fundamental particles – Polkinghorne http://polkinghorne.org/ Tue, 22 Feb 2022 00:16:45 +0000 en-US hourly 1 https://wordpress.org/?v=5.9.3 https://polkinghorne.org/wp-content/uploads/2022/01/icon-2022-01-25T202759.511-150x150.png fundamental particles – Polkinghorne http://polkinghorne.org/ 32 32 The Absolutely Incredible Theory of Almost Everything https://polkinghorne.org/the-absolutely-incredible-theory-of-almost-everything/ Sat, 15 Jan 2022 08:00:00 +0000 https://polkinghorne.org/the-absolutely-incredible-theory-of-almost-everything/ How does our world work at the subatomic level? The standard model. What a boring name for the most accurate scientific theory known to human beings. More than a quarter of the Nobel Prizes in Physics of the last century are direct inputs or direct results of the Standard Model. Still, its name suggests that […]]]>

How does our world work at the subatomic level?

The standard model. What a boring name for the most accurate scientific theory known to human beings.

More than a quarter of the Nobel Prizes in Physics of the last century are direct inputs or direct results of the Standard Model. Still, its name suggests that if you can afford a few extra bucks a month, you should buy the upgrade. As a theoretical physicist, I would prefer The Absolutely Incredible Theory of almost anything. That’s what the standard model really is.

Many remember the enthusiasm of scientists and the media over the 2012 discovery of the Higgs boson. But this high-profile event didn’t come out of nowhere — it capped a five-decade unbeaten streak for the standard model. All fundamental forces except gravity are included. All attempts to overthrow it to demonstrate in the laboratory that it needs substantial reworking – and there have been many over the past 50 years – have failed.

In short, the standard model answers this question: what is it all made of and how does it fit together?

The smallest building blocks

You know, of course, that the world around us is made of molecules, and molecules are made of atoms. Chemist Dmitri Mendeleev discovered in the 1860s how to arrange all of the atoms – aka the elements – in the periodic table that you probably studied in college. But there are 118 different chemical elements. There’s antimony, arsenic, aluminum, selenium… and 114 others.

Periodic table

But these elements can be broken down further. Credit: Ruben Vera Koster

Physicists like simple things. We want to boil things down to their essence, a few basics. More than a hundred chemical elements is not simple. The ancients believed that everything was made up of only five elements: earth, water, fire, air and ether. Five is much simpler than 118. It’s also wrong.

In 1932, scientists knew that all these atoms were made up of only three particles: neutrons, protons and electrons. Neutrons and protons are tightly bound in the nucleus. Electrons, thousands of times lighter, whirl around the nucleus at speeds close to the speed of light. The physicists Planck, Bohr, Schroedinger, Heisenberg and their friends had invented a new science – quantum mechanics – to explain this movement.

It would have been a satisfying place to stop. Just three particles. Three is even easier than five. But how to hold together? Negatively charged electrons and positively charged protons are bound by electromagnetism. But the protons are all packed into the nucleus, and their positive charges should powerfully push them away. Neutrons can’t help.

What binds these protons and these neutrons? “Divine intervention” a man told me on a Toronto street corner; he had a pamphlet, I could read all about it. But this scenario seemed to pose a lot of problems, even for a divine being – to keep an eye on every one of the 108° protons and neutrons in the universe and bend them to his will.

Expand the Particle Zoo

Meanwhile, nature has cruelly refused to limit its particle zoo to just three. Really four, because you would have to count the photon, the particle of light described by Einstein. Four changed to five when Anderson measured electrons with a positive charge – positrons – hitting Earth from space. At least Dirac had predicted these first antimatter particles. Five became six when the pawn, which Yukawa believed would hold the core together, was found.

Then came the muon – 200 times heavier than the electron, but otherwise a twin. “Who ordered this? II Rabi joked. That sums it all up. Number seven. Not only not simple, redundant.

In the 1960s, there were hundreds of “fundamental” particles. Instead of the neatly organized periodic table, there were only long lists of baryons (heavy particles like protons and neutrons), mesons (like Yukawa pions) and leptons (light particles like the electron and the elusive neutrinos) – with no organization and no guiding principles.

Into this breach has slipped the standard model. It wasn’t an overnight flash of brilliance. No Archimedes jumped out of a bathtub shouting “eureka”. Instead, there was a series of crucial ideas from a few key people in the mid-1960s that turned this quagmire into a simple theory, and then five decades of experimental verification and theoretical elaboration.

Standard model of elementary particles

The standard model of elementary particles provides a list of ingredients for everything around us. Credit: National Fermi Accelerator Laboratory

Quarks. They come in six varieties which we call flavors. Like ice cream, except it’s not as tasty. Instead of vanilla, chocolate and so on, we have high, low, weird, charm, low and high. In 1964, Gell-Mann and Zweig taught us the recipes: mix and match three quarks to get a baryon. Protons are two ups and one down quark bound together; neutrons are two lows and one high. Choose a quark and an antiquark to get a meson. A pion is an up or down quark bound to an anti-up or an anti-down. All the material of our daily life is composed only of quarks, anti-quarks and electrons.

Simple. Well, it’s simple, because keeping those quarks bound is a feat. They are so closely related to each other that you never find a single quark or antiquark. The theory of this binding, and the particles called gluons (laughs) that are responsible for it, is called quantum chromodynamics. It is an essential piece of the standard model, but mathematically difficult, even posing an unsolved problem of basic mathematics. We physicists do our best to calculate with it, but we are still learning how.

The other aspect of the standard model is “a lepton model”. It’s the name of Steven Weinberg’s landmark 1967 paper that brought together quantum mechanics with the essential knowledge of how particles interact and organized the two into a single theory. He incorporated the familiar electromagnetism, associated it with what physicists called “the weak force” that causes certain radioactive decays, and explained that they were different aspects of the same force. It incorporated the Higgs mechanism to give mass to fundamental particles.

Since then, the Standard Model has predicted the results of experiment after experiment, including the discovery of several varieties of quarks and W and Z bosons, heavy particles that are to weak interactions what the photon is to electromagnetism. The possibility that neutrinos are not massless was overlooked in the 1960s, but slipped easily into the Standard Model in the 1990s, a few decades later.

CERN particle accelerator Higgs boson decay SM

3D view of an event recorded at the CERN particle accelerator showing the expected characteristics of the decay of the SM Higgs boson into a pair of photons (dashed yellow lines and green towers). Credit: McCauley, Thomas; Taylor, Lucas; for the CMS CERN collaboration

Discovering the Higgs boson in 2012, long predicted by the Standard Model and long sought after, was a thrill but not a surprise. It was yet another crucial victory for the Standard Model over the dark forces that particle physicists have repeatedly warned were looming on the horizon. Concerned that the Standard Model did not adequately embody their expectations of simplicity, worried about its mathematical consistency, or anticipating the possible need to incorporate the force of gravity, physicists made numerous proposals for theories beyond of the norm. Model. These go by exciting names like Grand Unified Theories, Supersymmetry, Technicolor, and String Theory.

