theoretical physics – Polkinghorne http://polkinghorne.org/ Mon, 07 Mar 2022 02:18:05 +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 theoretical physics – Polkinghorne http://polkinghorne.org/ 32 32 Particle physics experiment may have directly observed dark energy https://polkinghorne.org/particle-physics-experiment-may-have-directly-observed-dark-energy/ Fri, 29 Oct 2021 16:09:08 +0000 https://polkinghorne.org/particle-physics-experiment-may-have-directly-observed-dark-energy/ About 25 years ago, astrophysicists noticed something very interesting about the Universe. The fact that it was expanding had been known since the 1920s, thanks to the observation of Edwin Hubble. But thanks to the observations that astronomers made with the space observatory that bore his name (the The Hubble Space Telescope), they began to […]]]>

About 25 years ago, astrophysicists noticed something very interesting about the Universe. The fact that it was expanding had been known since the 1920s, thanks to the observation of Edwin Hubble. But thanks to the observations that astronomers made with the space observatory that bore his name (the The Hubble Space Telescope), they began to notice how the rate of cosmic expansion was accelerating!

This led to the theory that the Universe is filled with an invisible and mysterious force, known as dark energy (DE). Decades after its proposal, scientists are still trying to pin down this elusive force that accounts for about 70% of the Universe’s energy budget. According to a recent study by an international team of researchers, the XENON1T experiment may have already detected this elusive force, opening new possibilities for future ED research.

The research was led by Dr Sunny Vagnozzi, a researcher at the Kavli Institute of Cosmology (KICC) at the University of Cambridge, and Dr Luca Visinelli, a Fellowship for Innovation (FELLINI) researcher (who is maintained with the support of the Marie Bourse Sklodowska-Curie) at the National Institute of Nuclear Physics (INFN) in Frascati, Italy. They were joined by researchers from the Institute for Theoretical Physics (IPhT), the University of Cambridge and the University of Hawaii.

Both DM and DE are part of the Lambda Cold Dark Matter (LCDM) model of cosmology, which posits that the Universe is filled with cold, slow-moving (DM) particles that interact with normal matter via the force of gravity alone. Lambda represents DE, which is accelerating the expansion of the Universe. Since they are only discerned by observing their effect on the large-scale structure of the Universe, conventional thought holds that none of the forces interact with normal matter via electromagnetism or the weak or strong nuclear force. .

However, some DM theories posit that there is some level of interaction with visible matter, which researchers are actively testing. However, instead of more test results, astrophysicists and cosmologists still don’t know how DE fits into the physical laws that govern the Universe. Candidates so far include a modification of Einstein’s general relativity (GR), the presence of a new field, or a cosmological constant (CC). As Dr. Visinelli told Universe Today via email:

“For this reason, dark energy is perhaps even more mysterious than dark matter. We are seeing the effects of dark energy across a number of observations, starting with the seminal work on 1A supernovae in as standard candles. Assuming that dark energy is indeed a field, the quanta associated with it would be extremely light and carry very little energy. This is the reason why very little work has been done on this type of searches.

Their work is based on new research that goes beyond the standard LCDM model of cosmology to consider that DE interacts with light by affecting its properties (i.e. polarization, color, direction ). However, these interactions could be subject to screening mechanisms that prevent local experiments from detecting them. In this model, it is predicted that dark energy quanta can be produced in the Sun.

XENON1T detector

The XENON1T detector, shown below. Credit: XENOX Collaboration

As Dr. Vagnozzi explained, the possible connection between screening and dark energy first came to him when he was taking a shower one day:

“I remember it was June 20 and I was taking a shower and thinking about solar axions (without) explaining XENON, and I realized the obvious solution was screening, because that would stop production in the denser stars. Screening is usually associated with patterns of dark energy and/or altered gravity, and there has been the “click”.

“I immediately Whatsapped Luca and we immediately started working on it (and reached out to our other co-authors who are experts in filtered dark energy/modified gravity patterns).”

For the purposes of their study, the team led by Dr. Vagnozzi and Dr. Visinelli reviewed data published by the XENON Collaboration, a DM research team made up of 135 researchers from 22 institutions around the world. At the heart of their experiment is a 3,500 kg (7,715 lb) detector of ultra-radio-pure liquid xenon housed in a 10 m (32.8 ft) tank of water. Located at the INFN Laboratori Nazionali del Gran Sasso, XENON is also the most sensitive dark matter (DM) experiment ever performed.

