standard model – Polkinghorne http://polkinghorne.org/ Fri, 11 Mar 2022 06:23:39 +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 standard model – Polkinghorne http://polkinghorne.org/ 32 32 Lancaster receives £2.9m for particle physics research https://polkinghorne.org/lancaster-receives-2-9m-for-particle-physics-research/ Thu, 10 Mar 2022 13:14:00 +0000 https://polkinghorne.org/lancaster-receives-2-9m-for-particle-physics-research/ Lancaster University has received £2.9 million from the Science and Technology Facilities Council (STFC) as part of its ongoing support for the particle physics research community in the UK. This funding helps keep the UK at the forefront of answering some of the most important and complex scientific questions and supports the next generation of […]]]>

Lancaster University has received £2.9 million from the Science and Technology Facilities Council (STFC) as part of its ongoing support for the particle physics research community in the UK.

This funding helps keep the UK at the forefront of answering some of the most important and complex scientific questions and supports the next generation of UK particle physicists.

The funding will allow the Experimental Particle Physics Group at Lancaster to continue its world-class research to study phenomena in particle physics with a focus on determining the dominance of matter over antimatter in the Universe, precise measurements of the best current theoretical description of particle physics. (the “standard model”) as well as theories that go beyond this theory.

The program uses facilities around the world including CERN (Switzerland/France), Fermilab (USA), JPARC (Japan) and SNOLab (Canada) and the group participates in and leads many activities at CERN (ATLAS and NA62 ) and neutrino ( DUNE, T2K, HK, MicroBooNE, SBND).

Professor Roger Jones of Lancaster University said: “At a time of very tight budgets, we are pleased to have increased our grant support and will be able to continue a broad and exciting program addressing the fundamental questions of particle physics.

Particle physics studies the world at the smallest possible distance scales and at the highest attainable energies, seeking answers to fundamental questions about the structure of matter and the composition of the Universe.

Ten years after British researchers contributed to the Nobel Prize-winning detection of the Higgs boson, some of the questions the community is struggling to answer include:

  • What is the Universe made of and why?
  • What is the underlying nature of neutrinos?
  • Why is there an imbalance between matter and antimatter in the Universe?
  • How to detect dark matter?
  • Are there any new particles or particle interactions we can find?

Professor Grahame Blair, Executive Director of Programs at STFC, said:

“The STFC continues to support the experimental particle physics community in the UK by answering fundamental questions about our Universe.

“Grants are essential to support technicians, engineers and academics in their skills and expertise in the field, while encouraging career development in basic research with universities and international collaborators.

“This investment supports the UK physics community and enables the UK to continue to lead the field of experimental particle physics.”

/Public release. This material from the original organization/authors may be ad hoc in nature, edited for clarity, style and length. The views and opinions expressed are those of the author or authors. See in full here.

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Some thoughts on the Standard Model of Particle Physics – Kashmir Reader https://polkinghorne.org/some-thoughts-on-the-standard-model-of-particle-physics-kashmir-reader/ Sat, 05 Feb 2022 19:58:00 +0000 https://polkinghorne.org/some-thoughts-on-the-standard-model-of-particle-physics-kashmir-reader/ It doesn’t answer the most fundamental mystery: what constitutes the dark energy and dark matter that make up the majority of our universe? The Standard Model became the fundamental model of elementary particle physics in the second half of the 20th century. It is considered today as the best description of the constituent elements of […]]]>

It doesn’t answer the most fundamental mystery: what constitutes the dark energy and dark matter that make up the majority of our universe?

