Tag Archives: quark

We might have a new dark matter candidate particle — and we’ve already discovered it before

This image, taken with the NASA/ESA Hubble Space Telescope, focuses on an object named UGC 695, which is located 30 million light-years away within the constellation Cetus (The Sea Monster), also known as The Whale. Credit: European Space Agency.

Most of the mass of the universe is invisible even to our most sensitive instruments. We have no idea what it actually looks like or what it’s made of, but this mysterious stuff must be out there. We’re sure of this because we can see its strong gravitational effect. What’s more, without it, the universe’s acceleration would have slowed down instead of accelerating as astronomers have observed.

Scientists refer to this elusive mass as dark matter and believe it outnumbers “normal” (read: visible) matter five to one. Now, a new study is proposing a candidate particle that might be part of dark matter.

What’s interesting about this particle is that researchers have already detected it in previous experiments.

Tangible dark matter?

We know more about what dark matter isn’t made of than what it is. Studies have shown that dark matter cannot be explained by baryons, antimatter, nor galaxy-sized black holes as had been proposed over the years.

Credit: ZME Science Data Vizualization Studios.

In order to explain dark matter, physicists have proposed a number of candidate particles, including axions, dark photons, weakly-interacting massive particles (WIMPs), and superheavy gravitinos.

All of these candidates are hypothetical, in the sense that they haven’t been confirmed experimentally. This makes this latest study even more intriguing. It suggests that dark matter may be made of d-star hexaquark — more formally, d*(2380) — a particle that was detected in experiments in 2014.

“The origin of dark matter in the Universe is one of the biggest questions in science and one that, until now, has drawn a blank,” said Daniel Watts, a nuclear physicist at the University of York in the UK and lead author of the new study.

“Our first calculations indicate that condensates of d-stars are a feasible new candidate for dark matter. This new result is particularly exciting since it doesn’t require any concepts that are new to physics.”

Instead of being made up of sets of three quarks, like is the case for protons and neutrons, d-stars are particles made of six quarks, hence the ‘hexaquark’.

This means d-stars are bosons that can form an exotic form of matter called Bose-Einstein condensate (BEC) when chilled to almost absolute zero.

BEC, also known as the fifth state of matter, was first predicted in the 1920s by Albert Einstein and Indian physicist Satyendra Bose but it wasn’t until very late in 1995 that scientists were able to produce the necessary conditions for this extreme state of matter to occur. 

At room temperature, atoms are incredibly fast and behave akin to billiard balls, bouncing off each other when they interact. As you lower the temperature (remember temperature reflects atomic agitation or vibration), atoms and molecules move slower. Eventually, once you get to about 0.000001 degrees above absolute zero, atoms become so densely packed they behave like one super atom, acting in unison. 

The physicists at the University of York propose that soon after the Big Bang, conditions would have been enough for d-star hexaquarks to come together as BECs. And, according to their calculations, if the particles gathered in large enough numbers, they could have potentially caused analogous effects to dark matter.

In the future, the researchers plan on testing their hypothesis in a laboratory setting. Meanwhile, they hope astronomers can join in and search for signals that may indicate d-star BECs somewhere in the galaxy or beyond.

“The next step to establish this new dark matter candidate will be to obtain a better understanding of how the d-stars interact – when do they attract and when do they repel each other,” said Mikhail Bashkanov, co-author of the study. “We are leading new measurements to create d-stars inside an atomic nucleus and see if their properties are different to when they are in free space.”

The findings were reported in the Journal of Physics G: Nuclear and Particle Physics.

Quark-Gluon Plasma that filled the early Universe investigated by ALICE

The secrets of the Quark-Gluon Plasma that filled the early universe are being unlocked by the ALICE collaboration at CERN with the first measurement of the flow of bottomonium particles.

Quark-Gluon Plasma that filled the early Universe investigated by ALICE (Author's Collection)

Quark-Gluon Plasma that filled the early Universe investigated by ALICE (Author’s Collection)

 

In a paper presented at the European Physical Society’s conference on high-energy physics, the ‘A Large Ion Collider Experiment’ (ALICE) collaboration has documented the first-ever measurement of the flow of a heavy meson particle — bottomonium.

The measurement of particles like bottomonium — a type of ‘upsilon’ particle — helps the researchers understand the Quark-Gluon Plasma (QGP) that filled the hot, dense early universe. 

By observing pairs of ‘heavy electrons’ — known as muons — produced by the decay of bottomonium, the team discovered bottomonium particles have small values of elliptic flow — a measure of how uniform energy and momentum is distributed across the particles when viewed from the beamline. 

This is quite unexpected as all other hadrons investigated thus far have exhibited significant elliptic flow. 

David Evans, a professor of high energy physics at the University of Birmingham, leads the UK participation in ALICE.

He says: “ Elliptical flow measurements in ALICE show that the Quark-Gluon Plasma flows like an almost perfect liquid, with the light quarks (up, down, strange, and charm) flowing with the system.”

“The fact that no significant elliptical flow is seen for the bottomonium suggests b-quarks are only produced in the initial collision of the lead ions, before the QGP is formed.”

