̽��ֱ�� of Cambridge - Val Gibson

Cambridge physicists announce results that boost evidence for new fundamental physics

Anonymous — Tue, 19 Oct 2021 12:44:47 +0000

In March 2020, the same experiment released evidence of particles breaking one of the core principles of the Standard Model – our best theory of particles and forces – suggesting the possible existence of new fundamental particles and forces.

Now, further measurements by physicists at Cambridge’s Cavendish Laboratory have found similar effects, boosting the case for new physics.

̽��ֱ��Standard Model describes all the known particles that make up the universe and the forces that they interact through. It has passed every experimental test to date, and yet physicists know it must be incomplete. It does not include the force of gravity, nor can it account for how matter was produced during the Big Bang, and contains no particle that could explain the mysterious dark matter that astronomy tells us is five times more abundant than the stuff that makes up the visible world around us.

As a result, physicists have long been hunting for signs of physics beyond the Standard Model that might help us to address some of these mysteries.

One of the best ways to search for new particles and forces is to study particles known as beauty quarks. These are exotic cousins of the up and down quarks that make up the nucleus of every atom.

Beauty quarks don’t exist in large numbers in the world around as they are incredibly short-lived – surviving on average for just a trillionth of a second before transforming or decaying into other particles. However, billions of beauty quarks are produced every year by CERN’s giant particle accelerator, the Large Hadron Collider, which are recorded by a purpose-built detector called LHCb.

̽��ֱ��way beauty quarks decay can be influenced by the existence of undiscovered forces or particles. In March, a team of physicists at LHCb released results showing evidence that beauty quarks were decaying into particles called muons less often than to their lighter cousins, electrons. This is impossible to explain in the Standard Model, which treats electrons and muons identically, apart from the fact that electrons are around 200 times lighter than muons. As a result, beauty quarks ought to decay into muons and electrons at equal rates. Instead, the physicists at LHCb found that the muon decay was only happening around 85% as often as the electron decay.

̽��ֱ��difference between the LHCb result and the Standard Model was about three units of experimental error, or ‘3 sigma’ as it is known in particle physics. This means there is only around a one in a thousand chance of the result being caused by a statistical fluke.

Assuming the result is correct, the most likely explanation is that a new force that pulls on electrons and muons with different strengths is interfering with how these beauty quarks decay. However, to be sure if the effect is real more data is needed to reduce the experimental error. Only when a result reaches the ‘5 sigma’ threshold, when there is less than a one in a million chance of it being due to random chance, will particle physicists start to consider it a genuine discovery.

“ ̽��ֱ��fact that we’ve seen the same effect as our colleagues did in March certainly boosts the chances that we might genuinely be on the brink of discovering something new,” said Dr Harry Cliff from the Cavendish Laboratory. “It’s great to shed a little more light on the puzzle.”

Today’s result examined two new beauty quark decays from the same family of decays as used in the March result. ̽��ֱ��team found the same effect – the muon decays were only happening around 70% as often as the electron decays. This time the error is larger, meaning that the deviation is around ‘2 sigma’, meaning there is just over a 2% chance of it being due to a statistical quirk of the data. While the result isn’t conclusive on its own, it does add further support to a growing pile of evidence that there are new fundamental forces waiting to be discovered.

“ ̽��ֱ��excitement at the Large Hadron Collider is growing just as the upgraded LHCb detector is about to be switched on and further data collected that will provide the necessary statistics to either claim or refute a major discovery,” said Professor Val Gibson, also from the Cavendish Laboratory.

Results announced by the LHCb experiment at CERN have revealed further hints for phenomena that cannot be explained by our current theory of fundamental physics.

̽��ֱ��fact that we’ve seen the same effect as our colleagues did in March certainly boosts the chances that we might genuinely be on the brink of discovering something new

Harry Cliff

CERN

View of the LHCb detector

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Quantum projects launched to solve universe’s mysteries

sc604 — Wed, 13 Jan 2021 09:00:00 +0000

UK Research and Innovation (UKRI) is supporting seven projects with a £31 million investment to demonstrate how quantum technologies could solve some of the greatest mysteries in fundamental physics. Researchers from the ̽��ֱ�� of Cambridge have been awarded funding on four of the seven projects.