Unfortunately, at least for their proponents, theories beyond the Standard Model have not yet successfully predicted a new experimental phenomenon or an experimental divergence from the Standard Model.

After five decades, far from needing an upgrade, the Standard Model deserves to be celebrated as an absolutely incredible theory of almost everything.

Written by Glenn Starkman, Distinguished University Professor of Physics, Case Western Reserve University.

This article first appeared in The Conversation.The conversation

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New results from MicroBooNE provide clues to the mystery of particle physics https://polkinghorne.org/new-results-from-microboone-provide-clues-to-the-mystery-of-particle-physics/ Thu, 28 Oct 2021 07:00:00 +0000 https://polkinghorne.org/new-results-from-microboone-provide-clues-to-the-mystery-of-particle-physics/ MicroBooNE detector being lowered into the Fermilab experimental facility. Credit: Fermilab New results from a more than a decade-long physics experiment offer insight into unexplained electronic-like events discovered in previous experiments. The results of the MicroBooNE experiment, while not confirming the existence of a proposed new particle, the sterile neutrino, open the way to exploring […]]]>

MicroBooNE detector being lowered into the Fermilab experimental facility. Credit: Fermilab

New results from a more than a decade-long physics experiment offer insight into unexplained electronic-like events discovered in previous experiments. The results of the MicroBooNE experiment, while not confirming the existence of a proposed new particle, the sterile neutrino, open the way to exploring physics beyond the Standard Model, the fundamental force theory of nature and elementary particles.

“The results so far from MicroBooNE make the explanation for the electronic-like anomalous events of the MiniBooNE experiment more likely to be physics beyond the Standard Model,” said William Louis, a physicist at Los Alamos National Laboratory. and member of the MicroBooNE collaboration. “What exactly the new physics is remains to be seen.”

The MicroBooNE experiment at the US Department of Energy’s Fermi National Accelerator Laboratory explores a striking anomaly in particle beam experimentation first discovered by researchers at Los Alamos National Laboratory. In the 1990s, the liquid scintillator neutrino detector experiment at the Laboratory saw more electron-like events than expected, compared to calculations based on the Standard Model.

In 2002, the MiniBooNE follow-up experiment at Fermilab began collecting data to further investigate the LSND outcome. MiniBooNE scientists also saw more electronic-like events than calculations based on the Standard Model prediction. But the MiniBooNE detector had a particular limitation: it was unable to tell the difference between electrons and photons (particles of light) near where the neutrino was interacting.

The MicroBooNE experiment seeks to explore the source of the anomaly for additional events. The MicroBooNE detector is built on state-of-the-art techniques and technology, using special light sensors and over 8,000 painstakingly attached wires to capture particle trails. It is housed in a 40-foot-long cylindrical container filled with 170 tons of pure liquid argon. The neutrinos hit the dense, transparent liquid, releasing additional particles that the electronics can record. The resulting images show detailed particle trajectories and, importantly, distinguish electrons from photons.

“Liquid argon technology is relatively new in neutrino physics, and MicroBooNE has been a pioneer for this technology, demonstrating what amazing physics can be done with it,” said Sowjanya Gollapinni, laboratory physicist and co-lead of analysis. “We had to develop all the tools and techniques from scratch, including how to process the signal, how to reconstruct it, and how to do the calibration, among other things.”

MicroBooNE included a series of measurements: one measurement of photons and three measurements of electrons. In early October, the results of the photon measurement, which specifically looked for Delta radiative decay, provided the first direct evidence disfavoring an excess of neutrino interactions due to this abnormal single photon production as an explanation for the excess of MiniBooNE energy. Delta radiative decay was the only background that the MiniBooNE experiment could not directly constrain.

The three new electron analyzes address the question of whether the excess is due to the scattering of an electron neutrino off an argon nucleus, producing an outgoing electron. The new results disfavor this process as an explanation for excess MiniBooNE, leaving the question of what causes the MiniBooNE anomaly still unanswered.

“In my mind, the fact that neither photon nor electron production explains the excess makes understanding the MiniBooNE results more interesting and more likely to venture into some very interesting physics beyond the Standard Model. “, said Louis.

New results from MicroBooNE provide clues to the mystery of particle physics

Interior of the MicroBooNE Time Projection Chamber detector. Credit: Fermilab

With only half of the MicroBooNE data still evaluated, possible explanations yet to be considered (or tested in future experiments) include the possibility that as yet unproven sterile neutrinos could decay into gamma rays. The decay of the axion – the axion is another hypothetical elementary particle – into gamma or an electron-positron pair could also be responsible. Neutrinos and sterile axions could be linked to the dark sector, the hypothetical realm of yet unobserved different physics and particles.

“The possibilities are endless,” Gollapinni said, “and MicroBooNE will be on a mission to explore each one with the full data set. The results pave the way for further physics experiments, but a full understanding of the results will also depend on our colleagues in theoretical physics, who are very intrigued by these results.”

MicroBooNE is part of a suite of neutrino experiments looking for answers. The ICARUS detector starts collecting physical data and the Short Baseline Proximity Detector (SBND) will come online in 2023; both detectors use liquid argon technology. Together with MicroBooNE, the three experiments form Fermilab’s short-base neutrino program and will yield a wealth of neutrino data. For example, in one month, SBND will record more data than MicroBooNE collected in two years. Today’s results from MicroBooNE will help guide some of the research in the trio’s extensive portfolio.

Building further on MicroBooNE’s techniques and technology, liquid argon will also be used in the Deep Underground Neutrino Experiment (DUNE), a flagship international experiment hosted by Fermilab which already has more than 1,000 researchers from over 30 countries. DUNE will study the oscillations by sending neutrinos 1,300 km (800 miles) through the earth to detectors at the underground research center in Sanford, South Dakota. Combining short- and long-range neutrino experiments will give researchers insight into how these fundamental particles work.

At Fermilab or underground in South Dakota, Laboratory researchers bring the technology and analytical understanding to probe the mysteries of particle physics. What awaits us is unknown, but exciting.

“What we have found and continue to find with MicroBooNE will have important implications for future experiments,” Gollapinni said. “These results point us in a new direction and tell us to think outside the box. MicroBooNE’s journey to explore the exciting physics that awaits us has just begun, and there is much more that MicroBooNE will reveal in the years to come.”


Scientists find no trace of sterile neutrino


Provided by Los Alamos National Laboratory

Quote: New results from MicroBooNE provide clues to the mystery of particle physics (2021, October 28) retrieved February 15, 2022 from https://phys.org/news/2021-10-results-microboone-clues-particle -physics.html

This document is subject to copyright. Except for fair use for purposes of private study or research, no part may be reproduced without written permission. The content is provided for information only.