The ALICE team’s results seem to support existing theories that bottonium and other upsilon particles split into their constituents during the early stages of their interactions with plasma.

This gives the researchers a better insight at the conditions in the early moments of the universe when it was filled with a plasma composed of free quarks and gluons. 

Evans continues: “This makes b-quarks (and particles made up of b-quarks) an ideal probe for studying the QGP as they experience the entire evolution of the system.”

Bottomonium particles — probing the Quark-Gluon Plasma at the dawn of the universe

Taking a trip through the ‘particle zoo’ to discover what these bottomonium particles actually are, helps us understand their role in the ALICE experiment. 

The six known types of quarks on the left and how they come together to form protons and neutrons on the right
The six known types of quarks on the left and how they come together to form protons and neutrons on the right

Bottonium is a heavy meson — particles which consist of a quark and its own antiparticle. In the case of bottomonium, a bottom (or beauty quark) — b quark — and its antiparticle counterpart.

These subatomic particles are extremely unstable, existing for short periods of time and only at high energies before decaying into other particles. When bottomonium decays it leaves behind a pair of ‘heavy electrons’ called muons. 

Bottomonium particles — which are formed in the LHC by the violent collision of heavy lead-lead ions — provide an excellent probe of the Quark-Gluon Plasma which filled the universe just a few millionths of a second after the big bang. 

Being produced so early in the collision event means bottomonium particles ‘experience’ the entire evolution of the plasma — from the moment it is produced to the moment it cools down and enters a state in which hadrons can form.

This extremely early stage in the universe’s evolution would have been the only time in history that quarks and gluons existed freely in plasma and not bound together in a state called ‘confinement’ in protons, neutrons and other hadrons.

These particles were only able to exist in this free state because of the incredible heat in the universe at this point. In our era, quarks and gluons are never observed as free particles.

Thus, it takes a tremendous amount of energy, to recreate these huge temperatures. At the moment, the Large Hadron Collider (LHC) is the only piece of apparatus on Earth capable of doing this, with collisions in the LHC able to generate temperatures a 100 thousand times hotter than the Sun. 

At these temperatures, protons and neutrons ‘melt’, freeing quarks and gluons from confinement, thus creating a Quark-Gluon Plasma and allowing them to form short-lived, unstable particles like bottonium. 

ALICE: Collision queen

The ALICE collaboration — consisting of over a 1000 scientists operating a 10-thousand-tonne, 16m tall detector buried 56m under the Alps — achieves this high-energy feat by slamming together beams of lead ions rather than the proton-proton collisions used in other LHC experiments. 

The decay of upsilon particles — another type of meson — into muon pairs as the result of a lead-lead collision. The red lines track the two muons the orange lines track the other particles produced (CERN)
The decay of upsilon particles — another type of meson — into muon pairs as the result of a lead-lead collision. The red lines track the two muons the orange lines track the other particles produced (CERN)

The benefit of colliding lead ions is that, as ALICE is looking to create Quark-Gluon Plasma, the more quarks available to it, the better the chance of observing something significant. 

A single proton and neutron each contain three quarks but as lead ions contain at least 56 protons and at least 204 neutrons this leaves the team with far more quarks to play with. 

ALICE then measures this plasma as it expands and cools, but it is still unable to measure the particles created directly— instead deducing the presence and properties of QGP from the signatures on pairs of muons it produced by decay. 

One of these signatures is the elliptic flow — the collective movement of the produced particles determined by several factors like particle type, mass, the angle at which the particles meet and the momentum they possess as they collide —  which is what the team measured. The flow is created by the expansion of hot plasma after the collision of the lead ions.

Upgrading ALICE: More collisions. More Quarks. More Results

Perhaps the most promising thing about ALICE’s mission to probe the early universe and its conditions is the fact that the forthcoming high-luminosity upgrade only promises to yield more data for researchers to investigate.

The ALICE Experiment is about to be revitalised (CERN)

The upgrade — which CERN hopes will be operational by 2021— aims to increase the luminosity of the LHC by a factor of 10. Luminosity, as described in reference to particle accelerators, is proportional to the number of collisions that occur. Thus increasing the luminosity also means increasing the number of collisions.

As an example of the usefulness of this upgrade, whereas the LHC produced 3 million Higgs boson particles in 2017, the High-Luminosity LHC is expected to produce 15 million per year.

In addition to the High-Luminosity upgrade — on which work began in 2018 — ALICE will also several other upgrades and improvements. As a result of these improvements, the ALICE team expect an overall gain of 100 times the current results.

Evans says: “With this huge increase in statistics and a new inner detector in ALICE, we will be able to measure particles made of b-quarks with much higher precision.”

As such, the experiment stands a very good chance of significantly improving our knowledge of the quark-gluon plasma and the conditions in the early universe, with these new bottomonium results pointing the way.

Evans concludes: “[The upgrades] allow us to probe the properties of the QGP in much more detail and hence learn more about the evolution of the early universe.”

