Physicists Crack the Code Between Matter and Antimatter Collisions in Groundbreaking Calculation todayheadline

In a remarkable mathematical feat that bridges seemingly unrelated quantum phenomena, researchers have demonstrated for the first time that the same fundamental physics governs both what happens when you bounce an electron off a pion and when matter and antimatter collide to create new particles.

The breakthrough calculation, published in Physical Review D, uses sophisticated lattice quantum chromodynamics (QCD) to mathematically connect two distinct processes: the “spacelike” interaction where electrons scatter off pions, and the “timelike” process where electrons and positrons annihilate to produce pion pairs.

Lead researcher Felipe Ortega-Gama, working alongside mentors Jozef Dudek and Robert Edwards from the Thomas Jefferson National Accelerator Facility and William & Mary, resolved a longstanding computational challenge that has puzzled nuclear physicists for decades.

“At face value, these two processes look completely different,” explains Dudek, a senior scientist at Jefferson Lab with a joint position at William & Mary. “But in fact, they’re described by the same physics. Their diagrams are just sort of rotated with respect to each other. Felipe has shown, in a single calculation done at the level of quarks and gluons, that they’re connected in a smooth, simple way.”

While experimental measurements had suggested this connection, this calculation provides the first rigorous mathematical proof derived directly from the laws of quantum chromodynamics – the theory describing how quarks and gluons interact to form particles like protons, neutrons, and pions.

Solving the “Box Problem” in Quantum Calculations

The study overcomes a fundamental challenge in computational quantum physics. When particles collide in laboratory experiments, the resulting particles travel vast distances before detection. But computational limitations force researchers to simulate these interactions within a tiny virtual “box” just a few times larger than the range of the strong nuclear force itself.

“That’s a problem, because how do you relate the results of a finite box to the infinite volume results measured by your experimental detector?” said Ortega-Gama, who completed this work as part of his Ph.D. research at William & Mary before joining the University of California, Berkeley as a postdoctoral scholar in September 2024.

To bridge this gap, Ortega-Gama built upon mathematical formalism developed by his mentors and other physicists that translates finite-volume calculations into predictions for real-world experiments. This formalism had previously been used for simpler cases, but Ortega-Gama extended it to handle unstable particles and complex interactions.

The calculation is particularly notable for its precision in describing the resonant behavior around the ρ (rho) particle, an unstable state that manifests in the energy region where pion pairs interact strongly.

Journey from Student Intern to Breakthrough Researcher

Ortega-Gama’s path to this discovery began as an undergraduate intern at Jefferson Lab, where he was introduced to quantum chromodynamics by Raúl Briceño, then a jointly appointed staff scientist at the lab and professor at Old Dominion University.

“Raúl showed me this plot that had the calculations and the experimental measurements of the mass for a bunch of particles lying on top of each other,” recalled Ortega-Gama. “That was the first time I realized you could use QCD to precisely predict the properties for all these particles.”

This moment sparked Ortega-Gama’s interest in QCD research and drew him back to Jefferson Lab for graduate studies at William & Mary, where he collaborated with Dudek and the Hadron Spectrum (HadSpec) collaboration.

As a Ph.D. student, Ortega-Gama benefited from weekly meetings with Dudek to refine computations and discuss ideas. “For every step of the calculation, I could reach out to him to collaborate so that we could adapt the code to the specific type of study that we were interested in,” Ortega-Gama said.

Dudek praised his student’s exceptional versatility: “The strongest researchers, I would say, in our field of lattice QCD are those who have expertise in both formalisms and actually doing numerical calculations and working with numerical data. This guy can do both of these things at the highest level.”

Opening New Doors in Strong Force Physics

This calculation represents more than just an elegant mathematical connection. It opens doors for more accurate predictions of particle interactions that were previously inaccessible to direct calculation from first principles.

By demonstrating that theoretical physicists can now move seamlessly between spacelike and timelike processes, the research paves the way for more precise calculations of other particle interactions and properties. This could help interpret results from current and future particle physics experiments, including those at Jefferson Lab’s Continuous Electron Beam Accelerator Facility.

The success of this project highlights the powerful research ecosystem of Jefferson Lab, where students, postdoctoral researchers, and senior scientists collaborate across theoretical and experimental domains. Ortega-Gama’s work leveraged computational infrastructure developed by the HadSpec collaboration, including extensive code developed by Edwards, a staff scientist in Jefferson Lab’s Theory Center.

Ortega-Gama has now reunited with his first mentor, Briceño, as a postdoctoral scholar at UC Berkeley, where he continues to advance QCD calculations. “It was definitely helpful to have such an important work to facilitate the transition from a Ph.D. to a postdoctoral scholar,” said Ortega-Gama.

As researchers continue to refine these computational techniques, they move closer to the ultimate goal of QCD: a comprehensive mathematical understanding of how the strong force binds the fundamental building blocks of matter into the world we observe.