ATLAS searches for new phenomena using unsupervised machine learning for anomaly detection

24 August 2023 |

ATLAS Collaboration

Since starting up in 2009, the Large Hadron Collider (LHC) has been at the forefront of scientific exploration – with researchers driven to uncover new particles and phenomena that go beyond the Standard Model. Over the years, thousands of scientists have channelled their expertise into refining analysis techniques and developing new ways to find these new-physics phenomena.

Figure 1: A schematic representation of the autoencoder architecture used for training and selection of the three anomaly regions. (Image: ATLAS Collaboration)

Traditionally, searches for new physics use complex computer simulations to reproduce what Standard Model processes should look like in collisions recorded by the ATLAS Experiment. These are then compared to simulations of new-physics models (e.g. dark matter, supersymmetry, etc.). Such models also help physicists determine the types of collisions where new-physics processes would be very prominent or where the collisions cannot be described by Standard-Model simulations – thus focusing their searches for new phenomena. Another style of searches involves looking at small deviations to a Standard-Model background caused by possible new phenomena.

Unsupervised machine learning can offer a new style of analyses which is completely agnostic to types of new-physics models and to any expectations of scientists. Researchers can design a complex neural network with millions of interconnections between “neurons”, and train this network on real data (see Figure 1). After training, the neural network can recognise “typical” LHC collisions and filter them out, leaving behind only the unrecognised or “atypical” collision events. On a technical side, such an unsupervised deep neural network (called an autoencoder) compresses input information, and then decompresses it while comparing inputs with outputs. Events with large reconstruction differences are called an “anomaly” since the algorithm finds itself in “trouble” in identifying such events. The chances that the anomalous events belong to new-physics phenomena are high. When using such neural networks, the idea is to look at the anomalous events, reconstruct the invariant masses of the particles in the collision, and then decide if they can be described by a Standard-Model process.

The new ATLAS result pioneers the use of unsupervised machine learning to search for anomalous collision events which could be from new-physics phenomena.

Figure 2: Example of the invariant mass (jet+muon) in the anomalous region defined by the unsupervised machine learning algorithm trained on a fraction of real data. The fit is represented by the red line, while the associated statistical uncertainties are indicated by the shaded band.The lower panel shows the bin-by-bin significances of deviations from the fit. (Image: ATLAS Collaboration)

In a new paper submitted to Phys. Rev. Lett., the ATLAS Collaboration pioneers the use of this style of physics analysis using LHC Run-2 data (collected 2015-2018). This analysis is the first of its kind, and marks the inaugural application of this type of unsupervised machine learning at a collider experiment, whether at the LHC or elsewhere.

ATLAS physicists observed no significant deviations from the Standard Model in the anomaly regions. The largest deviation was found for a mass at around 4.8 TeV with a significance of about 2.9 sigma for one decay channel (Figure 2). This level of statistical confidence typically means that the experimental observation could be a promising hint, but not sufficient for claiming the observation. The event display in the header of this briefing illustrates a typical collision event in the anomaly region with the jet+muon mass where the largest deviation is observed.

This analysis technique offers a new paradigm for searching for new-physics phenomena. One that relies less on wondering how the “new” phenomena may look, and instead focusing on new and unexpected model-agnostic signatures. In short, continuing the decade-long tradition of LHC physicists to discover a path into the unexplored realms of physics.About the event display: A display of an event with the reconstructed invariant mass of 4.72 TeV in the anomaly region as reported by the autoencoder trained using ATLAS data. The grey cones represent jets and the red lines represent muons. The green arrow indicates a missing transverse energy (MET). The red line closest to MET represents a high-energy muon. (Image: ATLAS Collaboration)

Learn more

Search for new phenomena in two-body invariant mass distributions using unsupervised machine learning for anomaly detection at 13 TeV with the ATLAS detector (arXiv:2307.01612, see figures)
EPS-HEP 2023 poster by Alkaid Cheng: 

Search for new physics using unsupervised machine learning for anomaly detection in 13 TeV collisions recorded by the ATLAS detector at the LHC
LHCP 2023 parallel talk by Rui Zhang:

  Search for new physics using unsupervised machine learning for anomaly detection with ATLAS
BOOST 2023 parallel talk by Wasikul Islam:

  Search for new phenomena in two-body invariant mass distributions using unsupervised machine learning for anomaly detection with the ATLAS detector

As the pickleball craze grows, doctors urge players not to ignore injuries

As pickleball-related sprains, strains and overuse injuries rise, survey finds many forgo care for nagging sports injuries

Reports and Proceedings

ORLANDO HEALTH

 

VIDEO: PICKLEBALL: ALL FUN AND GAMES UNTIL SOMEONE GETS HURT view more 

CREDIT: ORLANDO HEALTH

Orlando, Fla - Pickleball is the fastest growing sport in the country and has proven to be a great way to help millions stay active. And while it may seem like a fun game with a silly name, like any sport, it is not without risk. As doctors see more patients with pickleball-related injuries, a new national survey by The Harris Poll on behalf of Orlando Health finds many Americans are likely to forgo medical care for a nagging sports injury.

“Because pickleball is a relatively low impact activity, a lot of people think they won’t get hurt, but we’re seeing more and more people coming in with everything from broken bones and sprains to overuse injuries to the knees, shoulders and elbows,” said Luis Gandara, MD, a sports medicine physician at the Orlando Health Jewett Orthopedic Institute. “Any injury that doesn't seem to be getting better in a matter of a few days needs to be checked out by an orthopedic specialist to get a correct diagnosis and effective treatment.”

The survey found that while a third (33%) of Americans report avoiding participation in a sport or hobby because of a nagging injury, about half (49%) agree it’s not worth seeing a doctor for a sports injury they believe will heal on its own, something Gandara warns can exacerbate injuries and lead to more serious problems that are more difficult to treat.

