Latest news with #LHCb
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First Post
2 days ago
- Science
- First Post
Have scientists decoded why the universe exists? Cern study points to matter-antimatter asymmetry
The finding offers vital clues to the long-standing mystery of why the universe is composed predominantly of matter, rather than being annihilated by an equal amount of antimatter read more A new study has shed light on one of humankind's fundamental queries: Why does the universe exist? Image courtesy: Nasa A new study at CERN has provided critical insights into one of the most fundamental questions in physics: why does anything exist at all? Researchers working on the Large Hadron Collider beauty (LHCb) experiment have observed a rare form of symmetry violation in the decays of beauty baryons– particles containing a bottom quark. The finding offers vital clues to the long-standing mystery of why the universe is composed predominantly of matter, rather than being annihilated by an equal amount of antimatter. STORY CONTINUES BELOW THIS AD The study, published in Nature, reports the observation of charge–parity (CP) violation in a baryonic decay process, marking a significant development in the quest to understand the imbalance between matter and antimatter in the early universe. What did the scientists observe? The experiment focused on a specific decay of the beauty baryon, into a proton, a kaon (K−), and two pions (π+ and π−). This decay can occur via two different quark-level pathways: one involving a bottom-to-up (b → u) transition and another involving a bottom-to-strange (b → s) transition. Crucially, the researchers found that these two processes do not behave symmetrically when matter is swapped for antimatter. This violation of CP symmetry is a direct indication that the laws of physics are not entirely the same for matter and antimatter– a foundational requirement for explaining why the universe didn't simply self-destruct in a flash of mutual annihilation shortly after the Big Bang. Why is CP violation so important? CP violation had previously been observed in the decays of mesons– particles made of a quark and an antiquark. However, baryons (made of three quarks) are less explored in this context. The new findings from the LHCb collaboration represent the first clear evidence of CP violation in baryon decays, expanding the frontier of known symmetry-breaking phenomena. This asymmetry is a necessary component in explaining the observed dominance of matter in the universe. Without it, the Standard Model predicts that equal amounts of matter and antimatter would have been produced in the early universe– leading to their mutual destruction.
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Business Standard
4 days ago
- Science
- Business Standard
CERN discovery could hint at why universe is made of matter, not antimatter
Why didn't the universe annihilate itself moments after the big bang? A new finding at Cern on the French-Swiss border brings us closer to answering this fundamental question about why matter dominates over its opposite – antimatter. Much of what we see in everyday life is made up of matter. But antimatter exists in much smaller quantities. Matter and antimatter are almost direct opposites. Matter particles have an antimatter counterpart that has the same mass, but the opposite electric charge. For example, the matter proton particle is partnered by the antimatter antiproton, while the matter electron is partnered by the antimatter positron. However, the symmetry in behaviour between matter and antimatter is not perfect. In a paper published this week in Nature, the team working on an experiment at Cern, called LHCb, has reported that it has discovered differences in the rate at which matter particles called baryons decay relative to the rate of their antimatter counterparts. In particle physics, decay refers to the process where unstable subatomic particles transform into two or more lighter, more stable particles. According to cosmological models, equal amounts of matter and antimatter were made in the big bang. If matter and antimatter particles come in contact, they annihilate one another, leaving behind pure energy. With this in mind, it's a wonder that the universe doesn't consist only of leftover energy from this annihilation process. However, astronomical observations show that there is now a negligible amount of antimatter in the universe compared to the amount of matter. We therefore know that matter and antimatter must behave differently, such that the antimatter has disappeared while the matter has not. Understanding what causes this difference in behaviour between matter and antimatter is a key unanswered question. While there are differences between matter and antimatter in our best theory of fundamental quantum physics, the standard model, these differences are far too small to explain where all the antimatter has gone. So we know there must be additional fundamental particles that we haven't found yet, or effects beyond those described in the standard model. These would give rise to large enough differences in the behaviour of matter and antimatter for our universe to exist in its current form. Revealing new particles Highly precise measurements of the differences between matter and antimatter are a key topic of research because they have the potential to be influenced by and reveal these new fundamental particles, helping us discover the physics that led to the universe we live in today. Differences between matter and antimatter have previously been observed in the behaviour of another type of particle, mesons, which are made of a quark and an antiquark. There are also hints of differences in how the matter and antimatter versions of a further type of particle, the neutrino, behave as they travel. The new measurement from LHCb has found differences between baryons and antibaryons, which are made of three quarks and three antiquarks respectively. Significantly, baryons make up most of the known matter in our universe, and this is the first time that we have observed differences between matter and antimatter in this group of particles. The LHCb experiment at the Large Hadron Collider is designed to make highly precise measurements of differences in the behaviour of matter and antimatter. The experiment is operated by an international collaboration of scientists, made up of over 1,800 people based in 24 countries. In order to achieve the new result, the LHCb team studied over 80,000 baryons ('lambda-b' baryons, which are made up of a beauty quark, an up quark and a down quark) and their antimatter counterparts. Crucially, we found that these baryons decay to specific subatomic particles (a proton, a kaon and two pions) slightly more frequently – 5 per cent more often – than the rate at which the same process happens with antiparticles. While small, this difference is statistically significant enough to be the first observation of differences in behaviour between baryon and antibaryon decays. To date, all measurements of matter-antimatter differences have been consistent with the small level present in the standard model. While the new measurement from LHCb is also in line with this theory, it is a major step forward. We have now seen differences in the behaviour of matter and antimatter in the group of particles that dominate the known matter of the universe. It's a potential step in the direction of understanding why that situation came to be after the big bang. With the current and forthcoming data runs of LHCb we will be able to study these differences forensically, and, we hope, tease out any sign of new fundamental particles that might be present.


