Praxis Archives – Page 14 of 181

Bite-sized travels in particle physics

Faszinierende Teilchenphysik is certainly not the first popular book about elementary particle physics, and it won’t be the last. But its unique and clever structure make it stand out.

Think of it as a collection of short stories, organised in 12 chapters covering all ground from underlying theories and technologies to the limits of the Standard Model and ideas beyond it. The book begins with a gentle introduction to the world of particles and finishes by linking the infinitely small to the infinitely large. Each double-page spread within these chapters features a different topic in particle physics, its players, rules of play, tools, concepts and mysteries. Turn a page, and you find a new topic.

Among these 150 spreads, which are referred to as “articles” by the diverse team of authors, the reader can learn about neutrinos, lattice QCD, plasma acceleration, Feynman diagrams, multi-messenger astronomy and much more. Each one manages to convey both the fascination of the subject as well as all the central ideas and open questions within the two allocated pages. This makes for a great way of reading: the article about antimatter, for example, cross-references to the article about baryogenesis, so flip from page 18 to page 304 to dig deeper into the antimatter mystery. Not sure what a baryon is? Check the glossary, then maybe jump on the article about matter and antimatter, CP violation or symmetries. There is no need to read this book from cover to cover. On the contrary, browsing is so deeply embedded in its concept that it even features a flip-book illustration of a particle collision on the bottom right-hand-side of each spread. With a bit more care for captivating illustrations and graphic design, it could pass as a Dorling Kindersley-style travel guide to particle physics.

The authors, who are based at different universities and labs in Germany, have backgrounds covering theoretical and experimental particle physics, astroparticle physics, accelerator and nuclear physics, and science communication. They have obviously put as much thought into this publication as they put in hours, because they manage to write about each topic in a way that is easy to follow, even if it’s hard to digest. Puns, comparisons to everyday life and drawings to accompany the articles make for a full browsing experience, and the references within the text and at the bottom of each page show how everything is connected deep down.

When I received Faszinierende Teilchenphysik for review, one of the authors jokingly accompanied it with the words “this book is meant for retired engineers and for aunts looking for a present for their science-student-to-be nieces.” That may well be the case, but this book’s target audience is much wider. Physics fans and amateurs will enjoy sinking their teeth into a new world of interlinked topics; undergraduates will value it as a quick reference source that is less obscure and more fun to read than Wikipedia; and physics professionals will find it a useful refresher for topics beyond their expertise. The book even dedicates its final article to those questioning whether it is worth spending money and brain power on tiny particles, ending with a passionate case for the many benefits of fundamental research – not just spin-offs such as tumour therapy or artificial intelligence, but in pushing boundaries of knowledge outward.

And if you’re afraid that your school German might let you down, don’t worry: the English edition is already in the works and due to come out in 2024.

Complexity, Entropy and the Physics of Information

“This quantum business is so incredibly important and difficult that everyone should busy himself with it,” wrote Einstein in a 1908 letter, cited by John Wheeler at the workshop “Complexity, Entropy and the Physics of Information” held at the Santa Fe Institute in 1989. More than a century after Einstein’s letter, many fundamental questions connecting physics and information remain unanswered.

The book Complexity, Entropy and the Physics of Information consists of 32 essays capturing the talks given at the Santa Fe workshop. Building on the fundamental work by Claude Shannon, the aim of the workshop was to explore fundamental questions relating to the foundations of quantum theory and quantum information science. Most of the questions raised are still relevant today, as many contributions to this two-volume reprint of proceedings demonstrate.

The workshop started with Wheeler’s famous talk “It from bit”, in which he aimed to “deduce the quantum from existence”. Those remain a guiding principle in the life of a researcher in the field. Indeed, in a talk at the QTML 2023 conference held at CERN, Max Welling (University of Amsterdam) motivated his recent work on “General Message Belief Propagation” for quantum computations using Wheeler’s principle, linking machine-learning models to thermodynamics.

