Science Highlights

An important part of physics research is examining why theoretical calculations and experimental results sometimes don’t match. A recent physics experiment on the helium-4 nucleus and how it transitions from its basic energy state to its first excited state found evidence of a disagreement between theory and experiment. Now new calculations of the observed transition found agreement with the recent experimental results.

Flowing liquid lithium over a series of slats could offer an ideal solution for drawing excess heat off of a fusing plasma.

Atomic nuclei vary in shape from prolate to oblate, and these shapes have different moments of inertia, such that it takes different amounts of energy to spin different nuclei. Previous research has suggested that the amount of energy to spin some nuclei ever faster changes unexpectedly due to an anomalous increase in the moment of inertia, possibly because nuclei start to bulge out. New simulations have found instead that the moment of inertia does not change but several competing prolate and oblate shapes emerge that on average appear spherical.

Researchers have found similarities in how concepts of energy, pressure, and confinement apply to atomic nuclei and superconductivity. Specifically, in both hadrons and superconductors, how particles are confined to a specific volume can be described with the same mathematical framework derived from quantum chromodynamics. These dynamics even have similarities to the theories of how the universe expands.

The fusion of two nuclei is a complex process influenced by the relative energy and angular momentum of the nuclei and how their structures evolve as they collide. In this study, the researchers performed the most comprehensive computation to date of fusion reaction processes. The results indicate differences between the simulation results and experimental measurements which point to the presence of presently unaccounted for phenomena in fusion models.

Because of the number and density of neutrinos involved, it is nearly impossible to calculate the movement of neutrinos from compact astrophysical systems such as core-collapse supernovae and neutron star mergers. Researchers have now examined a potential way to solve this challenge by expanding traditional methods of calculating neutrino movement to include quantum mechanical flavor change. This reduces the complexity of the calculations.

Scientists use collisions of heavy ions to produce quark-gluon plasma containing large numbers of the heavy charm and bottom quarks. The recombination of freely moving charm and bottom quarks facilitates the production of Bc mesons. In this study, researchers carried out theoretical simulations of charm and bottom quarks diffusing through the quark gluon plasma and found that these quarks’ recombination can enhance the production of Bc mesons.