Computer simulation predicts new exotic particle composed of two baryons

Artist impression of the di-Omega particle. Credit: Keiko Murano

Artist impression of the di-Omega particle. Credit: Keiko Murano

Japanese researchers have used one of the world’s most powerful supercomputers to predict the existence of a strange new type of particle. The proposed particle is composed of two baryons, rather than a single baryon like almost all the other particles in the world.

Baryons are composite particles made of three quarks, as opposed to mesons, which are composite particles made of one quark and one antiquark. Both protons and neutrons, as well as other particles, are baryons.

A quark is a subatomic particle — one of two currently recognized groups of fundamental particles —  that represent the smallest known unit of matter. Twelve fundamental particles – six quarks and six leptons (the other type) – are the basic building blocks for everything in the universe. Both types of particles are distinguished in terms of flavors or colors, as they’re sometimes called. For quarks, there are six types of colors: up, down, top, bottom, strange, and charm.

Most particles are made of just one baryon, except an outlier called deuteron, or heavy hydrogen. Such particles are called dibaryon particles, and now researchers at RIKEN’s Advanced Institute for Computational Science in Japan have predicted the existence of a second one.

It took them three years of crunching numbers, working with an insanely fast computer capable of performing 10 quadrillion operations per second, to come to a result — that’s how computational intensive this kind of search can be. Running simulations based on quantum chromodynamics (QCD), the theory that describes quark interactions, the team eventually found a new tentative particle called di-Omega.

The new particle ought to be composed out of two “Omega baryons” that contain three strange quarks each.

“We were very lucky to have been able to use the K computer to perform the calculations. It allowed fast calculations with a huge number of variables. Still, it took almost three years for us to reach our conclusion on the di-Omega,” said Shinya Gongyo from the RIKEN Nishina Center.

In the future, it remains to be seen if di-Omega is really a thing of reality. The researchers have already proposed a series of experiments with heavy ion collisions in Europe and Japan for this purpose.

“We believe that these special particles could be generated by the experiments using heavy ion collisions that are planned in Europe and in Japan, and we look forward to working with colleagues there to experimentally discover the first dibaryon system outside of deuteron. This work could give us hints for understanding the interaction among strange baryons (called hyperons) and to understand how, under extreme conditions like those found in neutron stars, normal matter can transition to what is called hyperonic matter—made up of protons, neutrons, and strange-quark particles called hyperons, and eventually to quark matter composed of up, down and strange quarks,” said Tetsuo Hatsuda from RIKEN iTHEMS.

Scientific reference: Shinya Gongyo et al. Most Strange Dibaryon from Lattice QCD, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.120.212001.

 

Credit: ThePressProject.

Scientists discover new type of fusion reaction — merging quarks is eight times more powerful than single reactions in H-bomb

Israeli and American physicists have come across a new type of fusion reaction that is startlingly powerful. Initially, the scientists were a bit scared and thought it’s better not to publish the research least it fell into the wrong hands, leading to a planetary-bomb. The fusion, however, can’t sustain a chain reaction so scientists say the process is, for all practical reasons, harmless.

Credit: ThePressProject.

Credit: ThePressProject.

Matter, the stuff we see and interact with, is made of atoms,. In turn, these are made of protons and neutrons, which, in their own turn, are made of elementary particles called quarks and leptons. There are six ‘flavors’ or types of quarks physicists know of: up, down, strange, charm, top, and bottom. Yes, physicists have a knack for giving silly names to particles and phenomena. Up and down quarks have the lowest masses of all quarks.

Researchers at Tel Aviv University and the University of Chicago found a way to fuse two bottom quarks together. When they fuse, the two bottom quarks form a larger particle called a nucleon and release up to eight times more energy as the individual reactions in a Hydrogen-bomb, specifically 138 megaelectronvolts (MeV).

Quarks

Credit: Wikimedia Commons.

In the case of a hydrogen bomb, there are millions of fusion events going on, so imagine what a quark-bomb would look like. You don’t need to run the math to realize it could even obliterate a planet.

Marek Karliner of Tel Aviv University and colleagues almost wanted to pull the plug on the research until they realized it is all a ‘one-trick pony’. What Karliner means by that is bottom quarks exist for just one picosecond or a mere one-trillionth of a second before turning into up quarks. That’s a way too brief period for a chain reaction to sustain itself so a quark-bomb would just fizzle instantly.

“We suggest some experimental setups in which the highly exothermic nature of the fusion of two heavy-quark baryons might manifest itself. At present, however, the very short lifetimes of the heavy bottom and charm quarks preclude any practical applications of such reactions,” the authors wrote in the study published in the journal Nature.

In and of itself, the research is highly valuable because it proves that subatomic particles can release massive amounts of energy when fusing together.

“It is important to emphasize that although our findings have aroused considerable interest in theory, they have no practical application,” said Karliner. “A nuclear fusion that occurs in a reactor or a hydrogen bomb is a chain reaction in a mass of particles, creating a huge amount of energy. This is not possible by melting heavy quarks, simply because the raw material cannot be accumulated in the melting process. If we thought for a moment that our discovery had some dangerous application, we would not publish it.”