In 2020, the Collaboration published the results of its experimental campaign (2016 to 2018), which showed an unexpected rate of electronic recoil events. According to the collaboration, this did not constitute a detection of DM but could be explained by a tiny residual quantity of tritium in the experiment, the existence of a new particle (such as the solar axion), or an unexplained property of the neutrinos.

Upper PMT Matrix

The upper PMT network with all the electrical cables. Credit: XENON Dark Matter Project

For the purposes of their study, however, the team led by Vagnozzi and Visinelli speculated that this may have been the first direct detection of DE. Said Vagnozzi:

“In our model, dark energy has special properties: its mass term is related to the density of the environment, so denser materials would shield the effects of dark energy, while denser environments light such as intergalactic space would allow for long range dark energy.

“In this model called the ‘chameleon’, quanta of dark energy are produced in the region of the Sun in which the electromagnetic field is strongest, the tachocline, which is the region in which the transport of energy to the interior of the Sun changes from radiative to convection.The high energy density of the electromagnetic radiation in the region allows a strong coupling with the chameleon field and its production.

If true, this would mean that experiments around the world currently focused on dark matter research could also be devoted to the hunt for dark energy. To that end, Dr. Vagnozzi and Dr. Visinelli hope that this study will spark interest in particle models of ED and that the search for these elusive particles can be conducted in parallel with ongoing DM research. At the very least, these experiments will test theories about ED that go beyond the LCDM model, helping scientists narrow down the list of candidates. Says Dr. Visinelli:

“Many other experiments designed for Dark Matter may also contain information about these chameleons, and we hope that the design of future setups for this research will be considered. An independent test using cosmological data crossed with the predictions of the chameleon model would also be necessary. As for us, we plan to refine our paper’s calculations using a solar model, study chameleon production in massive stars, and get in touch with experimentalists for updates.

Illustris dark matter simulation

Illustris simulation, showing the distribution of dark matter in 350 million by 300,000 light-years. Galaxies are represented by high density white dots (left) and normal baryonic matter (right). Credit: Markus Haider/Illustris

In a recent paper, Dr. Vagnozzi and Dr. Visinelli conducted a study to examine whether pure elastic scattering between dark energy and baryonic (aka normal) matter could leave a visible imprint in cosmological observations. They determined that this was not likely, at least when applied to observations sensitive to the linear evolution of cosmic structure, such as the cosmic microwave background (CMB) and large-scale structure clustering. at the linear level.

However, Dr. Vagnozzi also works with a Ph.D. student in Munich to extend this study and predict the implications of DE interaction with normal matter. Specifically, they want to examine the effect this would have on the nonlinear clustering of the large-scale structure of the Universe, as well as the structure of galaxies and galaxy clusters. Coupled with large-scale surveys, which will benefit from next-generation telescopes in the years to come, astronomers and cosmologists could be on the verge of shedding light on the “Dark Universe!”

Originally published on Universe Today.

To learn more about this research, read XENON1T Experiment May Have Detected Dark Energy.

Reference: “Direct Dark Energy Detection: XENON1T Excess and Future Prospects” by Sunny Vagnozzi, Luca Visinelli, Philippe Brax, Anne-Christine Davis and Jeremy Sakstein, September 15, 2021, Physical examination D.
DOI: 10.1103/PhysRevD.104.063023

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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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A particle physics experiment could have directly observed dark energy https://polkinghorne.org/a-particle-physics-experiment-could-have-directly-observed-dark-energy/ Wed, 22 Sep 2021 07:00:00 +0000 https://polkinghorne.org/a-particle-physics-experiment-could-have-directly-observed-dark-energy/ About 25 years ago, astrophysicists noticed something very interesting about the Universe. The fact that it was expanding had been known since the 1920s, thanks to the observation of Edwin Hubble. But thanks to the observations that astronomers made with the space observatory that bore his name (the The Hubble Space Telescope), they began to […]]]>

About 25 years ago, astrophysicists noticed something very interesting about the Universe. The fact that it was expanding had been known since the 1920s, thanks to the observation of Edwin Hubble. But thanks to the observations that astronomers made with the space observatory that bore his name (the The Hubble Space Telescope), they began to notice how the rate of cosmic expansion was accelerating!

