(ORDO NEWS) — A modest proton is the core of the material Universe. Its characteristics define chemistry, manipulating the clusters of electrons that turn atoms into molecules and molecules into dazzling complexity.
Whatever we understand about its behavior, the proton’s internal structure is a chaotic mess of activity that scientists are still trying to decipher.
A new experiment at the US Department of Energy’s Thomas Jefferson National Accelerator Facility is shedding light on this mystery by revealing more information about the interior of the proton and how matter itself works on the smallest scales.
Researchers from all over the US have been able to measure the movements of the tiny fundamental particles called gluons that hold protons together.
This dimension, previously called the gluon gravitational form factor of the proton, acts as a kind of window into the mass structure of a positively charged nuclear particle.
The team found that the proton’s mass radius varies. from a radius covering the distribution of its electric charge, often used as a proxy for the size of a proton.
While these values don’t have to match, the differences between them can tell scientists more about how the proton works.
“The radius of this mass structure is smaller than the radius of the charge, and so it sort of gives us an idea of the hierarchy of the mass and charge structure of the nucleon,” says Mark Jones, senior scientist at the Thomas Jefferson National Accelerator Facility in Virginia.
Because gluons lack charge and mass, they must be measured indirectly, such as from the decay products of pairs of quarks and antiquarks known as mesons.
The experiment used electron and photon beams passing through liquid hydrogen, resulting in interactions that produced a type of meson called the J/ψ particle.
By measuring fallout from the J/ψ particles and comparing the results with theoretical models, the scientists calculated the various distributions of mass and electrical charge within the proton.
The larger radius of the electric charge means that the proton’s mass is concentrated, which suggests some gluons may stray beyond the mass-carrying quarks, possibly limiting them.
Don’t let the ubiquitous nature of the proton fool you. Under the hood, it’s a buzz of oddities, quantum particles appearing and disappearing in ways that are difficult to map.
Additional knowledge about the structure of the mass and charge of the proton is based on our fundamental understanding of the particles that make up the universe around us.
However, there is still a lot of work to be done. These results are partly based on theoretical models mentioned in addition to experimental observations, and it is not yet clear exactly how the proton mass is distributed and how it is related to gluon activity.
Further research is already planned, including different instruments and experimental methods and a higher level of accuracy. Soon we may find out exactly what the proton does.
“The bottom line for me is that there is excitement now,” Meziani says. “Can we find a way to confirm what we see? Will this new image information take root?”
“But for me it’s really very interesting. Because if I think about the proton now, we now have more information about it than ever before.”
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