LHC signals hint at flaws in the Standard Model of Physics

An intriguing signal reported at the LHC might signal some “cracks” in the Standard Model – the theory which describes how different forces interact with each other.

A view inside the LHCb experiment’s muon detector at the Large Hadron Collider. Image credits: CERN.

The LHC has already accumulated a trove of valuable data, and researchers are still working on analyzing it. Now, a study on data gathered during 2011–12 at the collider at CERN suggests that in some particular decays, some short-lived particles (B-mesons) create some particles (taus) more than others (muons); but according to the Standard Model, the decay should be happening at the same rate, so something is clearly not as expected. Let’s explain that a bit.

Quarks are elementary particles – they’re the smallest thing we know of, the very basis of subatomic particles. Hadrons are composite particles made of quarks. Mesons are a specific type of hadrons made from one quark and one anti-quark – and B-mesons are a type of mesons. They are very short-lived, so studying their decay is particularly difficult. The discrepancy that was observed is so small we can’t rule out a statistical fluctuation (a satisfying statistical threshold has not yet been reported).

But physicists are excited because a similar thing has been reported at two other experiments: the ‘BaBar’ experiment at the SLAC National Accelerator Laboratory in Menlo Park, California, which reported it in 2012, and the ‘Belle’ experiment at Japan’s High Energy Accelerator Research Organization (KEK) in Tsukuba, which reported its latest results at a conference in May. LHCb’s result is “bang on” the previous two. as Mitesh Patel, a physicist at Imperial College London who works on the experiment, explained.

“A 2-sigma difference in a single measurement isn’t interesting by itself,” says Tara Shears, a particle physicist at the University of Liverpool, UK, and a member of the LHCb collaboration. “But a series of 2-sigma differences, found in different types of decay and independently by different people in a different experiment, become very intriguing indeed.”

The “2-sigma” difference is an indicator of accuracy used in control charts. When comparing 2-sigma vs 3-sigma control charts, 3-sigma control charts help ensure process stability whereas 2 sigma control charts are used to detect small shifts in the project or process. For such discoveries, 5-sigma is usually required, while this discovery only has 2.1-sigma. But as Patel said, a series of 2-sigma is worth much more than just one, isolated event.

Since the 1970s, experiments have time and again proved the accuracy of the standard model – with surprising consistency. However, the Standard Model is incomplete at best, and quite possibly inexact as well. Its failure to account for gravity and dark matter seems to suggest that it’s merely an approximation of some other, underlying, and even more intriguing truth.

The finding will be published in Physical Review Letters this month (it’s already published on the arXiv pre-print server).

New Particles Found at Large Hadron Collider

It’s really awesome when the practice confirms the theory! Experiments at the Large Hadrdon Collider have revealed two never before seen particles – exotic types of baryons which were previously predicted by theoretical research. The new measurements serve to confirm and refine the existing theory of subatomic particles and help pave the way for the discovery of more particles predicted by the Standard Model.

The LHCb experiment at CERN’s Large Hadron Collider.
CERN

The LHC is the world’s largest and most powerful particle collider, and actually the largest single machine in the world. Its goal is to test if theoretical predictions are correct and either confirm or infirm the Standard Model – a theory that classifies all the subatomic particles.

In this case, they discovered two types of baryons – Xiband Xib*(pronounced “zi-b-prime” and “zi-b-star”), February 10 in Physical Review Letters. (They posted a preprint of their paper in November on the arXiv server).

“These were two things that very much should have existed,” says Matthew Charles of Paris 6 University Pierre and Marie Curie, a co-author of the study. “Of course, you still have to check because every now and then you get a surprise.”

Baryons are composite subatomic particles made up of three quarks. The most familiar baryons are the protons and neutrons that make up most of the atoms, but some baryons are more exotic, depending on the quarks they are made from. Quarks are elementary particles (as opposed to composite particles, like baryons); there are  six types of quarks, known as flavors: up, down, strange, charm, top, and bottom.

The two newfound baryons are higher-energy configurations, and their masses had been estimated on a theory called quantum chromodynamics (QCD), which describes the strong force – one of the four fundamental forces, responsible in part for nuclear attractions. The fact that the theoretical predictions fitted perfectly with what was observed in experiments is remarkable.

“This is a validation that the theoretical approach is the correct one and that we have the calculation under control,” says theorist Richard Woloshyn of the Canadian particle physics laboratory TRIUMF, who published a prediction of the Xib masses in 2009.

 

A view of the LHCb experiment at underground Point 8 on the Large Hadron Collider (LHC). The prominent tube is the LHC beam pipe, in which protons circulate at close to the speed of light (Image: Anna Pantelia/CERN)

New exotic subparticle confirmed by LHC scientists

Once with the discovery and confirmation of the Higgs boson, the Large Hadron Collider in Geneva proved its money worth and garnered international appraise. Despite the LHC is currently shutdown for its periodical maintenance (the restart procedure is well underway, with the particle accelerator expected to become fully operational again in 2015), physicists aren’t slaking. The data gathered from experiments performed at the LHC is enough to keep scientists busy for years to come. For instance,  the LHCb collaboration, who run one of four large experiments at the LHC, confirms the existence of a new exotic particle, first discovered in Japan a few years ago.

