progressed from handling a single analysis when I started on the project as a freshman to handling all 3 chief analyses for the past 6 months, which has resulted in me delivering a series of talks to CMS faculty around the globe via teleconference and culminating in the delivery of a talk to physics professors and graduate students at the April meeting of the American Physical Society (APS). Being able to interact collaboratively with physicists from around the world, being on a first-name basis with professors who help run the CMS experiment as a whole and work at the LHC itself, and ultimately having the opportunity, as an undergraduate, to present the results of our research in front of dozens of experts in the field at a national conference has been one of the great privileges of my life, and I am incredibly grateful to have had this experience as a I confront the final frontier of doctoral research after graduation.

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