The Standard Model became the fundamental model of elementary particle physics in the second half of the 20th century. It is considered today as the best description of the constituent elements of the universe. It explains how quarks (which form protons and neutrons) and leptons (electrons, etc.) make up all known matter. It is also an explanation of how quarks and leptons are influenced by the exchange of intermediate force carriers. It describes three of the four fundamental interactions that sum up the structure of matter up to the measurement of 10 high at -18 meter. It is in short a quantum theory of three basic theories of electromagnetic interaction, strong interaction and weak interaction. The development of the Standard Model has been led by a large number of experimental and theoretical physicists alike. The structure or mathematical framework of the Standard Model is provided by quantum field theory
According to the standard model, all matter is made up of three types of elementary particles: leptons, quarks and their mediators. There are six leptons divided into three generations. There are also six anti-leptons, so the total number of leptons is 12. Similarly, the number of quarks is six, each of which comes in three colors (this color bears no resemblance to the concept of color in our daily life), which represents 36 quarks in total, including the antiquarks. Quarks like leptons have three generations. Finally, for each interaction, we have a mediator. The carrier of the electromagnetic interaction is a massless photon while the carriers of the weak interaction are called intermediate vector bosons, which are two charged Ws and a neutral heavy Z. Finally, for the strong interaction exchange, we have 8 gluons.
The missing link of the Standard Model, the Higgs boson theoretically predicted by Peter Higgs in the early 1960s, which explains the mass of elementary particles via the Higgs mechanism, involving chiral symmetry breaking, was discovered in 2012 at Large Hadron Collider in Geneva, Switzerland. The marvelous achievement of the Standard Model can be measured by the simple fact that it has led to more than 50 Nobel Prizes in Physics so far.
Loopholes:
Even though the Standard Model is currently the best description we have of the subatomic world, but despite its robust predictions, there is a consensus among physicists that the Standard Model is neither complete nor the final theory. “There is a certain degree of ugliness in the standard model,” says Steve Weinberg, one of its main architects. First, the standard model is completely silent about dark energy and dark matter. This does not answer the question of what constitutes the dark energy and dark matter that make up the majority of matter in our universe. Second, it fails to explain neutrino oscillations and, more importantly, it fails to incorporate one of the most fundamental interactions, gravity, which explains the large-scale structure of the universe. At a more fundamental level, he fails to explain why there are precisely three generations of quarks and leptons. Likewise, the difference in masses of the elementary particles that they acquire due to their interaction with the Higgs field via the Higgs boson remains a mystery.
Possible output:
In order to accommodate many of the shortcomings of the Standard Model listed above, physicists over time have come up with different theories and approaches. All of these theories and approaches fall under the category “Physics Beyond the Standard Model”. Theories that lie beyond the Standard Model include the various extensions of supersymmetry and entirely new explanations and theories such as string theory, looping quantum gravity, and extra dimensions. But the theory that has gained most prominence among them is string theory. String theory has captured the imagination of a generation of particle physicists over the past 40 years. String theory not only promises the reconciliation of quantum mechanics with Einstein’s general relativity and eliminates the infinities that plague quantum field theory, it also provides a unified theory of everything from which all elementary particle physics , including gravity, would emerge as an inevitable consequence. But the bottleneck of particle physics, as string theorist and Nobel laureate David Gross puts it, is experimental, not theoretical, so in the absence of experimental evidence to back up his predictions, the future of string theory seems grim, or at least you have to cross your fingers. If string theory lives up to expectations, which seems unlikely, it will be the ultimate triumph of the human spirit.

—The author is a physics student
[email protected]





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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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Wobbling in the history of particle physics – now. Powered by Northrop Grumman https://polkinghorne.org/wobbling-in-the-history-of-particle-physics-now-powered-by-northrop-grumman/ Mon, 18 Oct 2021 07:00:00 +0000 https://polkinghorne.org/wobbling-in-the-history-of-particle-physics-now-powered-by-northrop-grumman/ Particle physics is the quest to discover the fundamental components of the universe by analyzing, cataloging and measuring the particles that combine to create everything. It’s no easy task – the variety and variability of these physical firmaments makes them an ever-changing puzzle that can seem completely impenetrable until a new secret is unlocked. Now, […]]]>

Particle physics is the quest to discover the fundamental components of the universe by analyzing, cataloging and measuring the particles that combine to create everything. It’s no easy task – the variety and variability of these physical firmaments makes them an ever-changing puzzle that can seem completely impenetrable until a new secret is unlocked.

Now, new research on the muon – a small electron-like particle 200 times heavier than its negatively charged cousin – could pave the way for the particle’s next pivot: oscillations.

Standard operation procedure

To help make sense of the universe and how it works, scientists created the Standard Model. It was not an easy task either. As SciTechDaily notes, while the electron was discovered in 1897, the last element in the current framework – the Higgs boson – wasn’t confirmed until 2012.

The model makes it possible to reconcile three of the four fundamental forces: electromagnetism, the strong nuclear force and the weak nuclear force. It also highlights the role of quarks and leptons as the building blocks of all matter, including the familiar trio of protons, neutrons and electrons. Work on the Standard Model has shown that photons play a role in the transport of electromagnetism, while the strong force relies on gluons to ensure the stability of atomic nuclei and the weak force exploits W and Z bosons. to drive the powerful nuclear processes that keep stars burning for billions of years. year.