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New MicroBooNE Results Provide Clues to Particle Physics Mystery – Los Alamos Reporter https://polkinghorne.org/new-microboone-results-provide-clues-to-particle-physics-mystery-los-alamos-reporter/ Wed, 27 Oct 2021 07:00:00 +0000 https://polkinghorne.org/new-microboone-results-provide-clues-to-particle-physics-mystery-los-alamos-reporter/ MicroBooNE detector being lowered into the Fermilab experimental facility. Photo courtesy Fermilab LANL PRESS RELEASE New results from a more than a decade-long physics experiment offer insight into unexplained electronic-like events discovered in previous experiments. The results of the MicroBooNE experiment, while not confirming the existence of a proposed new particle, the sterile neutrino, open […]]]>

MicroBooNE detector being lowered into the Fermilab experimental facility. Photo courtesy Fermilab

LANL PRESS RELEASE

New results from a more than a decade-long physics experiment offer insight into unexplained electronic-like events discovered in previous experiments. The results of the MicroBooNE experiment, while not confirming the existence of a proposed new particle, the sterile neutrino, open the way to exploring physics beyond the Standard Model, the fundamental force theory of nature and elementary particles.

“The results so far from MicroBooNE make the explanation for the electronic-like anomalous events of the MiniBooNE experiment more likely to be physics beyond the Standard Model,” said William Louis, physicist at Los Alamos National Laboratory. and member of the MicroBooNE collaboration. “What exactly the new physics is – that remains to be seen.”

The MicroBooNE experiment at the US Department of Energy’s Fermi National Accelerator Laboratory explores a striking anomaly in particle beam experimentation first discovered by researchers at Los Alamos National Laboratory. In the 1990s, the liquid scintillator neutrino detector experiment at the Laboratory saw more electron-like events than expected, compared to calculations based on the Standard Model.

In 2002, the MiniBooNE follow-up experiment at Fermilab began collecting data to further investigate the LSND outcome. MiniBooNE scientists also saw more electronic-like events than calculations based on the Standard Model prediction. But the MiniBooNE detector had a particular limitation: it was unable to tell the difference between electrons and photons (particles of light) near where the neutrino was interacting.

The MicroBooNE experiment seeks to explore the source of the additional event anomaly. The MicroBooNE detector is built on state-of-the-art techniques and technology, using special light sensors and over 8,000 painstakingly attached wires to capture particle trails. It is housed in a 40-foot-long cylindrical container filled with 170 tons of pure liquid argon. The neutrinos hit the dense, transparent liquid, releasing additional particles that the electronics can record. The resulting images show detailed particle trajectories and, importantly, distinguish electrons from photons.

“Liquid argon technology is relatively new in neutrino physics, and MicroBooNE has been a pioneer for this technology, demonstrating what amazing physics can be done with it,” said Sowjanya Gollapinni, laboratory physicist and co-lead of analysis. “We had to develop all the tools and techniques from scratch, including how to process the signal, how to reconstruct it, and how to do the calibration, among other things.”

MicroBooNE included a series of measurements: one measurement of photons and three measurements of electrons. In early October, the results of the photon measurement, which specifically looked for Delta radiative decay, provided the first direct evidence disfavoring an excess of neutrino interactions due to this abnormal single photon production as an explanation for the excess of MiniBooNE energy. Delta radiative decay was the only background that the MiniBooNE experiment could not directly constrain.

The three new electron analyzes address the question of whether the excess is due to the scattering of an electron neutrino off an argon nucleus, producing an outgoing electron. The new results disfavor this process as an explanation for excess MiniBooNE, leaving the question of what causes the MiniBooNE anomaly still unanswered.

“In my mind, the fact that neither photon nor electron production explains the excess makes understanding the MiniBooNE results more interesting and more likely to venture into some very interesting physics beyond the Standard Model. “, said Louis.

With only half of the MicroBooNE data still evaluated, possible explanations yet to be considered (or tested in future experiments) include the possibility that as yet unproven sterile neutrinos could decay into gamma rays. The decay of the axion – the axion is another hypothetical elementary particle – into gamma or an electron-positron pair could also be responsible. Neutrinos and sterile axions could be linked to the dark sector, the hypothetical realm of yet unobserved different physics and particles.

“The possibilities are endless,” said Gollapinni, “and MicroBooNE will be on a mission to explore each one with the full data set. The results pave the way for further experiments in physics, but a full understanding of the results will also depend on our colleagues in theoretical physics, who are very intrigued by these results.

MicroBooNE is part of a suite of neutrino experiments looking for answers. The ICARUS detector starts collecting physical data and the Short Baseline Proximity Detector (SBND) will come online in 2023; both detectors use liquid argon technology. Together with MicroBooNE, the three experiments form Fermilab’s short-base neutrino program and will yield a wealth of neutrino data. For example, in one month, SBND will record more data than MicroBooNE collected in two years. Today’s results from MicroBooNE will help guide some of the research in the trio’s extensive portfolio.

Building further on MicroBooNE’s techniques and technology, liquid argon will also be used in the Deep Underground Neutrino Experiment (DUNE), a flagship international experiment hosted by Fermilab which already has more than 1,000 researchers from over 30 countries. DUNE will study the oscillations by sending neutrinos 1,300 km (800 miles) through the earth to detectors at the underground research center in Sanford, South Dakota. Combining short- and long-range neutrino experiments will give researchers insight into how these fundamental particles work.

At Fermilab or underground in South Dakota, Laboratory researchers bring the technology and analytical understanding to probe the mysteries of particle physics. What awaits us is unknown, but exciting.
“What we have found and continue to find with MicroBooNE will have important implications for future experiments,” Gollapinni said. “These results point us in a new direction and tell us to think outside the box. MicroBooNE’s journey to explore the exciting physics that awaits us has just begun, and there is much more that MicroBooNE will reveal in the years to come.

Inside the MicroBooNE Time Projection Chamber detector.pPhoto courtesy of Fermilab

MicroBooNE is supported by the US Department of Energy, US National Science Foundation, Swiss National Science Foundation, UK Science and Technology Facilities Council, UK Royal Society and European Union Horizon 2020.

On Los Alamos National Laboratory
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Triad, a public service-focused national security science organization equally owned by its three founding members. : the Battelle Memorial Institute (Battelle), the Texas A&M University System (TAMUS), and the University of California (UC) Regents for the Department of Energy’s National Nuclear Security Administration.

Los Alamos strengthens national security by ensuring the safety and reliability of America’s nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and addressing issues related to energy, environment, infrastructure, to global health and security issues.

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UNM’s QuarkNet Workshop at Explora Helps Educators Understand Particle Physics : UNM Newsroom https://polkinghorne.org/unms-quarknet-workshop-at-explora-helps-educators-understand-particle-physics-unm-newsroom/ Tue, 28 Sep 2021 07:00:00 +0000 https://polkinghorne.org/unms-quarknet-workshop-at-explora-helps-educators-understand-particle-physics-unm-newsroom/ The role of science in our everyday world has perhaps never been more important than in the past 18 months as a pandemic gripped the world. With that in mind, teaching the next generation of scientists is mission critical, and nurturing that interest in K-12 students is a key area for realizing big gains. It’s […]]]>

The role of science in our everyday world has perhaps never been more important than in the past 18 months as a pandemic gripped the world. With that in mind, teaching the next generation of scientists is mission critical, and nurturing that interest in K-12 students is a key area for realizing big gains. It’s a mission that the National Science Foundation (NSF) and the University of New Mexico take seriously.

