Praxis Archives – Page 15 of 179

Going where the crowd is

Summer means holidays, beaches, long evenings outside and, for many, attending an outdoor festival. Music festivals in particular have expanded all over the world, and the competition to offer new experiences to curious festival goers has created opportunities to share CERN’s work and science with this untapped audience, many of whom never normally go to science events. Based on the success of CERN’s first Science Pavilion at Peter Gabriel’s world music festival WOMAD in 2016, the project has grown to become a highly successful outreach effort known as the CERN Festival Programme. The generally three-day programme offers a variety of shows, presentations, talks and hands-on workshops tailored to each country and demographic. The Pavilions are a real collaboration, a partnership between CERN, collaborating institutes in each country and the festival itself, each sharing costs and person power.

In 2019, four Science Pavilions were held in four different music and culture festivals in four different countries: the Big Bang Stage at the Ostrava festival in the Czech Republic, produced in partnership with Charles University and the Czech Technical University; the Magical Science Pavilion at the Pohoda Festival in Slovakia – an incredible space produced with Comenius University; the World of Physics at WOMAD in the UK, going strong year after year thanks to an enduring collaboration with Roger Jones of Lancaster University; and the Science Pavilion at the Roskilde Festival in Denmark, a highly successful relationship with Jørgen Beck Hansen at the Niels Bohr Institute in Copenhagen. More than 20,000 people came to the four spaces in 2019!

Workshops give people a chance to interact in a direct way with science and technology, as well as with physicists working on different experiments at CERN. They often can’t believe that these people who work for CERN have actually come to the festival to talk to them. A variety of topics are covered ranging from what’s new in physics to technological and scientific advances in the news that touch on people’s everyday lives, such as artificial intelligence. For 2023 we introduced a successful “scientific speed dating” with the young audience at Roskilde. A talk from CERN’s director for accelerators and technology Mike Lamont on physics and medicine and an informal “Chat with the AI experts” in the sunshine also proved incredibly popular at WOMAD this year. Between 4000 and 6000 people come to each Science Pavilion in each festival every year. Requests for new collaborations in other countries are coming in, and as a result there are currently ongoing discussions for Pavilions at festivals in the Netherlands and Spain. Physicists love the idea and their students are always an important asset to the event, with the most forward-thinking institutes keen to be part of the programme.

The feedback from visitors is clear: people love finding science at a music festival. The fact that the science is taken to them, where they are at their most comfortable, relaxed and receptive to new things, is key to the programme’s success. Comments range from “It’s a welcome break to sit in a cool space and learn something interesting and talk about stuff other than drinking and partying” to “I never liked science at school, I found it so boring and complicated, but here you make it fun and I’ve come back every year, I love it!”.

Recently, the Festival Programme was approved to be part of the CERN and Society Foundation. This means that an individual wishing to support this fantastic form of outreach and communication, or a company that understands the benefit of the programme and would like to have their logo at the festival next to ours, can now do so. It’s a great opportunity to reach new audiences, and especially to engage in those countries whose people are actually funding CERN.

Physicists go direct

As recently as 10 years ago, scientists had to work hard to convince conference organisers of the value of sessions on communication, education and outreach. Today, major conferences such as ICHEP, EPS-HEP and LHCP not only offer parallel sessions, but also plenary talks where the state of the art in the field is reviewed. Abstracts from around the world describe events organised in multiple contexts and languages, via formal and informal partnerships between scientists and local communities, artists, teachers and many others. Each of the major LHC experiments now has a dedicated outreach group that, with the help of a few professional communicators, develops material and shares best practice within the collaboration. Institutes and funding agencies are on board, and younger generations are increasingly encouraged to include outreach on their CVs. A fraction of this energy and creativity is captured in reports, such as the one presented each year to the CERN Council by the International Particle Physics Outreach Group (IPPOG) – a collaboration initiated by former CERN Director-General Chris Llewellyn-Smith in the early days of the LHC project, and that now counts 33 countries, seven experiments and three large laboratories.

