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. </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> 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> Today at CERN, the Large Hadron Collider collaborations ATLAS and CMS jointly announced the discovery of the Higgs boson transforming into bottom quarks as it decays. This is predicted to be the most common way for Higgs bosons to decay, yet was a difficult signal to isolate because background processes closely mimic the subtle signal. This new discovery is a big step forward in the quest to understand how the Higgs enables fundamental particles to acquire mass.

After several years of refining their techniques and gradually incorporating more data, both experiments finally saw evidence of the Higgs decaying to bottom quarks that exceeds the 5-sigma threshold of statistical significance typically required to claim a discovery. Both teams found their results were consistent with predictions based on the Standard Model.

“The Higgs boson is an integral component of our universe and theorized to give all fundamental particles their mass,” said Patty McBride, distinguished scientist at Fermi National Accelerator Laboratory and recently elected deputy spokesperson of the CMS experiment. “But we haven’t yet confirmed exactly how this field interacts—or even if it interacts—with all the particles we know about, or if it interacts with dark matter particles, which remain to be detected.”

Higgs bosons are only produced in roughly one out of a billion LHC collisions and live only a tiny fraction of a second before their energy is converted into a cascade of other particles. Because it’s impossible to see Higgs bosons directly, scientists use these secondary particle decay products to study the Higgs’ properties. Since its discovery in 2012, scientists have been able to identify only about thirty percent of all the predicted Higgs boson decays.

“We expected the Higgs would decay into bottom quarks most often, but it is crucial to see and measure it,” said Young-Kee Kim, the Louis Block Distinguished Service Professor in Physics and chair of the Department of Physics at the University of Chicago, who worked on the bottom quark decay of the Higgs with the ATLAS experiment in the past. “We now have seen all of the primary decay modes of the Higgs predicted by the current theory of particle physics, the Standard Model. This marks a very important moment in particle physics!”

According to Viviana Cavaliere, a physicist at DOE’s Brookhaven National Laboratory who works on the ATLAS experiment, finding the Higgs boson decaying into bottom quarks has been priority number one for the last several years because of its large decay rate.

“Theory predicts that sixty percent of Higgs bosons decay into bottom quarks,” said Cavaliere, who is also using this process to search for new physics. “Finding and understanding this channel is critical because it opens up the possibility for us to examine the behavior of the Higgs, such as whether it could interact with new, undiscovered particles.”

The Higgs field is theorized to interact with all massive particles in the Standard Model, the best theory scientists have to explain the behavior of subatomic particles.

“However, questions remain which cannot be answered by the Standard Model,” said Kim. “For example, is the Higgs responsible for giving mass to dark matter particles, the dominant form of matter in the universe?”

Kim's group is currently studying whether or not some fraction of Higgs bosons created in the LHC decay into dark matter particles.

Even though this decay is the most popular path, spotting it in the experimental data was no walk in the park. Every proton-proton collision at the LHC produces a splattering of subatomic byproducts, one of the most common being bottom quarks. These bottom quarks then quickly decay into other kinds of particles, leaving behind vast showers of particles in the detectors. Tracing these particle showers back to two bottom quarks (and then figuring out which ones came from a Higgs boson) is extremely delicate and labyrinthine work.

“Being able to identify and isolate bottom quarks in the experimental data is a huge challenge and required precise detector calibration and sophisticated tagging capabilities to identify b-quarks,” said Giacinto Piacquadio, a physicist at Stony Brook University who co-leads the Higgs-to-bottom-quarks analysis group. “We were only able to do these analyses thanks to years of work that came before.” </s> 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> 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> Six years after the strange, elusive Higgs boson particle was discovered, scientists working with the world's largest particle accelerator have finally observed its mysterious, yet most common, decaying process.

Using data from the Large Hadron Collider, physicists caught the boson decaying into two smaller particles - a bottom quark and its antimatter equivalent, an antibottom quark.

The Standard Model of particle physics predicts that a Higgs boson will decay into bottom quarks - the second-heaviest of the quark flavours - about 60 percent of the time.