William Wootters’ contribution, on the other hand, builds on the work of John Bell, who showed that quantum mechanics is inherently non-local, i.e. that correlations between spatially separated systems are stronger than what is allowed in a hidden-variable theory. In contrast, Wootter focusses on the locality of quantum mechanics – specifically stating that local measurements on parts of a system and correlations between those measurements allow the state of an ensemble to be determined. Furthermore, Benjamin Schumacher presents his thoughts on the “physics of communication” and discusses the connections between information and entropy. He promotes the idea that “it is not the number of available signals but rather their distinguishability that matters in communication.”

Wojciech Zurek focusses on the implications of a quantum measurement, which converts a collection of possible alternatives to a definite outcome and thus decreases the statistical entropy. In this regard, he discusses the connections between physical and statistical entropy (Shannon entropy) and the algorithmic information content of the data (Kolmogorov complexity). Applications in non-equilibrium systems highlight the fundamental cost of information erasure that was first mentioned by Landauer in 1961.

Charles Bennett asks “what is complexity?” and presents various suitable notions for a “formal measure of complexity” based on computational theory, information theory and thermodynamics. He thus highlights the notion of “logical depth”, which is the execution time needed to generate the object of interest by a near-incompressible universal computer program. The behaviour of complexity measures in dynamical systems exhibiting self-organisation and phase transitions are also discussed.

A noteworthy collection of essays

Tommaso Toffoli explores whether the principles of mechanics are universal and fundamental because they emerge from an extremely fine-grained underlying structure, in which case they would be of mathematical rather than physical origin. This mode of thought is in line with statistical mechanics, where laws emerge due to collective effects in systems with many elements.

In his contribution, Edwin Jaynes focuses on the meaning of probability in quantum mechanics, which he regards not as a “physically real thing” but relevant for quantifying the role of incomplete information and the precision with which a theory is able to predict results. In case of its infiniteness, the theory is unable to predict this quantity and, hence, the uncertainty is infinite. But he stresses that it does not mean that the physical quantity is infinite.

This is just snapshot of the many rich contributions. Besides quantum information theory, the book also touches on cosmology, quantum gravity and dynamical systems. An introduction from Seth Lloyd, who attended the Santa Fe workshop, also provides valuable context to the significance of the proceedings.

Complexity, Entropy and the Physics of Information forms a noteworthy collection of essays linking information, computation and complexity, as well as physics and especially quantum mechanics. As it contains many individual essays grouped thematically, readers may pick out topics based on their own interest. I would recommend this work for anyone who is interested in this area, especially researchers and students working in quantum physics and computational theory.

Bikash Sinha 1945–2023

Bikash Sinha, a pioneer in the field of quark–gluon plasma and the early universe, passed away on 11 August 2023 at the age of 78. His influence on heavy-ion physics is woven into the fabric of not only the ALICE experiment but also the broader field.

Bikash Sinha was born on 16 June 1945 in Kandi, Murshidabad in the state of West Bengal, India. After graduating in physics from Presidency College, Kolkata in 1964, he went to the UK where he completed the natural sciences Tripos course at King’s College, Cambridge in 1967, and then gained a PhD in nuclear physics from the University of London in 1970. He returned to India on invitation from nuclear physicist Raja Ramanna and joined the Bhabha Atomic Research Centre (BARC) in 1976.

In the early 1980s Bikash started working in high-energy physics, particularly relativistic heavy-ion collisions and the formation of quark–gluon plasma. He was appointed director of the Variable Energy Cyclotron Centre in 1987 and held concurrent charge as director of Saha Institute of Nuclear Physics from 1992 to 2009. He received numerous awards and honours, including the Padma Shri Award in 2001 and the Padma Bhusan Award (the third-highest civilian award in the Republic of India) in 2010 for his significant contributions to science and technology. He had also been a member of the scientific advisory council to the Indian prime minister.

