Dark matter hunt yields unexplained signal

BBC ^ | 06/17/2020 | Paul Rincon

[BenLurkin]

Scientists working on the Xenon1T experiment have detected more activity within their detector than they would otherwise expect.

There are three potential explanations for the new signal from the Xenon1T experiment. Two require new physics to explain, while one of them is consistent with a hypothesised dark matter particle called a solar axion.

There are several theories to account for what that particle might be like. The most favoured one has been the WIMP, or Weakly Interacting Massive Particle.

Physicists working on the Xenon series of experiments have spent more than a decade hunting for signs of these WIMPs.

...

Its detector was filled with 3.2 tonnes of ultra-pure liquefied xenon, two tonnes of which served as a "target" for interactions between the xenon atoms and other particles that were passing through.

Most of these interactions - also known as events - are with particles we already know about, such as muons, cosmic rays and neutrinos. This constitutes what scientists refer to as the background signal

A potential signal from an undiscovered particle needs to be strong enough to rise above this background noise.

Scientists carefully estimated the number of background events in Xenon1T. They expected to see roughly 232, but the experiment instead saw 285 - an excess of 53 events.

...

...[T]he excess is most consistent with a signal from solar axions, a very light as-yet undetected particle, which is also a dark matter candidate

In statistical terms, the solar axion hypothesis has a significance of 3.5 sigma.

While this significance is fairly high, it is not large enough to conclude that axions exist. Five sigma is generally the accepted threshold for a discovery.

The significance of both the tritium and neutrino magnetic moment hypotheses corresponds to 3.2 sigma, meaning that they are also consistent with the data.

[LibWhacker]

Nice find, thanks. I love the way in which physicists design their experiments. It seems almost like cornering the truth... “Awww, shucks. Okay, you caught me. It’s me, the axion.”

[SuperLuminal]

There is at least one truism in what passes for modern "science":
Potentially amazing discoveries seem to occur (as in, highly correlated with) whenever funding resources need replenishment or political cover...