Image copyright CERN

Scientists have detected a new particle at the Large Hadron Collider at Cern.

The discovery will help researchers learn more about the so-called "strong force" which holds the centres of atoms together.

The existence of the new particle was theoretically predicted but this is the first time it has been identified.

The details of the Xi-cc++ particle were presented at a high-energy physics conference in Venice.

The study was carried out at the LHCb experiment and led by Dr Patrick Spradlin of Glasgow University. He said that the discovery would "shed light on a longstanding puzzle and open an exciting new branch of investigation".

His colleague, Prof Paul Soler, also from Glasgow University, described the development as "a new frontier in understanding the strong force".

Nearly all the matter that we see around us is made of neutrons and protons, which form the centres of atoms. These are made up of three smaller particles called quarks which can be either light or heavy.

New arrangement

There are, however, six different types of quarks which combine in different ways to form other kinds of particle. Those that have been detected so far contain at most, one heavy quark.

This is the first time that researchers have confirmed the existence of one with two heavy quarks. According to Prof Guy Wilkinson of Oxford University, there is an intriguing difference between the new particle and the ones that have been discovered before.

"In contrast to other particles of this type, in which the three quarks perform an elaborate dance around each other, a particle with two heavy quarks is expected to act like a planetary system, where the heavy quarks are like two stars orbiting one around the other, with the lighter quark orbiting around this binary system."

The research team will now measure the properties of the Xi-cc++ to establish how this new arrangement of quarks behaves and how the strong force holds the system together. They also expect to find more double heavy quark particles.

Another unusual property of the particle is that it has two positive charges double that of the proton and it is four times heavier.

The researchers have submitted a paper reporting these findings to the journal Physical Review Letters.

Follow Pallab on Twitter</s>CERN scientists have just discovered a new "charming" subatomic particle, which they believe may help further our understanding of one of the four forces holding the universe together. Physicists working with the Large Hadron Collider (LHC) announced that they've found a long theorised particle, heavier than a proton. They are calling it the Xi-cc++ particle.

The new particle is a type of baryon and contains "two charm quarks and one up quark." Baryons make up the most matter, including protons and neutrons and are in essence triplets of smaller elementary particles called quarks. The new particle is four times heavier than a proton and the physicists are very excited about the discovery as it is the first time that the existence of such a particle has been confirmed.

"The existence of this particle from the baryon family was expected by current theories, but physicists have been looking for such baryons with two heavy quarks for many years. It is the first time that such a particle has been unambiguously detected," CERN said in a statement.

"Finding a doubly heavy-quark baryon is of great interest as it will provide a unique tool to further probe quantum chromodynamics, the theory that describes the strong interaction, one of the four fundamental forces," said Giovanni Passaleva, new Spokesperson of the LHCb collaboration. "Such particles will thus help us improve the predictive power of our theories."

"In contrast to other baryons, in which the three quarks perform an elaborate dance around each other, a doubly heavy baryon is expected to act like a planetary system, where the two heavy quarks play the role of heavy stars orbiting one around the other, with the lighter quark orbiting around this binary system," added Guy Wilkinson, former Spokesperson of the collaboration.

Scientists hope that the discovery of the new particle can help them investigate further the theory of the "strong force". In other words, this is the nature of the interaction between particles – essentially one of the basic forces of nature binding all matter and by extension, the universe together.</s>European scientists said Thursday they have discovered a new subatomic particle containing a never-before-seen combination of quarks — the most basic building blocks of matter.

The particle, a baryon dubbed Xicc++, contains two heavy "charm" quarks and one "up" quark, and has about four times the mass of a more familiar baryon — the proton.

The particle is predicted in the Standard Model of particle physics, and its discovery was "not a shock," said Matthew Charles of the LPNHE physics lab in Paris.

He is one of about 800 scientists to attach their names to the discovery by the Large Hadron Collider (LHC) of the European Organization for Nuclear Research (CERN).