“Playing through an injury that doesn’t resolve with rest, ice and elevation causes that injury to become increasingly unstable,” he said. “If a patient comes to us right away, there is a good chance we can treat them with less-invasive options to help common injuries like a strained ligament, torn muscle or a hairline fracture heal. But if an injury is left to worsen over time without intervention, a patient is more likely to require surgery and a longer and more difficult recovery.”

The survey also found 44% believe making a doctor’s appointment for an injury that is not too painful is too much work. That’s why the Jewett Orthopedic Institute opened several walk-in clinics, where patients can see an orthopedic specialist without an appointment or a referral, to ensure patients can get the care they need quickly and conveniently.

“Unlike going to the ER or an urgent care center, an orthopedic walk-in clinic is staffed with specialists who can assess sports injuries and immediately initiate effective treatment, whether that involves physical therapy and non-invasive treatments like injections or a same day referral to a specific type of surgeon,” Gandara said.

Robbin Murray fell in love with pickleball a decade ago. But as she played more frequently and competitively, she began to have issues with her knee that were painful enough to keep her off the court.

“I was hooked right from the start and would play as much as I could, all day long, eventually traveling to compete in senior tournaments,” Murray said. “It all added up and I started experiencing sharp pains that would take me down to the ground in the middle of a game.”

Robbin worried she would need knee replacement surgery, but after consulting with Dr. Gandara, has been able to safely participate in the sport she loves and manage her injury with a specialized brace, anti-inflammatory injections and physical therapy to strengthen and stretch the area.

Gandara encourages people to get out and enjoy pickleball or any healthy activity they enjoy, but emphasizes the importance of easing into any new activity, taking precautions like stretching and wearing supportive shoes and listening to your body when something doesn’t feel right.

B-ROLL, SOUND BITES, WEB ELEMENTS & HI-RES STILL PHOTOS - Including HD video available for free/unrestricted use by the news media: https://bit.ly/44yMLLB 
Courtesy: Orlando Health

For assistance in downloading, or if you have any questions, contact: allison@mediasourcetv.com or call: 423.742.5091.

Survey Method

This survey was conducted online within the United States by The Harris Poll on behalf of Orlando Health from June 15 - 20, 2023 among 2,076 U.S. adults ages 18 and older. The sampling precision of Harris online polls is measured by using a Bayesian credible interval. For this study, the sample data is accurate to within +/- 2.7 percentage points using a 95% confidence level. For complete survey methodology, including weighting variables and subgroup sample sizes, please contact allison@mediasourcetv.com. 

Luis Gandara, MD, examines a patient at The Orlando Health Jewett Orthopedic Institute who suffered an injury while playing the increasingly popular sport of pickleball. While he encourages patients to participate in active hobbies they enjoy, he stresses the importance of seeking care for nagging aches and pains to prevent injuries from worsening.

Pickleball is a great way to stay active, but like any sport, it comes with risks. A new national survey by Orlando Health finds many Americans are likely to forgo treatment for nagging sports injuries, something doctors warn can lead to more serious conditions and complicated treatments.

CREDIT

Orlando Health

About Orlando Health
Orlando Health, headquartered in Orlando, Florida, is a not-for-profit healthcare organization with $9.2 billion of assets under management that serves the southeastern United States and Puerto Rico. 

Founded more than 100 years ago, the healthcare system is recognized around the world for Central Florida’s only pediatric and adult Level I Trauma program as well as the only state-accredited Level II Adult Trauma Center in Pinellas County. It is the home of the nation’s largest neonatal intensive care unit under one roof, the only system in the southeast to offer open fetal surgery to repair the most severe forms of spina bifida, the site of an Olympic athlete training facility and operator of one of the largest and highest performing clinically integrated networks in the region. Orlando Health has pioneered life-changing medical research and its Graduate Medical Education program hosts more than 350 residents and fellows. 

The 3,888-bed system includes 29 hospitals and emergency departments – 24 of which are currently operational with five coming soon. The system also includes nine specialty institutes, more than 100 adult and pediatric primary care practices, skilled nursing facilities, an in-patient behavioral health facility under the management of Acadia Healthcare, and more than 60 outpatient facilities that include imaging and laboratory services, wound care centers, home healthcare services in partnership with LHC Group, and urgent care centers in partnership with FastMed Urgent Care. More than 4,750 physicians, representing more than 100 medical specialties and subspecialties have privileges across the Orlando Health system, which employs more than 27,000 team members and more than 1,200 physicians. 

In FY22, Orlando Health served nearly 142,000 inpatients and 3.9 million outpatients. The healthcare system provided more than $782 million in total value to the communities it serves in the form of charity care, community benefit programs and services, community building activities and more in FY 21, the most recent period for which this information is available. Additional information can be found at http://www.orlandohealth.com, or follow us on LinkedIn, Facebook, Instagram and Twitter @orlandohealth.

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METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

People

THAT GOD(DAMN) PARTICLE

ATLAS and CMS Collaborations Find First Evidence of Rare Higgs Boson Decay

ATLAS and CMS combined their datasets from the second run of the LHC

ByAditya Saikrishna
May 27, 2023

Photo Credit: Twitter/CMSExperiment

SWITZERLAND: Scientists at CERN’s Large Hadron Collider (LHC) have achieved another breakthrough in particle physics as the ATLAS and CMS collaborations joined forces to provide the first evidence of the Higgs boson decaying into a Z boson and a photon.

This rare decay process could shed light on particles beyond the Standard Model and deepen our understanding of the nature of the Higgs boson.

The discovery of the Higgs boson in 2012 opened new avenues for research in particle physics. Since then, scientists have meticulously explored its properties and investigated its various decay processes.

At the recent Large Hadron Collider Physics conference, ATLAS and CMS presented their joint efforts to uncover the elusive decay of the Higgs boson into a Z boson and a photon.- Advertisement -

The decay of the Higgs boson into a Z boson and a photon resembles a degeneration into two photons. However, these decays do not occur directly but involve an intermediate “loop” of “virtual” particles that researchers cannot observe directly.

