production mechanisms. The upper panel shows the schematics of the quark line at the electroweak peak, and the lower panels show the corresponding production scheme for the computer cases. (a) color-enhanced, (b) color suppression, and (c) non-analysable color suppression mechanisms. Credit: TJ Burns et al, physical review d (2022). DOI: 10.1103/ PhysRevD.106.054029
Theorists at the University of Pittsburgh and Swansea University have shown that recent experimental results from the CERN collider give strong evidence for a new form of matter.
The experiment at CERN, the site of the world’s highest-energy particle collider, examined a heavy particle called Lambda b that decays into lighter particles, including the familiar proton and the famous J/psi, discovered in 1974.
In a research paper published online today in physical review dPhysicists Tim Burns of Swansea, Wales, and Eric Swanson of Pitt argue that the data can only be understood if a new type of matter exists.
Most of the observable mass in the universe comes from particles called quarks that combine to form the familiar protons, neutrons, and a host of other particles that interact much more vigorously than electrons or neutrinos. These highly interacting particles are collectively known as hadronsDescribed in Quantum Dynamics Theory. Although this theory is approaching its fiftieth birthday, its inner workings can still be hard to discern.
“Quantum dynamics is the problem with the Standard Model,” Swanson said. “Learning what he says about hadrons has required the world’s fastest computers to run for years, making it difficult to answer the dozens of questions that this single experiment raises.”
For this reason, performing experiments with hadrons – and correctly interpreting the results – is vital to understanding quantum chromodynamics.
Until recently, all hadrons could be understood as groups of a quark And the Antiquark, such as J/psi, or groups of three quarks, such as a proton. Despite this, it has long been suspected that combinations of other quarks are possible – which amounts to new forms of matter. Then in 2004 came the discovery of a particle called X (3872), which appeared to be a mixture of two quarks and two antiquarks. Other candidate novelties have appeared since then, although none of them can be conclusively identified as exotic new groups of quarks.
“Sometimes the bump in the data is a nice new thing, and sometimes it’s just a bump,” Swanson said.
The new work combines CERN data with other trials from 2018 and 2019 to arrive at a consistent interpretation of all results.
“We have a model that beautifully explains the data and, for the first time, includes all of the experimental limitations,” Burns said. The explanation requires the existence of several new particles made up of four quarks and one antiquark called “pentaquarks”. The research also indicates that pentaquarks are about to be observed in other laboratories.
“There’s really no other way to interpret the data – pentaquark states have to exist,” Burns said. The conclusion raises the possibility that other pentaquarks are possible, and that a whole new class of matter is on the cusp of discovery.
TJ Burns et al, Production of PC states in b decay, physical review d (2022). DOI: 10.1103/ PhysRevD.106.054029
University of Pittsburgh
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