Just as quantum computing promises to revolutionise traditional computing, technologies such as quantum sensors have the potential to radically change our approach to understanding our universe.

̽��ֱ��projects are supported through the Quantum Technologies for Fundamental Physics programme, delivered by the Science and Technology Facilities Council (STFC) and the Engineering and Physical Sciences Research Council (EPSRC) as part of UKRI’s Strategic Priorities Fund. ̽��ֱ��programme is part of the National Quantum Technologies Programme.

AION: A UK Atom Interferometer Observatory and Network has been awarded £7.2 million in funding and will be led by Imperial College London. ̽��ֱ��project will develop and use technology based on quantum interference between atoms to detect ultra-light dark matter and sources of gravitational waves, such as collisions between massive black holes far away in the universe and violent processes in the very early universe. ̽��ֱ��team will design a 10m atom interferometer, preparing the construction of the instrument in Oxford and paving the way for larger-scale future experiments to be located in the UK. Members of the AION consortium will also contribute to MAGIS, a partner experiment in the US.

̽��ֱ��Cambridge team on AION is led by Professor Valerie Gibson and Dr Ulrich Schneider from the Cavendish Laboratory, alongside researchers from the Kavli Institute for Cosmology, the Institute of Astronomy and the Department of Applied Mathematics and Theoretical Physics. Dr Tiffany Harte will co-lead the development of the cold atom transport and final cooling sequences for AION, and Dr Jeremy Mitchell will co-lead the data readout and network capabilities for AION and MAGIS, and undertake data analysis and theoretical interpretation.

“This announcement from STFC to fund the AION project, which alongside some seed funding from the Kavli Foundation, will allow us to target key open questions in fundamental physics and bring new interdisciplinary research to the ̽��ֱ�� for the foreseeable future,” said Gibson.

“Every physical effect, known or unknown, leaves its fingerprint on the phase evolution of a coherent quantum system such as cold atoms; it only requires sufficiently sensitive detectors,” said Schneider. “We are excited to contribute our cold-atom technology to this interdisciplinary endeavour and to develop atom interferometry into a powerful detector for fundamental physics.”

̽��ֱ��Quantum Sensors for the Hidden Sector (QSHS) project, led by the ̽��ֱ�� of Sheffield, has been awarded £4.8 million in funding. ̽��ֱ��project aims to contribute to the search for axions, low-mass ‘hidden’ particles that are candidates to solve the mystery of dark matter. They will develop new quantum measurement technology for inclusion in the US ADMX experiment, which can then be used to search for axions in parts of our galaxy’s dark matter halo that have never been explored before.

“ ̽��ֱ��team will develop new electronic technology to a high level of sophistication and deploy it to search for the lowest-mass particles detected to date,” said Professor Stafford Withington from the Cavendish Laboratory, Co-Investigator and Senior Project Scientist on QSHS. “These particles are predicted to exist theoretically, but have not yet been discovered experimentally. Our ability to probe the particulate nature of the physical world with sensitivities that push at the limits imposed by quantum uncertainty will open up a new frontier in physics.

“This new window will allow physicists to explore the nature of physical reality at the most fundamental level, and it is extremely exciting that the UK will be playing a major international role in this new generation of science.”

Professor Withington is also involved in the Determination of Absolute Neutrino Mass using Quantum Technologies, which will be led by UCL. ̽��ֱ��project aims to harness recent breakthroughs in quantum technologies to solve one of the most important outstanding challenges in particle physics – determining the absolute mass of neutrinos. One of the universe’s most abundant particles neutrinos are a by-product of nuclear fusion within stars, therefore being key to our understanding of the processes within stars and the makeup of the universe. Moreover, knowing the value of the neutrino mass is critical to our understanding of the origin of matter and evolution of the universe. They are poorly understood however, and the researchers aim to develop pioneering new spectroscopy technology capable to precisely measure the mass of this elusive but important particle.

Professor Zoran Hadzibabic has received funding as part of the Quantum Simulators for Fundamental Physics project, led by the ̽��ֱ�� of Nottingham. ̽��ֱ��project aims to develop quantum simulators capable of providing insights into the physics of the very early universe and black holes. ̽��ֱ��goals include simulating aspects of quantum black holes and testing theories of the quantum vacuum that underpin ideas on the origin of the universe.