Reaching out to the world

Workshops and hands-on activities have multiplied in recent years. Cloud-chamber building is one of the most popular, and is used by a growing number of institutes when they host students for a day. Created in 2005, the International Masterclasses programme brings another level of activity, offering guests the chance to analyse data from contemporary experiments with direct help from the physicists involved. Each year, more than 10,000 teachers and 15–19-year-old students have been given this opportunity. Initially organised in the EU time zone with a scientist at CERN, the programme now also runs in US and Japanese time zones. The range of analyses offered encompasses the four LHC experiments, Belle II, particle therapy, the Pierre Auger cosmic-ray detector and neutrino experiments in the US. During the pandemic, masterclasses were made available online, and the tools developed now help to reach people in countries and regions that do not yet have any high-energy physics institutes.

The large number of CERN visitors is proof of public interest in face-to-face interactions. But what about those who can’t come in person? What about teachers who want to inspire their students by inviting a scientist into their classrooms? Or institutes that would like to show a detector their teams have built and where the data come from? Pioneered by ATLAS in 2010, the LHC experiments virtual-visit programme breaks down geographical barriers. Thanks to a video conference tool, a scientist working on an experiment can walk audiences through underground installations or control rooms, the diversity of international-collaboration members offering a wide range of languages to let the public meet and engage with “one of theirs”. The most important part of the event is a lengthy Q&A session, which has allowed tens of thousands of children and adults to share the scientific experience.

Coming together

Organised by interactions.org, a network that groups the communications activities of the world’s particle-physics labs, Dark Matter Day offers a scientific twist to Halloween. Since 2017, more than 350 global, regional and local events have been held on and around 31 October. Institutions and individuals engage the public in discussions about what is known and what mysteries experiments are seeking to solve. International Cosmic Day, where students, teachers and scientists come together to talk and learn about cosmic rays, follows each November. Activities range from the construction of a detector to data analysis, and the coordination of such events is kept light, to let the primary actors – the scientists who proposed and built the 17 presently listed activities – be as creative and engaged as they are in everyday life. As with all community-driven outreach activities, that authenticity is hard to beat.

Empowering children to aspire to science

The new labs and exhibitions in Science Gateway offer children as young as five and eight, respectively, the opportunity to have fun with science. Why would CERN target such young audiences? And what CERN-related content could possibly be accessible to such an age group?

CERN has traditionally tailored education and outreach material predominantly towards high-school students, in particular those already expressing an interest in science. For this age group, it is relatively easy to find overlaps between school curricula and work at CERN. Such visitors will continue to find engaging content in our exhibitions. However, if CERN is to connect to a broader section of the public and attract a more diverse cohort of future scientists, it needs to reach out beyond existing science fans, attracting younger audiences before stereotypes set in.

Positive contacts

Over the decades, communication best-practice has evolved from the idea that to inspire children to choose a career in science, you just need to make it sound interesting. Now, it is recognised that there are multiple factors influencing choice. The Aspires research project at University College London, for example, has highlighted the importance of “science capital”, a notion based on the variety of positive contacts with science that children experience. This includes knowing people who work in science, talking with family and friends, doing science-based activities outside school and there being a generally positive attitude towards science within the family setting.

At schools, careers information often comes once choices to drop science subjects have already been made. And without role models to identify with, or contact with science or science-related professions through family and friends, it can be extremely difficult for some students to imagine themselves as future scientists. Hence the drop in pupils expressing such aspirations from the end of primary education onwards that occurs in many countries. By offering younger students the opportunity to experiment and play in a scientific environment, Science Gateway seeks to counter this drop. In addition to the existing science-fan visitors, it aims to reach those with less science capital at home, so that children can discover new opportunities.

There is a slogan in the exhibitions world: “hands on, minds on”. A good exhibit creates memorable experiences that empower visitors to explore and engage, rather than simply transmitting knowledge in a unidirectional way. Science Gateway offers activities – such as designing a detector or collaborating to lower equipment into a cavern – where children are encouraged to think logically, and exhibits that encourage them to make their own deductions, helping them to become more confident that science is for them. Here the exhibition guides play a key role in encouraging interaction and play.

