The 7th Edition of Imagine Magazine

JENNIFER ROLOFF

NEW RESEARCHER Q&A

By Valerie DeLaCámara

Assistant Professor Jennifer Roloff joined the department this year, specializing in experimental particle physics. She is a musician who studied music dually with physics. When it came time to decide whether to pursue higher learning in music or physics, Brown Physics is pleased to report that physics won the day!

Q. You are an experimental particle physicist working on the CMS experiment. Your work focuses on precision tests of QCD, searches for physics beyond the Standard Model, and novel reconstruction and calibration methods for jets. Tell us about your research.

A. As an experimental particle physicist, I study the interactions between particles to answer fundamental questions about the universe. I do this using the CMS experiment, one of four main experiments at the Large Hadron Collider, where we collide protons at high energies, allowing us to study interactions between particles. My work focuses on jets, collimated sprays of particles produced from fundamental particles called quarks and gluons. This sector of physics, studying interactions between quarks and gluons, is referred to as quantum chromodynamics (QCD), and is responsible for the existence of protons and neutrons, which are composed of quarks bound together by gluons. In particular, my research explores the process of jet production as well as novel experimental reconstruction techniques for jets. While I am primarily focused on QCD, my work connects to many other research areas in particle physics since jets are used quite broadly for things such as Higgs physics and electroweak physics and searches for new physics that could answer questions about dark matter.

Jets are quite complicated composite objects, and I’ve found it a rewarding area of research where there is always something new to learn.

Q Can you explain the calibration methods for jets and how that aspect of your research developed?

A. Much of my work focuses on both jet reconstruction and jet calibration. This work aims to turn detector signals into something usable and correct them to be close to what we think happened in a collision. I have also done a lot of work on “pileup mitigation,” essentially removing noise from overlapping collisions. This process has many challenges, which means there is also a lot of room to improve on what we do. As a simple example, the detector isn’t uniform, and we need to be able to account for these effects. I started this work as a graduate student, where I was developing and testing different pileup mitigation algorithms. Over time, I realized that my work on QCD measurements had a deep connection to jet reconstruction. So, I am now working on developing better strategies for reconstruction and calibrations using insights from QCD.

Q. What background would a graduate student need to work with your research group?

A. There are a lot of different skills that are useful for my research, but a graduate student certainly doesn’t have to have all of them when they start working with me, and it’s more important that they are willing to learn. On the technical side, the most important thing to learn is coding and statistics since much of my work involves data analysis. In addition, since I work on a large experiment, it’s important to be interested in collaborating with others and to develop good communication skills since it is a large part of our job as scientists.

Q. Who influenced you most while you studied physics?

A. This is a tough question for me — I don’t think any single person influenced me the most, but I was fortunate to have a large community of people at CERN from whom I could learn and with whom to discuss ideas. In my opinion, this makes experimental high-energy physics special since we work in huge collaborations, which gives us opportunities to build large communities.

Q. How did your academic interests lead you to where you are today? Was physics your first love?

A. No, actually not! As an undergraduate, I studied oboe performance and physics; music was originally my main focus. I started doing physics research as an undergraduate, and I tried out a couple of projects before I had the opportunity to spend the summer doing research at CERN. Working at CERN was incredible since I got to meet

other students and researchers from all over the world working on a common goal, so I kept returning. I eventually had to choose between grad school in physics or music, and I chose physics largely because of how much I enjoyed the research I had done.

Q. What activities or hobbies do you enjoy when you're not immersed in physics? Could you share with us your favorite spots in Providence and Rhode Island?

A. Currently, my main interests are gardening, baking and sewing, and depending on the season, I also enjoy hiking and skiing. I’m new to Providence, so I’m still exploring everything the city offers. I’ve particularly enjoyed trying all of the different restaurants in downtown Providence, though it’s hard to name a single favorite place since there are so many places I want to try!