Guide to the Cosmos

 Making the Wonders of our Universe Accessible to Everyone

A Dark Force in the Universe?


A shoestring experiment may have discovered a new force of nature.


For nearly a century, physicists believed every interaction in nature was driven by one of four fundamental forces:


Gravity pulls massive objects together and keeps us on the ground.


Electromagnetism powers our homes and factories, and lights up the sky in thunderstorms.


• The Strong force holds protons and neutrons together, making the core of the atoms in everything we see.


• The Weak force allows particles to morph from one type into another, enabling the creation of essential elements, including carbon, oxygen, and iron.


Now, there are hints of a new force, perhaps a dark force controlling the dark side and dominating the universe — very Darth Vader-ish.


If confirmed by more research, this will be the greatest surprise and the most important discovery in particle physics in 40 years.


And the best part of the story is that this discovery uses technology that was state-of-the-art 60 years ago — its beam energy is 5 million times less than the LHC (Large Hadronic Collider), and the experiment cost about 10,000 times less.


Hungarian physicists, lead by Attila Krasznahorkay, report finding a new fundamental boson that is produced 200,000 times less often than normal bosons. As yet unnamed, I’ll call it Attila.


All fundamental bosons, except Higgs, are force carriers. For example, photons (the particles of light) carry the electromagnetic force between charged particles — electrons repel other electrons by exchanging photons. Protons attract neutrons by exchanging other bosons.


By extension, theoretical physicists Tim Tait and colleagues at UC Irving propose that Attila carries a new force. Its feeble interaction with normal matter means this fifth force might answer the biggest mystery in physics: what is dark matter?


Two caveats. Firstly, Attila’s group has previously announced discoveries that were never confirmed. Secondly, many public reports say Tait has “confirmed” Attila’s discovery — that is incorrect. Theorists can explain what observations mean, but in science, observations of nature can only be confirmed by more observations. Math can help us model nature, but nature is not constrained by our equations.


We will have to wait several more years for more experiments and more answers.


I’ll end with technical highlights of Krasznahorkay’s and Tait’s research papers. Like all other force-carrying bosons, Attila has spin 1. It has zero charge and mass 16.7 MeV. It decays to electron e / antielectron e+ pairs, with a lifetime of roughly 0.01 trillionths of a second. In the micro-world, that’s a long time. This means its mass width is only 0.06 eV, making it extremely hard to produce in colliding beam machines — impossible if one didn’t know where to look.


The key evidence for Attila is the excess e / e+ pair production shown below (bars above the curve, to the left of “x4”).





The excess is greatest along curve (b) at a proton beam of energy 1.10 MeV, with less excess along curve (c) at 1.04 MeV, and no significant excess at 1.20 or 0.80 MeV.


Protons incident on a Lithium-7 target produce the 18.15 MeV excited state of Beryllium-8. This decays to its ground state by emitting a gamma ray most of the time, but rarely (about 5.8 times per million), it emits Attila instead.


The e / e+ angle is 180º in Attila’s rest frame; it peaks at 140º in the lab frame.


Tait suggests Attila interacts with electrons and neutrons, but not with protons, thus making it even more elusive.


Best Regards,




Sept 6, 2016


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