Researchers will use cutting-edge quantum technologies to transform our understanding of the universe and answer key questions such as the nature of dark matter and black holes.

NASA Goddard Space Flight Center

New Simulation Sheds Light on Spiraling Supermassive Black Holes

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Cambridge academics recognised in 2021 New Year Honours

sc604 — Thu, 31 Dec 2020 09:52:29 +0000

Professor Simon Baron-Cohen, Director of Cambridge’s Autism Research Centre and a Fellow of Trinity College, has been knighted for services to autism research and autistic people. He is one of the top autism researchers in the world, and is a Fellow of the British Academy, the Academy of Medical Sciences, and the British Psychological Society. He served as Chair of the NICE Guidelines for autism and is Director of the charity the Autism Centre of Excellence and Vice President of the National Autistic Society. He was President of the International Society for Autism Research. He created the first clinic worldwide to diagnose autism in adults and championed the human rights of autistic people at the UN. He is author of ̽��ֱ��Essential Difference, Zero Degrees of Empathy, and ̽��ֱ��Pattern Seekers, which have captured the public imagination.

Professor Baron-Cohen said: “This honour came as a complete surprise, and I accept it on behalf of the talented team of scientists at the Autism Research Centre in Cambridge, and on behalf of the Autism Research Trust, the charity that has supported us. ̽��ֱ��basic needs and human rights of autistic people and their families are still not being met by statutory services, due to insufficient funding, so we are creating a new charity, the Autism Centre of Excellence, to address this gap.”

Professor Usha Goswami, Director for the Centre for Neuroscience in Education, Professor of Cognitive Developmental Neuroscience and Fellow of St. John’s College, becomes CBE for services to educational research.

Her research focuses on children’s cognitive development, particularly the development of language and literacy. Her world-leading work on dyslexia led to the discovery that children with the disorder hear language differently, showing it to be a language disorder and not a visual disorder as previously thought. This significant finding is enabling the development of transformative new educational interventions, which will benefit millions of children with dyslexia worldwide.

“I am deeply honoured to receive this award,” said Professor Goswami. “I have been interested in children’s development since training as a primary school teacher and it is wonderful to have my research recognised in this way.

Professor Val Gibson, Professor of High Energy Physics at the Cavendish Laboratory, ̽��ֱ�� Gender Equality Champion and Fellow of Trinity College, has been made OBE for service to Science, Women in Science and Public Engagement.

Her research interest is the search for new phenomena using particles containing heavy quarks, which are produced in copious amounts at the Large Hadron Collider, and hold the key to our understanding of the matter-antimatter imbalance in the Universe. From 2004-2008, she was the UK Spokesperson and PI for the LHCb experiment and had ultimate responsibility to deliver the UK contributions to the experiment. She is currently the Chair of the LHCb Collaboration Board, the decision-making body for the experiment, with representatives from 78 institutes across the world.

Professor Gibson said: “It is an honour to be recognised for all three of my passions: research into the most fundamental particles and forces of nature, including the mystery of why we live in a Universe made of matter and not antimatter; support for gender equality and diversity in science; and the public engagement activities I have undertaken over many years.”

Dr Michael Weekes from the Cambridge Institute for Therapeutic Immunology and Infectious Disease (CITIID) has been awarded the British Empire Medal for or services to the NHS during COVID-19. He developed a comprehensive COVID-19 screening programme for Cambridge ̽��ֱ�� Hospitals healthcare workers, Cambridge ̽��ֱ�� staff and students.

Dr Weekes said: "I’m deeply honoured to have had the chance to be part of the team that set up COVID testing for Cambridge ̽��ֱ�� Hospitals. I’d particularly like to acknowledge the contribution of Steve Baker, Rob Howes and Giles Wright, who played vital roles in testing and organisation. I hope that vaccination will soon mean that hospitals become even safer places to work and be cared for."

Researchers from the ̽��ֱ�� of Cambridge have been recognised in the 2021 New Year Honours, in recognition of their outstanding contributions to society.