As the director of two major institutes in Kolkata, Bikash promoted research in different fields of science. In nuclear and particle physics, his efforts put India on the global map, and he was a strong supporter of the engagement of India with the international community via programmes at CERN. Early on, he broke through scientific bureaucracy to press the need for a multi-agency funding model for the nascent collaborations taking shape for the SPS WA93/WA98 experiments. Subsequently, India’s contributions expanded to the LHC, to RHIC at Brookhaven National Laboratory, and then to FAIR at GSI in Germany.

From modest beginnings in the early 1990s – armed with only a handful of collaborators, students and borrowed equipment, but a grand vision and unbeatable spirit – Bikash nourished and led the Indian team to become a major pillar of ALICE, and of heavy-ion physics more broadly. He embraced every challenge, be it the MANAS chip for the large muon chambers or the photon multiplicity detector, made possible on account of his generous attitude in promoting talents and giving chances to youngsters.

As an individual, Bikash was a synthesis of science, culture, philosophy and society. He initiated the medical cyclotron in Kolkata for the diagnosis and treatment of prostate cancer, and was inspired by the works of the great Indian poet and Nobel Laureate Rabindranath Tagore. In May 2022 he fused his passions for science and art in a one-of-a-kind international conference Microcosmos, Macrocosmos, Accelerator and Philosophy (CERN Courier July/August 2023 p22).

In 1988 Bikash initiated a very successful international conference series on the Physics and Astrophysics of Quark Gluon Plasma, and in 2008 he organised and chaired the annual Quark Matter conference in 2008 held in Jaipur, India. Along the way, his efforts paved the way for India to become one of the most prominent non-member-state participants at CERN, culminating in its accession to associate member in 2017.

While the passing of Bikash leaves an undeniable void, his legacy is a vibrant and thriving team that is primed to continue the journey he embarked upon. We will always remember him for his charismatic personality, great kindness, openness and generosity. We honour his memory, and with deepest condolences we extend our sympathy to his family.

Philippe Bernard 1935–2023

Electrical engineer Philippe Bernard, who made notable technical and managerial contributions across the various sectors at CERN in which he worked, passed away on 10 October 2023.

Born in 1935, Philippe completed his studies at the prestigious Ecole supérieure d’éléctricité in 1956. He began working at CERN in 1962 as engineer-in-charge of the Proton Synchrotron. He went on to design and develop radio-frequency (RF) separators, making substantial contributions to the improvement of these devices that provide well-selected secondary beams. This was particularly important in the early 1970s for experiments with the CERN 2 m hydrogen chamber, the Saclay-built Mirabelle chamber at Serpukhov, and the Big European Bubble Chamber at CERN.

Realising the potential of superconductivity for RF structures, Philippe, together with Herbert Lengeler, was entrusted by CERN Director-General John Adams to develop RF cavities for CERN accelerators in 1978. A vigorous programme with international participation led to the development of five-cell cavities, first made of pure niobium and, later, of niobium sputtered on the more stable copper-substrate to produce robust cavities. This allowed accelerating fields of up to 7 MV/m to be reached.

After tests of prototypes at PETRA (DESY) and the Super Proton Synchrotron, 320 such cavities were produced for the Large Electron-Positron collider (LEP) using niobium-film technology. In the framework of the LEP2 upgrade programme, which started in 1987, these cavities were gradually added to the complement of normal-conducting cavities, which were partially replaced. This enabled an increase in the electron and positron beam energy from 46 GeV in 1989 to 104 GeV by 2000. In addition to this successful development, in the late 1990s Philippe took a strong interest in the design and development of a system of coupled superconducting cavities as a sensitive detector of gravitational waves.

Philippe was also involved in numerous CERN-wide activities, including chairing the purchasing policy monitoring board and serving as president of the CERN health insurance scheme (CHIS). He also served as president and vice-president of the CERN Pensioners’ Association during a critical period.