This led to the theory that the Universe is filled with an invisible and mysterious force, known as dark energy (DE). Decades after its proposal, scientists are still trying to pin down this elusive force that accounts for about 70% of the Universe’s energy budget. According to a recent study by an international team of researchers, the XENON1T experiment may have already detected this elusive force, opening new possibilities for future ED research.

The research was led by Dr Sunny Vagnozzi, a researcher at the Kavli Institute of Cosmology (KICC) at the University of Cambridge, and Dr Luca Visinelli, a Fellowship for Innovation (FELLINI) researcher (who is maintained with the support of the Marie Bourse Sklodowska-Curie) at the National Institute of Nuclear Physics (INFN) in Frascati, Italy. They were joined by researchers from the Institute for Theoretical Physics (IPhT), the University of Cambridge and the University of Hawaii.

Both DM and DE are part of the Lambda Cold Dark Matter (LCDM) model of cosmology, which posits that the Universe is filled with cold, slow-moving (DM) particles that interact with normal matter via the force of gravity alone. Lambda represents DE, which accelerates the expansion of the Universe. Since they are only discerned by observing their effect on the large-scale structure of the Universe, conventional thought holds that none of the forces interact with normal matter via electromagnetism or the weak or strong nuclear force. .

However, some DM theories posit that there is some level of interaction with visible matter, which researchers are actively testing. However, instead of more test results, astrophysicists and cosmologists still don’t know how DE fits into the physical laws that govern the Universe. Candidates so far include a modification of Einstein’s general relativity (GR), the presence of a new field, or a cosmological constant (CC). As Dr. Visinelli told Universe Today via email:

“For this reason, dark energy is perhaps even more mysterious than dark matter. We are seeing the effects of dark energy across a number of observations, starting with the seminal work on 1A supernovae in as standard candles. Assuming that dark energy is indeed a field, the quanta associated with it would be extremely light and carry very little energy. This is the reason why very little work has been done on this type of searches.

Their work is based on new research that goes beyond the standard LCDM model of cosmology to consider that DE interacts with light by affecting its properties (i.e. polarization, color, direction ). However, these interactions could be subject to screening mechanisms that prevent local experiments from detecting them. In this model, it is predicted that dark energy quanta can be produced in the Sun.

The XENON1T detector, shown below. Credit: XENOX Collaboration.

As Dr. Vagnozzi explained, the possible connection between screening and dark energy first came to him when he was taking a shower one day:

“I remember it was June 20 and I was taking a shower and thinking about solar axions (without) explaining XENON, and I realized the obvious solution was screening, because that would stop production in the denser stars. The screening is usually associated with dark energy and/or altered gravity patterns, and it just clicked.

I immediately WhatsApped Luca and we started working on it immediately (and reached out to our other co-authors who are experts in dark energy/modified gravity patterns).

For the purposes of their study, the team led by Dr. Vagnozzi and Dr. Visinelli reviewed data published by the XENON Collaboration, a DM research team made up of 135 researchers from 22 institutions around the world. At the heart of their experiment is a 3,500 kg (7,715 lb) detector of ultra-radio-pure liquid xenon housed in a 10 m (32.8 ft) tank of water. Located at the INFN Laboratori Nazionali del Gran Sasso, XENON is also the most sensitive dark matter (DM) experiment ever performed.

In 2020, the Collaboration published the results of its experimental campaign (2016 to 2018), which showed an unexpected rate of electronic recoil events. According to the collaboration, this did not constitute a detection of DM but could be explained by a tiny residual quantity of tritium in the experiment, the existence of a new particle (such as the solar axion), or an unexplained property of the neutrinos.

The upper PMT network with all the electrical cables. Credit: XENON Dark Matter Project

However, for the purposes of their study, the team led by Vagnozzi and Visinelli speculated that this may have been the first direct detection of DE. Said Vagnozzi:

“In our model, dark energy has special properties: its mass term is related to the density of the environment, so denser materials would shield the effects of dark energy, while denser environments light such as intergalactic space would allow for long range dark energy.

“In this model called “chameleon”, dark energy quanta are produced in the region of the Sun in which the electromagnetic field is strongest, the tachocline, which is the region in which the transport of energy to the interior of the Sun goes from the radiative transition to the convection.The high energy density of the electromagnetic radiation in the region allows a strong coupling with the chameleon field and its production.