QuarkNet, a nonprofit collaboration dedicated to developing America’s tech workforce, is an NSF-funded partnership between Fermilab and the University of Notre Dame that provides science teachers with the means to further develop their skills and to bring real research experience to classrooms across the United States.

Through a nationwide network of QuarkNet Centers, including the University of New Mexico, NSF brings together science teachers and academic researchers in active research projects in contemporary physics with focused hands-on workshops covering a variety of topics. in physics. Teachers gain experience in actual scientific research, maximizing their talents and effectiveness in the classroom; researchers achieve educational impact from their research and engagement with their local communities; and students immerse themselves in meaningful scientific research, preparing them for post-secondary education and developing essential intellectual skills.

At a recent workshop held in Albuquerque at the Explora Science Center & Childen’s Museum, QuarkNet staff Shane Wood led a group of teachers who traveled from Grants, Durango, Ft. Wingate, Roswell, Laguna-Acoma School and several in Albuquerque, including Public Academy of the Performing Arts, Desert Ridge Middle School, and Escuela del Sol Montessori, through a series of activities and experiences designed to help teachers bring real-world research experience in their classrooms.

“Our mission is really to work with teachers who, in turn, work with students. From this process, I think there are a lot of potential gains that we see happening,” said Wood, who works at the University of Notre Dame where NSF funds for QuarkNet are allocated. “We work on everything from researching our future particle physicists, who may not have known about it until they learned about it in their high school physics class, to simply having an appreciation and an informed taxpayer.

“I think the fact that students and therefore society in general have a better understanding of how science works really allows us to have a more informed public. We really have many goals along these roads, but our main mission is to work with teachers to then bring 21st century research experiences into the classroom.

“The idea is to help teachers become more aware, comfortable and interested in particle physics. We were happy to offer this workshop to all teachers of science, technology and mathematics , and that is precisely because particle physics is not so well known.” – Professor Sally Seidel, UNM Department of Physics and Astronomy

UNM’s QuarkNet program is led by Professor Sally Seidel of the Department of Physics and Astronomy. Seidel’s research interests include particle physics instrumentation and high energy collider physics. She is currently working on the Atlas experiment in high energy physics at the Large Hadron Collider, the largest and most powerful particle accelerator in the world. Seidel has coordinated QuarkNet activities at UNM since proposing a center and became the 48th QuarkNet member in 2016.

Events at the recent QuarkNet Workshop held at Explora included a presentation given by Seidel titled “The Beauty of Particle Physics”, a basic introduction to particle physics also known as high-energy physics, which studies the most small building blocks of nature. This particular field of science is a way to learn what the universe was like just seconds after it was born, billions of years before life existed to see it first hand.

Other activities included mixing the particle game, an activity based on particle maps describing the fundamental particles and their characteristics to become familiar with the Standard Model. Another fun activity was Rolling with Rutherford where the probe and target are a number of balls lined up in a row. The activity consists of rolling another marble in the aligned area. The data then consists of calculating the diameter of the target balls to use indirect measurements to determine a parameter. Teachers also took part in a real-time experiment to visualize particle tracks in a portable cloud chamber detector. The workshop also included a presentation on the LHC and what happens there.

“The idea is to help teachers be more aware, comfortable and interested in particle physics. We were happy to bring this to all science, technology and math teachers, and that’s precisely because particle physics is not so well known,” said Seidel, who enjoys helping people understand the technological implications of particle physics. “People like Shane and I partner with community engagement events like this to engage teachers and build this science education to try to help people understand the scientific description of the world.”

Previous QuarkNet@UNM activities have included a guided behind-the-scenes technical tour of the Very Large Array, a science heritage history tour at Los Alamos, and a high school workshop with a variety of presentations where students must be teachers themselves.

Turtle Haste, who has participated in QuarkNet twice at Desert Ridge Middle School in Albuquerque, enjoyed the workshop and thinks mentoring young students in STEM fields is imperative.

“It is extremely important. We come from a generation where there is a lot of bias against women in science,” Haste said. “It took me a long time to find someone who would take me in no matter what and get me through it. If I hadn’t had that mentor, I probably would have ended up being a secretary for that period. But because I had someone like, ‘Hey, you know what? You get this, let’s go. So I think it’s really important to mentor young students.

The Quarknet@UNM program is open to all New Mexico middle and high school teachers interested in gaining research experience. For more information, visit QuarkNet@UNM.

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Nobel Prize in Particle Physics Steven Weinberg ’54 Dies at 88 https://polkinghorne.org/nobel-prize-in-particle-physics-steven-weinberg-54-dies-at-88/ Tue, 24 Aug 2021 07:00:00 +0000 https://polkinghorne.org/nobel-prize-in-particle-physics-steven-weinberg-54-dies-at-88/ Steven Weinberg ’54, the theoretical physicist whose Nobel Prize-winning work transformed scientists’ understanding of fundamental forces, died on July 23. He was 88 years old. “[His work] is basically the foundation of everything we do in particle physics, what we now call the Standard Model,” said physicist Professor Csaba Csaki. The Standard Model explains the […]]]>

Steven Weinberg ’54, the theoretical physicist whose Nobel Prize-winning work transformed scientists’ understanding of fundamental forces, died on July 23. He was 88 years old.

“[His work] is basically the foundation of everything we do in particle physics, what we now call the Standard Model,” said physicist Professor Csaba Csaki. The Standard Model explains the fundamental particles and interactions that make up the universe.

In his most significant work, the former Cornell student and former guest speaker proposed the electroweak force, which unifies the electromagnetic and weak forces, two of the fundamental forces that explain the behavior of all particles in the universe.

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Steven Weinberg obituary | Particle physics https://polkinghorne.org/steven-weinberg-obituary-particle-physics/ Mon, 02 Aug 2021 07:00:00 +0000 https://polkinghorne.org/steven-weinberg-obituary-particle-physics/ The American theoretical particle physicist Steven Weinberg, who died at the age of 88, was one of the leading figures of the 20th century in this field. In 1979, he won a Nobel Prize for his work uniting two of nature’s fundamental forces, which became a foundation of the Standard Model of particle physics, the […]]]>

The American theoretical particle physicist Steven Weinberg, who died at the age of 88, was one of the leading figures of the 20th century in this field. In 1979, he won a Nobel Prize for his work uniting two of nature’s fundamental forces, which became a foundation of the Standard Model of particle physics, the theory that describes all known particles and fundamental forces in the universe. .

From Weinberg’s prodigious work – in research, in his technical and popular books on quantum field theory and cosmology, and in scientific commentary articles – his work demonstrating that the transmutation of elements by the weak nuclear force is fundamentally related to electromagnetism constituted a truly remarkable breakthrough.