His open mind, his wide-ranging views and his solid technical knowledge made Philippe a recognised leader. His critical and thoughtful attitude made him a respected discussion partner for the CERN management. Philippe’s commitment to CHIS and to long-term improvements in the social conditions of CERN and ESO staff was widely appreciated and acknowledged. We remember him as a generous, witty and vivacious friend.

New CERNs for a fractured world

Although a brief period of hubris and short-sightedness at the end of the Cold War led some in the West to proclaim “the end of history” and a path to a unified global community, underlying and historically ever-present geopolitical tensions have surfaced again, perhaps as strongly as in the past. At the same time, the past decades have witnessed increased education of talented scientists and technologists across the globe, including in low- and middle-income countries that were once outside the leading science communities. To address the science and technology challenges of our time, we need to find ways to steady the ship to best navigate this changing global scene.

Just as CERN was born out of the ashes of global destruction and disarray – a condition that called for collaboration out of necessity – we propose that the resurgence of nationalism along with pressing challenges such as climate change, disease and artificial intelligence call for stronger scientific communities. At the time of CERN’s founding 70 years ago, European physicists, especially in sub-atomic physics, faced marginalisation. Devastated European countries could not separately fund the “big science” facilities necessary to do cutting-edge research. Moreover, physicists were divided by national loyalties to countries that had been enemies during the war. In the period that followed, it seemed that subatomic research would be dominated by the US and the USSR. Worse, it seemed all too likely that the nationalistic agendas in those nations would push for advances in catastrophic new military technologies.

**Leonard Lynn** is professor emeritus of management policy at Case Western Reserve University. Credit: L Lynn

The creation and operation of CERN in that environment was monumental. CERN brought together scientists from various countries, eventually extending beyond Europe. It greatly advanced basic knowledge in fundamental physics and spun-off practical technologies such as the web and medical equipment. It has also served as a template (greatly underused in our view) for other international science and technology organisations such as SESAME in the Middle East. Today, the challenges for global cooperation in science and technology are different from those facing the founders of CERN. Mostly Western Europeans, with a few US supporters, they shared the discipline of subatomic physics and included Nobel Laureates and other highly respected people who were able to enlist the help of supportive diplomats in the various founding states.

Moment for change

The current geopolitical moment calls forth the need for more CERN-like organisations, just as occurred in that brief post-war moment. New global institutes and organisations to address global problems will have to span a broad range of countries and cultures. They will have to overcome techno-nationalistic opportunism and fears, and deal with potential capture by multinational enterprises (as happened with the response to COVID).

New global institutes and organisations to address global problems will have to span a broad range of countries and cultures

Since its founding, CERN has increasingly shown the ability to cross cultural and political boundaries – most nations of the world have sent scientists to participate in CERN projects, and non-European countries such as India, Pakistan and Turkey are associate members. Some mention the importance of facility cafeterias and other venues where scientists from different countries can meet and have unofficial discussions. CERN has striven to keep decision-making separate from national interests by having a convention that precludes its involvement in military technologies, and by having decisions about projects made primarily by scientists. It has strong policies regarding the sharing of intellectual property developed at its facilities.

**Hal Salzman** is professor of planning and policy at Rutgers University. Credit: H Salzman

CERN’s contributions to basic science and to various important technologies is undisputed. We suggest its potential contributions to the organisation of global science and technology cooperation also deserve greater attention. A systematic examination of CERN’s governance system and membership should be undertaken and compared with the experiences of others. Analysing how the CERN model fits social science-studies of design principles, it is clear that the CERN success brings important additional principles for when the common-pool resources are science and technology, and members come from diverse cultural backgrounds. CERN has addressed issues of bringing together scientists from countries that may have competing techno-nationalistic agendas, providing shelter against not only government but also multinational enterprises. It has focused on non-military technologies and on sharing its intellectual property. It is time that this organisational experience is rolled out for even greater common good.