If true, this would mean that experiments around the world currently focused on dark matter research could also be devoted to the hunt for dark energy. To that end, Dr. Vagnozzi and Dr. Visinelli hope that this study will spark interest in particle models of ED and that the search for these elusive particles can be conducted in parallel with ongoing DM research. At the very least, these experiments will test theories about ED that go beyond the LCDM model, helping scientists narrow the list of candidates. Says Dr. Visinelli:

“Many other experiments designed for Dark Matter may also contain information about these chameleons, and we hope that the design of future setups for this research will be considered. An independent test using cosmological data crossed with the predictions of the chameleon model would also be necessary. As for us, we plan to refine our paper’s calculations using a solar model, study chameleon production in massive stars, and get in touch with experimentalists for updates.

Illustris simulation, showing the distribution of dark matter in 350 million by 300,000 light-years. Galaxies are represented by high density white dots (left) and normal baryonic matter (right). Credit: Markus Haider/Illustris

In a recent paper, Dr. Vagnozzi and Dr. Visinelli conducted a study to examine whether pure elastic scattering between dark energy and baryonic (aka normal) matter could leave a visible imprint in cosmological observations. They determined that this was not likely, at least when applied to observations sensitive to the linear evolution of cosmic structure, such as the cosmic microwave background (CMB) and large-scale structure clustering. at the linear level.

However, Dr. Vagnozzi also works with a Ph.D. student in Munich to extend this study and predict the implications of DE interaction with normal matter. Specifically, they want to examine the effect this would have on the nonlinear clustering of the large-scale structure of the Universe, as well as the structure of galaxies and galaxy clusters. Coupled with large-scale surveys, which will benefit from next-generation telescopes in the years to come, astronomers and cosmologists could be on the verge of shedding light on the “dark universe”!

Further reading: physical examination D

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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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Microsoft has helped theoretical physicists explore the implications of our potentially self-taught universe https://polkinghorne.org/microsoft-has-helped-theoretical-physicists-explore-the-implications-of-our-potentially-self-taught-universe/ Fri, 09 Apr 2021 07:00:00 +0000 https://polkinghorne.org/microsoft-has-helped-theoretical-physicists-explore-the-implications-of-our-potentially-self-taught-universe/ Credit: Stephen Brashear/Getty Images for Microsoft Who doesn’t love theoretical physics papers on a Friday? Today, April 9, a voluminous seventy-nine page research paper titled “The self-taught universe” has been uploaded (via tnw). Its authors include physicists from Brown University and the Flatiron Institute. Signing in to Microsoft is simple. According to the article’s acknowledgments […]]]>

Credit: Stephen Brashear/Getty Images for Microsoft

Who doesn’t love theoretical physics papers on a Friday? Today, April 9, a voluminous seventy-nine page research paper titled “The self-taught universe” has been uploaded (via tnw). Its authors include physicists from Brown University and the Flatiron Institute.

Signing in to Microsoft is simple. According to the article’s acknowledgments section, Microsoft provided “computing, logistical, and other general support” for the work that made the article possible. Kevin Scott, Microsoft Chief Technology Officer and Executive Vice President of Technology and Research, received a personal thank you for his support.

So what exactly was Microsoft helping to empower theoretical physicists to write? Well, to put it simply: the theory that our universe is a massive machine that is constantly learning about itself. Just as we humans understand ourselves, our limitations and our abilities more and more as we age, the idea is that the universe is on a similar journey, evolving its own laws as it goes. as he learns more about them.

Pretty crazy, right? Here is a fascinating passage from page sixty-six of the article for your enjoyment, education, and mystification:

The example of memes in human social structures shows that a learning system that is not constrained by “brutal survival” can sometimes become dominated by “economic network effects” in self-reference. It is interesting to consider cosmological criteria other than raw survival that could give rise to self-didactic structures resistant to disconnection with an environment.

This isn’t the first time Microsoft and the idea of ​​memes as a basis for understanding the world have intersected. Far from there-memes were the centerpiece of an interactive virtual philosophy course called Metal Gear Rising: Revengeance, released for Microsoft’s Xbox 360 in 2013. It’s been a while since the impact of memes on our understanding of the universe overlaps with operations from Microsoft, but now, eight years later, it happened again.

