Home Tags Posts tagged with "higgs particle"

higgs particle

0

CERN scientists reporting at conferences in the UK and Geneva, Switzerland, claim the discovery of a new particle consistent with the Higgs boson.

The particle has been the subject of a 45-year hunt to explain how matter attains its mass.

Both of the two Higgs-hunting experiments at the Large Hadron Collider have reached a level of certainty worthy of a “discovery”.

More work will be needed to be certain that what they see is a Higgs, however.

Both teams claimed they had seen a “bump” in their data corresponding to a particle weighing in at about 125-126 gigaelectronvolts (GeV) – about 130 times heavier than the proton at the heart of every atom.

The results announced at CERN, home of the LHC in Geneva, were each met with thunderous applause.

CERN scientists reporting at conferences in the UK and Geneva claim the discovery of a new particle consistent with the Higgs boson

CERN scientists reporting at conferences in the UK and Geneva claim the discovery of a new particle consistent with the Higgs boson

Prof. Peter Higgs, the former University of Edinburgh theoretician who with five others predicted the Higgs particle’s existence in 1964, praised the LHC teams, calling the results “a testament to the expertise of the researchers”.

“I never expected this to happen in my lifetime and shall be asking my family to put some champagne in the fridge,” he said.

The CMS team claimed that by combining two of its data sets, they had attained a confidence level just at the “five-sigma” point – about a one-in-3.5 million chance that the signal they see would appear if there were no Higgs particle.

However, a full combination of the CMS data brings that number just back to 4.9 sigma – a one-in-2 million chance.

Joe Incandela, spokesman for CMS, was unequivocal.

“The results are preliminary but the five-sigma signal at around 125 GeV we’re seeing is dramatic. This is indeed a new particle,” he told the Geneva meeting.

Fabiola Gianotti, spokeswoman for the ATLAS experiment, announced even more irrefutable results.

“We observe in our data clear signs of a new particle, at the level of five sigma, in the mass region around 126 GeV,” she said.

Anticipation had been high and rumors were rife before the announcement.

Indications are strong, but it remains to be seen whether the particle the team reports is in fact the Higgs – those answers will certainly not come on Wednesday.

A confirmation would be one of the biggest scientific discoveries of the century; the hunt for the Higgs has been compared by some physicists to the Apollo programme that reached the Moon in the 1960s.

Two different experiment teams at the LHC observe a signal in the same part of the “search region” for the Higgs – at a rough mass of 125 GeV.

Hints of the particle, revealed to the world by teams at the LHC in December 2011, have since strengthened markedly.

The $10 billion LHC is the most powerful particle accelerator ever built: it smashes two beams of protons together at close to the speed of light with the aim of revealing new phenomena in the wreckage of the collisions.

The ATLAS and CMS experiments, which were designed to hunt for the Higgs at the LHC, each detect a signal with a statistical certainty of more than 4.5 sigma.

Five sigma is the generally accepted benchmark for claiming the discovery of a new particle. It equates to a one in 3.5 million chance that there is no Higgs and the “bump” in the data is down to some statistical fluctuation.

Prof. Stefan Soldner-Rembold, from the University of Manchester, said earlier this week: “The evidence is piling up… everything points in the direction that the Higgs is there.”

The Higgs is the cornerstone of the Standard Model – the most successful theory to explain the workings of the Universe.

But most researchers now regard the Standard Model as a stepping stone to some other, more complete theory, which can explain phenomena such as dark matter and dark energy.

Once the new particle is confirmed, scientists will have to figure out whether the particle they see is the version of the Higgs predicted by the Standard Model or something more exotic.

Scientists will look at how the Higgs decays or – transforms – into other, more stable particles after being produced in collisions at the LHC.