At the turn of the last century, things were much simpler for the lives of physicists. We knew all matter is comprised of molecules and atoms, which at their own turn are comprised of a nuclear core (made up of protons and neutrons) and an orbiting electron shell. Physics has long evolved past this basic knowledge however, once with quantum field theory. Following the first particle colliders, both in space and on Earth, physicists have found that particles are comprised of a number of truly elementary subparticles, like quarks, leptons or bosons. Then there’s a slew of so-called hypothetical subparticles predicted by supersymmetry, but as of yet unconfirmed.

Exotic hadron

A view of the LHCb experiment at underground Point 8 on the Large Hadron Collider (LHC). The prominent tube is the LHC beam pipe, in which protons circulate at close to the speed of light (Image: Anna Pantelia/CERN)

A view of the LHCb experiment at underground Point 8 on the Large Hadron Collider (LHC). The prominent tube is the LHC beam pipe, in which protons circulate at close to the speed of light (Image: Anna Pantelia/CERN)

In 2008 the Belle Collaboration in Japan reported the observation of a new exotic particle, the  Z(4430)–  (of negative charge). The initial readings suggested that the particle has a mass that puts it in a dense forest of charmonium states (particles made up of specific quarks like charm quark and charm antiquark), yet all particles in this state have a neutral charge.

This is where the LHC step in to elucidate. Researchers here performed more than 180 trillion collisions resulting in 25,000 decays of mesons  (quarks paired with antiquarks). After finally shifting through all the date, researchers have announced recently that the existence of Z(4430) with extremely high confidence: significance of 13.9 sigma, well above the usual 5 sigma threshold required to declare a discovery. The LHCb didn’t just confirm the particle, however, it went on to characterize its state – spin and polarity.

“The significance of the Z (4430) signal is overwhelming – at least 13.9 sigma – confirming the existence of this state,” says LHCb spokesperson Pierluigi Campana. “The LHCb analysis establishes the resonant nature of the observed structure, proving that this is really a particle, and not some special feature of the data.”

Now that the Z(4430)  particle has been confirmed by two independent experiments, physicists can concentrate on unraveling its nature. For instance, it’s believed the particle is the firmest evidence yet of a tetraquark – a four-quark state. LHC physicists believe the particle  is most likely to be made of a charm, anti-charm, down and anti-up quark. A truly exotic particle,  Z(4430)   isn’t likely to be alone. No doubt more similar findings will come off the LHC project, once it goes back online.

The findings were reported in a paper published in the journal Physical Review Letters.

A three-dimensional view of a p-Pb collision that produced collective flow behavior. The green lines are the trajectories of the sub-atomic particles produced by the collision reconstructed by the CMS tracking system. The red and blue bars represent the energy measured by the instrument's two sets of calorimeters. (CMS Collaboration)

Smallest liquid droplets created at LHC are 100,000th the size of a hydrogen atom

Scientists closely working with the  Large Hadron Collider, the largest and most powerful particle accelerator in the world, have identified evidence of the minuscule droplets produced in the aftermath of high energy proton and lead ions collisions. If their calculations are right, then these are the smallest droplets of liquid ever encountered thus far, just three to five protons in size. That’s about one-100,000th the size of a hydrogen atom or one-100,000,000th the size of a virus. WOW!

“With this discovery, we seem to be seeing the very origin of collective behavior,” said  Julia Velkovska, professor of physics at Vanderbilt who serves as a co-convener of the heavy ion program of the CMS detector, the LHC instrument that made the unexpected discovery. “Regardless of the material that we are using, collisions have to be violent enough to produce about 50 sub-atomic particles before we begin to see collective, flow-like behavior.”

A three-dimensional view of a p-Pb collision that produced collective flow behavior. The green lines are the trajectories of the sub-atomic particles produced by the collision reconstructed by the CMS tracking system. The red and blue bars represent the energy measured by the instrument's two sets of calorimeters. (CMS Collaboration)

A three-dimensional view of a p-Pb collision that produced collective flow behavior. The green lines are the trajectories of the sub-atomic particles produced by the collision reconstructed by the CMS tracking system. The red and blue bars represent the energy measured by the instrument’s two sets of calorimeters. (CMS Collaboration)

These tiny droplets “flow” in a manner similar to the behavior of the quark-gluon plasma, a state of matter that is a mixture of the sub-atomic particles that makes up protons and neutrons and only exists at extreme temperatures and densities. Some scientists claim that at the very dawn of the Universe’s existence shortly after the big bang, this primordial cosmic goo was everywhere, because of much higher temperature and density conditions.

These interactions weren’t actually targeted for observation by the LHC researchers, though. Scientists were looking to check the validity of their lead-lead results, and scheduled a proton-lead ion collision for as a simply control run – they ended up with quark-gluon plasma in the process.