The collider is most famous for discovering the Higgs boson, which confers mass on matter.

The new particle is the first seen with two such heavy quarks, said the team.

There are six types of quark, with exotic names such as "charm," "strange," and "beauty."

The "charm," "top," and "bottom" quarks are the heaviest types.

Quarks make up baryons such as protons and neutrons that comprise most of the mass in the known universe.

Baryons gather together in atoms, which form the molecules that constitute matter.

"This type of particle, these doubly-charmed baryons... they've been quite elusive," Charles told AFP.

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From their short-lived existence in the early Universe, none are left today. And to produce them in the lab requires an extreme concentration of energy, such as can be generated by the new, upgraded LHC.

The Xicc++ is an unstable baryon, said Charles. It lives for "a very small fraction of a second" before decaying into other, lighter particles.

Its discovery will allow scientists to continue testing the Standard Model of physics — the mainstream theory of the fundamental particles that make up matter, and the forces that govern them.

It does not, however, explain dark matter, or why there is more matter than anti-matter in the universe.

Critically, the model is incompatible with Einstein's theory of general relativity — the force of gravity as we know it does not seem to work at the subatomic quantum scale.

"A big part of our work as a field is trying to put our finger on the place where the Standard Model breaks down," to eventually find alternative explanations, said Charles.

"We're testing things in as many different places as we can," he said. "One of the things we... will be able to do with particles like this is to use them... for making further tests."</s>SWITZERLAND-Physicists using the Large Hadron Collider beauty (LHCb) experiment at CERN in Geneva, Switzerland, have discovered a new kind of heavy particle, they announced this week at a conference in Venice. The particle, known as Xi-cc++ (pronounced “Ks?-CC plus-plus”), is composed of three smaller elementary particles called quarks—specifically, one lighter-weight “up” quark like those found in protons and neutrons as well as two “charm” quarks, which are a heavier and more exotic variety.

The Standard Model of particle physics predicts Xi-cc++ and many other possible particles with various configurations of the six known flavors of quarks. But until now such “doubly charmed” particles had eluded conclusive detection. Further studies of the new particle and other members of the doubly charmed particle family could reinforce the Standard Model or lead to new vistas in particle physics.

Either way, the new particle could be a tool to unlock a deeper understanding of the fundamental “strong” force that binds quarks together to form protons and neutrons, which in turn form atoms as well as planets, stars, galaxies and people.

Any particle made of quarks is called a hadron. The world’s largest and most powerful particle accelerator, CERN’s Large Hadron Collider (LHC), slams these particles together in search of new particles and interactions. Hadrons fall into two broad families: mesons, exotic particles with one quark and one antiquark; and baryons, particles composed of three quarks. The new Xi-cc++ particle is a baryon. But due to its doubly charmed nature it is almost four times heavier than more familiar baryons such as protons and neutrons, which are made up entirely of light quarks rather than heavy ones. “Finding a doubly heavy quark baryon is of great interest, as it will provide a unique tool to further probe quantum chromodynamics [QCD]—the theory that describes the strong [force], one of the four fundamental forces,” LHCb spokesperson Giovanni Passaleva said in a statement. “Such particles will thus help us improve the predictive power of our theories.”

The featherweight quark triplets within protons and neutrons all uniformly zip around one another at nearly the speed of light, making them very challenging to study. In a Xi-cc++ particle, the sole light quark whips at high speed around the heavier, slower-moving heavy quark pair, creating a situation easier for physicists to investigate. The situation, says former LHC spokesperson and University of Oxford physicist Guy Wilkinson, is roughly analogous to a planetary system in which the light quark is akin to a planet orbiting a binary pair of massive stars.</s>The world’s biggest atom smasher has once again done its job and found a new subatomic particle.

Physicists at the Large Hadron Collider (LHC) in Europe announced the fleeting discovery of a long-theorised but never-before-seen type of baryon.

