Proton radius mystery deepens as deuterium measurement comes up short. Improving mass accuracy. In a commentary written to accompany the research, Niels Madsen of Swansea University in the UK points ...

A new detector sensitive to low-mass dark matter particles too light for current experiments to see has been proposed by physicists in the US. Built around a bath of superfluid helium-4, the device ...

Muons are essentially heavy versions of electrons, so substituting one for another in an atom is relatively simple. And a muon's mass provides some advantages for these sorts of measurements.

The artificial atom was stable for several nanoseconds, or a few billionths of a second. A short time indeed, but over 1,000 times longer than typical interactions between atomic nuclei and pions ...

An elusive type of atom known as pionic helium has been directly excited by laser light for the first time. The work establishes a promising experimental platform for probing fundamental physics ...

Helium is the simplest multi-body atom. Its energy levels can be calculated with extremely high precision only relying on a few fundamental physical constants and the quantum electrodynamics (QED ...

Laser physicists have captured an atomic-level event – an electron being ejected from a helium atom after being struck by a photon – with an accuracy of a trillionth of a billionth of a second ...