Sharing disappointing results with a world of researchers working to find what they hope will be the “discovery of the century” isn’t an easy task, but that is what Penn State theoretical physicist Zoltan Fodor and his international research group did five years ago with their extensive calculation of the strength of the magnetic field around the muon —a sub-atomic particle similar to, but heavier than, an electron. At the time, their finding was the first to close the gap between theory and experimental measurements, bringing it in line with the Standard Model, the well-tested physics theory that has guided particle physics for decades.

Earlier on the same day, after almost 20 years, a new experimental result was also published showing a strong discrepancy between the theory and the experiment. This was interpreted by most physicists as a sign of new physics, and many physicists shared some skepticism of Fodor’s results and hoped that with more research, the other groups’ result would ring true.

Why? Twenty-four years ago, in an experiment at Brookhaven National Laboratory, physicists detected what seemed to be a discrepancy between measurements of the muon’s “magnetic moment”—the strength of its magnetic field—and theoretical calculations of what that measurement should be, raising the tantalizing possibility of undiscovered physical particles or forces. They reported that the muon was more magnetic than was predicted by the Standard Model.

New data from particle collisions at the Relativistic Heavy Ion Collider (RHIC), an “atom smasher” at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, reveals how the primordial soup generated in the most energetic particle collisions “splashes” sideways when it is hit by a jet of energetic particles.

The evidence comes from the first measurement at RHIC of reconstructed jets produced in collisions back-to-back with photons, particles of light. Scientists have long anticipated using measurements of photon-correlated jets to study the matter generated in these collisions. The findings, described in two papers just published in Physical Review Letters and Physical Review C, offer fresh insight into this primordial soup, which is known as a quark-gluon plasma (QGP)—and raise new questions about its extraordinary properties.

“Measuring reconstructed jets gives us unique views of how the strongly interacting plasma responds as the jets move through it,” said Peter Jacobs, a physicist at DOE’s Lawrence Berkeley National Laboratory and member of RHIC’s STAR Collaboration, which published these results. “Instead of focusing on what happens to the jet, we want to turn it around and see what the jet can tell us about the QGP.”

A research team has observed multibody interaction-induced EPs and hysteresis trajectories in cold Rydberg atomic gases. They revealed the phenomenon of charge-conjugation parity (CP) symmetry breaking in non-Hermitian multibody physics.

The team was led by Prof. Guo Guangcan, Prof. Shi Baosen and Prof. Ding Dongsheng from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences, and their study was published in Nature Communications.

CP-symmetry is an important discrete symmetry in particle physics. When certain physical processes exhibit asymmetry under CP transformation, it is referred to as the breaking of CP-symmetry, such as in the decay of neutral K mesons (K⁰) and B meson decay.