However, despite its usefulness, the standard model has a blind spot: gravity. While the model does an excellent job of describing which particles underlie the other three fundamental forces, gravity is conspicuously absent. This is because scientists have never been able to link a specific particle to the creation and distribution of gravity. While it plays a vital role in the workings of our universe – whether it’s counteracting the expansive tendencies of nuclear reactions within our sun or keeping our feet firmly planted on planet Earth – this apparently appealing operation simple has historically resisted deep understanding.

But new muon measurements could change all that.

Crack the code

What is important to remember from scientists – and particle physicists in particular – is that they are never satisfied with the status quo. Although the Standard Model provides a starting point for understanding the universe, obvious shortcomings in the current framework mean there is still work to be done. In practice, this work involves finding new approaches to potentially breaking the model by conducting experiments, taking measurements, and then comparing the results to what the model predicts.

The challenge? For years, the model has found the right answers, much to the frustration of physicists who know something is missing. Repeated experiments using different particle approaches have produced precise measurement after precise measurement – ​​so far. Recent follow-up work on earlier muon experiments using more advanced equipment suggests a crack in the current model and raises hope that scientists may finally have found the key to a new revolution in particle physics.

Meet the muon

So what exactly is a muon? Think electron, but heavier. Much heavier – 200 times heavier, in fact. As Science Daily notes, muons and electrons “are essentially tiny magnets with their own magnetic field.” However, unlike electrons, muons are much less stable, existing only a few millionths of a second before decaying. It is also difficult to observe muons, even during their brief stay here, because the vacuum they occupy is not empty.

“It’s your cappuccino-foam version of a vacuum, where there are virtual particles appearing and disappearing all the time,” Lawrence Gibbons, who led the Cornell team involved in the new research, told Science Daily. “And that turns out to affect the strength of a muon’s magnetic field.”

Through work at CERN in 1959, followed by more precise experiments in 1966 and 1969, and then another round at Brookhaven National Laboratory in 1999, the researchers finally found something: a disconnect between the observed magnetic measurements and predicted when the muons made their way into this void. New efforts at Fermilab with more precise and advanced equipment have confirmed these findings – and could pave the way for a much more massive muon impact.

Let’s Get Physics-al

Work at CERN, Brookhaven and Fermilab all focus on the same thing: the g-2 value of the muon, which represents the amount it “wobbles” via vacuum interactions. As Jessica Esquivel, a particle physicist at Fermilab, notes, this oscillation is called the precession frequency.

“When muons enter a magnetic field, they precess or spin like a top,” she told Vox.

To measure precession, efforts at Fermilab used a powerful particle accelerator – capable of creating 20 times more muons than those previously used at CERN – to shoot an intense beam of muons into highly sensitive detectors, which measured their precession frequency. As the Standard Model predicts, this precession occurs when muons collide with virtual particles, which Esquivel describes as “a kind of ghosting of real particles.”

“We have photons going in and out and they’re just kind of like there, but not really there,” she told Vox. However, despite this recurring strangeness, these virtual particles have a physical impact on muon oscillations.

But this is where it gets really weird: Experiments at Fermilab confirm that muons flicker more than they should, according to the Standard Model. Even more exciting? Scientists don’t know why.

Stumbling our way forward

The lack of certainty here is what makes these experimental results so interesting. According to the Standard Model, g-2 muon values ​​are explainable using actual particle interactions and should produce predictable results. However, Fermilab’s efforts suggest that something else is causing this additional oscillation – something outside the current functional framework, as Esquivel and his colleagues told Vox.

And while there have been discussions about this “breaking” of the Standard Model before, it’s more about filling in the details where the data was clearly missing. Esquivel likens it to adding elements to the periodic table.

“Even back then,” she tells Vox, “they had places where they knew an item had to go, but they hadn’t been able to see it yet. That’s basically where we are now. In practice, this movement of muons opens the door to a multitude of potential operations on the particles.This unexpected oscillation could be caused by an interaction with dark matter or long-predicted dark energy particles, or it could help establish a particle-based link with the peripheral fourth fundamental gravitational force.

Esquivel simply explains the impact of this measurement of movement: “It’s once in a lifetime. We are looking for new physics and we are so close that we can taste it. A meal of muons, an extra oscillation – it happens!