The Independent
6 days ago
- Science
- The Independent
Scientists make antimatter discovery that could unlock secrets of big bang
Why didn't the universe annihilate itself moments after the big bang? A new finding at Cern on the French-Swiss border brings us closer to answering this fundamental question about why matter dominates over its opposite – antimatter. Much of what we see in everyday life is made up of matter. But antimatter exists in much smaller quantities. Matter and antimatter are almost direct opposites. Matter particles have an antimatter counterpart that has the same mass, but the opposite electric charge. For example, the matter proton particle is partnered by the antimatter antiproton, while the matter electron is partnered by the antimatter positron. However, the symmetry in behaviour between matter and antimatter is not perfect. In a paper published this week in Nature, the team working on an experiment at Cern, called LHCb, has reported that it has discovered differences in the rate at which matter particles called baryons decay relative to the rate of their antimatter counterparts. In particle physics, decay refers to the process where unstable subatomic particles transform into two or more lighter, more stable particles. According to cosmological models, equal amounts of matter and antimatter were made in the big bang. If matter and antimatter particles come in contact, they annihilate one another, leaving behind pure energy. With this in mind, it's a wonder that the universe doesn't consist only of leftover energy from this annihilation process. However, astronomical observations show that there is now a negligible amount of antimatter in the universe compared to the amount of matter. We therefore know that matter and antimatter must behave differently, such that the antimatter has disappeared while the matter has not. Understanding what causes this difference in behaviour between matter and antimatter is a key unanswered question. While there are differences between matter and antimatter in our best theory of fundamental quantum physics, the standard model, these differences are far too small to explain where all the antimatter has gone. So we know there must be additional fundamental particles that we haven't found yet, or effects beyond those described in the standard model. These would give rise to large enough differences in the behaviour of matter and antimatter for our universe to exist in its current form. Revealing new particles Highly precise measurements of the differences between matter and antimatter are a key topic of research because they have the potential to be influenced by and reveal these new fundamental particles, helping us discover the physics that led to the universe we live in today. Differences between matter and antimatter have previously been observed in the behaviour of another type of particle, mesons, which are made of a quark and an antiquark. There are also hints of differences in how the matter and antimatter versions of a further type of particle, the neutrino, behave as they travel. The new measurement from LHCb has found differences between baryons and antibaryons, which are made of three quarks and three antiquarks respectively. Significantly, baryons make up most of the known matter in our universe, and this is the first time that we have observed differences between matter and antimatter in this group of particles. The LHCb experiment at the Large Hadron Collider is designed to make highly precise measurements of differences in the behaviour of matter and antimatter. The experiment is operated by an international collaboration of scientists, made up of over 1,800 people based in 24 countries. In order to achieve the new result, the LHCb team studied over 80,000 baryons ('lambda-b' baryons, which are made up of a beauty quark, an up quark and a down quark) and their antimatter counterparts. Crucially, we found that these baryons decay to specific subatomic particles (a proton, a kaon and two pions) slightly more frequently – 5 per cent more often – than the rate at which the same process happens with antiparticles. While small, this difference is statistically significant enough to be the first observation of differences in behaviour between baryon and antibaryon decays. To date, all measurements of matter-antimatter differences have been consistent with the small level present in the standard model. While the new measurement from LHCb is also in line with this theory, it is a major step forward. We have now seen differences in the behaviour of matter and antimatter in the group of particles that dominate the known matter of the universe. It's a potential step in the direction of understanding why that situation came to be after the big bang. With the current and forthcoming data runs of LHCb we will be able to study these differences forensically, and, we hope, tease out any sign of new fundamental particles that might be present.