The high-speed collisions at the LHC created, for a fraction of a second, a baryon particle called Xi cc.

The researchers hope this new finding will help further explain a key force that binds matter together.

A baryon particle called Xi cc was created at the LHC when atoms were smashed (John Von Radowitz/PA)

So what exactly is a baryon?

Baryons are subatomic particles made up of quarks – which are the fundamental constituents of matter.

The most common type of baryons are protons and neutrons.

Quarks are even smaller particles that come in light and heavier types.

Image representing the new particle containing two charm quarks and one light quark (Daniel Dominguez/Cern)

The Xi cc has two heavy quarks — both of a type that are called “charm” — and a light one.

In the natural world, baryons have at most one heavy quark.

It may have been brief, but according to Oxford physicist Guy Wilkinson, in particle physics, it lived for “an appreciably long time”.

Wilkinson says the two heavy quarks are in a dance that’s just like the interaction of a star system with two suns and the third lighter quark circles the dancing pair.

The LHC was instrumental in the discovery of the Higgs boson in 2012 (John Von Radowitz/PA)

He believes the discovery opens up a whole new “family” of baryons for physicists to find and study.

“It gives us a very unique and interesting laboratory to give us an interesting new angle on the behaviour of the strong interaction (between particles), which is one of the key forces in nature,” Wilkinson added.

Built by the European Organisation for Nuclear Research (known by its French acronym CERN) and located in a 16.8-mile (27km) tunnel beneath the Swiss-French border, the LHC was instrumental in the discovery of the Higgs boson in 2012.

The team has submitted a paper to the journal Physical Review Letters.</s>Physicists using the Large Hadron Collider beauty (LHCb) experiment at CERN in Geneva, Switzerland, have discovered a new kind of heavy particle, they announced this week at a conference in Venice.

The particle, known as Xi-cc++ (pronounced “Ksī-CC plus-plus”), is composed of three smaller elementary particles called quarks—specifically, one lighter-weight “up” quark like those found in protons and neutrons as well as two “charm” quarks, which are a heavier and more exotic variety. (The designations “up” and “charm” are two of the six “flavors” physicists assigned to quarks based on the particles’ varying masses and charges.) The Standard Model of particle physics predicts Xi-cc++ and many other possible particles with various configurations of the six known flavors of quarks. But until now such “doubly charmed” particles had eluded conclusive detection. Further studies of the new particle—and other members of the doubly charmed particle family—could reinforce the Standard Model or lead to new vistas in particle physics. Either way, the new particle could be a tool to unlock a deeper understanding of the fundamental “strong” force that binds quarks together to form protons and neutrons, which in turn form atoms—as well as planets, stars, galaxies and people.

Any particle made of quarks is called a hadron. The world’s largest and most powerful particle accelerator, CERN’s Large Hadron Collider (LHC), slams these particles together in search of new particles and interactions. Hadrons fall into two broad families: mesons, exotic particles with one quark and one antiquark; and baryons, particles composed of three quarks. The new Xi-cc++ particle is a baryon. But due to its doubly charmed nature it is almost four times heavier than more familiar baryons such as protons and neutrons, which are made up entirely of light quarks rather than heavy ones. “Finding a doubly heavy quark baryon is of great interest, as it will provide a unique tool to further probe quantum chromodynamics [QCD]—the theory that describes the strong [force], one of the four fundamental forces,” LHCb spokesperson Giovanni Passaleva said in a statement. “Such particles will thus help us improve the predictive power of our theories.”

The featherweight quark triplets within protons and neutrons all uniformly zip around one another at nearly the speed of light, making them very challenging to study. In a Xi-cc++ particle, the sole light quark whips at high speed around the heavier, slower-moving heavy quark pair, creating a situation easier for physicists to investigate. The situation, says former LHCb spokesperson and University of Oxford physicist Guy Wilkinson, is roughly analogous to a planetary system in which the light quark is akin to a planet orbiting a binary pair of massive stars.