Leading in collaborations

Are we at the vanguard of every facet of our field? In our quest for knowledge, physicists have charted nebulae, quantified quarks and built instruments and machines at the edge of technology. Yet, there is a frontier that remains less explored: leadership. As a field, particle physics has only just begun to navigate the complexities of guiding our brightest minds.

Large-experiment collaborations such as those at the LHC achieve remarkable feats. Indeed, social scientists have praised our ability to coordinate thousands of researchers with limited “power” while retaining individual independence. Similarly, as we continuously optimise experiments for performance and quality, and there also exist opportunities to refine behaviours and practices to facilitate progress and collective success.

A voice for all

Hierarchies in any organisation can inadvertently become a barrier rather than a facilitator of open idea exchange. Often, decision-making is confined to higher levels, reducing the agency of those implementing actions and leading to disconnects in roles and responsibilities. Excellence in physics doesn’t guarantee the interpersonal skills that are essential for inspiring teams. Moreover, imposter syndrome infects us all, especially junior collaborators who may lack soft-skills training. While striving for diversity we sometimes overlook the need to embrace different personality types, which, for example, can make large meetings daunting for the less outspoken. Good leadership can help navigate these challenges, ensuring that every voice contributes to our collective progress.

Leadership is not management (using resources to get a particular job done), nor is it rank (merely a line on a CV). It is guidance and influence of others towards a shared vision – a pivotal force as essential as any tool in our research arsenal. Good leadership is a combination of strategic foresight, emotional intelligence and adaptive communication; it creates an inclusive environment where individual contributions are not commanded but empowered. These practices would improve any collaboration. In large physics experiments this type of leadership is incidental instead of being broadly acknowledged and pursued.

Luckily, leadership is a skill that can be taught and developed through training. True training is a craft and is best delivered by experts who are not just versed in theory but are also skilled practitioners. Launched in autumn 2023 based on the innovative training approach of Resilient Leaders Elements, a new course “Leading in Collaborations” is tailored specifically for our community. The three-month expert-facilitated course includes four half-day workshops and two one-hour clinics, addressing two main themes: “what I do”, which equips participants with decision-making skills to set clear goals and navigate the path to achieving them; and “who I am”, which encourages participants to channel their emotions positively and motivate both themselves and others effectively. The course confronts participants with the question “What is leadership in a large physics collaboration?” and provides a new framework of concepts. Through self-assessment, peer-feedback sessions, individualised challenges and buddy-coaching, participants are able to identify blind spots and hidden talents. A final assessment shows measurable change in each skill.

The first cohort of 20 participants, displaying a diverse mix of physics experience from various institutions and nationalities, was welcomed to the programme at University College London on 14 and 15 November 2023. More than half of the participants were women – in line with the programme’s aim to ensure that those often overshadowed are given the visibility and support to become more impactful leaders. The lead facilitator, Chris Russell, masterfully connected with the audience via his technical physics background and proceeded to build trust and impart knowledge in an open and supportive atmosphere. When discussing leadership, the initial examples given cited military and political figures; reframing led to a participant’s description of a conductor giving their orchestra space to play through an often-rehearsed tough section as an example of great leadership.

Crucial catalyst

Building on the experience of the first cohort, the aim is to offer the programme more broadly so that we can encourage common practice and change the culture of leadership in large collaborations. Given that the LHC hosts the largest collaborations in physics, the programme also hopes to find a home within CERN’s learning and development portfolio.

The Leading in Collaborations programme is a crucial catalyst in the endeavour to ensure that our precious resources are wielded with precision and purpose, and thus to amplify our collective capacity for discovery. Join the leadership revolution by being the leader you wish you had, no matter your rank. Together, we will become the cultural vanguard!