“The proton-lead collisions are something like shooting a bullet through an apple while lead-lead collisions are more like smashing two apples together: A lot more energy is released in the latter,” said Velkovska.

Indeed, last September LHC researchers found that in five percent of the  protons and lead nuclei collisions —those that were the most violent – evidence of collective behavior was encountered. In turn, this allowed for the formation of   liquid droplets about one tenth the size of those produced by the lead-lead or gold-gold collisions.  The data gathered then, however, wasn’t enough to discount the influence of particle jets. New experiments in January and February of this year resulted in hundreds of cases where the collisions produced more than 300 particles flowing together.

According to doctoral student Shengquan Tuo, who recently presented the new results at a workshop held in the European Centre for Theoretical Studies in Nuclear Physics and Related Areas in Trento, Italy, only two models were advanced to explain their observations at the workshop. Of the two, the plasma droplet model seems to fit the observations best.

The new observations are contained in a paper submitted by the CMS collaboration to the journal Physics Letters B and posted on the arXiv preprint server.

[source]

Light quark mass determines carbon and oxygen production and the viability of carbon-based life. Image credit: Dean Lee. Earth and Mercury images from NASA.

When laying the foundations for life, the Universe leaves little room for error

Light quark mass determines carbon and oxygen production and the viability of carbon-based life. Image credit: Dean Lee. Earth and Mercury images from NASA.

Light quark mass determines carbon and oxygen production and the viability of carbon-based life. Image credit: Dean Lee. Earth and Mercury images from NASA.

All life as we know it is primarily based on two elements: carbon and oxygen. Scientists at North Carolina State University investigating the conditions required for the formation of these life essential ingredients found that the Universe lives little room for error.

Carbon and oxygen are formed as combustion byproducts after helium burns inside a giant red star. However, for Carbon-12 to form – an essential carbon isotope we’re all made of – specific conditions need to be facilitated. Carbon-12 can only form when alpha particles (helium-4 nuclei) combine in  a specific manner – to be more precise, carbon-12 needs to be under an excited state known as the Hoyle state. Similarly, Oxygen is produced  by the combination of another alpha particle and carbon.

NC State physicists worked off previous research that confirmed both the existence and structure of the Hoyle state with a numerical lattice, which formed the basis for simulations of proton-neutron interactions. Protons and neutrons consist of elementary particles known as quarks. A fundamental property of these elementary particles is the light quark mass, which affects the particles’ energies. The Hoyle state has a very specific energy – measured at 379 keV (or 379,000 electron volts) above the energy of three alpha particles.

The physicists ran a new lattice calculation using massive computing power at the Juelich Supercomputer Centre and found that a tiny variation of the light quark mass will dramatically alter the Hoyle state energy in such a manner that carbon and oxygen would not be produced. So, in a way, the Universe has a very tight hold on how life may form.

“The Hoyle state of carbon is key,” NC State physicist Dean Le says. “If the Hoyle state energy was at 479 keV or more above the three alpha particles, then the amount of carbon produced would be too low for carbon-based life.

“The same holds true for oxygen,” he adds. “If the Hoyle state energy were instead within 279 keV of the three alphas, then there would be plenty of carbon. But the stars would burn their helium into carbon much earlier in their life cycle. As a consequence, the stars would not be hot enough to produce sufficient oxygen for life. In our lattice simulations, we find that more than a 2 or 3 percent change in the light quark mass would lead to problems with the abundance of either carbon or oxygen in the universe.”

The findings were reported in a paper published in the journal Nuclear Theory.

quarks make protons

Hottest temperature on Earth reached after scientists create quark-gluon particle soup

quarks make protonsNot one, but two independent high-energy particle physics laboratories in New York (Relativistic Heavy Ion Collider – RHIC) and Geneva ( Large Hadron Collider – LHC) have managed to create quark-gluon plasma after smashing particles into another at very high speeds. The resulting plasma, which only lasted for a fraction of a moment,  is the hottest matter ever recorded – somewhere between 4 trillion and 6 trillion degrees Celsius.

“We now have created matter in a unique state, composed of quarks and gluons that have been liberated from inside protons and neutrons,” said Steven Vigdor, a physicist at Brookhaven National Laboratory, which hosts the RHIC.

Any proton or neutron, the building blocks of an atom, is made out of three quarks bound together by gluons, which are mass-less and hold the quarks together like a sort of glue. After colliding lead ions at extremely high velocities, a quark–gluon plasma was created, denser than a neutron star and the hottest man-made matter ever. This subatomic soup and unique state of matter is thought to have existed just moments after the Big Bang. Evidently, better understanding this incipient phase of the Universe would help unravel a number of secrets.

The ALICE heavy-ion experiment at CERN. (c) CERN

The ALICE heavy-ion experiment at CERN. (c) CERN

Scientists theorize that during a similar state to the one experimented by scientists at both RHIC and CERN, quarks and gluons would have combined to form protons and neutrons, which would have grouped with electrons a while later to form atoms. Eventually, this would latter on form cosmic dust, gas and lead to the birth of cosmic bodies like stars, galaxies and so on.