These virtual particles could include yet undiscovered particles that interact with the Higgs boson, potentially challenging the predictions of the Standard Model.

According to the Standard Model, around 0.15% of Higgs bosons with a mass of approximately 125 billion electronvolts should decay into a Z boson and a photon

However, theories extending beyond the Standard Model propose different decay rates. Scientists gain valuable insights into physics beyond the Standard Model and the characteristics of the Higgs boson itself by measuring the decay rate.

Previously, both ATLAS and CMS independently conducted extensive searches for the Higgs boson decay using data from proton-proton collisions at the LHC.

Employing similar strategies, they identified the Z boson through its decay into pairs of electrons or muons, heavier counterparts of electrons. The team found these Z boson decays in approximately 6.6% of the cases.

In their searches, ATLAS and CMS looked for collision events associated with the Higgs boson decay, represented by a narrow peak in the combined mass distribution of the decay products against a smooth background.

The collaborations categorized events based on the characteristics of the Higgs boson’s production processes and implemented advanced machine-learning techniques to distinguish between signal and background events.

In a new study, ATLAS and CMS combined their datasets from the second run of the LHC (2015-2018) to maximize the statistical precision of their search.

The collaboration resulted in the first evidence of the Higgs boson decaying into a Z boson and a photon, with a statistical significance of 3.4 standard deviations.

While the standard deviation falls short of the conventional requirement of 5 standard deviations for claiming an observation, the measured signal rate is 1.9 standard deviations above the Standard Model prediction.

Pamela Ferrari, an ATLAS physics coordinator, emphasized the significance of rare Higgs decays, stating that each particle has a unique relationship with the Higgs boson and searching for it is a high priority.

Florencia Canelli, a CMS physics coordinator, highlighted the potential implications of new particles on rare Higgs decay modes and expressed optimism about future advancements using the ongoing third run of the LHC and the forthcoming High-Luminosity LHC.

This collaborative effort by ATLAS and CMS brings us one step closer to unravelling the mysteries surrounding the Higgs boson and provides an insightful test of the Standard Model.

With further advancements and precision expected in future experiments, scientists anticipate probing even rarer Higgs decays, potentially uncovering new particles and revolutionizing our understanding of the universe’s fundamental building blocks.

PAKISTAN

ISI and MI say Imran Riaz not in their custody, senior cop tells LHC

Rana Bilal 

DAWN

Published May 25, 2023 

Lahore police Deputy Inspector General (Investigation) Kamran Adil told the high court on Thursday that both the Inter-Services Intelligence (ISI) and the Military Intelligence (MI) had said that anchorperson Imran Riaz Khan — whose whereabouts remain unknown since his arrest on May 11 — was not in their custody.

The police official made the remarks as the Lahore High Court (LHC) resumed hearing a plea seeking the recovery of the anchorperson, who was among the individuals apprehended in the wake of protests that erupted in the country after the arrest of PTI chairman Imran Khan.

Later, his lawyer told Dawn.com that a writ petition was filed on May 12 over the anchorperson’s arrest and the LHC directed the attorney general to present him before the court the same day. But, after its orders were not followed, Sialkot police were given a 48-hour deadline to recover Imran.

A first information report (FIR) pertaining to the matter was registered with Civil Lines police on May 16 on the complaint of the anchorperson’s father, Muhammad Riaz.


The FIR was registered against “unidentified persons” and police officials for allegedly kidnapping Imran, invoking Section 365 (kidnapping or abducting with intent secretly and wrongfully to confine person) of the Pakistan Penal Code.

At the previous hearing, Punjab Inspector General Dr Usman Anwar had told the court that there was no trace of the journalist at any police department across the country.

The LHC had subsequently directed the ministries of interior and defence to “discharge their constitutional duties to effect the recovery” of the missing anchorperson.
The hearing

LHC Chief Justice Muhammad Ameer Bhatti presided over today’s hearing during which the Lahore police DIG (Investigation) appeared before the court instead of the Punjab IG.

The lawyer representing the Punjab government requested the court to exempt the provincial police chief from appearing as he was attending a ceremony in connection with Martyrs Respect Day in Gujranwala.

The LHC CJ inquired about the IG’s schedule and asked for the record to be submitted. The DIG assured the court that the record would be submitted to the court.

During the hearing, the DIG stated, “The ISI and MI have said that Imran Riaz is not in their custody”.

Meanwhile, the anchorperson’s counsel, Advocate Azhar Siddique, told the court that Imran’s father, Muhammad Riaz, wished to speak.

Justice Bhatti emphasised the court’s commitment to upholding fundamental rights while Riaz said his son was “being punished for making a vlog”.

The court directed the journalist’s lawyers to meet with the police team later today and told them to provide the police with any evidence that was in their possession.

The hearing was later adjourned.
Info minister called out for remarks on Imran’s disappearance

Earlier this week, journalists and human rights activists had strongly criticised Information Minister Marriyum Aurangzeb’s comments regarding Imran’s case.

Journalist Secunder Kermani, a Channel4 News foreign correspondent, had shared a video of an exchange with the information minister about the missing anchorperson.



He questioned Aurangzeb about journalists going missing and being detained, adding that these were the same issues that the PML-N had raised as matters of concern when in opposition during the previous PTI government.

In response, Aurangzeb asked Kermani to name even a single journalist who was missing. When Kermani mentioned Imran, the minister responded, “Imran Riaz is a political party spokesperson now. You really have to draw [a] distinction.”

She further said, “You have to differentiate between journalists and the journalists who have joined political parties. Once they have joined political parties, they are inciting violence, they are spokespersons of that political parties.”

Aurangzeb’s response elicited severe criticism from several journalists and rights activists, who reminded the minister that a person’s disappearance was an issue of basic human rights irrespective of what political party they favoured.

Lawyer and social activist Jibran Nasir said that Aurangzeb believed Imran “should be seen as a supporter of PTI and hence considered a sub-human who deserves the treatment being meted out to them.

