a 5th force ?

"Recently a 6.8σ anomaly has been reported in the opening angle and invariant mass distributions of e+e− pairs produced in 8Be nuclear transitions. The data are explained by a 17 MeV vector gauge boson X that is produced in the decay of an excited state to the ground state, 8Be∗→8BeX, and then decays through X→e+e−. The X boson mediates a fifth force with a characteristic range of 12fm and has milli-charged couplings to up and down quarks and electrons, and a proton coupling that is suppressed relative to neutrons. The protophobic X boson may also alleviate the current 3.6σ discrepancy between the predicted and measured values of the muon's anomalous magnetic moment."

This would be quite a surprising step beyond the standard model, but why did nobody else notice this 17 Mev boson before?

added later: There are now some doubts about the experiment.

added much later: A pretty good explanation of the experiment, relevant theories and also some other anomalies which may or may not be related.


CapitalistImperialistPig said...

I'm pretty sure there is a fifth force, because I know that it has been discovered at least a dozen times in my lifetime. Maybe we can use it to power reactionless space drives.

wolfgang said...

As far as I understand it, the effect is > 5 sigma but it is less clear if it is indeed an X boson or something else.

Lee said...

>> but why did nobody else notice this 17 Mev boson before?

I don't know, but Jonathan Feng isn't a crackpot, and I doubt that he is going to risk his reputation on pure nonsense. It would be very cool if there were a 5th force. I suppose CIP is right though and Feng's explanation will ultimately go into the same bin as those 5th forces discovered before.