Following Peter Higgs’ discovery in 1964 that fundamental particles can, in theory, gain mass through the “Higgs mechanism”, he, Weinberg and others tried to find examples where this mechanism is used in the nature. These attempts initially focused on the strong force that binds atomic nuclei, but no consistent correspondence emerged, until 1967, while on his way to work at MIT (the Massachusetts Institute of Technology), Weinberg had an inspired thought: they had implemented the right idea. , but to the wrong problem.

Instead of the strong force, Weinberg realized that the mechanism could apply to the weak nuclear force, manifested by radioactivity. As a bonus, Weinberg realized that thanks to this application, he could describe in a single mathematical diagram both the phenomena of electromagnetism and the form of radioactivity which is the key to the creation of elements in stars. This idea would become the basis of the current standard model of particles and forces.

A viable quantum field theory of electromagnetism – quantum electrodynamics (QED) – had been known since 1947. The key to its consistency was that the photon – the basic particle of electromagnetic radiation – is massless. Weinberg’s marriage of weak and electromagnetic forces required the existence of analogues of the photon. These “W and Z bosons” were later discovered and confirmed to be very massive, as Weinberg had predicted.

There was a problem, however: being massive, they apparently undermined the mathematical coherence of the theory. Weinberg conjectured, but was unable to prove, that if the W and Z gained their masses through the Higgs mechanism, his extension of QED would indeed be a viable quantum theory of two forces.

Initially his paper had little impact, with one prominent scientist later describing the response: “Rarely has such a great achievement been so widely ignored.” Then, in 1971, a young Dutch student, Gerard ‘t Hooft, proved the model to be a complete and viable theory, winning himself a Nobel Prize in 1999 for this feat.

With the demonstration that Weinberg had indeed constructed a coherent relativistic quantum theory of electromagnetic and weak force fields, the predictions of which were soon confirmed in a variety of experiments, his seminal paper quickly became the most cited in all of theoretical physics. Its implications were so profound that they determined the direction of high-energy particle physics during the last decades of the 20th century. In what was to prove to be of momentous importance, his papers drew attention to a cornerstone of his theoretical construction – the necessary role of the ‘Higgs boson’. The search for this particle would take four decades; its discovery in 2012 was the final piece in a structure whose architectural design owed much to the genius of Weinberg.

Born in New York, Steven was the son of Jewish immigrants, Eva (née Israel) and Frederick Weinberg, a court stenographer. Steven’s love for science began in childhood with the gift of a chemistry set. He attended Bronx Science High School, which produced eight Nobel laureates, including Weinberg’s contemporary Sheldon Glashow, whose freelance work led him to share the 1979 prize with Weinberg and Abdus Salam. He earned a bachelor’s degree at Cornell University in 1954, and that year married Louise Goldwasser, whom he had met while a student; she became a law professor. After a year at what is now the Niels Bohr Institute in Copenhagen, Weinberg returned to the United States and Princeton University, where he earned a doctorate (1957).

After two years at Columbia University and six at Berkeley, in 1966 Weinberg joined Harvard University, first as a lecturer, and from 1973 as a professor of physics. Early in his Harvard stint, Weinberg had a joint appointment at MIT, and it was while driving there in his red Camarro that he had his weak nuclear force epiphany.

In 1982 he moved to the University of Texas at Austin, where he spent the rest of his career. He never retired and continued teaching until the spring of that year.

For decades, Weinberg’s ideas outside of his 1967 paper inspired new lines of research. His work on “effective field theories” redefined the direction of work in quantum field theory and influenced attempts to find a viable quantum theory of gravity. He was one of the founders of the concept of “chiral perturbation theory” as a mathematical approach to understanding aspects of the strong nuclear force.

In addition to these seminal research contributions, Weinberg wrote an influential text on gravitation, a masterful three-volume set of textbooks on quantum field theory, and authored the popular best-selling cosmology book The First Three Minutes (1977).

In 1992 he published Dreams of a Final Theory, which has become a classic discourse on the goal of fundamental physics at the dawn of the 21st century.

In his later years he became an authoritative historian of science, his gravity and wisdom making him a respected commentator on science policy as well as social issues, and making him one of the most respected figures in science. world.

He is survived by his wife, Louise, whom he married in 1954, their daughter, Elizabeth, and one granddaughter.

Steven Weinberg, theoretical physicist, born May 3, 1933; passed away on July 23, 2021

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Argonne aurora will accelerate particle physics discoveries at CERN https://polkinghorne.org/argonne-aurora-will-accelerate-particle-physics-discoveries-at-cern/ Thu, 22 Jul 2021 07:00:00 +0000 https://polkinghorne.org/argonne-aurora-will-accelerate-particle-physics-discoveries-at-cern/ July 22, 2021 – The U.S. Department of Energy’s (DOE) Argonne National Laboratory will house one of the nation’s first exascale supercomputers when Aurora arrives in 2022. To prepare code for the architecture and System-wide, 15 research teams are taking part in the Aurora Early Science program through the Argonne Leadership Computing Facility (ALCF), a […]]]>

July 22, 2021 – The U.S. Department of Energy’s (DOE) Argonne National Laboratory will house one of the nation’s first exascale supercomputers when Aurora arrives in 2022. To prepare code for the architecture and System-wide, 15 research teams are taking part in the Aurora Early Science program through the Argonne Leadership Computing Facility (ALCF), a DOE Office of Science user facility. With access to pre-production time on the supercomputer, these researchers will be among the first in the world to use an exascale machine for science.

Early philosophers first formulated the idea of ​​the atom around the fifth century BCE. And just when we thought we had understood its basic structure – protons, neutrons and electrons – theories and technologies emerged to prove us wrong. It turns out that there are still more fundamental particles, like quarks, bound together by aptly named gluons.

Physicists discovered many of these and other particles in the huge beasts of machinery we call colliders, helping to develop what we know today as the Standard Model of physics. But there are questions that keep nagging: is there something even more fundamental? Is the standard model all there is?

Determined to find out, the high-energy physics community is working to integrate ever larger colliders and more sophisticated detectors with exascale computing systems. Among them is Walter Hopkins, assistant physicist at Argonne National Laboratory and collaborator on the ATLAS experiment at CERN’s Large Hadron Collider (LHC), near Geneva, Switzerland.

In collaboration with researchers from Argonne and Lawrence Berkeley National Lab, Hopkins is leading an Aurora Early Science Program project through the ALCF to prepare software used in LHC simulations for exascale computing architectures, including the upcoming exascale machine d ‘Argonne, Aurora. With a trillion calculations per second, Aurora is at the frontier of supercomputing and at the height of the next particle physics challenge of gargantuan scale.

The project was started several years ago by physicist and Argonne Emeritus James Proudfoot, who saw the distinct advantages of exascale in enhancing the impact of such complex science.

Align the codes on the new architecture

The collisions produced in the LHC occur in one of the many detectors. The one the team is focusing on, ATLAS, witnesses billions of particle interactions every second and the new particle signatures these collisions create in their wake.

One type of code the team is focusing on, called event generators, simulates the underlying physical processes that occur at interaction points in the 17-mile-circumference collider ring. Aligning the physics produced by the software with that of the Standard Model helps researchers accurately simulate collisions and predict the types, trajectories and energies of residual particles.

