The X17 factor: A particle new to physics might solve the dark matter mystery – Phys.org

A crew of scientists in Hungary unprejudiced no longer too prolonged ago published a paper that hints at the existence of a beforehand unknown subatomic particle. The crew first reported finding traces of the particle in 2016, and in train that they now legend extra traces in a diversified experiment.

If the outcomes are confirmed, the so-called X17 particle might perchance well encourage to expose sad topic, the mysterious substance scientists possess accounts for larger than 80% of the mass in the universe. It might per chance well well be the provider of a “fifth force” past the four accounted for in the neatly-liked model of physics (gravity, electromagnetism, the primitive nuclear force and the sturdy nuclear force).

Smashing atoms

Most researchers who hunt for recent particles use broad accelerators that rupture subatomic particles together at excessive velocity and uncover at what comes out of the explosion. The biggest of these accelerators is the Astronomical Hadron Collider in Europe, where the Higgs boson—a particle scientists had been attempting for many years—became as soon as present in 2012.

Attila J. Krasznahorkay and his colleagues at ATOMKI (the Institute of Nuclear Study in Debrecen, Hungary) contain taken a diversified means, conducting smaller experiments that fireplace the subatomic particles called protons at the nuclei of diversified atoms.

In 2016, they checked out pairs of electrons and positrons (the antimatter model of electrons) produced when beryllium-8 nuclei went from a excessive energy grunt to a low energy grunt.

They stumbled on a deviation from what they expected to gaze when there became as soon as an infinite angle between the electrons and positrons. This anomaly will be handiest be explained if the nucleus emitted an unknown particle which later “split” into an electron and a positron.

This particle would must be a boson, which is the form of particle that carries force, and its mass might perchance well be spherical 17 million electron volts. That is ready as heavy as 34 electrons, which is reasonably lightweight for a particle bask in this. (The Higgs boson, to illustrate, is larger than 10,000 cases heavier.)

Due to its mass, Krasznahorkay and his crew called the hypothetical particle X17. Now they contain seen some irregular behavior in helium-4 nuclei which would perchance per chance well well even be explained by the presence of X17.

This newest anomaly is statistically necessary—a seven sigma self assurance diploma, which blueprint there is handiest a in point of fact microscopic possibility the consequence befell by likelihood. This is correctly past the identical earlier 5-sigma identical earlier for a brand recent discovery, so the consequence would appear to counsel there is a pair of recent physics right here.

Checking and double checking

Alternatively, the recent announcement and the one in 2016 had been met with skepticism by the physics community—the form of skepticism that failed to exist when two teams simultaneously announced the discovery of the Higgs boson in 2012.

So why is it so laborious for physicists to possess a brand recent lightweight boson bask in this is able to per chance well exist?

First, experiments of this kind are sophisticated, and so is the diagnosis of the records. Indicators can appear and depart. Help in 2004, to illustrate, the community in Debrecen stumbled on proof they interpreted because the imaginable existence of an even lighter boson, nonetheless as soon as they repeated the experiment the signal became as soon as long past.

Second, one needs to guarantee the very existence of X17 is correctly matched with the outcomes from diversified experiments. In this case, both the 2016 consequence with beryllium and the recent consequence with helium might also be explained by the existence of X17 nonetheless an unprejudiced check from an unprejudiced community is peaceable a necessary.

Krasznahorkay and his community first reported primitive proof (at a 3-sigma diploma) for a brand recent boson in 2012 at a workshop in Italy.

Since then the crew has repeated the experiment using upgraded gear and efficiently reproduced the beryllium-8 results, which is reassuring, as are the recent ends in helium-4. These recent results had been equipped at the HIAS 2019 symposium at the Australian Nationwide University in Canberra.

What does this contain to total with sad topic?

Scientists possess that most of the topic in the universe is invisible to us. So-called sad topic would handiest work along with identical earlier topic very weakly. We can infer that it exists from its gravitational effects on far away stars and galaxies, nonetheless it completely has by no blueprint been detected in the lab.

So where does X17 near in?

In 2003, in one of us (Boehm) showed that a particle bask in X17 might perchance well exist, in work co-authored with Pierre Fayet and on my own. It will lift force between sad topic particles in powerful the identical blueprint photons, or particles of gentle, cease for neatly-liked topic.

In among the scenarios I proposed, lightweight sad topic particles might perchance well occasionally originate pairs of electrons and positrons in a approach that is similar to what Krasznahorkay’s crew has viewed.

This scenario has ended in many searches in low-energy experiments, which contain dominated out rather a pair of possibilities. Alternatively, X17 has no longer but been dominated out—all over which case the Debrecen community can contain certainly stumbled on how sad topic particles keep up a correspondence with our world.

More proof required

Whereas the outcomes from Debrecen are very attention-grabbing, the physics community usually are no longer convinced a brand recent particle has certainly been stumbled on unless there is unprejudiced affirmation.

So we’re going to assign a question to many experiments all over the field which are procuring for a brand recent lightweight boson to originate attempting for proof of X17 and its interaction with pairs of electrons and positrons.

If affirmation arrives, the next discovery might perchance well be the sad topic particles themselves.

---

---

This text is republished from The Conversation beneath a Ingenious Commons license. Learn the customary article.