The hunt for new physics may have to continue for a while longer.
Scientists have found traces of an ultra-rare process to form top quarks, the particles that make up protons and neutrons. And that process seems to operate just as predicted by the Standard Model, the long-standing, yet incomplete, model that describes the subatomic particles that make up the universe.
Though the new results don't rule out other physics theories to explain the existence of dark matter and energy, they do suggest scientists have to look elsewhere for any hint of as-yet unknown physics. [Beyond Higgs: 5 Elusive Particles That May Lurk in the Universe]
Protons and neutrons are made up of tiny particles known as quarks, which come in several "flavors" (up, down, top, bottom, strange and charm). These quarks are bound together by other particles, known as gluons.
In 1995, scientists at the Fermi National Accelerator Laboratory in Batavia, Ill., discovered the top quark, the heaviest subatomic particle known. At 170 times the mass of a proton, it dwarfs even the Higgs boson, which is thought to explain how other particles get their mass, said Gregorio Bernardi, a research director at the University of Paris, and a spokesman for the new experiments.
The Standard Model, in turn, predicts several ways that one of these hefty top quarks could be produced. Scientists had found evidence for all of these processes, but one remained.
The one that remained was a "quite rare process, which at the same time you have this annihilation of a quark and an anti-quark," Bernardi told Live Science, referring to the annihilation that occurs whenever matter and antimatter come into contact.
For just the briefest flicker of time, this annihilation creates a w-boson, the particle that mediates the so-called weak interaction force. The w-boson rapidly decays, creating a top and bottom quark. Those two then decay into a shower of particles, as well as an electron or a muon and a neutrino, a ghostly particle that rarely interacts with matter, said Luciano Ristori, a physicist at the Istituto Nazionale di Fisica Nucleare in Italy, and a spokeman for one of the experiments. [Wacky Physics: The 6 Coolest Little Particles in Nature]
But the w-boson is much lighter than the top quark, so in order to get the w-boson to decay into a much heavier particle, the process required an incredible amount of energy, making it quite rare.
To find traces of this process, researchers combed through 500 trillion proton-antiproton collisions from two experiments conducted at the Tevatron at Fermilab from 2001 to 2011. (The Tevatron closed in 2011.) From this, they found evidence for 40 interactions where a top quark was formed from the weak interaction force.
The two experiments smashed a beam of protons and anti-protons into one another, producing a soup of other particles. Because top quarks vanish so quickly, scientists detected their presence based on a shower of other particles as they traveled through heavy iron, lead or uranium detectors, as well as changes in an electromagnetic field as the electron or muons travel through a charged gas. Though neutrinos weren't detected directly, they can be traced by the missing energy in the interaction, Ristori said.
Based on the frequency at which these events were detected, the new analysis confirms the Standard Model's prediction about how top quarks should behave, Ristori said.
"The chance is less than one in a million that what we saw was just a lucky combination of some coincidences," Ristori told Live Science.
Though it was hardly unexpected, the findings are yet another reminder that scientists are still in the dark when it comes to physics beyond the Standard Model. The Standard model cannot account for astronomical dark matter and energy observations.
"The big mystery at this point in physics is dark matter and dark energy and we have to find a way to explain that. And we have nothing yet," Ristori said.
Follow Tia Ghose on Twitter and Google+. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.
Copyright 2014 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Our 2024 Coverage Needs You
It's Another Trump-Biden Showdown — And We Need Your Help
The Future Of Democracy Is At Stake
Our 2024 Coverage Needs You
Your Loyalty Means The World To Us
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
The 2024 election is heating up, and women's rights, health care, voting rights, and the very future of democracy are all at stake. Donald Trump will face Joe Biden in the most consequential vote of our time. And HuffPost will be there, covering every twist and turn. America's future hangs in the balance. Would you consider contributing to support our journalism and keep it free for all during this critical season?
HuffPost believes news should be accessible to everyone, regardless of their ability to pay for it. We rely on readers like you to help fund our work. Any contribution you can make — even as little as $2 — goes directly toward supporting the impactful journalism that we will continue to produce this year. Thank you for being part of our story.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
It's official: Donald Trump will face Joe Biden this fall in the presidential election. As we face the most consequential presidential election of our time, HuffPost is committed to bringing you up-to-date, accurate news about the 2024 race. While other outlets have retreated behind paywalls, you can trust our news will stay free.
But we can't do it without your help. Reader funding is one of the key ways we support our newsroom. Would you consider making a donation to help fund our news during this critical time? Your contributions are vital to supporting a free press.
Contribute as little as $2 to keep our journalism free and accessible to all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. Would you consider becoming a regular HuffPost contributor?
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. If circumstances have changed since you last contributed, we hope you'll consider contributing to HuffPost once more.
Support HuffPostAlready contributed? Log in to hide these messages.