Led by University of Glasgow physicist Patrick Spradlin, the LHCb team found evidence of more than 300 of the new particles in data collected last year by the experiment, teasing out their signals from a dense forest of more common particles produced by high-energy proton collisions at the LHC. Specifically, they looked for a telltale distribution of “daughter” particles, including other baryons as well as kaons and pions—exotic particles produced by the decay of short-lived Xi-cc++ particles. The distributions they observed show not only that the LHC’s collisions are producing Xi-cc++ particles but also hint that other researchers’ previous claims of double-charm particle production may be spurious.

In 2002 researchers using the SELEX experiment at the Fermilab accelerator in Illinois announced they had found a similar particle. That detection, however, was just below the threshold of unassailable statistical significance, and the putative particle’s estimated mass was wildly out of sync with predictions. After other facilities failed to confirm the results, many theorists began questioning the claim. By contrast, the signal of the LHCb’s newfound particle “is statistically overwhelming and matches very nicely with the theoretical expectations,” Wilkinson says. “It looks, smells and tastes like a doubly charmed baryon should.” The LHCb team’s findings have been submitted to Physical Review Letters.

With the detection of the new, heavy particle firmly in hand, physicists at the LHC are now producing more of these particles to precisely measure their lifetimes and learn exactly how often they are created in collisions. Next, Wilkinson says, the LHCb experiment will seek out other postulated members of the doubly charmed family, such as the Xi-cc+ and Omega-cc particles. “All these results can be compared against predictions to test QCD,” he says. “There are exciting times ahead!”</s>Quarks come in three "generations". The first, lightest generation has down (mass 4.8 MeV) and up (mass 2.4 MeV). The second generation has strange (95 MeV, a heavier version of down) and charm (1275 MeV, a heavier version of up.) The third generation has bottom (4180 MeV, heaver version of down and strange) and top (172440 MeV, heaver version of up and charm.)

When they combine into particles, you either get paired quark+anti-quark (e.g. up+anti-down is a pi+ particle) or a triple of same type: quark+quark+quark or anti-quark+anti-quark+anti-quark. (E.g. a proton is up+up+down.)

This [newsweek.com] article says the new particle has two charm quarks.

This [wikipedia.org] article says Xi baryons are a class of particles which have a single up or down plus two more massive quarks: either strange, charm or bottom, and Xi baryons have been known since 1952.

From this I conclude that when they say "light" quarks they mean down, up and strange. (I was very frustrated that they didn't say what they meant by "light" quarks.)</s>Scientists at the Large Hadron Collider in Switzerland have discovered an exciting new particle—or rather, an exciting combination of particles. It doesn’t have quite the same impact that the Higgs Boson (the one people called the God Particle) did five years ago. But it does have people talking, and many folks are thinking about a controversial set of results from an older experiment.

The particle in question is an arrangement of three quarks called the Ξ ++ or the “doubly charged, doubly charmed xi particle” in English, discovered by the LHC’s LHCb detector. You may remember that the nucleus of an atom consists of protons and neutrons. Protons have two up quarks and a down quark, and one unit of positive electric charge. Neutrons have an up quark and two down quarks, and their charge is zero. The new xi particle consists of two of a very heavy flavor of quark, called the charm quark, and its charge equals two.

“We produce charm quarks in pairs, but having two charm quarks in the same particle is very rare,” physicist Patrick Koppenburg from Nikhef, the Dutch National Institute for Subatomic Physics, told Gizmodo. The charm quark makes up one of six possible quarks, including the up, down, charm, strange, top and bottom. The heaviest are the charm, bottom [also called beauty] and top [also called truth], but the top is probably too heavy to arrange with other quarks, he said. The other quarks should theoretically be able to arrange into groups of two, three, four or five, or even into a sort of quark liquid if things get hot enough.