The Hindu
6 days ago
- Science
- The Hindu
What is the universe's antimatter mystery?
The story so far: On July 16, an international collaboration of scientists based in Europe reported that they had, for the first time, observed that the matter and antimatter versions of a type of subatomic particle called a baryon decay at different rates. The result revealed a new difference in their behavior that may help explain why the universe is made mostly of matter. Why is the universe made mostly of matter? The Big Bang 13.8 billion years ago should have created equal amounts of matter and antimatter. But when we look around, we see a universe filled with matter — stars, planets, people — while antimatter is almost nowhere to be found. This lopsidedness is one of the biggest unsolved mysteries in science. Physicists believe subtle differences in how matter and antimatter behave, especially something called CP violation, could be a major clue to understanding this imbalance. CP stands for charge conjugation (C) and parity (P). Charge conjugation means swapping a particle for its antiparticle (which has the opposite electric charge) and parity means flipping left and right, like looking in a mirror. If the universe treated matter and antimatter exactly the same, even after a particle swap and a mirror flip we'd say CP symmetry holds. But experiments have shown that this symmetry can be broken. This is called CP violation. CP violation is crucial because it's one of the conditions necessary for a universe to end up with more matter than antimatter. Has CP violation been seen before? 'While CP violation had previously been observed in mesons, particles made of quark-antiquark pairs, it had never before been seen in baryons, three-quark particles such as protons and neutrons that constitute the majority of visible matter in the universe,' Indian Institute of Science, Bengaluru, experimental high-energy physicist Minakshi Nayak told The Hindu. The new result is the first to show CP violation in baryon decays, specifically in a particle called the Λb0 baryon. The Λb0 baryon is a heavy subatomic particle made of three quarks: an up quark, a down quark, and a bottom quark. Its antiparticle, the Λb0-bar, has the corresponding antiquarks. In the new study, scientists studied how the Λb0 baryon decays into a proton, a negatively charged kaon, and two pions (one positive, one negative). They also looked at the same decay for the antiparticle but with opposite charges. How're particle decays observed? The experiment took place at the Large Hadron Collider (LHC) in Europe, and data for its analysis was collected by the machine's LHCb detector. Over several years, the team collected data from billions of proton-proton collisions, which occasionally produced Λb0 and Λb0-bar baryons. Sophisticated algorithms and machine learning techniques then helped the researchers pick out the rare events where these baryons decayed into the specific set of particles they were looking for. The key is to compare how often the Λb0 baryon decays into the chosen set of particles with how often its antiparticle does. If the laws of physics treated matter and antimatter identically, these rates would be the same. Any difference, after accounting for possible experimental biases, would be evidence of CP violation. The researchers measured a quantity called the CP asymmetry, which is the difference in decay rates divided by the total number of decays. The researchers were very careful about identifying and removing other effects that mimic CP violation. For example, the LHC might produce slightly more Λb0 baryons than Λb0-bar antibaryons or the LHCb detector might be better at spotting one over the other. To correct for these effects, the team used a control channel, a similar decay where no CP violation is expected. By measuring any asymmetry in this control channel, they could subtract these nuisance effects and isolate the true CP violation signal. What was the main result? The researchers found a clear difference in the decay rates: the CP asymmetry was measured to be about 2.45%, with a very small uncertainty. 'Statistically, the measured CP asymmetry deviates from zero by 5.2 standard deviations, surpassing the 5-sigma threshold required to claim a discovery in particle physics,' Dr. Nayak said. 'This historic discovery holds the potential to deepen our understanding of the matter-antimatter imbalance'. It's a big step forward, although the amount of CP violation observed is still too small to account for the large imbalance between matter and antimatter in the universe. Scientists can now look for CP violation in other baryon decays and try to measure it more precisely. Theoretically, they can work to understand the complex dynamics that produce these effects and search for signs of previously undiscovered particles and forces, in a bid to plug the gaps in our knowledge of our universe. The ultimate goal is to find out whether there are additional sources of CP violation that could explain matter's dominance. The finding also addresses a fundamental question about our existence: why is there something rather than nothing? Every atom in your body, every star in the sky, exists because matter somehow won out over antimatter. By uncovering the subtle differences in how nature treats matter and antimatter, scientists are piecing together the story of how our universe came to be the way it is.