“Now just imagine the plight of ordinary citizens suffering military trials,” he added.

Pakistan Initiative at Atlantic Council’s South Asia Centre Director Uzair Younus said Imran’s status as a journalist or not should not matter.

He said that Imran had fundamental constitutional rights granted to him on account of his Pakistani citizenship.

“Stop violating his rights and those of countless others. These disappearances are heinous!” he tweeted.

If the Higgs can reach the Hidden Valley, we will see new physics already in next-generation accelerators

Peer-Reviewed Publication

THE HENRYK NIEWODNICZANSKI INSTITUTE OF NUCLEAR PHYSICS POLISH ACADEMY OF SCIENCES

 

IMAGE: THE SEARCH FOR EXOTIC HIGGS BOSON DECAYS IN FUTURE LEPTON COLLIDERS: 1) AN ELECTRON AND A POSITRON FROM OPPOSING BEAMS COLLIDE; 2) THE COLLISION PRODUCES A HIGH-ENERGY HIGGS BOSON; 3) THE BOSON DECAYS INTO TWO EXOTIC PARTICLES MOVING AWAY FROM THE AXIS OF THE BEAMS; 4) EXOTIC PARTICLES DECAY INTO PAIRS OF QUARK-ANTIQUARK, VISIBLE TO DETECTORS. view more 

CREDIT: SOURCE: IFJ PAN

It may be that the famous Higgs boson, co-responsible for the existence of masses of elementary particles, also interacts with the world of the new physics that has been sought for decades. If this were indeed to be the case, the Higgs should decay in a characteristic way, involving exotic particles. At the Institute of Nuclear Physics of the Polish Academy of Sciences in Cracow, it has been shown that if such decays do indeed occur, they will be observable in successors to the LHC currently being designed.

When talking about the 'hidden valley', our first thoughts are of dragons rather than sound science. However, in high-energy physics, this picturesque name is given to certain models that extend the set of currently known elementary particles. In these so-called Hidden Valley models, the particles of our world as described by the Standard Model belong to the low-energy group, while exotic particles are hidden in the high-energy region. Theoretical considerations suggest then the exotic decay of the famous Higgs boson, something that has not been observed at the LHC accelerator despite many years of searching. However, scientists at the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow argue that Higgs decays into exotic particles should already be perfectly observable in accelerators that are successors to the Large Hadron Collider – if the Hidden Valley models turn out to be consistent with reality.

“In Hidden Valley models we have two groups of particles separated by an energy barrier. The theory is that there could then be exotic massive particles which could cross this barrier under specific circumstances. The particles like Higgs boson or hypothetic Z’ boson would act as communicators between the particles of both worlds. The Higgs boson, one of the most massive particle of the Standard Model, is a very good candidate for such a communicator,” explains Prof. Marcin Kucharczyk (IFJ PAN), lead author of an article in the Journal of High Energy Physics, which presents the latest analyses and simulations concerning the possibility of detecting Higgs boson decays in the future lepton accelerators.

The communicator, after passing into the low energy region, would decay into two rather massive exotic particles. Each of these would, in picoseconds – that is, trillionths of a second – decay into another two particles, with even smaller masses, which would then be within the Standard Model. So what signs would be expected in the detectors of future accelerators? The Higgs itself would remain unnoticed, as would the two Hidden Valley particles. However, the exotic particles would gradually diverge and eventually decay, generally into quark-antiquark beauty pairs visible in modern detectors as jets of particles shifted from the axis of the lepton beam 

“Observations of Higgs boson decays would therefore consist of searching for the jets of particles produced by quark-antiquark pairs. Their tracks would then have to be retrospectively reconstructed to find the places where exotic particles are likely to have decayed. These places, professionally called decay vertices, should appear in pairs and be characteristically shifted with respect to the axis of the colliding beams in the accelerator. The size of these shifts depends, among other things, on masses and average lifetime of exotic particles appearing during the Higgs decay”, says Mateusz Goncerz, M.Sc. (IFJ PAN), co-author of the paper in question.

The collision energy of protons at the LHC, currently the world's largest particle accelerator, is up to several teraelectronvolts and is theoretically sufficient to produce Higgs capable of crossing the energy barrier that separates our world from the Hidden Valley. Unfortunately, protons are not elementary particles – they are composed of three valence quarks bound by strong interactions, capable of generating huge numbers of constantly appearing and disappearing virtual particles, including quark-antiquark pairs. Such a dynamic and complex internal structure produces huge numbers of secondary particles in proton collisions, including many quarks and antiquarks with large masses. They form a background in which it becomes practically impossible to find the particles from the exotic Higgs boson decays that are being sought.

The detection of possible Higgs decays to these states should be radically improved by accelerators being designed as successors to the LHC: the CLIC (Compact Linear Collider) and the FCC (Future Circular Collider). In both devices it will be possible to collide electrons with their anti-material partners, the positrons (with CLIC dedicated to this type of collision, while FCC will also allow collisions of protons and heavy ions). Electrons and positrons are devoid of internal structure, so the background for exotic Higgs boson decays should be weaker than at the LHC. Only will it be sufficiently so to discern the valuable signal?

In their research, physicists from the IFJ PAN took into account the most important parameters of the CLIC and FCC accelerators and determined the probability of exotic Higgs decays with final states in the form of four beauty quarks and antiquarks. To ensure that the predictions cover a wider group of models, the masses and mean lifetimes of the exotic particles were considered over suitably wide ranges of values. The conclusions are surprisingly positive: all indications are that, in future electron-positron colliders, the background of exotic Higgs decays could be reduced even radically, by several orders of magnitude, and in some cases could even be considered negligible.

The existence of particle-communicators is not only possible in Hidden Valley models, but also in other extensions of the Standard Model. So if the detectors of future accelerators register a signature corresponding to the Higgs decays analysed by the Cracow researchers, this will only be the first step on the road to understanding new physics. The next will be to collect a sufficiently large number of events and determine the main decay parameters that can be compared with the predictions of theoretical models of the new physics.