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Gravity, particle physics and a “theory of everything” https://polkinghorne.org/gravity-particle-physics-and-a-theory-of-everything/ Tue, 23 Feb 2021 08:00:00 +0000 https://polkinghorne.org/gravity-particle-physics-and-a-theory-of-everything/ For almost a century, physics has been stretched in a tussle between the science of the very big and the indescribably small. For planets and galaxies, gravity is easily noticeable. But in the realm of microparticle interactions, gravity is weak because the size of matter is tiny. Too small, many thought, for it to have […]]]>

For almost a century, physics has been stretched in a tussle between the science of the very big and the indescribably small. For planets and galaxies, gravity is easily noticeable. But in the realm of microparticle interactions, gravity is weak because the size of matter is tiny. Too small, many thought, for it to have a significant role in major cosmic events like particle formation – where electromagnetic and nuclear forces are far more powerful.

However, physicists are rethinking the place of gravity in the building blocks of nature, assigning the cosmic force a small but essential role in explaining how fundamental particles might appear, according to a recent study published in the journal Universe.

Gravitational particle physics

A duo of physicists from the Institute of Gravitation and Cosmology at the Russian Peoples’ Friendship University (RUDN University) revisits the idea of ​​giving gravity a role in the creation of particles. For typical elementary particles (like electrons), the electromagnetic force of attraction is 10^40 times stronger than the attraction of gravity.

From a conventional point of view, including gravity in the description of the behavior of an electron near the nucleus of an atom is like including the effect of a mosquito on a windshield when talking about a car accident.

Either way, study authors Vladimir V. Kassandrov and Ahmed Alharthy suspect the mosquito may be getting more bites than we thought — at least at the disproportionately small level called the Planck scale.

Physicists have used semi-classical models to include gravity

“Gravity can potentially play an important role in the microworld, and this hypothesis is supported by some data,” Kassandrov said in a blog post shared on the RUDN University website.

Surprisingly, the scientific consensus on the solutions of the fundamental equations of field theory in curved spacetime (actually what gravity is) leaves a tiny gap for gravity to have a non-zero influence. As the distances between the particles decrease, the force of gravity becomes comparable to that of the charges attracted.

In some models, the tiny effects of gravity could also enhance solitary waves forming in quantum fields.

The physicist duo used semi-classical models for electromagnetic field equations, replacing equations that typically eliminated gravity and applying ones that left room to change some quantities without affecting others.

Some scenarios have suggested a role for gravity in particle physics

This switch-and-swap method allowed scientists to define the charge and mass of known elementary particles and to search for solutions capable of describing how the particles formed.

Unfortunately, the duo couldn’t find a distinct case where gravity played a necessary role – at least for particles we know exist.

Some scenarios – where the distance between particles was reduced to around 10^-33 meters for charged objects with a mass of 10^-5 grams – showed solutions.

While these parameters may not describe something typically found throughout the universe, the physicists’ response found bounds on a spectrum related to hypothetical semi-quantum particles – known as maximons .

Fusion of hypothetical cases in physics

Although hypothetical overlaps may seem far-fetched, this represents a major achievement in theoretical physics. Often in science – which is based on empirical observation – we know nothing of new phenomena until we witness them. This is not the case for theoretical physics. Einstein’s theory of gravity predicted the existence of black holes, which no one had observed before.

If particle physicists confirm the existence of maximons and astronomers discover bosonic stars, we have preformed ideas of how gravity plays a role in their behavior – merging hypothetical cases on physics and bringing us closer to discoveries further insights into the fundamental forces of the universe.

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Secondary school teachers, meet particle physics https://polkinghorne.org/secondary-school-teachers-meet-particle-physics/ Tue, 05 Jan 2021 08:00:00 +0000 https://polkinghorne.org/secondary-school-teachers-meet-particle-physics/ Imagine this: a stationary object such as a vase suddenly explodes, sending fragments flying. Given the final energies and momentum of the fragments, can you determine the mass of the object before it shattered? Dave Fish introduces his students to this common momentum conservation problem, with a twist. Instead of describing the explosion of a […]]]>

Imagine this: a stationary object such as a vase suddenly explodes, sending fragments flying. Given the final energies and momentum of the fragments, can you determine the mass of the object before it shattered?

Dave Fish introduces his students to this common momentum conservation problem, with a twist. Instead of describing the explosion of a macroscopic object like a vase, it describes the transformation of a top quark and a top antiquark into other fundamental particles.