Detecting physics in this way creates a mountain of data and requires equally significant computational time. And now CERN is upping the ante as it prepares to upgrade the LHC’s luminosity, enabling more particle interactions and a 20-fold increase in data output.

As the team looks to Aurora to handle this increase in its simulation needs, the machine is not without some challenges.

Workers inside ATLAS, one of several primary detectors at CERN’s Large Hadron Collider. ATLAS witnesses a billion particle interactions every second and the signatures of new particles created in proton-proton collisions at near light speed. (Picture: CERN)

Until recently, event generators ran on computer processors (central processing units). Although they work fast, a processor can usually only perform several operations at a time.

Aurora will feature both CPUs and GPUs (graphics processing units), the choice of gamers around the world. GPUs can handle many operations by breaking them up into thousands of smaller tasks spread across many cores, the engines that drive both types of units.

But it takes a lot of effort to move CPU-based simulations to GPUs efficiently, Hopkins notes. So making this move to prepare for both Aurora and the onslaught of new LHC data presents several challenges, which have become a central part of the team’s goal.

“We want to be able to use Aurora to help us meet these challenges,” says Hopkins, “but that forces us to study computing architectures that are new to us and our code base. For example, we focus on a generator used in ATLAS, called MadGraph, which runs on GPUs, which are more parallel and have different memory management requirements.

A particle interaction simulation code, MadGraph, has been written by an international team of high-energy physics theorists and meets the simulation needs of the LHC.

Simulation and AI support experimental work

The LHC has played an important role in bringing the predictions to fruition. Even more famously, the Standard Model predicted the existence of the Higgs boson, which imparts mass to all fundamental particles; ATLAS and its counterpart detector, CMS, confirmed the existence of Higgs in 2012.

But, as is often the case in science, big discoveries can lead to more substantial questions, many of which are not predicted by the Standard Model. Why does the Higgs have the mass it is? What is dark matter?

“The reason for this very large LHC upgrade is that we hope to find that needle in the haystack, that we will find an anomaly in the dataset that offers a hint of physics beyond the Standard Model,” says Hopkins. .

A combination of computing power, simulation, experience, and artificial intelligence (AI) will greatly aid this research by providing accuracy in both prediction and identification.

When the ATLAS detector witnesses these particle collisions, for example, it records them as electronic signals. These are reconstructed in the form of pixels of bursts of energy which can correspond to the passage of an electron.

“But just like in AI, where the canonical example identifies cats and dogs in images, we have algorithms that identify and reconstruct those electronic signals into electrons, protons, and other things,” says Taylor Childers, computer scientist at the ALCF, member of the team. .

Data reconstructed from real crash events is then compared to simulated data to look for differences in patterns. This is where the accuracy of the physical models comes in. If they perform well and the real and simulated data do not match, you continue to measure and eliminate anomalies until it is likely that you found that needle, that something that doesn’t fit the standard pattern.

The team is also using AI to quantify uncertainty, to determine the likelihood that they have correctly identified a particle.

Humans are able to identify particles to a limited extent – several parameters like moment and position could tell us that a certain particle is an electron. But base that characterization on 10 interrelated parameters, then that’s another story altogether.

“This is where artificial intelligence really shines, especially if these input parameters are correlated, like the momentum of the particles around an electron and the momentum of the electron itself,” says Hopkins. “These correlations are hard to deal with analytically, but because we have so much simulation data, we can teach artificial intelligence and it can tell us, it’s an electron with this probability because I have all this information from Entrance. “

Exascale computing and the way forward

In preparation for Aurora, the team continues to work on programming languages ​​for new architectures and code to run on Intel hardware that will be used on Aurora, as well as hardware from other vendors.

“Part of the R&D we do with our partner Intel is to make sure the hardware does what we expect it to do and does it efficiently,” says Childers. “Having a machine like Aurora will give us lots of computing power and lots of nodes to effectively reduce solution time, especially when we move to the upgraded LHC.”

The solution is an answer to a fundamental question: is there more beyond the standard model? — and one that could have repercussions unimaginable a hundred years from now, Hopkins notes.

“Basic research can give us knowledge that can lead to societal transformation, but if we don’t do research, it won’t lead anywhere,” he says.

The ALCF is a DOE Office of Science user facility.

Funding for this project was provided by the DOE Office of Science: Offices of High Energy Physics and Advanced Scientific Computing Research. ATLAS is an international collaboration supported by the DOE.

About the ALCF

The Argonne Leadership Computing Facility provides supercomputing capabilities to the scientific and engineering community to advance fundamental discovery and understanding across a wide range of disciplines. Supported by the Advanced Scientific Computing Research (ASCR) program of the U.S. Department of Energy’s (DOE) Office of Science, the ALCF is one of two DOE advanced computing facilities dedicated to open science.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts cutting-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state, and municipal agencies to help them solve their specific problems, advance American scientific leadership, and prepare the nation for a better future. With employees in more than 60 countries, Argonne is managed by UChicago Argonne, LLC for the US Department of Energy’s Office of Science.

The U.S. Department of Energy’s Office of Science is the largest supporter of basic physical science research in the United States and works to address some of the most pressing challenges of our time. For more information, visit https://​ener​gy​.gov/​s​c​ience.

Click here to find out more.


Source: JOHN SPIZZIRRI, ALCF

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Muons don’t fit the standard model of particle physics https://polkinghorne.org/muons-dont-fit-the-standard-model-of-particle-physics/ Fri, 16 Apr 2021 07:00:00 +0000 https://polkinghorne.org/muons-dont-fit-the-standard-model-of-particle-physics/ Share this Item You are free to share this article under the Attribution 4.0 International License. Fundamental particles called muons behave in ways that scientists’ best theory to date, the Standard Model of particle physics, does not predict, the researchers report. The discovery comes from early results from the Muon g-2 experiment at the US […]]]>

Fundamental particles called muons behave in ways that scientists’ best theory to date, the Standard Model of particle physics, does not predict, the researchers report.

The discovery comes from early results from the Muon g-2 experiment at the US Department of Energy’s Fermi National Accelerator Laboratory.

“This experience is a bit like a detective novel.”

This historic result confirms a discrepancy that has plagued researchers for decades.

The strong evidence that muons deviate from the Standard Model calculation could hint at some exciting new physics. The muons in this experiment act as a window into the subatomic world and could interact with as yet unknown particles or forces.

“This experiment is a bit like a detective novel,” says team member David Hertzog, a University of Washington physics professor and founding spokesperson for the experiment. “We analyzed data from the inaugural Muon g-2 test at Fermilab and discovered that the Standard Model alone cannot explain what we found. Something else, perhaps beyond the standard model, may be required. »

A muon is about 200 times more massive than its cousin the electron. They occur naturally when cosmic rays hit the Earth’s atmosphere. Fermilab’s particle accelerators can produce large numbers of them. Like electrons, muons act as if they have a small internal magnet. In a strong magnetic field, the direction of the muon magnet precedes, or “wobbles,” much like the axis of a spinning top. The strength of the internal magnet determines the muon’s precession rate in an external magnetic field and is described by a number known as the g-factor. This number can be calculated with ultra-high precision.