A bright future for the Higgs sector

The 13th Higgs Hunting workshop, organised in Orsay and Paris from 11 to 13 September 2023, was a timely opportunity to gather theorists and experimentalists interested in recent results related to the Higgs sector. While the large 140 fb^–1 dataset collected by the ATLAS and CMS experiments during LHC Run 2 is still being exploited to measure the Higgs-boson properties in more detail, the first results based on Run 3 data collected since 2022 were also shown, along with searches for phenomena beyond the Standard Model.

Experimental highlights focused on the latest results from CMS and ATLAS. CMS presented a new measurement of the associated production of a Higgs boson with top quarks decaying into b quarks, while ATLAS showed a new measurement of the associated production of a vector boson and a boosted Higgs boson in fully hadronic final states. A major highlight was a new CMS measurement of the Higgs-boson mass in the four-lepton decay channel, reaching the highest precision to date in a single decay channel as well as placing indirect constraints on the Higgs-boson width. Precision measurements were also shown in the framework of effective field theory, which allows potential subtle deviations with respect to the Standard Model to be probed. A small number of intriguing excesses observed, for instance, in the search for partners of the Higgs boson decaying into W-boson or photon pairs were also extensively discussed.

Following a historical talk on the “long and winding road” that led particle physicists from LEP to the discovery of the Higgs boson by Steve Myers, who was CERN director of accelerators and technology when the LHC started up, a dedicated session discussed Higgs-physics prospects at colliders beyond the High-Luminosity LHC (HL-LHC). Patrizia Azzi (INFN Padova) presented the experimental prospects at the proposed Future Circular Collider, and Daniel Schulte (CERN) described the status of muon colliders, highlighting the strong interest within the community and leading to a lively discussion.

The latest theory developments related to Higgs physics were discussed in detail, starting with state-of-the-art predictions for the various Higgs-boson production modes by Aude Gehrmann-De Ridder (ETH Zurich). Andrea Wulzer (CERN) overviewed the theory prospects relevant for future collider projects, while Raffaele Tito D’Agnolo (IPhT, Saclay) presented the connections between the properties of the Higgs boson and cosmology and Arttu Rajantie (Imperial College) focused on implications of the Higgs vacuum metastability on new physics. Finally, a “vision” talk by Matthew McCullough (CERN) questioned our common assumption that the Higgs boson discovered at the LHC is really compatible with Standard Model expectations, considering the current precision of the measurements of its properties.

During several experimental sessions, recent results covering a wide range of topics were presented – in particular those related to vector-boson scattering, since their high-energy behaviour is driven by the properties of the Higgs boson. The Higgs-boson self-coupling was another topic of interest. The best precision on this measurement is currently achieved by combining indirect constraints from processes involving a single Higgs boson together with direct searches for the rare production of a Higgs-boson pair. While the Run 3 data set will provide an opportunity to further improve the sensitivity to the latter, its observation is expected to take place towards the end of HL-LHC operations. Finally, Stéphanie Roccia (LPSC) presented the implications of experimental measurements of the neutron electron dipole moment on the CP-violating couplings of the Higgs boson to fermions, absent in the Standard Model. Concluding talks were given by Massimiliano Grazzini (University of Zurich) and Andrea Rizzi (University and INFN Pisa). The next Higgs Hunting workshop will be held in Orsay and Paris from 23 to 25 September 2024.

Golden anniversaries in Spain

The golden jubilees of the International Meeting on Fundamental Physics (IMFP23) and the National Centre for Particle Physics, Astroparticles and Nuclear Physics (CPAN) Days were celebrated from 2 to 6 October 2023 at Palacio de la Magdalena in Santander, Spain, organised by the Institute of Physics of Cantabria (IFCA). More than 180 participants representing the entire Spanish community in these disciplines, together with several international researchers, convened to foster cooperation between Spanish research groups and identify key priorities.