Physicists have been trying to observe this process, because it will either support the Standard Model, or show that it's insufficient - requiring a search for new physics to explain the discrepancy.

The problem is that the process is extraordinarily hard to catch in action. The Higgs boson is produced by a collision between two protons. If two gluons inside the protons fuse and produce two top quarks, these top quarks can recombine into a Higgs boson.

This particle exists for about one-septillionth of a second before it decays into less massive particles. It's the detection of these particles from which particle physicists infer the existence of the Higgs boson.

There are several ways these particles decay, including into a fermion-antifermion pair, a pair of photons, or a pair of gauge bosons, which are relatively easy to observe.

But with bottom quarks, it gets a little trickier, because every proton-proton collision produces a shower of subatomic particles, including bottom quarks. These then rapidly decay into other particles.

Since the Higgs boson's existence is so brief, it's been impossible to determine whether the bottom quarks detected were the result of a decaying Higgs boson, or of proton collision background processes.

To find the decay, two collaborations - ATLAS and CMS - combined data from the first and second runs of the Large Hadron Collider, and analysed it to try and find bottom quarks from the particle showers they produced. Then they had to trace those bottom quarks back to a Higgs boson.

"Finding just one event that looks like two bottom quarks originating from a Higgs boson is not enough," said Chris Palmer, a physicist at Princeton University who worked on the CMS analysis.

"We needed to analyse hundred of thousands of events before we could illuminate this process, which is happening on top of a mountain of similar-looking background events."

However, there are a few particles that are identifiable by-products of the Higgs boson production mechanism.

"We used these particles to tag potential Higgs events and separate them out from everything else," Palmer explained. "So we really got a two-for-one deal with this analysis because not only did we find the Higgs decaying to bottom quarks, but we also learned a lot about its production mechanisms."

And they confirmed - again - the Standard Model of particle physics, with which the measured rate of decay matched.

It's a result that opens a new possibility for scientists to study the behaviour of the Higgs boson in closer detail, and how it interacts with other matter, plus whether it could interact with particles that haven't been discovered yet (such as dark matter).

The next step in the research is to refine the measurements to study the decay mode in much higher resolution.

Both collaborations have submitted their papers for publication in science journals, and in the meantime can be found on arXiv: the CMS research is available here, and the ATLAS research is available here. </s> Six years after the discovery of the Higgs boson, physicists have observed it decaying to fundamental particles known as bottom quarks. The discovery is a huge contribution to scientists’ understanding of the Standard Model of particle physics and the universe at large. The finding was presented on Tuesday at CERN1 by the ATLAS and CMS collaborations at the Large Hadron Collider (LHC). In 2012, physicists discovered the Higgs boson - an elementary particle predicted by the Standard Model which relates to how objects have mass.

The Standard Model of particle physics predicts that about 60 percent of the time a Higgs boson will decay to a pair of bottom quarks - the second-heaviest of the six flavours of quarks. The finding provides major support for the Standard Model, which has many implications for how we understand the world and the universe. Jessie Shelton, a high-energy particle physicist at the University of Illinois said: “The Higgs boson is the least well-known and in many ways the most baffling particle in the standard model. “Observing its decay to bottom quarts is a major milestone in our understanding of its properties.”

The discovery of the decay has been a long time coming, as there are many other ways of producing bottom quarks in proton-proton collisions. This makes it hard to isolate the Higgs boson decay from the background “noise” associated with such processes. The finding is another big step to better understand the Higgs boson and the universe. Each new discovery or observation, has the potential to give way to new questions and experiments.

James Beacham, an experimental high-energy particle physicist said: “First [you] discover the thing. Then you want to measure everything about it.” Karl Jakobs, spokesperson of the ATLAS collaboration, said the observation is a “major milestone in the exploration of the Higgs boson.” He said: “It shows that the ATLAS and CMS experiments have achieved deep understanding of their data and a control of backgrounds that surpasses expectations. “ATLAS how now observed all couplings of the Higgs boson to the heavy quarks and leptons of the third generation as well as all major production modes.” </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!”
Scientists announce the detection of a new subatomic particle at the Large Hadron Collider.