But “most of these particles” with three or more quarks “containing two heavy quarks, charm or beauty, have not yet been found,” said Koppenburg. “This is the first in a sense.”

In a sense, said Koppenburg, because there’s a contested result from as early as 2002, when the SELEX collaboration at Fermilab in Illinois announced that they’d found a related particle called the Ξ +, the singly-charged, doubly charmed xi particle (that’s one plus sign instead of two). That particle also has two charm quarks, but has a down quark instead of an up quark like the new xi from LHCb. The one plus sign-xi also has an elemental charge of one, like a proton.

Koppenburg said that several other experiments have failed to reproduce SELEX’s particle. And this new particle casts further doubt on the SELEX discovery. “This one,” the LHCb’s new particle, “had a mass so different than the mass from the SELEX collaboration that it makes their mass unlikely,” said Koppenburg. The new xi particle weighs around 3600 MeV, or four times the mass of the proton. SELEX’s similar-but-different xi particle weighs about 100 MeV less, despite differing in composition only by the very light up or down quarks.

But the new CERN paper, which will be published in an upcoming edition of Physical Review Letters, points out that past attempts to recreate SELEX’s xi particle were different kinds of experiments than SELEX, so those “null results do not exclude the original observations.”

I reached out to James Russ, Professor of Physics at Carnegie Mellon and one of SELEX’s spokespeople, who was only just sitting down to read the new paper when I called. He reminded me that the two particles in question are different and that SELEX’s results were very clean. He stands by his experiment’s observed particle but remarked that LHCb’s results are certainly important. “Having a new observation will push theory in a certain direction,” he said, “so this is definitely an important observation.”

When Russ finished looking over the LHCb paper, he told Gizmodo: “The LHCb observation is very solid.” As far as the third, lighter quarks causing such a large mass difference, he’s said it’s unlikely to be related to differences arising from the quarks’ properties. “Both experiments seem to have done their analysis correctly,” he said. “If both particles are really there, there is a theoretical question about how two charm-charm-quark systems can behave so differently.”

None of this stuff is easy. Scientists are looking for incredibly elusive particles that exist for less than a picosecond, or a trillionth of a second. But since they’re moving at nearly the speed of light, they still travel a few millimeters before decaying into particles detected by the trails they leave in the LHCb experiment. Specific particles can set off a trigger letting the experiment know to keep the data on the event to analyse later. Reconstructing the specific tracks the particles left allows researchers to determine whether they spotted their xi.

And that particle must emerge as a signal over all of the background noise caused by other physics and other particles flying through the detector. In this case, the scientists saw a “12-sigma” significance, meaning it’s incredibly unlikely that their observations were random noise that just so happened to look like the new xi particle.

Regardless of past results, the LHCb scientists I spoke with pointed out that this new particle will allow them to better understand particle physics in general, and continue refining their theories about what quarks do when they stick together.

“We’re understanding that there are more complicated structures in nature than we thought there were before,” Sheldon Stone, Syracuse University physicist, told Gizmodo. This new xi particle can’t really exist on Earth except for in experiments, but probably existed right after the Big Bang when things were a lot hotter and closer together. Understanding the ways quarks could arrange themselves might offer further insights into the physics of that primordial era.

And while disproving a theory is exciting, this new xi quark seems to have the mass theorists expected, said Stone.</s>Scientists have discovered a new kind of particle that could open a 'new frontier' in physics.

The particle, which the scientists have named Xi-cc++, was discovered using the Large Hadron Collider.

While the particles were predicted to exist, this is the first time that scientists have been able to confirm their existence.

The discovery could shed new light on the 'strong force' which holds the centres of atoms together.

According to the Standard Model, the most basic particles can be broken down into fermions and bosons. Fermions can then be broken down further into two categories – leptons and quarks. Quarks come in six known 'flavours' – up, down, charm, strange, top and bottom. And baryons – such as Xi-cc++, are particles made up of three quarks. The most commonly known types of baryons are protons and neutrons, which are made up of light 'up' and 'down' quarks. But there are six types of existing quarks, and theoretically many different potential combiations that could form other types of baryon.