Concerning the exact temperature at which the matter was recorded, things aren’t exactly certain yet. One can imagine, keeping in mind the extremely fast decay time and record breaking temperature levels, that measuring such an experiment requires technology and innovation at the forefront of science. Spokesmen from ALICE,  a heavy-ion experiment and a lesser-known sibling to ATLAS (one of the teams which announced the Higgs boson discovery), say their data shows  an estimated 5.5 trillion degrees measured temperature or 100,000 times hotter than the center of the sun.  “It’s a very delicate measurement,” Paolo Giubellino, Alike spokesman says. “Give us a few weeks and it will be out.”

If you’re curious as to what’s the maximum possible temperature, well it is believed to be 1.416833(85) x 1032 Kelvin degrees, and at temperatures above it, the laws of physics just cease to exist

Brookhaven’s Relativistic Heavy Ion Collider (RHIC) have been studying the plasma from 2005, around the time when the first experiments were conducted. In terms of properties, they found that the plasma behaves like perfect, frictionless liquids. Meaning zero viscosity – no friction! This plasma is also extremely dense, with particles packed in more tightly than neutron stars.

“We do have now the tools in place to really experiment with it …and figure out precisely what kind of stuff this really is and why it has these extraordinary properties,” said Jurgen Schukraft, a physicist at the CERN physics lab in Geneva, home of the LHC.

Findings were published in Nature.

Physicists discover rare hypernucleus, a component of strange matter

It looks like not all is going bad for Italian researchers, after the trial of the seismologists: physicists from Italy have discovered the first evidence of a nucleus that doesn’t exist in nature and survives only for 10-10 seconds when created in a laboratory.

Strange matter

Hypernuclei contain all sorts of protons and neutrons, but unlike regular nuclei, they also contain at least a hyperon, a particle that consists of three quarks, including at least one strange quark; hypernuclei are considered to be the core of strange matter that may exist in distant parts of the universe and could prove valuable to researchers in understanding this phenomena. Whoa! Wait a minute, strange matter?

Let’s start from the beginning. You’ve probably learned in school that the world we see around us is built from ‘atoms’ – the building blocks of the Universe – which themselves consist of protons, neutrons and electrons. But scientists love to dig more and ask more questions, so they found other fundamental particles which build these particles. Among these smallest particles (that we know of at the moment, at least) are quarks, which go together and build neutrons and protons. Strange quarks are just a type of quarks, named so because, well, scientists have a sense of humor. Which gets us to our point: strange matter is a type of quark matter, usually thought of as a “liquid” of up, down, and strange quarks.

Hydrogen six Lambda

The particular hypernucleus analyzed here was called “hydrogen six Lambda” (6ΛH), and it was first predicted to exist in 1963. Now, researchers from the FINUDA experiment at the Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali di Frascati (INFN-LNF) in Frascati, Italy have reported the first ever ‘sighting’ of such a phenomena, in a study published in the recent issue of Physical Review Letters.

As the name suggest, the atom is a species of Hydrogen which consists of six particles: four neutrons, one proton, and one Lambda (Λ) hyperon. Since the Hydrogen atom has only one proton and no neutrons, other species which do have neutrons are called ‘heavy hydrogen’, like deuterium (one neutron) and tritium (two neutrons). Since 6ΛH has four neutrons plus a L hyperon, physicists refer to it as “heavy hyperhydrogen.” The hyperon is practically a composite particle which contains one strange quark.

Without the L hyperon, it would practically be impossible to observe the Hydrogen atom with four neutrons, because it increases its lifetime from 10-22 seconds to 10-10 seconds.

The FINUDA experiment

The findings could shed light on strange matter, which many researchers believe to exist at the core of ultra-dense neutron stars. They can also serve as good tools to measure the current atomic model.

“The fact that a hypernucleus has a strange quark does give it interesting characteristics compared to normal nuclei, since it allows the component L particle to act as a probe that can go very deep into the nucleus to test the description that the single particle shell model gives of nuclear matter,” Botta said. “In this respect, the study of hypernuclear physics allows us to get information not directly accessible otherwise.”

Via Physorg

Densest material ever created announced at LHC

The Large Hadron Collider (LHC) continues on its quest to find out exactly what happened in the first seconds after the Big Bang, unveiling what is the densest material known so far to man.

Exotic densest substance

Known as the quark-gluon plasma, this amazing exotic substance can exist only at incredibly high temperatures or pressures, and it consists almost entirely of free quarks and gluons; it is possible that the whole universe was filled only with this substance in the immediate aftermath of the Big Bang.

It is about 100 times hotter than the inside of the Sun and denser than a neutron star.

“Besides black holes, there’s nothing denser than what we’re creating,” said David Evans, a physicist at the University of Birmingham in the U.K. and a team leader for the LHC’s ALICE detector, which helped observe the quark-gluon plasma. “If you had a cubic centimeter of this stuff, it would weigh 40 billion tons.”

Quark gluon plasma acts like perfect liquid

By unleashing the fantastic energy of thousands of ultrahigh-speed collisions each second physicists at the LHC are breaking subatomic particles into even denser and hotter forms of matter, hoping to find out what the universe was made of right after the Big Bang; to be more exact, one trillionth of a second after it.