“The main conclusion of our work is therefore purely practical. We are not sure whether the new physics particles involved in Higgs boson decays will belong to the Hidden Valley model we used. However, we have treated this model as representative of many other proposals for new physics and have shown that if, as predicted by the model, the Higgs bosons decay into exotic particles, this phenomenon should be perfectly visible in those electron and positron colliders which are planned to be launched in the near future”, concludes Prof. Kucharczyk.

The research in question was funded by an OPUS grant from the Polish National Science Centre.

The Henryk Niewodniczański Institute of Nuclear Physics (IFJ PAN) is currently one of the largest research institutes of the Polish Academy of Sciences. A wide range of research carried out at IFJ PAN covers basic and applied studies, from particle physics and astrophysics, through hadron physics, high-, medium-, and low-energy nuclear physics, condensed matter physics (including materials engineering), to various applications of nuclear physics in interdisciplinary research, covering medical physics, dosimetry, radiation and environmental biology, environmental protection, and other related disciplines. The average yearly publication output of IFJ PAN includes over 600 scientific papers in high-impact international journals. Each year the Institute hosts about 20 international and national scientific conferences. One of the most important facilities of the Institute is the Cyclotron Centre Bronowice (CCB), which is an infrastructure unique in Central Europe, serving as a clinical and research centre in the field of medical and nuclear physics. In addition, IFJ PAN runs four accredited research and measurement laboratories. IFJ PAN is a member of the Marian Smoluchowski Kraków Research Consortium: "Matter-Energy-Future", which in the years 2012-2017 enjoyed the status of the Leading National Research Centre (KNOW) in physics. In 2017, the European Commission granted the Institute the HR Excellence in Research award. As a result of the categorization of the Ministry of Education and Science, the Institute has been classified into the A+ category (the highest scientific category in Poland) in the field of physical sciences.

SCIENTIFIC PUBLICATIONS:

“Search for exotic decays of the Higgs boson into long-lived particles with jet pairs in the final state at CLIC”

M. Kucharczyk, M. Goncerz

Journal of High Energy Physics, 131, 2023

DOI: https://doi.org/10.1007/JHEP03(2023)131

LINKS:

http://www.ifj.edu.pl/

The website of the Institute of Nuclear Physics, Polish Academy of Sciences.

http://press.ifj.edu.pl/

Press releases of the Institute of Nuclear Physics, Polish Academy of Sciences.

IMAGES:

IFJ230518b_fot01s.jpg                                 

HR: http://press.ifj.edu.pl/news/2023/05/18/IFJ230518b_fot01.jpg

The search for exotic Higgs boson decays in future lepton colliders: 1) an electron and a positron from opposing beams collide; 2) the collision produces a high-energy Higgs boson; 3) the boson decays into two exotic particles moving away from the axis of the beams; 3) exotic particles decay into pairs of quark-antiquark, visible to detectors. (Source: IFJ PAN)

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JOURNAL

Journal of High Energy Physics

DOI

10.1007/JHEP03(2023)131 

ARTICLE TITLE

Search for exotic decays of the Higgs boson into long-lived particles with jet pairs in the final state at CLIC

ARTICLE PUBLICATION DATE

17-Mar-2023

Demystifying vortex rings in nuclear fusion, supernovae

A mathematical model linking these vortices with more pedestrian types, like smoke rings, could help engineers control their behavior in power generation and more

Peer-Reviewed Publication

UNIVERSITY OF MICHIGAN

Images

Better understanding the formation of swirling, ring-shaped disturbances—known as vortex rings—could help nuclear fusion researchers compress fuel more efficiently, bringing it closer to becoming a viable energy source. 

The model developed by researchers at the University of Michigan could aid in the design of the fuel capsule, minimizing the energy lost while trying to ignite the reaction that makes stars shine. In addition, the model could help other engineers who must manage the mixing of fluids after a shock wave passes through, such as those designing supersonic jet engines, as well as physicists trying to understand supernovae.

"These vortex rings move outward from the collapsing star, populating the universe with the materials that will eventually become nebulae, planets and even new stars—and inward during fusion implosions, disrupting the stability of the burning fusion fuel and reducing the efficiency of the reaction," said Michael Wadas, a doctoral candidate in mechanical engineering at U-M and corresponding author of the study.

"Our research, which elucidates how such vortex rings form, can help scientists understand some of the most extreme events in the universe and bring humanity one step closer to capturing the power of nuclear fusion as an energy source," he said.

Nuclear fusion pushes atoms together until they merge. This process releases several times more energy than breaking atoms apart, or fission, which powers today's nuclear plants. Researchers can create this reaction, merging forms of hydrogen into helium, but at present, much of the energy used in the process is wasted.

Part of the problem is that the fuel can't be neatly compressed. Instabilities cause the formation of jets that penetrate into the hotspot, and the fuel spurts out between them—Wadas compared it to trying to squish an orange with your hands, how juice would leak out between your fingers. 

Vortex rings that form at the leading edge of these jets, the researchers have shown, are mathematically similar to smoke rings, the eddies behind jellyfish and the plasma rings that fly off the surface of a supernova.

Perhaps the most famous approach to fusion is a spherical array of lasers all pointing toward a spherical capsule of fuel. This is how experiments are set up at the National Ignition Facility, which has repeatedly broken records for energy output in recent years. 

The energy from the lasers vaporizes the layer of material around the fuel—a nearly perfect, lab-grown shell of diamond in the latest record-setter in December 2022. When that shell vaporizes, it drives the fuel inward as the carbon atoms fly outward. This generates a shockwave, which pushes the fuel so hard that the hydrogen fuses.

While the spherical fuel pellets are some of the most perfectly round objects humans have ever made, each has a deliberate flaw: a fill tube, where the fuel enters. Like a straw stuck in that crushed orange, this is the most likely place for a vortex-ring-led jet to form when the compression starts, the researchers explained.