Researchers, led by the University of Glasgow, discovered the Xi-cc++ particle at the Large Hadron Collider beauty experiment (LHCb) at CERN.

The particle is part of a family of 'doubly charmed baryons' that were predicted to exist by the Standard Model theory of particle physics.

While previous attempts to detect the particles have been unsuccessful, the Glasgow researchers were able to collect data on more than 300 Xi-cc++ particles.

According to the Standard Model, the most basic particles can be broken down into fermions and bosons.

Fermions can then be broken down further into two categories – leptons and quarks.

Quarks come in six known 'flavours' – up, down, charm, strange, top and bottom.

And baryons – such as Xi-cc++, are particles made up of three quarks.

The most commonly known types of baryon are protons and neutrons, which are made up of light 'up' and 'down' quarks.

But there are six types of existing quarks, and theoretically many different potential combinations that could form other types of baryon.

Until now, all previously observed baryons contain at most one heavy quark, and this is the first time that anyone has observed a baryon with two heavy charm quarks.

Dr Patrick Spradlin, who led the study, said: 'The properties of the newly discovered Xi-cc++ baryon shed light on a longstanding puzzle surrounding the experimental status of baryons containing two charm quarks, opening an exciting new branch of investigation for LHCb.'

The Xi-cc++ baryon contains two heavy charm quarks and an up quark, and is around 3.5 times heavier than protons and neutrons.

It also has double the electric charge of a proton, with two positive charges.

Professor Paul Soler, Professor in Experimental Particle Physics at the University of Glasgow, said: 'This is the first time that a baryon has been conclusively observed containing two heavy charm quarks and is a new frontier in understanding the strong force that binds quarks together.'

Giovanni Passaleva, new Spokesperson of the LHCb collaboration said: 'Finding a new heavy-quark baryon is of great interest as it will provide a unique tool to further probe quantum chromodynamics, the theory that describes the strong interaction, one of the four fundamental forces.

'Such particles will thus help us improve the predictive power of our theories.'</s>Scientists at CERN have discovered a doubly charming new subatomic particle, a discovery they say could add to our understanding of how matter sticks together.

The particle’s existence was announced on Thursday at a physics conference in Venice. Scientists at the European Organisation for Nuclear Research, known by its French acronym CERN, observed it using the atom-smashing Large Hadron Collider. It is a long-predicted baryon, a subatomic particle made of quarks.

The most common baryons are protons and neutrons. Quarks are smaller, and include two types that are light and relatively common, and four types that are heavier and more unusual.

Scientists have been deliberately creating high-energy collisions of protons in CERN’s 27-kilometre tunnel on the Swiss-French border near Geneva to see what they can discover about the makeup of the universe and its tiniest particles. The aim is to investigate dark matter, antimatter and the creation of the universe, which many theorize occurred in a massive explosion known as the Big Bang.



Those collisions created a baryon particle called Xi cc during just a fraction of a second, according to Oxford physicist Guy Wilkinson, who was part of the experiment. Baryons usually have just one heavy quark and two light ones, but this one has two heavy quarks, both called “charm”, and one lighter one.



“In contrast to other baryons, in which the three quarks perform an elaborate dance around each other, a doubly heavy baryon is expected to act like a planetary system, where the two heavy quarks play the role of stars orbiting one around the other, with the lighter quark orbiting around this binary system,” Wilkinson said in a statementexternal link.



The team has submitted its findings in a paperexternal link to the peer-reviewed journal Physical Review Letters.



Five years ago, CERN announced the discovery of the Higgs boson, a subatomic particle that had long been suspected and searched for and that helps explain why matter has mass, which combines with gravity to give an object weight.
Scientists announce the detection of a new subatomic particle at the Large Hadron Collider.