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Rai successfully defends thesis, “Unveiling the Structure of the Perfect Superfluid using Correlation Functions”

Ananya Rai's thesis committee.
May 30, 2025

On May 21, Ananya Rai successfully defended the thesis “Unveiling the Structure of the Perfect Superfluid using Correlation Functions” (advisor: Helen Caines).

Rai explained, “The goal of my research is to better understand one of the fundamental forces of nature—the strong nuclear force—which holds the building blocks of matter together. To do this, I study fundamental particles called quarks and gluons, which interact through this force. When these particles are created in high-energy collisions at particle accelerators, they form narrow sprays of particles known as ‘jets’. My work focuses on exploring what’s happening inside these jets using a new tool called Energy Correlators. This technique helps us see how energy is distributed within a jet. By studying jets both in empty space (vacuum) and in an extremely hot, dense form of matter called the Quark Gluon Plasma, I can compare how the strong force behaves in different conditions and learn more about the structure and fluid-like properties of this exotic state of matter.”

Rai intends to do a one year long masters program in Education Policy focusing in Global and Comparative Education at Harvard starting this Fall. 

Rai added, “I want to just highlight how much I have enjoyed working with my RHIG family. It was a long-winded road to figure out what I enjoyed in grad school, and I am very happy that I found my way to RHIG. I will miss being here a lot. “

Thesis Abstract: The sequential clustering of particles into jets provides an algorithmic link between final-state hadrons and the partons from which they originated. Jet substructure techniques allow us to trace the radiation history of jets, offering a powerful framework to probe Quantum Chromodynamics (QCD) across different energy scales. Projected N-point Energy Correlators (ENCs) are a novel class of observables that explore the energy flow within hadronic jets.

This thesis presents the first measurements of the two-point (EEC) and projected three-point correlators (E3C) as well as their ratio (E3C/EEC) at √s = 13 TeV using Run 2 data from the ALICE experiment. The ENCs demonstrate characteristic scaling behavior, while their ratios reveal sensitivity to the running of the strong coupling constant, αs. Corresponding first measurements of E3C and E3C/EEC at √s = 5.02 TeV are also presented, showing consistent features across center of mass energies.
 
At extreme temperatures and densities, strongly interacting matter undergoes a phase transition into a deconfined state known as the Quark Gluon Plasma (QGP), which is created in heavy-ion collisions at the LHC. This thesis presents both the first application of, and the techniques to, measure higher-point Energy Correlators in heavy-ion collisions, thereby expanding the set of substructure tools available to probe the microscopic properties of the QGP.
 
Thesis committee: Helen Caines (advisor), Laura Havener, David Moore, Ian Moult, and Raaghav Kunnawalkam Elayavalli (external)
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