Sometimes in a hands-on science centre, one can have the impression that children are having so much fun racing from exhibit to exhibit that there is no valid experience. This is countered by research which shows that learning comes in a broad variety of forms. Informal learning experiences, such as those at Science Gateway, can have just as much impact as in-school learning.

The exhibitions offer a variety of different environments – playful areas and beautiful spaces, including artworks, that can be enjoyed by simply sitting back and reflecting. The exhibitions team has also collaborated with community groups to develop tactile content and ensure the exhibits are accessible to wheelchair users. Not all exhibits will be accessible for younger children, or for the visually impaired, but throughout there is a spread of different experiences that give something for everyone to enjoy.

The ambition is for CERN to become a popular destination for a fun day out, attracting a broad section of the public, both those who might one day become scientists themselves and those who might never choose that path, but who are curious to explore the new buildings that have popped up in their local area. Successful outcomes can be as simple as visitors having fun in a scientific environment. This is a first step towards being open to scientific ideas and methods – a valid goal in today’s world of misinformation and distrust, where science is sometimes talked of as something you might or might not choose to believe in.

Hands on, minds on, goggles on!

In 1826, the Swiss pedagogue and educational reformer Johann Heinrich Pestalozzi advocated for a natural and meaningful education through a holistic learning approach that engaged “the hands, head and heart”. One prime example of such an approach is found in science education, where experiments allow learners to experience scientific phenomena while manipulating ideas about experiments in their minds. Experiments are also associated with high affective value, as school students generally enjoy practical tasks and often rank them as preferred learning activities in school. As a result, experiments have long been considered an essential part of teaching the nature of science, and only very few science educators have questioned their necessity.

Consequently, it was long overdue for CERN to offer opportunities for visiting high-school students to get hands-on with particle physics. In 2014, CERN inaugurated its first particle-physics learning laboratory for high-school students. During its eight years of operations, “S’Cool LAB” gave nearly 40,000 visitors a unique opportunity to make discoveries independently, work scientifically and gain insight into modern science in the making.

A major factor in S’Cool LAB’s success was its connection to the latest thinking in physics education research. Interestingly, learning from hands-on experiments is (still) one of the central problems of physics education research. Even though students often enjoy doing experiments, various factors influence what and how much students learn from the exercise. To address this research gap, educational activities at S’Cool LAB were continually developed and improved through accompanying physics education research projects. For example, experimental tasks were designed to challenge scientifically inaccurate mental models (such as bar magnets having electrically charged poles) by allowing students to compare their predictions with surprising observations and thus foster conceptual understanding. Moreover, empirical research carried out based on questionnaires from students before and after taking part in lab workshops confirmed significant positive effects on high-school students’ interest in physics and their beliefs in their physics-related capabilities, and a surprisingly high correlation between these affective outcomes and students’ perceived level of cognitive activation. Remarkably, girls benefited more from S’Cool LAB with respect to their interest and self-beliefs. Consequently, the initial gender gap (with girls reporting slightly lower interest and self-beliefs than boys) was closed.

New incarnation

On 12 January 2023, excavators arrived to dismantle S’Cool LAB to make space for the new educational labs at CERN Science Gateway. Several considerations went into the design of the new labs. Firstly, they have a broader scope, catering not only to high-school students and their teachers but also to school students as young as five, as well as the general public. Indeed, Science Gateway offers regular workshops open to individual visitors, tourists and families. Moreover, workshops are adapted to different age groups and cover many different topics such as engineering challenges, different technologies, detection principles, or medical applications of particle physics. This diversity allows for better adaptation to the needs of students and teachers, who often prefer workshops that can be easily integrated into their science curriculum.