The congress started with parallel meetings on LHC physics, astroparticle physics, nuclear physics and theoretical physics. Two extra sessions were held, one covering technology transfer and the other discussing instrumentation R&D aimed at supporting the HL-LHC, future Higgs factories, and other developments in line with the European strategy for particle physics. The opening ceremony was followed by a lecture by Manuel Aguilar (CIEMAT), who gave an overview of the past 50 years of research in high-energy physics in Spain and the IMFP series. The first edition, held in Formigal (Spanish Pyrenees) in February 1973, was of great significance given the withdrawal of Spain from CERN in 1969, which put high-energy physics in Spain in a precarious position. The participation of prestigious foreign scientists in the first and subsequent editions undoubtedly contributed to the return of Spain to CERN in 1983.

LHC physics was one of the central themes of the event, in particular the first results from Run 3 as well as improvements in theoretical precision and Spain’s contribution to the HL-LHC upgrades. Other discussions and presentations focused on the search for new physics and especially dark-matter candidates, as well as new technologies such as quantum sensors. The conference also reviewed the status of studies related to neutrino oscillations and mass measurements, as well as searches for neutrinoless double beta decay and high-energy neutrinos in astrophysics. Results from gamma-ray and gravitational-wave observatories were discussed, as well as prospects for future experiments.

The programme included plenary sessions devoted to nuclear physics (such as the use of quantum computing to study the formation of nuclei), QCD studies in collisions of very high-energy heavy ions and in neutron stars, and nuclear reactions in storage rings. New technologies applied in nuclear and high-energy physics and their most relevant applications, especially in medical physics, complemented the programme alongside an overview of observational cosmology.

Roundtable discussions focused on grants offered by the European Research Council, R&D strategies and, following a clear presentation of the perspectives of future accelerators by ECFA chair Karl Jacobs (University of Freiburg), possible Spanish strategies for future projects with the participation of industry representatives. The congress also covered science policy, with the participation of the national programme manager Pilar Hernández (University of Valencia).

Prior to the opening of the conference, 170 students from various schools in Cantabria were welcomed to take part in an outreach activity “A morning among scientists” organised by IFCA and CPAN, while Álvaro de Rújula (University of Boston) gave a public talk on artificial intelligence. Finally, an excellent presentation by Antonio Pich (University of Valencia) on open questions in high-energy physics brought the conference to a close.

Widening Balkan bridges in theory

Twenty years ago, the participants of the UNESCO-sponsored Balkan Workshop BW2003 in Vrnjačka Banja, Serbia came to a common agreement on the creation of the Southeast European Network in Mathematical and Theoretical Physics (SEENET-MTP). The platform for the network was provided by the 1999–2003 Julius Wess initiative “Wissenschaftler in Global Verantwortung” (WIGV), which translates to “scientists in global responsibility”. Starting with a focus on the former Yugoslavia, WIGV aimed to connect and support individual researchers, groups and institutions from all over the Balkan region. The next natural step was then to expand the WIGV initiative to bridge the gap between the southeast region and the rest of Europe. Countries to the east and south of former Yugoslavia – such as Bulgaria, Greece, Romania and Turkey – have a reasonably strong presence in high-energy physics. On the other hand, they share similar economic and scientific problems, with many research groups facing insufficient financing, isolation and lacking critical mass.

The SEENET–MTP network has since grown to include 24 institutions from 12 countries, and more than 450 individual members. There are also 13 partner institutions worldwide. During its 20 years of existence, the network has undertaken: more than 20 projects; 30 conferences, workshops and schools; more than 360 researcher and student exchanges and fellowships; and more than 350 joint papers. Following initial support from CERN’s theoretical physics department, a formal collaboration agreement resulted in the joint CERN–SEENET–MTP PhD training programme with at least 150 students taking part in the first two cycles from 2015 to 2022. Significant support also came from the European Physical Society and ICTP Trieste, and the third cycle of the PhD programme will start in June 2024 in Thessaloniki, Greece.