L-R: Simon Baron-Cohen, Usha Goswami, Val Gibson

Yes

Antimatter matters at the Royal Society Summer Exhibition

Anonymous — Mon, 04 Jul 2016 14:07:01 +0000

Why we live in a universe made of matter, rather than a universe with no matter at all, is one of science’s biggest questions. ̽��ֱ��behaviour of antimatter, a rare oppositely charged counterpart to normal matter, is thought to be key to understanding why. However, the nature of antimatter is a mystery. Scientists use data from the LHCb and ALPHA experiments at CERN to study antiparticles and antiatoms in order to learn more about it. Some of these scientists, from the ̽��ֱ�� of Cambridge and other UK institutions, will present their work at the Royal Society’s annual Summer Science Exhibition which opens to the public tomorrow (5 July 2016).

At CERN’s Large Hadron Collider particle accelerator, matter and antimatter versions of fundamental particles are produced when the accelerator beams smash into each other. ̽��ֱ��LHCb experiment records the traces these particles leave behind as they fly outwards from the beam collisions with exquisite precision, enabling scientists to identify the particles and deduce whether they are matter or antimatter. At larger scales, antimatter is studied in CERN’s antiproton decelerator complex, when antiprotons are joined with antielectrons to form anti-hydrogen atoms. ̽��ֱ��ALPHA experiment holds these antiatoms in suspension so that their structure and behavior can be studied. Both experiments are currently recording data that will enable scientists to carefully build up an understanding of why antimatter appears to behave the way it does.

̽��ֱ�� ̽��ֱ�� of Cambridge is a founder institute of the LHCb experiment and plays a major part in the construction and operation of the detectors that determine the identity of particles. ̽��ֱ��detectors use the Ring-Imaging Cherenkov radiation technique via which particles emit radiation as they travel faster than the speed of light in the material of the detectors. ̽��ֱ��principles behind this technique and the data produced will be on view in the Royal Society Summer Science Exhibition for visitors to examine.

Professor Val Gibson of the ̽��ֱ�� of Cambridge and former UK Spokesperson for the experiment said: “Antimatter might sound like science fiction, but it is one of the biggest mysteries in science today. We’re going to show everyone just why it matters so much – from what it can tell us about the earliest universe, to how we study it at the frontiers of research, to how it has everyday uses in medical imaging.“

Visitors to the Exhibition will also be able to see how fundamental particles and antiparticles are identified with the LHCb experiment, talk to researchers to discover what this science is like, try the experimental techniques used to hold and study anti-atoms with the ALPHA experiment, and move, image and locate antimatter within a PET scanner system.

̽��ֱ��Royal Society’s Summer Science Exhibition is weeklong festival of cutting edge science from across the UK, featuring 22 exhibits which give a glimpse into the future of science and tech. Visitors can meet the scientists who are on hand at their exhibits, take part in activities and live demonstrations and attend talks. Entrance is free.

Scientists from the ̽��ֱ�� of Cambridge are presenting their research into the nature of antimatter at this year’s Royal Society Summer Exhibition.

Antimatter might sound like science fiction, but it is one of the biggest mysteries in science today.

Val Gibson

Summer Science Exhibition 2016: Antimatter Matters

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Firing up the proton smasher

fpjl2 — Mon, 16 Feb 2015 12:33:08 +0000

While it slept, we were allowed into the tunnels.

̽��ֱ��Large Hadron Collider (LHC) had shut down for two years to upgrade following the discovery of the Higgs boson. In the main ring, 175 m underground, chunks had been cut out of the snaking tubes for essential maintenance. These tubes fire protons in opposite directions, whipping them ever faster until they almost reach the speed of light. Along the 27 km run are four ‘experiments’: vast machines envelop the points at which tubes intersect and particles collide to capture the results. ̽��ֱ��largest of these, ATLAS, is the size of a six-storey building.

Each collision, known as an ‘event’, produces a splurge of elementary particles such as quarks, gluons and – as we now know – Higgs bosons. On average, events occur 40 million times a second in the LHC.