Scientific American
6 days ago
- Science
- Scientific American
Mysterious Antimatter Physics Discovered at the Large Hadron Collider
Matter and antimatter are like mirror opposites: they are the same in every respect except for their electric charge. Well, almost the same—very occasionally, matter and antimatter behave differently from each other, and when they do, physicists get very excited. Now scientists at the world's largest particle collider have observed a new class of antimatter particles breaking down at a different rate than their matter counterparts. The discovery is a significant step in physicists' quest to solve one of the biggest mysteries in the universe: why there is something rather than nothing. The world around us is made of matter—the stars, planets, people and things that populate our cosmos are composed of atoms that contain only matter, and no antimatter. But it didn't have to be this way. Our best theories suggest that when the universe was born it had equal amounts of matter and antimatter, and when the two made contact, they annihilated one another. For some reason, a small excess of matter survived and went on to create the physical world. Why? No one knows. So physicists have been on the hunt for any sign of difference between matter and antimatter, known in the field as a violation of 'charge conjugation–parity symmetry,' or CP violation, that could explain why some matter escaped destruction in the early universe. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. Today physicists at the Large Hadron Collider (LHC)'s LHCb experiment published a paper in the journal Nature announcing that they've measured CP violation for the first time in baryons —the class of particles that includes the protons and neutrons inside atoms. Baryons are all built from triplets of even smaller particles called quarks. Previous experiments dating back to 1964 had seen CP violation in meson particles, which unlike baryons are made of a quark-antiquark pair. In the new experiment, scientists observed that baryons made of an up quark, a down quark and one of their more exotic cousins called a beauty quark decay more often than baryons made of the antimatter versions of those same three quarks. 'This is a milestone in the search for CP violation,' says Xueting Yang of Peking University, a member of the LHCb team that analyzed the data behind the measurement. 'Since baryons are the building blocks of the everyday things around us, the first observation of CP violation in baryons opens a new window for us to search for hints of new physics.' The LHCb experiment is the only machine in the world that can summon sufficient energies to make baryons containing beauty quarks. It does this by accelerating protons to nearly the speed of light, then smashing them together in about 200 million collisions every second. As the protons dissolve, the energy of the crash springs new particles into being. 'It is an amazing measurement,' says theoretical physicist Edward Witten of the Institute for Advanced Study, who was not involved in the experiment. "Baryons containing b [beauty] quarks are relatively hard to produce, and CP violation is very delicate and hard to study.' The 69-foot-long, 6,000-ton LHCb experiment can track all the particles created during the collisions and the many different ways they can break down into smaller particles. 'The detector is like a gigantic four-dimensional camera that is able to record the passage of all the particles through it,' says LHCb spokesperson and study co-author Vincenzo Vagnoni of the Italian National Institute of Nuclear Physics (INFN). 'With all this information, we can reconstruct precisely what happened in the initial collision and everything that came out and then decayed.' The matter-antimatter difference scientists observed in this case is relatively small, and it fits within predictions of the Standard Model of particle physics—the reigning theory of the subatomic realm. This puny amount of CP violation, however, cannot account for the profound asymmetry between matter and antimatter we see throughout space. 'The measurement itself is a great achievement, but the result, to me, is not surprising,' says Jessica Turner, a theoretical physicist at Durham University in England, who was not involved in the research. 'The observed CP violation seems to be in line with what has been measured before in the quark sector, and we know that is not enough to produce the observed baryon asymmetry.' To understand how matter got the upper hand in the early universe, physicists must find new ways that matter and antimatter diverge, most likely via particles that have yet to be seen. 'There should be a new class of particles that were present in the early universe, which exhibit a much larger amount of this behavior,' Vagnoni says. 'We are trying to find little discrepancies between what we observe and what is predicted by the Standard Model. If we find a discrepancy, then we can pinpoint what is wrong.' The researchers hope to discover more cracks in the Standard Model as the experiment keeps running. Eventually LHCb should collect about 30 times more data than was used for this analysis, which will allow physicists to search for CP violation in particle decays that are even rarer than the one observed here. So stay tuned for an answer to why anything exists at all.