"Fusion experiments happen so fast that we really only have to delay the formation of the jet for a few nanoseconds," said Eric Johnsen, an associate professor of mechanical engineering at U-M, who supervised the study.

The study brought together the fluid mechanics expertise of Wadas and Johnsen as well as the nuclear and plasma physics knowledge in the lab of Carolyn Kuranz, an associate professor of nuclear engineering and radiological sciences.

"In high-energy-density physics, many studies point out these structures, but haven’t clearly identified them as vortex rings," said Wadas.

Knowing about the deep body of research into the structures seen in fusion experiments and astrophysical observations, Wadas and Johnsen were able to draw on and extend that existing knowledge rather than trying to describe them as completely new features.

Johnsen is particularly interested in the possibility that vortex rings could help drive the mixing between heavy elements and lighter elements when stars explode, as some mixing process must have occurred to produce the composition of planets like Earth.

The model can also help researchers understand the limits of the energy that a vortex ring can carry, and how much fluid can be pushed before the flow becomes turbulent and harder to model as a result. In ongoing work, the team is validating the vortex ring model with experiments. 

The research is funded by Lawrence Livermore National Laboratory and the Department of Energy, with computational resources provided by the Extreme Science and Engineering Discovery Environment through the National Science Foundation and the Oak Ridge Leadership Computing Facility.

Study: Saturation of vortex rings ejected from shock-accelerated interfaces. (DOI: 10.1103/PhysRevLett.130.194001)

JOURNAL

Physical Review Letters

DOI

10.1103/PhysRevLett.130.194001 

Europe’s CERN takes first steps toward building giant particle accelerator

Nuclear research organization says goal of Future Circular Collider is to ‘push the energy and intensity frontiers’ of particle smashers ‘in the search for new physics’

By AGNÈS PEDRERO

22 April 2023, 

A radio frequency particle accelerator is displayed in an exhibition during a press tour at the European Organization for Nuclear Research (CERN) on the Future Circular Collider (FCC) feasibility study, in Geneva, on April 19, 2023. (Fabrice Coffrini/AFP)

GENEVA (AFP) — Europe’s CERN laboratory has taken its first steps toward building a huge new particle accelerator that would eclipse its Large Hadron Collider — and hopes to see light at the end of the tunnel.

The Future Circular Collider (FCC) particle smasher would be more than triple the length of the LHC, already the world’s largest and most powerful particle collider, constructed in the hope of revealing secrets about how the universe works.

The FCC would form a new circular tunnel under France and Switzerland, 91 kilometers (56.5 miles) long and about five meters (16 feet) in diameter.

“The goal of the FCC is to push the energy and intensity frontiers of particle colliders, with the aim of reaching collision energies of 100 tera electron volts, in the search for new physics,” CERN says.

The tunnel would pass under the Geneva region and its namesake lake in Switzerland, and loop around to the south near the picturesque French town of Annecy.
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Eight technical and scientific sites would be built on the surface, with seven in France and one in Geneva, CERN engineer Antoine Mayoux told reporters this week.

CERN Radio-frequency head Eric Montesinos gestures next to a map of the actual Large Hadron Collider (LHC) during a press trip at the European Organization for Nuclear Research CERN on the Future Circular Collider (FCC) feasibility study, in Geneva, on April 19, 2023. (Fabrice Coffrini/AFP)

After carrying out a theoretical analysis, “we are now embarking for the first time on field activities” to study potential environmental issues, he said, with seismic and geotechnical studies to follow.
Mysteries of the universe

Once the feasibility studies are completed, CERN’s member states — 22 European countries plus Israel — will decide in the next five to six years on whether to build the FCC.

The FCC would accelerate electrons and positrons until 2060, and then hadrons until 2090, as it seeks answers to many remaining questions of fundamental physics, with about 95 percent of the mass and energy of the universe still a mystery.

CERN’s Large Hadron Collider — a 27-kilometer (17-mile) ring running about a hundred meters below ground — has already begun chipping away at the unknown.

Among other things, it was used to prove the existence of the Higgs Boson — dubbed the God particle — which broadened the understanding of how particles acquire mass, and earned two scientists who had theorized its existence the 2013 Nobel physics prize.

A simulated data projection of a Higgs boson collision. (Photo credit: CC BY Wikipedia)

But the LHC, which began operating in 2010, is expected to have run its course by around 2040.

“The problem with accelerators is that at some point, no matter how much data you accumulate, you hit a wall of systematic errors,” CERN physicist Patrick Janot said.

“Around 2040-2045, we will have taken away all the substance of the precision possible with the LHC,” he said.

“It will be time to move on to something much more powerful, much brighter, to better see the contours of the physics that we are trying to study.”
Opening doors to the future

Some researchers fear that this huge project will gobble up funds that could be used for other, less abstract physics research.

But others insist that pushing fundamental physics forward is vital for advances in applied physics as well.

“The benefits of our research are extremely important,” said Malika Meddahi, CERN’s deputy director for accelerators and technology, citing as examples medical imaging and the fight against tumors.

Janot agreed: “The day the electron gun was invented, it was the beginning of accelerators; we didn’t know it was going to give rise to television. The day general relativity was discovered, we didn’t know it was going to be used to run GPS.”

A projection on fundamental particles is seen during a press trip at the European Organization for Nuclear Research CERN on the Future Circular Collider (FCC) feasibility study, in Geneva, on April 19, 2023. (Fabrice Coffrini/AFP)

Harry Cliff, a particle physicist at Britain’s University of Cambridge, acknowledged that the FCC was an “expensive bit of kit.”

But he noted that it would be built by “a large international collaboration of nations working together over a very long period of time.”

“Particle physics isn’t about discovering new particles — it’s about understanding the fundamental ingredients of nature and the laws that govern them.”

Competition from China

More than 600 institutes and universities around the world use CERN’s facilities, and are responsible for funding and carrying out the experiments they take part in.

However, CERN has some competition: China announced in 2015 that it intended to start work within a decade on building the world’s largest particle accelerator.

