Physicists may have finally spotted elusive clusters of four neutrons or tetraneutron

This time not a new particle, but perhaps some other fascinating subatomic phenomenon! This research may even open the door to a new discipline in subatomic physics.

What goes on in time intervals of less than a billionth of a trillionth of a second? That humans even can measure such extremely short time intervals is almost magic. Questions of artifacts arise.

"Unlike an atomic nucleus, in which protons and neutrons are solidly bound together, the purported tetraneutrons seem to be quasi-bound, or resonant, states. ... last only for fleeting instants — in this case, less than a billionth of a trillionth of a second, the researchers report in the June 23 Nature.

Tetraneutrons fascinate physicists because, if confirmed, the clusters would help scientists isolate and probe mysterious neutron-neutron forces and the inner workings of atomic nuclei. ..."

From the abstract:

"A long-standing question in nuclear physics is whether chargeless nuclear systems can exist. To our knowledge, only neutron stars represent near-pure neutron systems, where neutrons are squeezed together by the gravitational force to very high densities. The experimental search for isolated multi-neutron systems has been an ongoing quest for several decades, with a particular focus on the four-neutron system called the tetraneutron, resulting in only a few indications of its existence so far, leaving the tetraneutron an elusive nuclear system for six decades. Here we report on the observation of a resonance-like structure near threshold in the four-neutron system that is consistent with a quasi-bound tetraneutron state existing for a very short time. ..."

Physicists may have finally spotted elusive clusters of four neutrons | Science News If confirmed, ‘tetraneutrons’ could help scientists better understand nuclear forces

Observation of a correlated free four-neutron system (open access)