Fish teaches high school physics and is a professor in residence at the Perimeter Institute for Theoretical Physics in Ontario. In Canada, particle physics is “one of those things that teachers tend to leave until the end of class and then they run out of time,” says Fish. “Most of us as secondary school teachers feel overwhelmed by the content.”

Particle physics makes its appearance in the curriculum of the International Baccalaureate, a program recognized as an entrance qualification to higher education by many universities around the world. The subject also appears in some state curricula, such as that of North Rhine-Westphalia in Germany. But in general, “there aren’t many programs that deal explicitly with particle physics,” says Jeff Wiener, head of teacher programs at CERN. “Those who do usually focus on rather boring stuff like, ‘Name two leptons.'”

Put particles in the program

Many high school science teachers who would like to teach particle physics say they feel insufficiently informed about the subject or don’t know how to include it without sacrificing required curriculum topics.

Fish and Wiener are two of many people hoping to change that. They see many opportunities to incorporate particle physics into standard curricula focused on general physics concepts. To teach conservation of momentum, try using real data from the discovery of the top quark (an activity developed by educators at the US Department of Energy’s Fermi National Accelerator Laboratory). To demonstrate the movement of charged particles in magnetic fields, show photographs of particle detectors called bubble chambers. To give an example of circular motion, discuss the mystery of dark matter.

One of Fish’s former students, Nikolina Ilic, considers a dark matter project she undertook in her class a turning point in her education. “I realized that we don’t know what 95% of the universe is made of, and that blew my mind,” she says. “That’s when I decided to pursue particle physics.”

Ilic continued her doctoral research at CERN, where she contributed to the statistical analysis for the discovery of the Higgs boson.

In the years he is not teaching high school students, Fish leads workshops at the Perimeter Institute to help other teachers bring particle physics into their classrooms. Each year, approximately 40 or 50 teachers from Canada and other countries attend a week-long EinsteinPlus workshop, participating in a variety of collaborative activities designed to teach them about modern physics. One of the most popular is a card sorting game that teaches standard pattern patterns and symmetries. In each activity, “we ask the teachers to be the students and ask the questions that the students would ask,” says Fish.

Fermilab organizes similar teacher workshops covering various physics topics for primary to secondary school teachers.

As the COVID-19 pandemic has forced many programs to move online, Fermilab has focused on finding ways to interact with teachers and students virtually. “We have career talks with lab staff, classroom presentations that we create with teachers and host virtually, Virtual Ask-a-Scientist, and Saturday Morning Physics,” says Amanda Early, program manager at Education at Fermilab which runs K-12 physical science programs. .

Each year, Fermilab organizes programs for educators and students, engaging them with the science of Fermilab. “The more you expose students to particle physics — the size and scale of it and its benefits — the more opportunities children will see to engage in science,” says Early.

In 2020, one of the Education Group’s summer science institutes focused specifically on helping high school teachers adapt modern physics lessons to the next-generation science standards used in many US states. Approximately 80 teachers from the Chicago area and across the country participated in the five-day interactive workshop, which in 2020 was offered online.

Next Generation Science Standards do not explicitly mention particle physics. But the cross-cutting concepts and scientific and engineering practices that frame them dovetail nicely with the subject, says David Torpe, an Illinois high school science teacher who has led professional development workshops at Fermilab for six years.

“Let’s talk about process, let’s talk about how particle physicists analyze data, let’s talk about how they solve problems,” says Torpe. “The ideas of energy and cause and effect naturally fit in too. I think a good strategy is to find a bit of particle physics that you find interesting and insert it here or there.

Bringing teachers to CERN, and CERN to teachers

Across the Atlantic, in Europe, CERN’s teacher programs attract more than 1,000 secondary school teachers from around the world to Geneva each year. Between physics lessons, professors visit the laboratories and have question-and-answer sessions with CERN scientists.

“The idea was that when we returned to Mexico, we would be ambassadors and encourage certain students to see that it is possible to go and do research at CERN”, explains Eduardo Morales Gamboa, who followed the program of teaching Spanish in 2019.

Since visiting the massive CMS detector and seeing particle tracks in a homemade cloud chamber, he has incorporated particle physics – and the many useful applications that have come from it – into his class discussions of intersections. of science, technology and society. Eventually, he says, he hopes to build a cloud chamber with his students.