Michael Benedikt, who is heading up the FCC feasibility studies, told AFP that CERN had more than 60 years of experience in developing long-lasting research infrastructure.

And political stability in Europe helped to “minimize the development risk for such long-term projects,” he said.

Meddahi also highlighted Europe’s leading position in the field, but warned that “China displays the same ambition.”

“Let’s be vigilant and be sure that we are not on the verge of a change in this hierarchy,” she said.

Scientists search for dark matter in the depths of an abandoned gold mine

Staff Writer | February 7, 2023 | 

In a South Dakota gold mine, a research team is hunting for a yet-undiscovered particle that could explain dark matter. (Image by Matthew Kapust, courtesy of the Sanford Underground Research Facility).

An interdisciplinary team of researchers is working to lure a hypothesized particle from outer space to the Sanford Underground Research Facility, housed in a former gold mine that operated at the height of the 1870s gold rush in the town of Lead, South Dakota.


In detail, they are prospecting for WIMPs —weakly interacting massive particles— which are thought to have formed when the universe was just a microsecond old and which may exist unseen all around us. The research facility suits this type of search because the depth prevents the intrusion of cosmic rays, which would otherwise interfere with experiments.

If WIMPs are observed, they could hold clues to some of the most perplexing problems in physics: the nature of dark matter and the very structure of the universe itself.

The US-based group is using the Large Underground Xenon-ZEPLIN (LZ) experiment, the most sensitive WIMP dark matter detector located at the Sanford Lab. Unlike experiments conducted at particle smashers like the Large Hadron Collider (LHC) in Switzerland, the LZ attempts to directly observe—rather than manufacture—dark matter.

Anwar Bhatti, a research professor at the University of Maryland, said there are pros and cons to both approaches.

In his view, the odds of finding irrefutable proof of WIMPs are slim, but he hopes previously undiscovered particles will show up in their experiment, leaving a trail of clues in their wake.

“There’s a chance we will see hints of dark matter, but whether it’s conclusive remains to be seen,” Bhatti said.
An underground mine – the perfect location

Lead scientist Carter Hall explained that these direct searches for dark matter can only be conducted underground because researchers need to eliminate surface-level cosmic radiation, which can muddle dark matter signals and make them easier to miss.

“Here, on the surface of the earth, we’re constantly being bathed in cosmic particles that are raining down upon us. Some of them have come from across the galaxy and some of them have come across the universe,” Hall explained. “Our experiment is about a mile underground, and that mile of rock absorbs almost all of those conventional cosmic rays. That means that we can look for some exotic component which doesn’t interact very much and would not be absorbed by the rock.”

In the LZ experiment, bursts of light are produced by particle collisions. Scientists then work backward, using the characteristics of these flashes of light to determine the type of particle.

The UMD research group calibrates the instrument that powers the LZ experiment, which involves preparing and injecting tritium—a radioactive form of hydrogen—into a liquefied form of xenon, an extremely dense gas. Once mixed, the radioactive mixture is pumped throughout the instrument, which is where particle collisions can be observed.

The researchers then analyze the mixture’s decay to determine how the instrument responds to background events that are not dark matter. By process of elimination, the researchers learn the types of interactions that are—and aren’t—important.

“That tells us what dark matter does not look like, so what we’re going to be looking for in the dark matter search data are events that don’t fit that pattern,” Hall said.

The researcher also pointed out that they will not know if they found dark matter until their next data set is released. This could take at least a year.

If detected, these WIMP particles would prompt a massive overhaul of the Standard Model of particle physics, which explains the fundamental forces of the universe. While this experiment could answer pressing questions about the universe, there is a good chance it will also create new ones.

“It would mean that a lot of our basic ideas about the fundamental constituents of nature would need to be revised in one way or another,” Hall said.

The 5 biggest scientific breakthroughs of 2022: Fusion energy, ‘life after death’, and more

Scientific Breakthroughs of the Year: 

From a breakthrough in nuclear fission energy technology to pigs being "revived" after their death, here are some of the biggest scientific breakthroughs that happened in 2022.

Written by Sethu Pradeep
New Delhi | Updated: December 17, 2022 

Scientific Discoveries of 2022: The year 2022 bore witness to many impressive scientific breakthroughs including the simulation of a wormhole to an artificial mouse embryo that developed a brain. 

(Image credit: Indian Express)

A major US breakthrough in nuclear fusion technology gave us a glimpse of a future where a renewable, clean and near-limitless source of energy might just be possible. This breakthrough capped off an exciting year for science, which bore witness to many scientific developments that promise to alter the course of humanity and our understanding of the universe. Here, we have put together five of the most significant scientific developments that happened this year.

Fusion energy breakthrough promises future of clean energy

Scientists announced on Tuesday (December 13) that researchers at the Lawrence National Laboratory in California conducted a nuclear fission reaction that produced more energy than what was used to ignite it. This marks a major breakthrough for the field. Nearly all the energy on the planet comes from nuclear fusion energy. Many of the energy sources that we know, from the food we eat to the fossil fuels that we burn, can be traced back to nuclear fission reactions that happen in the Sun. But we are still years, and maybe decades away, from mastering the process ourselves.

The conventional nuclear electric plants that we know and nuclear weapons derive their energy from a nuclear fission process, where the nucleus of an atom, usually Uranium, is split into two different nuclei, generating large amounts of energy.

Also read |Why fusion could be a clean-energy breakthrough

In an almost contrary process, nuclear fusion is when two nuclei fuse together to form a single heavier nucleus. When this happens, the mass of the new heavier nucleus is less than the sum of the individual nuclei combined, meaning that a little bit of mass is lost. E=MC^2, Einstein’s most famous equation, explains how this mass is converted into a large amount of energy.

While both fission and fusion reactions release large amounts of energy, the latter produces substantially more energy than the former. For example, the nuclear fusion of two nuclei of a heavier hydrogen isotope will produce four times as much energy as the fission of a uranium atom.