Being at the forefront of change, especially in space, physics and engineering, has been part of the Northrop Grumman culture for generations. Click here to search for jobs in these areas of scientific innovation.

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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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A physics experiment may have uncovered the mysterious force behind the expansion of the universe https://polkinghorne.org/a-physics-experiment-may-have-uncovered-the-mysterious-force-behind-the-expansion-of-the-universe/ Mon, 27 Sep 2021 07:00:00 +0000 https://polkinghorne.org/a-physics-experiment-may-have-uncovered-the-mysterious-force-behind-the-expansion-of-the-universe/ Representative image. | Photo credit: iStock Images What the universe is made up of at the most fundamental levels is a question that continues to both fascinate and frustrate scientists. The discovery of atoms, once thought to be nature’s smallest building blocks, paved the way for further study of subatomic particles such as electrons, protons […]]]>

Representative image. | Photo credit: iStock Images

What the universe is made up of at the most fundamental levels is a question that continues to both fascinate and frustrate scientists. The discovery of atoms, once thought to be nature’s smallest building blocks, paved the way for further study of subatomic particles such as electrons, protons and neutrons, which were found to be themselves made of particles. even smaller.

As our understanding of these particles grew, the Standard Model of particle physics was born. But after looking around the universe and measuring how widely galaxies are distributed and interact with each other, we soon realized that everything described in the Standard Model was only 5% of the matter in the universe.

What is the rest made up of, you ask? Well, we don’t really know, but about 27% of the universe, scientists are convinced, appears to be made up of something called dark matter – matter that doesn’t reflect any light but behaves similarly to normal matter. , exerting a force of gravity on everything around it.

As for the elements that make up the remaining 68% of the universe, our first clue came in the 1990s when scientists discovered that distant supernovae were fainter than their models had predicted. As more and more evidence came in, a new form of energy was theorized, one that exhibits properties that no other type of matter or radiation possesses – dark energy.

There’s next to nothing we can truly determine about the true nature of dark energy, but the measurements reveal one thing: it is remarkably uniform and constant across the universe, behaving fundamentally differently than other types of energy. energy.

It seems to be driving the expansion of the universe but, curiously, even as the volume of the universe increases, the energy density (of dark energy) remains constant. It is almost as if there is something uniformly present in space, the nature of which does not depend on anything residing in space. This prompted scientists to understand that dark energy could be a vast field that pervades the entire universe or even an inherent feature of spacetime itself.

A less explored theory though is that dark energy could be made up of particles we haven’t yet discovered, and that’s where the XENON1T experiment comes in. The XENON series of experiments were originally intended to search for theoretical dark matter particles that scientists call WIMPs. (massive particles interacting weakly).

Thousands of feet below Italy’s Gran Sasso mountain is a sensor-lined tank of 3.2 metric tons of pure xenon (chemically inert), forming a detector of unknown particles that can fly through the tank, causing ripples. The idea is that as these WIMPs move through xenon, they may occasionally hit a xenon nucleus, causing a brief flash of light that could be detected – what is called nuclear recoil.

But after years of not detecting nuclear recoil, scientists realized they could recalibrate their detector to look for electron recoil – phenomena where unknown particles collide with electrons rather than nuclei. of xenon. The researchers studied the first year’s worth of XENON1T data expecting to find 232 such setbacks – all caused by background contamination. But the experiment gave 285 – an excess of 53. It was confusing. What were these additional signals?

These findings have now led scientists to formulate three theories. The first of these – and obviously the most mundane – is that the result was an experimental hazard likely to wither away with improved accuracy and stats. The second is that some sort of unaccounted background contamination – possibly tritium in the water – may be causing these excess electron recoils.

The third, of which scientists say they are 95% certain, is the first-ever detection of an unknown type of dark energy particle that would require contortions of current particle physics theory. It’s clearly the most exotic of the three theories, but it may draw attention to a particular idea known as chameleon dark energy – a notion of a particle whose density is obscured in regions of the matter-rich spaces, but more noticeable in emptier regions. .

At the moment, however, this is only conjecture. A 95% confidence interval in physics is, after all, far from sufficient, and it is entirely possible that as the experimental framework refines, these findings may never happen again. But if substantiated, it would represent a giant step towards answering one of the greatest existential questions that have plagued humanity.

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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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