Observing cloud chambers at S’Cool LAB — **Lofty learning** High-school students observing cloud chambers at S’Cool LAB, which was dismantled in 2023 to make way for new educational labs at CERN Science Gateway. Credit: 2016–2023 CERN, Jeff Wiener

When designing labs for young learners, a critical choice involves balancing the level of openness and guidance. While open exploration is considered to be the ideal form of experimentation, young students can feel overwhelmed by the choices involved in developing research questions, experiment design and the interpretation of evidence. At the same time, giving students a choice in their learning can foster a sense of ownership and autonomy, leading to increased engagement and motivation to explore topics of personal interest. Providing the right level of guidance and support is therefore crucial to meaningful experimentation and a key element of the education labs at Science Gateway. It helps students enjoy hands-on activities while freeing up mental capacity to process new information effectively. To help teachers prepare their students for the new lab workshops, they now receive detailed information about its planned content and suggestions on how to integrate their experience at CERN into their classroom practice.

The impact of volunteers on students’ interest and self-beliefs was a striking result from physics education research at S’Cool LAB

Despite the variety of lab workshops offered, all activities are anchored in authentic CERN contexts and can even be linked to real objects and authentic equipment in the interactive exhibitions at Science Gateway. This approach helps foster students’ interest in science and provides them with an accurate image of science and scientists. For instance, one lab workshop for students aged 8–15 – the “Power of Air” – allows students to use 3D-printed components and toy balloons to investigate balloon hovercrafts on different surfaces, drawing connections with how engineers at CERN move massive slices of the LHC detectors via air pads.

Community input

To enhance the authenticity of lab workshops, volunteers from CERN’s scientific community accompany students during their learning process and engage in discussions about their findings. The impact of volunteers on students’ interest and self-beliefs was a striking result from physics education research at S’Cool LAB. Students were inspired by the enthusiasm displayed by their guides and appreciated the opportunity to ask questions in an enjoyable learning atmosphere. Therefore, the education labs at Science Gateway will continue to rely on volunteers to facilitate workshops and inspire the next generation of engineers and scientists. To address new challenges related to groups of very young learners, heterogeneous audiences, the diverse collection of lab workshops and the high volume of workshops held each year, a team of professional science educators provides continuous support and guidance to volunteers.

In conclusion, the educational labs at CERN Science Gateway have been designed to provide a wide range of hands-on learning experiences for learners of all ages. These labs aim to not only promote scientific understanding but also foster curiosity, interest and positive self-beliefs in students, empowering them to explore the world of science by demonstrating that science is for everyone.

Henri Navelet 1938–2023

Henri Navelet died on 3 July 2023 in Bordeaux, at the age of 84. Born on 28 October 1938, he studied at the École Normale Supérieure in Paris. He went on to become a specialist in strong interactions and was a leading member of the Service de Physique Théorique (SPhT, now Institut de Physique Théorique) of CEA Saclay since its creation in 1963. Henri stood out for his theoretical rigour and remarkable computational skills, which meant a great deal to his many collaborators.

In the 1960s, Henri was a member of the famous “CoMoNav” trio with two other SPhT researchers, Gilles Cohen-Tannoudji and André Morel. The trio was famous in particular for introducing the so-called Regge-pole absorption model into the phenomenology of high-energy (at the time!) strong interactions. This model was used by many physicists to untangle the multitude of reactions studied at CERN. Henri’s other noteworthy contributions include his work with Alfred H Mueller on very-high-energy particle jets, today commonly referred to as “Mueller-Navelet jets”, which are still the subject of experimental research and theoretical calculations in quantum chromodynamics.

Henri had a great sense of humour and human qualities that were highly motivating for his colleagues and the young researchers who met him during his long career. He was not only a great theoretical physicist, but also a passionate sportsman, training the younger generations. In particular, he ran the marathon in two hours, 59 minutes and 59 seconds. A valued researcher and friend has left us.

Roger Bailey 1954–2023

It was with deep sadness we learned that Roger Bailey, who played a key role in the operation of CERN’s accelerators, passed away on 1 June while mountain biking in Valais, Switzerland. He was 69.

Roger began his career with a doctorate in experimental particle physics from the University of Sheffield in 1979, going on to a postdoctoral position at the Rutherford Appleton Laboratory until 1983. Throughout this time, he worked on experiments at CERN’s Super Proton Synchrotron (SPS) and was based at CERN from 1977. In 1983 he joined the SPS operations group, where he was responsible for accelerator operations until 1989. Roger then moved to the Large Electron Positron collider (LEP), coordinating the team’s efforts through the commissioning phase and subsequent operation, and became operations group leader in the late 1990s.