The Standard Model is the simplest set of ingredients – elementary particles – needed to make up the world we see in the heavens and in the laboratory

• Quarks combine together to make, for example, the proton and neutron – which make up the nuclei of atoms today – though more exotic combinations were around in the Universe’s early days

• Leptons come in charged and uncharged versions; electrons – the most familiar charged lepton – together with quarks make up all the matter we can see; the uncharged leptons are neutrinos, which rarely interact with matter

• The “force carriers” are particles whose movements are observed as familiar forces such as those behind electricity and light (electromagnetism) and radioactive decay (the weak nuclear force)

• The Higgs boson came about because although the Standard Model holds together neatly, nothing requires the particles to have mass; for a fuller theory, the Higgs – or something else – must fill in that gap

 

0

Scientists at the Large Hadron Collider (LHC) are expected to reveal the strongest evidence yet for the Higgs particle in Geneva, Switzerland, shortly.

Anticipation is high and rumors have been rife about the announcement.

The Higgs boson would help explain why particles have mass, and fills a glaring hole in the current best theory to describe how the Universe works.

The strength of the LHC’s signal is understood to be just short of the benchmark for claiming a “discovery”.

But it will show that researchers are now tantalisingly close to confirming the Higgs’ existence and bringing to an end the decades-long quest for the most coveted prize in physics.

The $10 billion LHC is the most powerful particle accelerator ever built: it smashes two beams of protons together at close to the speed of light with the aim of revealing new phenomena in the wreckage of the collisions.

But why has so much time and effort been invested in detecting the boson?

Mass is a measure of how much stuff an object – such as a particle or molecule – contains. If it were not for mass, all of the fundamental particles that make up atoms would whiz around at light-speed and the Universe as we know it would never have clumped into matter.

The Higgs boson would help explain why particles have mass, and fills a glaring hole in the current best theory to describe how the Universe works

The Higgs boson would help explain why particles have mass, and fills a glaring hole in the current best theory to describe how the Universe works

According to the theory, all of space is filled by a field – known as the Higgs field, which is mediated by particles known as Higgs bosons.

Other particles gain mass when they interact with the field, much as a person feels resistance from the water – drag – as they wade through a swimming pool.

The boson is the last missing particle in the Standard Model, the most widely accepted theory of how the cosmos works. But the Higgs remains a theoretical construct that has never been observed in a particle accelerator.

Four of the six theoretical physicists credited with coming up with the Higgs mechanism in the 1960s – including Prof Peter Higgs, after whom it is named – have been invited to CERN in Geneva for the presentations, fuelling anticipation of a major announcement.

Unconfirmed reports suggest that the signal detected at a mass of 125 gigaelectronvolts (GeV), which was announced in December, has since strengthened.

“We now have more than double the data we had last year,” said CERN’s director for research and computing, Sergio Bertolucci.

“That should be enough to see whether the trends we were seeing in the 2011 data are still there, or whether they’ve gone away. It’s a very exciting time.”

Discovering particles is a numbers game, and scientists analyze many events that could be representative of a Higgs boson being produced in the LHC.

The hints of the Higgs revealed in 2011 had a statistical certainty of just two sigma.

Three sigma represents about one in 700 likelihood that a “bump” in the data is down to some statistical fluctuation, in the absence of a Higgs. But the benchmark for a discovery is five sigma, denoting a one-in-3.5 million likelihood that a result is down to such a fluctuation.

Rumors suggest the certainty level has now crept beyond four sigma. This might not be enough to announce that scientists have found the elusive particle. But it would suggest the LHC’s scientists are within touching distance, and several physicists privately say that such a signal is now unlikely to go away.

Also, the idea that some systemic error could affect all the experiments that see hints of the Higgs – including those at the LHC and the US Tevatron machine (which search for the particle in different ways) – seems just as improbable.

But if and when a new particle is discovered, it will not be clear straight away that it is the Higgs. Physicists will need to characterize its properties in order to confirm whether it is the version of the Higgs predicted by the Standard Model, a “non-conformist” Higgs that hints at new laws of physics, or something else entirely.

This will involve years of detailed and difficult work, said Dr. Tony Weidberg, a University of Oxford physicist and member of one of the LHC’s experimental teams, Atlas.

He said that even at a certainty level of five sigma, “you’re very far from proving it’s a Higgs particle at all, let alone a Standard Model Higgs”.

 

© © 2011 - 2023 BelleNews.com