̽��ֱ��precision required for these events is exquisite. Our guide tells us to imagine two people standing six miles apart and each simultaneously firing a gun so that the bullets meet exactly head-on. Except instead of bullets, imagine needles. Inside the tunnels, engineers zip past on bicycles – the best way to get around underground unless you’re a proton. Next to every lift shaft is a bike rack.

In the next few months, the LHC will be switched back on. ̽��ֱ��2012 triumph of demonstrating the Higgs boson affirmed the Standard Model: the elegant solution to the building blocks of the Universe. Now, with an anticipated almost doubling of energy for the LHC’s second run, physicists are aiming to “go beyond” the Standard Model.

One of the central goals is to prove or disprove the theory of supersymmetry: the “prime candidate” theory for unlocking the mystery of the dark matter in our Universe.

“Observable matter only makes up 5% of the Universe; the rest is what we call dark matter. We know it’s there because we can see galaxies rotating at velocities which require surrounding matter for such gravitational pull – but, unlike the part of the galaxies that we can see, we cannot detect it optically,” said Professor Val Gibson, Head of the Cambridge High Energy Physics (HEP) group.

Supersymmetry theory essentially predicts that every particle in the Standard Model has a matching particle waiting to be found. These partner particles (or ‘sparticles’) could be candidates for dark matter, but we haven’t yet seen them – perhaps because they are heavier and take more energy to generate, a problem LHC Run II could overcome.

“Supersymmetry theory predicts there is a sister particle of the electron called a ‘selectron’, which would have integer ‘spin’: its intrinsic angular momentum. For the quark, there would be a supersymmetric ‘squark’, and so on for every elementary particle we know,” said Gibson. If supersymmetry is correct, there would also be a further four Higgs bosons for us to discover.

“Proton collisions in the LHC might produce a heavy supersymmetric particle which decays into its lightest form, a light neutral particle, but different from those we know about in the Standard Model,” said Gibson.

“We have been looking for supersymmetry particles throughout the first run of the LHC, and the increase in power for Run II means we can look at higher energies, higher mass, and gradually blot out more areas of the map in which supersymmetrical particles could be hiding.”

Will supersymmetry be proved by the end of next year, or will the data show it’s a red herring? For HEP research associate Dr Jordi Garra Ticó, what is really fundamental is experimental evidence. “I just want to see what nature has prepared for us, whether that’s consistent with some current theory or whether it’s something else that no one has ever thought about yet, outside of current knowledge.”

̽��ֱ��two experiments that Cambridge researchers work on are the mighty ATLAS and the more subtle LHCb – known as LHC ‘Beauty’ – which is Gibson and Garra Ticó’s focus. Beauty complements the power of ATLAS, allowing scientists to ‘creep up’ on new physics by capturing rare particle decays that happen every 100 million events.

Garra Ticó spent six months in Cambridge before taking up residence at CERN, where he works on LHCb. LHCb’s 10 million events a second create 35 kbyte of data each, a figure that is expected to go up to 60 kbyte during Run II – too much to ever imagine storing. “There is no guidebook,” he explained. “These machines are prototypes of themselves.”

ATLAS, the biggest experiment, feels like the lair of a colossal hibernating robot. Engineers perch in the crevices of the giant machine, tinkering away like tiny cleaner birds removing parasites. And sealed in the heart of this monster is layer upon layer of the most intricate electronics ever devised.

Dr Dave Robinson arrived in CERN as a PhD student in 1985, and joined the Cambridge HEP group in 1993. He went back to CERN in 2004 – expecting a stint of “one to two years” – and has remained. He is now Project Leader for the most critical detector system within ATLAS, the Inner Detector, which includes the ‘semi-conductor tracker’ (SCT), partially built
in Cambridge.

Each collision event inside ATLAS leaves an impression on the layers of silicon that make up the SCT like an onion skin – enabling scientists to reconstruct the trajectory of particles in the events. “ ̽��ֱ��sensitivity of the tracker is vital for making precise measurements of the thousands of particles generated by the head-on collisions between protons, including decay products from particles like b-quarks which only exist for picoseconds after the collision,” said Robinson.