According to Wiener, Morales Gamboa’s experience is common. Many alumni of teacher programs even return to CERN, this time with their students for the trip, to ignite the next generation’s enthusiasm for particle physics.

The success of CERN’s outreach efforts stems in part from integration with physics education research. Indeed, CERN teacher programs are designed to equip participants with knowledge not only of particle physics, but also of the best pedagogical practices for science education.

One such practice is to have students move through “predict-observe-explain” cycles. “You encourage students to make a prediction of what will happen before doing the experiment. This way you make sure that they first activate their previous knowledge and become curious about the result,” says Julia Woithe, who coordinates the hands-on learning labs at CERN. “Then, if they’re surprised by the observed result, they have to work out as a team how to explain the differences between their predictions and their observations. This usually leads to a powerful ‘eureka!’ moment.”

In addition to organizing events at CERN, Wiener traveled to India to collaborate with educators from the International School of Geneva in the first science education program in South Asia last year. Eighty teachers from the region participated in the week-long program at Shiv Nadar Noida School in New Delhi.

Vinita Sharat, the school’s STEAM coordinator, taught particle physics for a decade but remembers initially facing resistance from organizations where she previously worked. “The first challenge is to change the mentality of authority,” she says. “They asked why I was teaching it since it’s not part of the curriculum.”

His students, on the other hand, had no scruples. Some found particle physics so fascinating that they stayed online until midnight to discuss quarks and leptons with Sharat. “Students will always be ready to learn something related to nature,” she says.

Sharat fosters the creative side of students in her particle physics classes by encouraging them to write poems, make videos or choreograph dances to explain the concepts they are studying. Like Fish, Sharat stayed in touch with several former students whom she inspired to pursue careers in physics.

“The basis of everything”

After the CERN program at her school, Sharat hopes more teachers across South Asia will incorporate particle physics into their classrooms. And Wiener plans to lead more teaching workshops around the world in the future.

For now, COVID-19 has interrupted in-person professional development workshops. But teachers can still access some online resources: CERN’s hands-on learning lab S’Cool LAB (until recently run by Woithe), the Perimeter Institute, Fermilab and QuarkNet offer free downloads of their teaching materials interactive.

For Morales Gamboa, the benefits of teaching particle physics in high school go beyond encouraging a few students to pursue careers in this field. Talking about connections to engineering shows how abstract scientific ideas are linked to everyday life, while describing massive international projects conveys the key collaborative spirit of modern science.

Stacy Gates, an Illinois high school science teacher who taught at Fermilab’s Summer High School Physics Institute alongside Torpe in 2020, points out that teaching particle physics fosters critical thinking. “I encourage my students to question me when they don’t believe that particles can behave in a certain way,” she says. “It’s such an important skill because that’s what scientists do. They question everything and try to prove and disprove.

Sharat agrees that particle physics holds valuable lessons. No matter where her students go in life, she wants them to understand that “particle physics is the foundation of everything,” she says.

“We should know the reason for our existence. We should know what we are made of.

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Proven Accurate Artificial Intelligence for Nuclear and Particle Physics | MIT News https://polkinghorne.org/proven-accurate-artificial-intelligence-for-nuclear-and-particle-physics-mit-news/ Thu, 24 Sep 2020 07:00:00 +0000 https://polkinghorne.org/proven-accurate-artificial-intelligence-for-nuclear-and-particle-physics-mit-news/ The Standard Model of particle physics describes all known elementary particles and three of the four fundamental forces governing the universe; anything but gravity. These three forces – electromagnetic, strong and weak – govern the formation of particles, their interaction and their disintegration. The study of particle and nuclear physics in this framework is however […]]]>

The Standard Model of particle physics describes all known elementary particles and three of the four fundamental forces governing the universe; anything but gravity. These three forces – electromagnetic, strong and weak – govern the formation of particles, their interaction and their disintegration.

The study of particle and nuclear physics in this framework is however difficult and relies on large-scale numerical studies. For example, many aspects of the strong force require numerically simulating the dynamics at the scale of 1/10th to 1/100th the size of a proton to answer fundamental questions about the properties of protons, neutrons and cores.

“Ultimately, we are computationally limited in studying proton and nuclear structure using lattice field theory,” says Phiala Shanahan, assistant professor of physics. “There are a lot of interesting problems that we know how to solve in principle, but we just don’t have enough compute, even though we’re running on the biggest supercomputers in the world.”

