SUNY Poly Professor of Physics Dr. Amir Fariborz recently published a paper in Physical Review D, a top-tier journal, titled “Spinless glueballs in generalized linear sigma model.” The work takes on a central challenge in modern physics: understanding how the strongest force in nature shapes the inner structure of matter, and how it may produce an unusual form of matter made entirely from the carriers of that force.

Here’s the quick background. Everything is made of atoms. Atoms have a nucleus made of protons and neutrons, and those are made of even smaller pieces called quarks. Quarks are held together by gluons, which carry the strong interaction described by Quantum Chromodynamics (QCD). Many particles physicists study, called hadrons, are built from quarks and gluons; hadrons fall into two main groups: mesons and baryons. QCD does a great job explaining what happens when particles collide at very high energies, but at lower energies it becomes much harder to calculate, so researchers use well-tested models that still follow QCD’s rules.

One of QCD’s most intriguing predictions is the existence of glueballs, particles made entirely of gluons. If confirmed, glueballs would represent matter composed purely of the messengers of a fundamental force. While glueballs have not yet been directly and cleanly observed, there is substantial indirect evidence supporting their existence from experiments and from large-scale supercomputer simulations, especially in lattice QCD. A major reason glueballs are hard to pin down is that they can “mix” with ordinary particles that have similar properties, making them difficult to identify unambiguously.

Dr. Fariborz’s new paper presents a comprehensive investigation of the internal substructure of scalar and pseudoscalar mesons, along with how these mesons can interact with and mix with glueball states. The study is carried out within the generalized linear sigma model of low-energy QCD, a framework introduced by Dr. Fariborz and collaborators more than two decades ago and used since then to study many low-energy processes with results that have aligned with experimental findings. In this approach, the theory is built using the underlying symmetries of the strong interaction as well as important quantum anomalies, providing a structured way to connect mathematics to measurable particle behavior.

This work provides detailed predictions for the internal structure of 12 categories of subatomic particles, encompassing 36 distinct states in total. More broadly, it marks a major step forward in using the generalized linear sigma model to clarify the complicated “spectroscopy” of scalar and pseudoscalar mesons and to sharpen the theoretical picture of glueball states in QCD. In practical terms, the work helps the field better interpret what experiments are seeing and brings researchers closer to identifying and characterizing glueballs, one of the most challenging predictions of the strong interaction.
 

To read Dr. Fariborz's paper, click here.