After LEP shut down in 2000, Roger became progressively more involved in the Large Hadron Collider (LHC), planning and building the team for commissioning with beam. He then took a leading role in the LHC’s early operation, helping to push the LHC’s performance to Higgs-discovery levels before becoming director of the CERN Accelerator School, sharing his wealth of experience and inspiring new generations of accelerator physicists.

Those of us who worked with Rog invariably counted him as a friend: it made perfect sense, given his calm confidence, his kindness and his generosity of spirit. He was straightforward but never outspoken and his well-developed common sense and pragmatism were combined with a subtle and wicked deadpan sense of humour. We had a lot of fun over the years in what were amazing times for CERN. Looking back, things he said, and did, can still make us chuckle, even in the sadness of his untimely passing. Rog had a passionate, playful eye for life’s potential and he wasn’t shy. There was an adventurous spirit at work, be it in the mountains or the streets of New York, Berlin or Chicago. His specialities were tracking down music and talking amiably to anyone.

During a service to celebrate Roger’s life on 16 June, a poem of his called It’s a Wrap was read by his daughter Ellie, revealing a physicist’s philosophical view on life and the universe. Two of his favourite quotes were on the order of service: Mae West’s “You only live once, but if you do it right, once is enough” and Einstein’s “Our death is not an end if we can live on in our children and the younger generation. For they are us, our bodies are only wilted leaves on the tree of life.” Another, by Hunter S Thompson, was mentioned in a homage given by his son, Rob: “Life should not be a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming “Wow! What a Ride!”

Way to go, Rog, way to go.

Fault-finding across sectors

Jack Heron always liked the idea of being an inventor. After completing a master’s in electronics engineering at Durham University, he spent a year in Bangalore, India as part of the “Engineers Without Borders” programme, where he designed solar-powered poverty-alleviation solutions in unelectrified slums. This sparked an interest in renewable energy, and he completed a PhD on smart grid techniques in 2020. With a passion for advanced technology and engineering at the peak of performance, he then joined the “digital twin” R&D programme of international defence company Babcock, dedicated to fault-prediction for defence assets in land, sea and air.

“The military is extremely interested in autonomous vehicles,” explains Jack. “But removing the driver from, say, a fleet of tanks, increases the number of breakdowns: many maintenance checks are triggered by the driver noticing, for example, a ‘funny noise on start-up’, or ‘a smell of oil in the cabin’.” Jack worked on trying to replicate this intuition by using very early signs in sensor signals. Such a capability permits high confidence in mission success, he adds. “It also ensures that during a mission, if circumstances change, dynamic asset information is available for reconfiguration.”

Working in defence was “exciting and fast- paced” and enabled Jack to see his research put to practical use – he got to drive a tank and attend firing tests on a naval frigate. “It’s especially interesting because the world of defence is something most people don’t have visibility on. Modern warfare is constantly evolving based on technology, but also politics and current affairs, and being on the cusp of that is really fascinating.” It also left him with a wealth of transferrable skills: “Defence is a high-performance world where product failure is not an option. This is hardcoded into the organisation from the bottom up.”

Back to his roots

Growing up in Geneva, CERN always had a mythical status for Jack as the epitome of science and exploration. In 2022 he applied for a senior fellowship. “Just getting interviewed for this fellowship was a huge moment for me,” he says. “I was lucky enough to get interviewed in person, and when I arrived I got a visitor pass with the CERN-logo lanyards attached. Even if I didn’t get the job I was going to frame it, just to remember being interviewed at CERN!”

I love the idea of working on the frontiers of science and human understanding

Jack now works on the “availability challenge” for the proposed Future Circular Collider FCC-ee. Availability is the percentage of scheduled physics days the machine is able to deliver beam, (i.e. is not down for repair). To meet physics goals, this must be 80%. The LHC – the world’s largest and most complex accelerator, but still a factor three smaller and simpler than the FCC – had an availability of 77% during Run 2. “Modern-day energy-frontier particle colliders aren’t built to the availabilities we would need to succeed with the FCC, and that’s without considering additional technical challenges,” notes Jack. His research aims to break down this problem system by system and find solutions, beginning with the radio frequency (RF).