As muons flow through the Muon g-2 magnet, they also interact with a “quantum foam” of subatomic particles that appear and disappear. Interactions with these short-lived particles affect the value of the g-factor, causing muon precession to accelerate or slightly slow down. The standard model predicts with great accuracy what the value of this “abnormal magnetic moment” should be. But if the quantum foam contains additional forces or particles not accounted for by the Standard Model, it would further alter the g-factor of the muon.

Hertzog, then at the University of Illinois, was a lead scientist in the previous experiment at Brookhaven National Laboratory. This attempt ended in 2001 and offered clues that the behavior of the muon did not conform to the Standard Model. The new measurement from the Muon g-2 experiment at Fermilab strongly agrees with the value found at Brookhaven and deviates from theory with the most accurate measurement to date.

The accepted theoretical values ​​for the muon are:

  • g-factor: 2.00233183620(86)
  • abnormal magnetic moment: 0.00116591810(43)

The new experimental global mean results announced today by the Muon g-2 collaboration are:

  • g-factor: 2.00233184122(82)
  • abnormal magnetic moment: 0.00116592061(41)

The combined results from Fermilab and Brookhaven show a difference with theoretical predictions at a significance of 4.2 sigma, a little short of the 5 sigma – or 5 standard deviations – that scientists prefer as a claim of discovery. But it’s still compelling evidence of new physics. The probability that the results are a statistical fluctuation is approximately 1 in 40,000.

“This result from the first run of the Fermilab Muon g-2 experiment is arguably the most anticipated result in particle physics in recent years,” says Martin Hoferichter, assistant professor at the University of Bern and member of the theoretical collaboration that predicts the value of the standard model. “After almost a decade, it’s great to see this massive effort finally come to fruition.”

The Fermilab experiment, which is underway, reuses the main component of the Brookhaven experiment, a superconducting magnetic storage ring 50 feet in diameter. In 2013, it was transported 3,200 miles by land and sea from Long Island to suburban Chicago, where scientists were able to take advantage of Fermilab’s particle accelerator and produce the states’ most intense muon beam. -United. Over the next four years, researchers mounted the experiment; tuned and calibrated an incredibly uniform magnetic field; developed new techniques, instruments and simulations; and thoroughly tested the entire system.

The Muon g-2 experiment sends a beam of muons into the storage ring, where they circulate thousands of times at near the speed of light. Detectors lining the ring allow scientists to determine how fast muons “wobble”.

Many Fermilab sensors and detectors have been built at the University of Washington, such as instruments to measure the muon beam as it enters the storage ring and to detect the telltale particles that appear when the muons decay . Dozens of scientists – including professors, postdoctoral researchers, technicians, graduate students and undergraduates – worked to assemble these sensitive instruments, then set them up and monitor them at Fermilab.

“The outlook for the new result has triggered a coordinated theoretical effort to provide our experimental colleagues with a robust and consensus prediction of the Standard Model,” says Hoferichter. “Future runs will motivate further refinements, to enable a conclusive statement whether physics beyond the Standard Model lurks in the muon’s anomalous magnetic moment.”

In its first year of operation, 2018, the Fermilab experiment collected more data than all previous muon g-factor experiments combined. The Muon g-2 collaboration has now completed the analysis of the movement of more than 8 billion muons from this first period.

Analysis of data from the second and third cycles of the experiment is in progress; the fourth is in progress and a fifth is planned. Combining the results from all five tests will give scientists an even more precise measurement of the muon’s ‘wobble’, revealing with greater certainty whether new physics is lurking in the quantum foam.

“So far, we’ve analyzed less than 6% of the data the experiment will eventually collect,” says Fermilab scientist Chris Polly, who is a co-spokesperson for the current experiment and was a graduate student. of the University of Illinois under Hertzog during the Brookhaven Experiment. “While these early results tell us there is an intriguing difference to the standard model, we will learn much more over the next two years.”

“With these exciting results, our team, especially our students, are excited to push hard on analyzing the remaining data and taking future data to achieve our ultimate goal of accuracy,” says Peter Kammel, research professor of physics at the University of Washington.

An article on the research appears in Physical examination letters. Hertzog will present the findings at a University of Washington Physics Department Symposium on April 12.

The Muon g-2 experiment is an international collaboration between Fermilab in Illinois and more than 200 scientists from 35 institutions in seven countries.

Source: University of Washington

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New muon measurements could rewrite particle physics | Smart News https://polkinghorne.org/new-muon-measurements-could-rewrite-particle-physics-smart-news/ Fri, 09 Apr 2021 07:00:00 +0000 https://polkinghorne.org/new-muon-measurements-could-rewrite-particle-physics-smart-news/ The 50-foot-wide hippodrome used to study muons traveled by barge around Florida and Mississippi, then by truck through Illinois. Reidar Hahn, Fermilab About 50 years ago, physicists came up with a rulebook to describe how fundamental particles interact to create the world as we know it. Since then, researchers have pushed this theoretical framework, called […]]]>

The 50-foot-wide hippodrome used to study muons traveled by barge around Florida and Mississippi, then by truck through Illinois.
Reidar Hahn, Fermilab

About 50 years ago, physicists came up with a rulebook to describe how fundamental particles interact to create the world as we know it. Since then, researchers have pushed this theoretical framework, called the Standard Model, to its limits in order to study its imperfections.

Today, the results of two particle physics experiments come close to uncovering a gap in the Standard Model.

The experiments focused on muons, which are similar to electrons. Both have electric charge and spin, causing them to oscillate in a magnetic field. But muons are more than 200 times larger than electrons, and they split into electrons and another particle, neutrinos, in 2.2 millionths of a second. Luckily, that’s just enough time to collect accurate measurements, with the right equipment, like a 50-foot-wide magnetic circuit.

Physicist Chris Polly of the Fermi National Accelerator Laboratory presented a graph at a seminar and press conference last week that showed a discrepancy between the theoretical calculation and actual measurements of muons moving through the racetrack.

“We can say with pretty high confidence that there has to be something contributing to that white space,” Polly said at the press conference, according to Dennis Overbye at the New York Times. “What monsters could be hiding there?”

The Standard Model aims to describe everything in the universe in terms of its fundamental particles, like electrons and muons, and its fundamental forces. The model predicted the existence of the Higgs boson particle, which was discovered in 2012. But physicists know that the model is incomplete: it takes into account three fundamental forces, but not gravity, for example.

A disconnect between theory and experimental results could help researchers uncover hidden physics and extend the Standard Model to more fully explain the universe.

“New particles, new physics could be just beyond our search,” Wayne State University particle physicist Alexey Petrov tells The Associated Press’ Seth Borenstein. “It’s tantalizing.”

The Standard Model requires such complex calculations that it took a team of 132 theoretical physicists, led by Aida El-Khadra, to come up with its prediction for the muon oscillation in the Fermi Lab experiment. The calculations predicted an oscillation lower than that measured by the Fermilab experiment.