He is currently working with Gibson and colleagues at the Cavendish Laboratory on the next generation of radiation-proof silicon technology in preparation for the LHC shutdown of 2020, the next time they will be able to get at the SCT, which is otherwise permanently locked in the core of ATLAS. ̽��ֱ��technology will have an impact on areas like satellite telecommunications, where cheaper, radiation-hardened electronics could have a huge effect.

This, for Gibson, is the way science works: solving technical problems to reveal nature’s hidden secrets, and then seeing the wider applications. She recalls being in CERN when she was a postdoc in the 1980s at the same time as Tim Berners-Lee, who was working on computer-sharing software to solve the anticipated data deluge from LHC-precursor UA1. He ended up calling it the World Wide Web.

Inset image – top: representation of the Higgs Boson particle; Credit: CERN.

Inset image – bottom: Professor Val Gibson.

̽��ֱ��Large Hadron Collider is being brought back to life, ready for Run II of the “world’s greatest physics experiment”. Cambridge physicists are among the army who keep it alive.

I just want to see what nature has prepared for us, whether that’s consistent with some current theory or whether it’s something else that no one has ever thought about yet, outside of current knowledge

Jordi Garra Ticó

CERN

Large Hadron Collider

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Supersymmetry squeezed as LHC spots ultra rare particle decay

ns480 — Tue, 13 Nov 2012 10:30:22 +0000

̽��ֱ��result is very damaging to new theories like the extremely popular Supersymmetry.

Current knowledge about the most fundamental matter particles (quarks and leptons, such as an electron) and the forces between them is embedded in the so-called Standard Model. ̽��ֱ��particle masses are a consequence of their interactions with the Higgs field. Exciting the Higgs field in particle collisions at the LHC recently resulted in the discovery of the Higgs boson.

However, the Standard Model is not the ultimate theory; it does not include gravity nor explain 95% of the Universe, which is in the form of Dark Matter and Dark Energy.

Supersymmetry is called in to fill some of the gaps of the Standard Model. Since it predicts new phenomena, the theory of Supersymmetry can be thoroughly tested at the LHC. A very good place to search is through the decay of a B_s particle (composed of a beauty quark and a strange anti-quark) into two muons (very heavy electrons). It is expected to be a very rare event but can be greatly enhanced be the presence of new physics.

This decay has been observed for the first time by a team at the LHC beauty (LHCb) experiment, a gigantic particle detector at one of the collision points on the 27 km LHC collider.

̽��ֱ��LHC, the world’s most powerful particle accelerator ever built, has been accelerating protons to almost the speed of light and bringing them to collision since November 2009. Each collision produces a shower of particles, among which a B_s particle is occasionally present. ̽��ֱ��B_s particle is not stable and decays an instant (within a million millionth of a second) after its production. During its short lifetime, it travels far enough (approximately a centimetre) to be observed by the LHCb detector. It can decay in a variety of other particles and in an extremely rare occurrence, about one in 300 million chance, into two muons.

̽��ֱ��team of physicists has analysed the tremendous amount of collisions recorded by LHCb, searching for this decay. In the end, they have spotted a handful of likely candidates. Observing this ultra-rare decay is a triumph for LHCb.

Professor Val Gibson, leader of the Cambridge LHCb team, says “An observation of this very rare decay is a key result that is putting our Supersymmetry theory colleagues in a spin. Results of this quality rely on the dedication and enthusiasm of research post-docs who analyse the data as it pours from the experiment”

̽��ֱ��observation is bang on the Standard Model prediction, but comes as very bad news for supporters of Supersymmetry. Indeed, new physics failed to show up where it had the best opportunity. “If new physics exists, then it is hiding very well behind the Standard Model” commented Cambridge physicist Dr Marc-Olivier Bettler, a member of the analysis team.

Nevertheless, Supersymmetry also benefits from this measurement, as Dr Bettler explains “This result is important because it tells us what new physics is not.”

Cambridge scientists at the Large Hadron Collider (LHC) at CERN, near Geneva, have spotted one of the rarest particle decays ever seen in nature.

An observation of this very rare decay is a key result that is putting our Supersymmetry theory colleagues in a spin. Results of this quality rely on the dedication and enthusiasm of research post-docs who analyse the data as it pours from the experiment

Professor Val Gibson

CERN

Primary interaction

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