The quark-gluon plasma was also created last year by smashing together lead ions that have been stripped of all their electrons, at a speed very close to the speed of light. As I told you before (and as the name suggests), the substance is made almost entirely out of quarks and gluons. Quarks are almost never found in isolation, due to a process called color confinement; they are the building blocks of particles called hadrons, out of which the most ‘famous’ and stable are protons and neutrons. Gluons are the exchange particles (or gauge bosons) for the color force between quarks, analogous to the exchange of photons in the electromagnetic force between two charged particles. The quark-gluon plasma is what is called a perfect liquid.

“If you stir a cup of tea with a spoon and then take the spoon out, the tea stirs for a while and then it stops. If you had a perfect liquid and you stirred it, it would carry on going around forever,” Evans explained.

Meanwhile, the LHC is still going at only half of its potential, which can only make you wonder about what they will find once they turn out the full engines.

New exotic particle behaviour found at CERN

The Large Hadron Collider at CERN has started doing some serious business. This time, an extremely rare particle containing equal parts of matter and antimatter popped up during experiments at the world’s largest and hottest particle accelerator.

CREDIT: CERN/Maximilien Brice, Rachel Barbier

 

The particle, named a B meson is made out of one quark (the building blocks of protons and neutrons) and one antiquark (the building blocks of antiprotons and antineutrons). What are antiprotons and antineutrons ? Well, they are just like their positive brothers… only they are negative. They have the exact same properties, only opposite in signs. For example, an antiproton has the exact same charge a proton has, but it is negative instead of positive.

All normal particles are thought to have antimatter analogues, and when matter and antimatter meets, they destroy each other. Scientists believe that at first, matter and antimatter were created equally, but if this is the case, then where is all the antimatter ? The most plausible solution would be that a huge quantity of matter and antimatter annihilated each other, and the remaining matter is what we see in our universe today.

The particle in case, the B meson, is thought to have been common right after the Big Bang, but it is believed that at the moment, it doesn’t occure naturally in nature. They aren’t stable, and after created, quickly start decaying; this process, a B meson decay has long been theoretized, but never seen before.

“Our experiment is set up to measure the decays of B mesons,” sayd Sheldon Stone, physicist at Syracuse University. “We discovered some new and interesting decay modes of B mesons, which hadn’t ever been seen before.”

Studying this type of behaviour can provide the answer to the ultimate question of antimatter – why do we see all this matter around us today, and no antimatter. Meanwhile, the search for the elusive Higgs boson is continued.

“When the universe was created in the Big Bang about 14 billion years ago, the number of particles and antiparticles was the same,” Stone said. “One of the major questions that we really don’t know the answer to is why are there particles around now and not antiparticles. By studying the differences we can learn maybe what the physics is behind that difference.”

Large Hadron Collider creates mini big bangs and incredible heat

The Large Hadron Collider at CERN has taken another step towards its goal of finding the so called ‘god particle‘: it recently produced the highest temperatures ever obtained through a science experiment. The day before yesterday, 7 November was a big one at the LHC, as the particle collider started smashing lead ions head-on instead of the proton – proton collisions that usually take place there.

Representation of a quark-gluon plasma

The result was a series of what is called mini big bangs: dense fireballs with temperatures of over 10 trillion Celsius degrees! At this kind of temperatures and energies, the nuclei of atoms start to melt in their constituend parts, quarks and gluons, and the result is called a quark-gluon plasma.

One of the primary goals of the Large Hadron Collider is to go back further and further in time, closer to the ‘birth’ of the Universe. The theory of quantum chromodynamics tells us that as we ‘travel’ in the past more and more, the strength of strong interactions drops fast and reaches zero; the process is called “asymptotic freedom”, and it brought David Politzer, Frank Wilczek and David Gross a Nobel Prize in 2004.

The quark-gluon plasma has been studied in great detail at the Relativistic Heavy Ion Collider (RHIC) at Upton, New York, which produced temperatures of 4 trillion degrees Celsius. These collisions will allow scientists to look at the world in a way they never could have before, showing how the Universe was about a millionth of a second after the big bang. One can only wonder what answers this plasma has to offer, and it already produced a huge surprise, acting like a perfect liquid instead of a gas, as expected. Still, one thing’s for sure: the Large Hadron Collider is producing more and more results each month, and whether it confirms current theories or proves them wrong, science will benefit greatly from this particle collider

Large Hadron Collider hints at infant Universe

Despite several setbacks and technical difficulties, the Large Hadrdon Collider is already starting to live up to it’s nickname, the Big Bang machine. Researchers have pinpointed what may very well be the dense, hot state state of matter that is believed to have filled the Universe during its first nanoseconds.

Generally speaking, quarks are bound together in groups of two or three, stuck together by gluons. However, right after the Big Bang, it was so hot that the quarks broke free, and the matter became a free flow of quarks and gluons.

In the snapshots taken from LHC’s detector, a flow similar to this has been observed.

Full report here.