On the back of an envelope, he says, the statistics are a concern: “The LHC has 16 superconducting RF cavities, which trip about once every five days. If we scale this up to FCC-ee numbers (136 cavities for the Z-pole energy mode and 1352 for the tt threshold), this becomes problematic. Orders of magnitude greater reliability is required, and that itself is a defining technical challenge.

Jack’s background in defence prepared him well for this task: “Both are systems that cannot afford to fail, and therefore have extremely tight reliability requirements. One hour of down time in the LHC is extremely costly, and the FCC will be no different.”

Mirroring what he did at Babcock, one solution could be fault prediction. Others are robot maintenance, and various hardware solutions to make the RF circuit more reliable. “Generally speaking, I love the idea of working on the frontiers of science and human understanding. I find this exploration extremely exciting, and I’m delighted to be a part of it.”

Big Science Business Forum 2024

BSBF 2024 is a business oriented congress which congregates the main European Research Infrastructures, focused on technology and with the aim to be the main meeting point between Research Infrastructures and industry.

This will be the third edition of the event after the success of the previous editions in Copenhagen and Granada, where more than 1,000 participants from more than 500 organisations and 29 countries gathered together to discuss the future prospects of the Big Science Market.

PHYSTAT systematics at BIRS

**On point** Ann Lee (Carnegie Mellon University) explaining the construction of confidence regions when the likelihood function is unavailable. Credit: PHYSTAT

The PHYSTAT series of seminars and workshops provides a unique meeting ground for physicists and statisticians. The latest in-person meeting, after previously being postponed due to COVID, covered the field of systematic errors (sometimes known as nuisance parameters), which are becoming increasingly important in particle physics as larger datasets reduce statistical errors in many analysis channels. Taking place from 23 to 28 April at the Banff International Research Station (BIRS) in the Canadian Rockies, the workshop attracted 42 delegates working not only on the LHC experiments but also on neutrino physics, cosmic-ray detectors and astrophysics.

The organisers had assigned half of the time to discussions, and that time was used. Information flowed in both directions: physicists learned about the Wasserstein distance and statisticians learned about jet energy scales. The dialogue was constructive and positive – we have moved on from the “Frequentist versus Bayesian” days and now everyone is happy to use both – and the discussions continued during coffee, dinner and hikes up the nearby snow-covered mountains.

Our understanding of traditional problems continues to grow. The “signal plus background” problem always has new features to surprise us, unfolding continues to present challenges, and it seems we always have more to learn about simple concepts like errors and significance. There were also ideas that were new to many of us. Optimal transport and the Monge problem provide a range of tools whose use is only beginning to be appreciated, while neural networks and other machine-learning techniques can be used to help find anomalies and understand uncertainties. The similarities and differences between marginalisation and profiling require exploration, and we probably need to go beyond the asymptotic formulae more often than we do in practice.

Another “Banff challenge”, the third in a sequence, was set by Tom Junk of Fermilab. The first two had a big impact on the community and statistical practice. This time Tom provided simulated data for which contestants had to find the signal and background sizes, using samples with several systematic uncertainties – these uncertainties were unspecified, but dark hints were dropped. It’s an open competition and anyone can try for the glory of winning the challenge.

Collaborations were visibly forming during the latest PHYSTAT event, and results will be appearing in the next few months, not only in papers but in practical procedures and software that will be adopted and used in the front line of experimental research.

This and other PHYSTAT activities continue, with frequent seminars and several workshops (zoom, in-person and hybrid) in the planning stage.

A treasure trove of LHC results

About 350 physicists attended the 11th edition of the Large Hadron Collider Physics (LHCP) conference in Belgrade, Serbia from 22 to 26 May. The first-in person edition since 2019, the conference triggered productive discussions between experimentalists and theorists across the full LHC physics programme. It also addressed the latest progress of the High-Luminosity LHC upgrades and future-collider developments, in addition to outreach, diversity and education. The conference took place in parallel with the successful restart of LHC Run 3, and saw about 40 new results released for the first time.

