New boson appears in nuclear decay, breaks standard model, Ars Technica

Mystery boson forces its way in –

Weird electron-positrons from decaying beryllium and helium hint at new boson.

Chris Lee –Dec (****************************************************************, ********************************************** 4: 54 pm UTC **************************

**************************************A collision in the LHC’s Compact Muon Solenoid (CMS) detector produces a Higgs boson signature. Thomas McCauley / Lucas Taylor, CMS In the world of physics, nothing gets the blood flowing like the thought that a new particle has been discovered. For decades now, physicists have been hunting for evidence that modern physics isn’t right. But, the smoking gun has remained elusive. In November, people started polishing a Nobel prize for a group of physicists who seemed to havefound new boson. And, a new boson means a new force, which is even more exciting. Is that gun smoking yet?Sometimes the gun just smolders This result has been cooking for quite some time. The first experimental results date back to 2015, with published in. Essentially, the scientists took some lithium and shot protons at it. By choosing the energy of the protons correctly, Beryllium in a particular excited state is produced, which quickly decays back to lithium by emitting an electron and a positron. Now, in these experiments, energy and momentum must be conserved. The lithium nucleus is quite a complicated beast and can rattle around in all sorts of ways, meaning that the electron and positron have a certain amount of freedom in the direction in which they are emitted.By contrast, the researchers observed that some electrons and positrons seem to be correlated in their emission direction. Computer modeling confirmed that this was not due to their equipment and could not be explained by the nuclear physics of beryllium, lithium, or any known background process. The correlation could, however, be explained by a new boson that decayed by emitting a positron and an electron. As long as the production was reasonably inefficient, and the mass was about MeV (million electron volts), then the data was beautifully explained.

The paper really got the juices flowing. Theorists jumped on the result so fast they inadvertently broke special relativity. Experimental physicists went back through old data searching for confirmation. Operating experiments were tweaked to look for the new particle.

Experimentally, it all seemed a wash. Old data revealed nothing, but, at the same time, those experiments weren’t exactly set up to look for the right particle. New experiments were still too fresh to be conclusive (even if they had started taking data).

Look, if we just tweak the Universe…

The theory situation is even more of a mess. It is always possible to extend our models of the Universe to include new particles, including new bosons and new forces. But, it isn’t good enough to match a single experimental result. You have to match all of them. Theend resultsareparticles that (look a bit like a) ************************ backyard panel-beating job. Yeah, the paint matches, but you can still see the wavy patches where the filler hasn’t been sanded flat. The problems arise from the mass – (MeV is at the low end of well-explored territory.)