If nuclear fission energy were to be commercialised, it would offer a clean and renewable source of energy that will help fight climate change, while also not producing the panoply of radioactive waste products that fission energy reactors are known for. The technology still has a long way to go before becoming a viable energy alternative, as fusion reactions currently being tested barely last a few minutes, due to the difficulty in maintaining the conditions required for the reactions to happen.
Large hadron collider gets back into action, producing almost immediate results

After a hiatus of over three years for maintenance and upgrades, the world’s largest particle accelerator, the large hadron collider (LHC), got back into action in April this year. This marked the beginning of the third run of LHC, when scientists will collect data from an unparalleled number of particle collisions happening at unprecedented energy levels.

The LHC did not take long after starting up again to deliver impressive new science. In July this year, CERN (European Organization for Nuclear Research) announced the discovery of three new exotic particles—a new pentaquark and a pair of new tetraquarks— using the particle accelerator.

Also read |“Everyone wants to look for a signal that goes beyond the standard physics model”: Scientist at Large Hadron Collider

“The newly-discovered pentaquark is still a baryon, but with the three quarks, it has an extra pair consisting of a quark and an anti-quark. The two tetraquarks are within the family of mesons, but instead of having pairs of quarks and anti-quarks, it has two pairs of quarks. These states were predicted in the nominal quark model introduced in the sixties, but these states were not found until now,” said Nicola Neri, a senior member of the LHCb (LHC beauty) experiment, to indianexpress.com at the time.

During its third run, the unrivalled number of collisions in LHC will allow physicists from around the world to study the Higgs boson particle in great detail, while also putting the “Standard model of particle physics” through its most rigorous tests yet.

“Baby wormhole” simulated in a quantum computer

Since they were first proposed by Albert Einstein and Nathan Rosen in 1935, wormholes have remained in the realm of speculative science fiction. Wormholes, or Einstein-Rosen bridges, are theoretical structures that can be considered a tunnel with two ends at different points in space-time. This tunnel could be connecting two points at large or small distances, or two different points in time.

Now, scientists have brought wormholes out of the worlds of “Interstellar” and “Star Trek” and have brought it into this world that we live in. Well, sort of. Researchers at the California Institute of Technology (CalTech) created two simulated black holes in a quantum computer and transmitted a message between them, essentially creating a tunnel in space-time.

While the researchers did not create a rupture in space and time in physical space, it appeared a traversable wormhole was formed based on quantum information “teleported” using quantum codes on the quantum computer.

“There’s a difference between something possible in principle and possible in reality. So don’t hold your breath about sending your dog through the wormhole. But you have to start somewhere. And I think it’s exciting that we can get our hands on this at all,” said Fermilab physicist and study co-author Joseph Lykken to Reuters, at the time.

While it may be a long time before we can send a person, or indeed, their dog, through a wormhole, this research still represents an important breakthrough. Scientists have long pursued a better understanding of these wormholes, and the new research will help them make progress towards that goal.

“Reversing death” by reviving pig cells

From the Greek mythological figure Achilles to the Hindu mythological figure Hiranyakashipu, who was killed by Narasimha, the quest for immortality is a tale as old as time. But new research published in the journal Nature this August by Yale scientists plays with that notion of immortality.

The New York Times reported how scientists pumped a custom-made solution called OrganEx into dead pigs’ bodies using a device similar to the heart-lung machines used in hospitals. As the machine began circulating the solution into the cadavers’ veins and arteries, its brain, heart, liver and kidney cells began functioning again. Also, the cadavers never got stiff, unlike typical dead bodies.

Even though the seemingly dead cells seemed revived, the pigs were not conscious. While this experiment was far off from immortality and actually reversing death, it opens up important questions about the scientific division between life and death.

One of the main goals of the researchers is to increase the supply of human organs for transplant in the future by letting doctors obtain viable organs long after a patient has died. They also hope this technology could be used to prevent severe damage to organs like the heart after a major heart attack or the brain after a stroke.

The OrganEx solution used by researchers consisted of nutrients, anti-inflammatory medications, drugs to prevent cell death, and interestingly, nerve blockers—substances that dampen the activity of neurons and prevent the possibility of the pigs regaining consciousness.

But what if the solution did not contain nerve blockers? Would the brains of the pigs be revived, essentially reanimating them from death? Well, these are questions that the researchers are still yet to answer. But any research in this direction will be burdened by many ethical considerations, apart from the scientific challenges.

Synthetic mouse embryo develops a beating heart

In another scientific breakthrough that will have you questioning what life means, the University of Cambridge and Caltech created an artificial embryo without using any sperm or egg cells. The embryo created using mouse stem cells developed a brain, a beating heart, and the foundations for all the other organs in the body, according to the University of Cambridge.

The stem cells are the body’s master cells and can develop into almost any of the many cell types in the body. The researchers mimicked the natural processes that happen at conception and guided three types of stem cells found in early mammalian development till they began interacting. They established a unique environment for their interactions and got the stem cells to talk to each other.

Due to this, the stem cells organised themselves into structures and progressed through developmental stages until the embryos had beating hearts and the foundations of the brain, along with the yolk sac from which embryos get nutrients in the first weeks. Unlike other synthetic embryos developed in the past, the researchers’ embryos reached the point where the entire brain began to develop.

“Our mouse embryo model develops not only a brain, but also a beating heart, all the components that make up the body. It’s unbelievable that we’ve got this far. This has been the dream of our community for years, and a major focus of our work for a decade, and finally we’ve done it,” said Magdalena Zernicka-Goetz, corresponding author of a research article published in the journal Nature.

This research was carried out on mice, but the researchers hope the technology can be used to develop certain human organ types. This research helps them understand the crucial organ development processes that could not be done with real human embryos. The “14-day rule” in the United Kingdom and other countries prevents scientists from studying human embryos in laboratory conditions.

But further investigating this science could potentially lead to a future where individual human organs can be grown in laboratory settings using stem cells, so that they can be transplanted to a human patient.