Strongly intriguing details of collisions at extreme energies

Peer-Reviewed Publication

THE HENRYK NIEWODNICZANSKI INSTITUTE OF NUCLEAR PHYSICS POLISH ACADEMY OF SCIENCES

 

IMAGE: CHILDREN'S INTELLIGENCE MAY APPEAR TO BE STATISTICALLY RELATED TO THEIR WEIGHT BECAUSE THE RELATIONSHIP IS SENSITIVE TO AGE FLUCTUATIONS WITHIN THE STUDY GROUP. A SIMILAR PHENOMENON OCCURS IN THE CASE OF THE CORRELATION VARIABLE SIGMA AND THE CENTRALITY OF HEAVY ION COLLISIONS IN THE LHC ACCELERATOR. view more 

CREDIT: SOURCE: IFJ PAN

Cracow, 14 September 2023

 

 

Strongly intriguing details of collisions at extreme energies

 

 

The initial phases of the heavy-ion collisions occurring at the maximum energies available at the CERN Large Hadron Collider continue to remain an enigma of modern nuclear physics. New theoretical tools improved by physicists from the Institute of Nuclear Physics of the Polish Academy of Sciences in Cracow will help to unlock this mystery.

 

 

The phenomena occurring during nuclear collisions are so fast and involve particles so small that they cannot be observed directly. Guessing the course of these sorts of processes resembles the work of a detective. Just as he is unable to observe the crime being committed and has to reconstruct an image of it based on witness statements, physicists try to reconstruct the course of nuclear phenomena on the basis of “accounts” given by the secondary particles born in collisions and recorded by detectors. Sherlock Holmes’s task, however, was much easier – he could talk freely to his witnesses, whereas physicists can only observe the particles’ behaviour. In order to reconstruct the actual course of the “crime” (the collisions of atomic nuclei), they have to create a suitable language for describing events (mathematical tools) and use it to recount what took place (with the help of a theoretical model of the phenomenon), and then compare whether the “testimony” thus obtained agrees with what the recorded particles appear to “say”.

 

Particularly difficult processes to study include phenomena occurring in the early stages of heavy-ion collisions in the LHC accelerator, when a quark-gluon plasma may be formed. This is a state of matter in which quarks and gluons behave like free particles (in the world around us, quarks and gluons are always bound by the strong interactions and remain inside hadrons, i.e. protons or neutrons). The quark-gluon plasma ends extremely quickly because it cools as it expands. Quarks and gluons are then trapped again in hadrons, creating secondary particles that are registered in detectors. It can be concluded whether a quark-gluon plasma was created by analyzing the so-called forward-backward correlations between particles produced in collisions.

 

“Forward-backward correlations measure the relationship between the number of particles produced forward and backward when beams of heavy ions collide. Although these correlations concern particles very far apart, they carry information about the early stage of the collision. This is because the correlations between the particles emitted forward and backward could only have formed before the particles moved away from each other, i.e. at the beginning of the collision!” says Dr. Iwona Sputowska of the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow, a physicist who is a member of the ALICE scientific collaboration at the LHC.

 

The problem with correlations, however, is that, used incompetently, they can lead to false conclusions. Suppose, for example, we conduct a study of children's intelligence in all the forms of a primary school. A correlation might then be found whereby the more intelligent a child is, the more they... weigh. However, we know that in reality intelligence and weight are correlated to another variable: the age of the child. So if we narrow down our study to children of the same age, the correlation between their intelligence and weight drops dramatically. The correlation between intelligence and weight is therefore sensitive to age fluctuations in the group of children – there are a lot of children of different ages in the whole school, but within the same form the age differences are small.

 

We encounter an analogous challenge when examining correlations in heavy ion collisions. The relationship between the number of particles produced forward and backward is sensitive to fluctuations in the way the two atomic nuclei collided with each other, such as whether they collided centrally or just brushed against each other. To deal with this problem, the concept of strongly intensive variables was introduced. These quantities are defined so that they depend neither on how the two ions collided with each other nor on how much the geometry of the collision fluctuated in the group of studied events.

 

A strongly intensive correlation variable is sigma. It was intended to provide information about the way in which the average source produces secondary particles. However, while analyzing data collected in the collisions of lead-lead and xenon-xenon nuclei as part of the ALICE experiment, Dr. Sputowska noticed that none of the most popular models used to describe these phenomena corresponds to the behavior of the sigma variable.

 

“There could only be one conclusion. Since our models do not correctly describe the experimental data for the highest-energy collisions available at the LHC, it means that we are incorrectly modelling how the average source produces secondary particles,” says Dr. Sputowska.

 

Unexpectedly, collision models proposed over 45 years ago by theoreticians from Cracow turned out to be helpful in understanding the behavior of sigma. They treated collisions of heavy atomic nuclei as multiple collisions of single nucleons of one nucleus with single nucleons of the other nucleus (in the wounded nucleon model) or as collisions not of protons and neutrons, but of quarks (in the wounded quark model). In these models, it is assumed that single, independent sources are responsible for the production of secondary particles, which are either nucleons or quarks, respectively.