The initial physics results from the Run 3 dataset collected in 2022 by ATLAS and CMS were shown, featuring the first measurement of the Higgs-boson production cross-section by ATLAS at 13.6 TeV. Clearly the Run 2 dataset is still a gold mine for the LHC experiments. The programme of precision measurements of Higgs-boson properties is continuing with improved accuracy from the full Run 2 dataset. In particular, ATLAS and CMS reported a new combined result targeting the rare decay H → Zγ, for which they found evidence at the level of 3.4σ and a measured rate slightly higher but comparable to that predicted by the Standard Model.

Innovative signatures

Searches for physics beyond the Standard Model (SM) remains a very active field of research at the LHC, with many innovative signatures explored, including those of long-lived particles. Some of these searches use new anomaly-detection techniques and explore potential lower-production cross sections. A new search of leptoquarks by CMS exploiting the leptonic tau content of the proton was reported, while ATLAS reported a search for stau production in supersymmetry models with much improved sensitivity. Many other searches were also presented, and while a few low-level excesses exist, more data will be required to check if these are statistical fluctuations or not.

The SM is under intense scrutiny but is still very successful at the high-energy frontier. A recent re-analysis of the W-boson mass by ATLAS with the 7 TeV dataset shows good agreement with SM predictions, unlike the CDF result released in 2022. Validating the model used for the ATLAS W-mass measurement, new precise measurements of the W and Z bosons’ transverse momentum distributions were reported by ATLAS using Run 2 data collected under lower pileup conditions. Vector-boson scattering processes are an important probe of the electroweak symmetry breaking mechanism, and most such processes are now observed at the LHC.

Exploring the top-quark sector, many recent results focused on rare top-production processes. Four-top production was observed recently by ATLAS and CMS. First evidence for the rare tWZ production mode was shown by CMS at LHCP 2023. Some of these rare production modes are seen with rates somewhat higher than predicted, and more data will be required to conclude if the differences are significant. Top production is also used to investigate more exotic scenarios. A new CMS result, measuring the tt– production cross section as a function of sidereal time, was reported. No indication of Lorentz invariance violation is observed.

Presentations covered the broad spectrum of physics at the LHC brilliantly

On the flavour-physics side, LHCb reported a new precise measurement of CP violation in the “golden” B → J/ψ K_sdecay, with the most precise extraction of the beta angle of the CKM quark-mixing matrix (see p16). Recent LHCb results on the flavour “anomalies” no longer show an indication for lepton universality violation in B → Ke⁺e^– compared to B → Kμ⁺μ^– decay rates, but some puzzles remain and there is still some tension in the tau-to-muon ratio in the tree-level decays B → B⁽^*⁾τ(µ)ν. Lepton-flavour violation is investigated in a new CMS result searching for the forbidden τ → 3µ decays, where an upper limit close to the Belle result was reported.

Characterisation of the quark–gluon plasma is actively studied using PbPb collision data. New results from ALICE regarding investigations of jet-quenching properties as well as charm fragmentation studies were shown at the conference.

The recent detections of collider-produced neutrinos by the new FASER and SND experiments were also presented, marking the start of a new physics programme at the LHC.

Broad spectrum

Several theory presentations highlighted recent progress in SM predictions for a wide range of processes including the electroweak sector, top-quark and Higgs-boson productions, as well as linking LHC physics to lattice QCD computations – work that is vital to fully exploit the physics potential of the LHC. Open questions in the various sectors were summarised and prospects for new-physics searches in Run 3, including those related to the Higgs-boson sector, were discussed. Links between LHC physics and dark matter were also highlighted, with examples of light dark-matter models and feebly interacting particles. Effective field theories, which are key tools to probe new physics in a generic way, were described with emphasis on the complementarity with searches targeting specific models.

Overall, the presentations covered the broad spectrum of physics at the LHC brilliantly. Future data, including from the High-Luminosity LHC phase, should allow physicists to continue to address many of the field’s open questions. Next year’s LHCP conference will be held at Northeastern University in Boston.

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