To overcome these limitations, Shanahan leads a group that combines theoretical physics with machine learning models. In their article “Equivariant flow-based sampling for lattice gauge theory”, published this month in Physical examination lettersthey show how integrating the symmetries of physical theories into machine learning and artificial intelligence architectures can provide much faster algorithms for theoretical physics.

“We use machine learning not to analyze large amounts of data, but to accelerate first-principles theory in a way that doesn’t compromise the rigor of the approach,” Shanahan says. “This particular work has demonstrated that we can build machine learning architectures with some of the Standard Model symmetries of particle and nuclear physics built in, and accelerate the sampling problem we are targeting by orders of magnitude.”

Shanahan started the project with MIT graduate student Gurtej Kanwar and Michael Albergo, who is now at NYU. The project has expanded to include Center for Theoretical Physics postdocs Daniel Hackett and Denis Boyda, NYU Professor Kyle Cranmer, and physics-savvy machine learning scientists from Google Deep Mind, Sébastien Racanière and Danilo. Jiménez Rezende.

This month’s article is part of a series aimed at enabling studies in theoretical physics that are currently computationally unsolvable. “Our goal is to develop new algorithms for a key component of numerical calculations in theoretical physics,” says Kanwar. “These calculations tell us about the inner workings of the Standard Model of particle physics, our most fundamental theory of matter. Such calculations are of vital importance for comparing the results of particle physics experiments, such as the Large Hadron Collider at CERN, both to constrain the model more precisely and to discover where the model breaks down and must be extended to something even more fundamental.

The only known systematically controllable method of studying the Standard Model of particle physics in the non-perturbative regime is based on sampling snapshots of quantum fluctuations in vacuum. By measuring the properties of these fluctuations, one can deduce the properties of the particles and collisions of interest.

This technique comes with challenges, says Kanwar. “This sampling is expensive, and we’re looking to use physics-inspired machine learning techniques to take samples much more efficiently,” he says. “Machine learning has already made great strides in image generation, including, for example, NVIDIA’s recent work to generate images of faces ‘imagined’ by neural networks. Considering these vacuum snapshots as images, we think it’s only natural to turn to similar methods for our problem.

Shanahan adds, “In our approach to sampling these quantum snapshots, we optimize a model that takes us from an easy-to-sample space to the target space: given a trained model, then sampling is efficient since it suffices to take independent samples. in the easy-to-sample space, and transform them via the learned pattern.

In particular, the group introduced a framework for building machine learning models that exactly respect a class of symmetries, called “gauge symmetries”, crucial for the study of high-energy physics.

As a proof of principle, Shanahan and colleagues used their framework to train machine learning models to simulate two-dimensional theory, resulting in efficiency gains of orders of magnitude over state-of-the-art techniques. and more accurate predictions from theory. This paves the way for significantly accelerating research into the fundamental forces of nature using physics-based machine learning.

The first papers of the group as a collaboration discussed the application of the machine learning technique to a simple lattice field theory and developed this class of approaches on compact and connected manifolds that describe field theories more complicated than the standard model. Now they are working to adapt the techniques to cutting-edge calculations.

“I think we’ve shown over the past year that there’s a lot of promise in combining physics insights with machine learning techniques,” Kanwar says. “We are actively considering how to overcome the remaining hurdles in how to perform large-scale simulations using our approach. I hope to see the first application of these methods to large-scale calculations within the next two years. If we are able to overcome the final hurdles, it promises to expand what we can do with limited resources, and I dream of soon performing calculations that will give us new insight into what is beyond our best understanding of physics. today.

This physics-based machine learning idea is also known to the team as “ab-initio AI”, a key theme of the Institute for Artificial Intelligence and Fundamental Interactions (IAIFI) of the National Science Foundation recently launched at MIT, where Shanahan is a researcher. coordinator for physical theory.

Led by the Nuclear Science Laboratory, IAIFI is made up of physics and artificial intelligence researchers from MIT and Harvard, Northeastern and Tufts universities.

“Our collaboration is a great example of the spirit of IAIFI, with a diverse team coming together to advance AI and physics simultaneously,” Shanahan says. Apart from research such as Shanahan’s targeting physics theory, IAIFI researchers are also working to use AI to improve the scientific potential of various facilities, including the Large Hadron Collider and the Wave Observatory. gravity of the laser interferometer, and to advance the AI ​​itself.

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