This week’s results closely follow new findings from the Large Hadron Collider. Last month, LHC researchers showed a startling rate of particles left over after breaking up high-speed muons.

“The LHC, if you will, is almost like crashing two Swiss watches against each other at high speed. The debris comes out and you try to piece together what’s inside,” University of Manchester physicist Mark Lancaster, who worked on the Fermilab experiments, tells Michael Greshko at National geographic. At Fermilab, “we have a Swiss watch, and we look at it very, very, very, very carefully and precisely, to see if it does what we expect it to do. »

The Fermilab group used the same 50-foot-wide ring that was first used in the 2001 muon experiments. The researchers shoot a particle beam into the ring, where the particles are exposed to magnets superconductors. The beam particles decay into several other particles, including muons. Then those muons swirl around the racetrack several times before decaying, giving physicists a chance to measure how they interact with the magnetic field, writes Daniel Garisto for American Scientist.

To avoid bias, the instruments the researchers used to measure muons gave encrypted results. The key – a number written on a piece of paper and hidden in two offices at Fermilab and the University of Washington – remained secret until a virtual meeting in late February. When the key was entered into the spreadsheet, the results became clear: the experiment did not match the theory.

“We were all really ecstatic, excited, but also shocked, because deep down I think we’re all a bit pessimistic,” Fermilab physicist Jessica Esquivel tells National geographic.

If the results hold as more data from the experiment emerges, they would upend “every other calculation made” in the field of particle physics, says David Kaplan, a theoretical physicist at Johns Hopkins University. , to the Associated Press.

Freya Blekman, a physicist from the Free University of Brussels, who did not take part in the work, says National geographic that the work “is Nobel-worthy, no doubt,” if it holds up.

Results to date should be published in journals Physical examination letters, A&B physical examination, Physical examination A and physical examination d. These results come from only six percent of the data that the Fermilab experiment expects to collect. Between this six percent and the experimental results from 2001, there is a one in 40,000 chance that the difference between theory and experiment is in error.

“It’s strong evidence that the muon is sensitive to something that’s not in our best theory,” says University of Kentucky physicist Renee Fatemi. New York Times.

But particle physics demands that researchers bring that down to a one in 3.5 million chance. The research team could have the final results by the end of 2023.

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Intriguing new results from the CERN Challenge Standard Model for Particle Physics | Physics https://polkinghorne.org/intriguing-new-results-from-the-cern-challenge-standard-model-for-particle-physics-physics/ Tue, 23 Mar 2021 07:00:00 +0000 https://polkinghorne.org/intriguing-new-results-from-the-cern-challenge-standard-model-for-particle-physics-physics/ The Standard Model of particle physics currently provides our best description of fundamental particles and their interactions. New results from CERN’s LHCb (Large Hadron Collider beauty) collaboration suggest that the particles are not behaving as they should according to the Standard Model. The disintegration of a B0 meson in a K0 and an electron-positron pair […]]]>

The Standard Model of particle physics currently provides our best description of fundamental particles and their interactions. New results from CERN’s LHCb (Large Hadron Collider beauty) collaboration suggest that the particles are not behaving as they should according to the Standard Model.

The disintegration of a B0 meson in a K0 and an electron-positron pair in the LHCb detector, which is used for a sensitive test of lepton universality in the Standard Model. Image credit: CERN.

The Standard Model of particle physics provides accurate predictions for the properties and interactions of fundamental particles, which have been confirmed by numerous experiments since the model’s inception in the 1960s.

However, it is clear that the standard model is incomplete. The model is unable to explain cosmological observations of the dominance of matter over antimatter, the apparent dark matter content of the Universe, or to explain observed patterns in particle interaction forces.

So particle physicists have been looking for the “new physics” — the new particles and interactions that can explain the shortcomings of the Standard Model.

“We were actually shaking when we first looked at the results, we were so excited. Our hearts beat a little faster,” said Dr Mitesh Patel, a physicist at Imperial College London and a member of the LHCb collaboration.

“It’s too early to tell if this is truly a departure from the Standard Model, but the potential implications are such that these results are the most exciting thing I’ve done in 20 years in the field. . It’s been a long road to get here. »

The measurement made by the LHCb team compares two types of beauty quark decays.

The first decay involves the electron and the second the muon, another elementary particle similar to the electron but about 200 times heavier.

Electron and muon, along with a third particle called tau, are types of leptons and the difference between them is called flavors.

The Standard Model predicts that decays involving different lepton flavors should occur with the same probability, a characteristic known as lepton flavor universality which is usually measured by the ratio of decay probabilities. In the Standard Model of particle physics, the ratio should be very close to one.

The new results show signs of a deviation from one: the statistical significance of the result is 3.1 standard deviations, implying a probability of about 0.1% that the data is consistent with the predictions of the standard model.

“If a violation of lepton flavor universality were to be confirmed, it would require a new physical process, such as the existence of new fundamental particles or interactions,” said Professor Chris Parkes, a physicist at the University of Manchester and at CERN and spokesperson. of the LHCb Collaboration.

“Further studies on related processes are underway using existing LHCb data. We’ll be happy to see if they bolster the intriguing clues in the current results.

The discrepancy presented today is consistent with a pattern of anomalies measured in similar processes by LHCb and other experiments around the world over the past decade.

The new results determine the ratio of decay probabilities with greater precision than previous measurements and use for the first time all the data collected by the LHCb detector so far.

“These new results offer tantalizing clues to the presence of a new fundamental particle or force that interacts differently with these different types of particles,” said Dr Paula Alvarez Cartelle, a physicist at the Cavendish Laboratory, based at the University of Cambridge. , and a member of the LHCb Collaboration.

“The more data we have, the stronger this result has become. This measurement is the most significant of a series of LHCb results from the last decade that all seem to agree – and could all point to a common explanation.

“The results did not change, but their uncertainties decreased, increasing our ability to see possible differences with the Standard Model.”

“Discovering a new force in nature is the holy grail of particle physics,” added Dr Konstantinos Petridis, physicist at the University of Bristol and member of the LHCb collaboration.

“Our current understanding of the constituents of the Universe is remarkably insufficient – we don’t know what 95% of the Universe is made of or why there is such a great imbalance between matter and anti-matter.”

“The discovery of a new fundamental force or particle, as evidence for differences in these measurements suggests, could provide the breakthrough needed to begin answering these fundamental questions.”

“This result will certainly make the hearts of physicists beat a little faster today,” said Dr. Harry Cliff, physicist at the Cavendish Laboratory and member of the LHCb collaboration.

“We’re going to have a terribly exciting few years as we try to figure out if we’ve finally glimpsed something entirely new.”

“It is now up to the LHCb collaboration to further verify its results by gathering and analyzing more data, to see if there is any evidence left for some new phenomena.”

The results have been submitted for publication in the journal Natural Physics.

_____

R.Aaij et al. (LHCb collaboration). 2021. Lepton Universality Test in Beauty Quark Decays. Natural Physics, submitted for publication; arXiv: 2103.11769

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