 

Previous models have assumed that the average source generates secondary particles with the same forward and backward probabilities. Sigma, by definition, should then be equal to one. It turns out that its actual dependance on the geometry of collision can be reproduced if one allows for the possibility that the average source emits particles forward with a slightly different probability than backward. In the wounded nucleon model, an extra term then appears in the sigma formula, depending on the collision geometry, and sigma ceases to be a strongly intensive variable.

 

However, this situation gives rise to an intriguing contradiction, for sigma loses its status as a strongly intensive variable and yet correctly describes experimental data that do not depend on changes in collision geometry. Why? The solution to the problem turned out to be in the fact that in the wounded source model sigma always gives the values of the forward-backward correlation for the average number of wounded nucleons/quarks, i.e. for the average collision geometry in a given collision group. This situation can be compared to measuring the correlation between intelligence and weight of children in a group where the average age of the child is fixed.

 

“A detailed understanding of the nature of sigma allowed us to determine the fragmentation function, linking the number of particles produced by nucleons in the model with the number of particles measured in the detectors. For the first time, for the highest collision energies at the LHC, we have been able to construct tools that allow us to reliably falsify this highly intriguing sigma behaviour,” Dr. Sputowska concludes.

 

Dr Sputowska's achievement is presented in a paper published in the journal Physical Review C. The research was funded by the 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:

 “Forward-backward correlations with the Σ quantity in the wounded-constituent framework at energies available at the CERN Large Hadron Collider”

I. A. Sputowska

Physical Review C 108, 1, 014903,  2023

DOI: 10.1103/PhysRevC.108.014903

 

 

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:

 

IFJ230914b_fot01s.jpg

HR: http://press.ifj.edu.pl/news/2023/09/14/IFJ230914b_fot01.jpg

Children's intelligence may appear to be statistically related to their weight because the relationship is sensitive to age fluctuations within the study group. A similar phenomenon occurs in the case of the correlation variable sigma and the centrality of heavy ion collisions in the LHC accelerator. (Source: IFJ PAN)

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JOURNAL

Physical Review C

DOI

10.1103/PhysRevC.108.014903 

ARTICLE TITLE

Forward-backward correlations with the Σ quantity in the wounded-constituent framework at energies available at the CERN Large Hadron Collider

 

Bielefeld researchers using European supercomputers

Researchers at Bielefeld University have landed computing time on European supercomputers LUMI-G and Leonardo.

Grant and Award Announcement

BIELEFELD UNIVERSITY

Supercomputers are often indispensable in modern scientific research: they are an essential tool for processing the ever-increasing volumes of data needed for statistics, forecasts, and other calculations across a wide range of disciplines.
The collaborative ‘European High Performance Computing Joint Undertaking’ (https://eurohpc-ju.europa.eu) project has invested a great deal of funding into the construction of new European flagship supercomputers over the past years. Since June 2023, the supercomputers ‘LUMI’ in Finland and ‘Leonardo’ in Italy came in third and fourth place in the global ranking of the 500 most powerful supercomputers around the globe. First place is currently held by the ‘Frontier’ supercomputer in the United States, and second by ‘Fugaku’ in Japan.

As responsible project leads for an international team of scientists, Bielefeld researchers Dr. Olaf Kaczmarek and Dr. Christian Schimdt-Sonntag were successful in the first round of a call for applications for computing time on these systems. The won out over myriad competitors from around the world in a rigorous application review process and have now been allocated 60 mil-lion core hours on LUMI-G and 22 million core hours on Leonardo – corresponding to the annual computing power of 20,000 and 6,000 laptops, respectively. This computing time will facilitate their research, which investigates the properties of matter under extreme conditions.

This research into extreme conditions of matter deals with temperatures and particle densities that are, for instance, believed to have been present in our universe shortly after the Big Bang, but also with temperatures and particle densities similar to those produced and measured in heavy ion experiments in the Large Hadron Collider (LHC) at the ‘CERN’ European Organisation for Nuclear Research in Geneva, Switzerland, and in the Relativistic Heavy Ion Accelerator (RHIC) at the Brookhaven National Laboratory (BNL) in Long Island, New York. These research projects are part of the Collaborative Research Centre TransRegio 211, ‘Strong-Interaction Matter under Extreme Conditions’ (https://crc-tr211.org/), which brings together researchers from the Goethe University Frankfurt, Bielefeld University, and the Technical University of Darmstadt.
As members of the North Rhine-Westphalian Competence Network for High-Performance Computing (HPC.NRW), a consortium that was recently extended through the end of 2025, Olaf Kaczmarek and Christian Schmidt-Sonntag provide support to Bielefeld researchers and their projects at the Bielefeld GPU Cluster, and also offer advice on how to apply for computing time at other supercomputers in the region, namely in Germany and Europe.  

For more information, please see:

•    SIMULATEeQCD: https://doi.org/10.5281/zenodo.7994982
•    BNL News zum Projekt über schwere Quarks: https://www.bnl.gov/newsroom/news.php?a=121223
•    PUNCH4NFDI: https://www.punch2nfdi.de
•    HPC.NRW: https://hpc.dh.nrw/de/
 

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METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

Disclaimer: AAAS and Eure

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