Networking is the most promising auxiliary mechanism to preserve and build local capacity in fundamental physics in the region

Unfortunately, the general focus on (Western) Balkan states has shifted during the past few years to other parts of the world. However, networking is the most natural and promising auxiliary mechanism to preserve and build local capacity in fundamental physics in the region. The central SEENET-MTP event in this anniversary year, the BWXX workshop held in Vrnjačka Banja from 29 to 31 August 2023, marked the endurance of the initiative and offered 30 participants an opportunity to consider topics such as safe supersymmetry breaking (B Bajc, Slovenia), string model building using quantum annealers (I Rizos, Greece), entropy production in open quantum systems (A Isar, Romania), advances in noncommutative field theories and gravity (M Dimitrijević Ćirić, Serbia), and the thermodynamic length for 3D holographic models and optimal processes (T Vetsov, Bulgaria).

A subsequent meeting held during an ICTP workshop on string theory, holography and black holes from 23 to 27 October 2023, partially supported by CERN, invited participants to brainstorm about future SEENET–MTP activities – the perfect setting to trace the directions of this important network’s activity in its third decade.

Machine-learning speedup for HL-LHC

The fourth edition of the Fast Machine Learning for Science Workshop was hosted by Imperial College London from 25 to 28 September 2023, marking its first venture outside the US. The series was launched in response to the need for microsecond-speed machine-learning inference for the High-Luminosity LHC (HL-LHC) detectors, in particular in the hardware trigger systems of the ATLAS and CMS experiments. Achieving this level of speed requires non-standard and generally custom hardware platforms, which are traditionally very challenging to program. While machine learning is becoming widespread in society, this ultrafast niche is not well served by commercial tools. Consequently, particle physicists have developed tools, techniques and an active community in this area.

The workshop gathered almost 200 scientists and engineers in a hybrid format. Students, including undergraduates, and early-career researchers were strongly represented, as were key industry partners. A strong aim of the conference was to engage scientific communities outside particle physics to develop areas where the tools and techniques from particle physics could be game-changing.

The workshop focused on current and emerging techniques and scientific applications for deep learning and inference acceleration, including novel methods for efficient algorithm design, ultrafast on-detector inference and real-time systems. Acceleration as a service, hardware platforms, coprocessor technologies, distributed learning and hyper-parameter optimisation. The four-day event consisted of three workshop-style days with invited and contributed talks, and a final day dedicated to technical demonstrations and satellite meetings.

The tools and techniques from particle physics could be game-changing

The interdisciplinary nature of the workshop – which encompassed particle physics, free electron lasers, nuclear fusion, astrophysics, computer science and biology – made for a varied and interesting agenda. Attendees heard talks on how fast machine learning is being harnessed to speed up the identification of gravitational waves, and how it is needed to handle the high data rates and fast turnaround of experiments at free-electron lasers. In the medical arena, speakers addressed the need for faster image processing and data analysis for diagnosis and treatment, and the use of fast machine learning in biology to search for known and unknown features in large, heterogeneous datasets. The use of machine learning in control systems and simulations was discussed in the context of laser-driven accelerators and nuclear-fusion experiments, while in theoretical physics the application of machine learning to solve the electron wave equation in condensed matter, working towards a detailed and fundamental understanding of superconductivity, was presented.

Industry partners including AMD, Graphcore, Groq and Intel discussed current- and future-generation hardware platforms and architectures, and facilitated tutorials on their development toolchains. Researchers from Groq and Graphcore presented their latest dedicated chips for artificial-intelligence applications and showed that they have interesting applications to problems in particle physics, weather forecasting, protein folding, fluid dynamics, materials science and solving partial differential equations. AMD and Intel demonstrated the flexibility of their FPGA platforms and explained how to optimise them for scientific machine-learning applications.

A highlight of the social programme was a public lecture from Grammy Award-winning rapper Lupe Fiasco, who discussed his work with Google on large-language models. The workshop will return to the US next year, before landing in Zurich in 2025.

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Moment for change

A voice for all

Crucial catalyst