Physicists at the University of Southampton are collaborating with experts in Croatia's largest multidisciplinary scientific research centre to help unlock understanding of Dark Matter.

Professor Stefano Moretti and Professor Alexander Belyaev have been awarded International Exchanges funding from the Royal Society to partner with Ruder Boskovic Institute's Dr Tania Robens on the ground-breaking research.

The two-year award will combine the complementary expertise of researchers from Southampton and Zagreb to devise novel search strategies for Beyond Standard Model (BSM) physics. The teams' findings will be used to decode the true dynamics of new physics once Dark Matter signals are observed at the Large Hadron Collider or future accelerators.

Professor Moretti says: "So far, the so-called Standard Model of particle physics is the best explanation for the dynamics of matter and forces in our universe. However, there are fundamental aspects of nature on which it falls short. In particular, astrophysical measurements lead us to believe that there is a significant proportion of new matter in the universe that cannot be 'seen' by standard experiments - aptly named 'Dark Matter' (DM).

"One important ingredient in the quest for new physics is the interpretation of current experimental results which may already constrain the viability of DM models, so that this will be the first step of our endeavour. Armed with this knowledge, we will then proceed to select suitable DM models and exploit new ideas on how to look for their collider signals. Our studies, driven by theoretical physicists yet connecting to experimental analysis, will be a key ingredient to make progress in understanding DM."

The Nobel-prize-winning discovery in 2012 of a Higgs boson, the last particle completing the Standard Model, heralded the beginning of a new and exciting era in exploring the unknown physics that may lie beyond it.

The NExT Institute, directed by Professor Moretti, fosters interactions between theory and experiment in an interdisciplinary and multi-sited environment to accelerate advances in the field. The partnership, which was founded by the Southampton High Energy Physics (SHEP) group and the Rutherford Appleton Laboratory (RAL) in 2006, expanded last year to welcome King's College London to its six member organisations.

The new International Exchanges collaboration will include four male and three female physicists involved at all levels from PhD to professor.

Professor Belyaev says: "Being part of the NExT Institute, Southampton is an ideal place for joint theoretical and experimental projects. Its members are world leaders in both model building and phenomenology as well as developers of key numerical tools for BSM physics, while Zagreb has world-leading experience in exploring the parameter space of DM models with extended scalar sectors. This project will benefit from the unique experience of these two teams in not only devising novel search strategies for BSM models of DM, but also deploying sophisticated Monte Carlo simulations leading to real data analyses."

Inspirational lectures delivered by physicists from the University of Southampton are setting Italian school pupils on a pathway to pioneering scientific careers.

Leading experts at Southampton’s School of Physics and Astronomy are supporting the international Academy of Distinction (AoD) programme, which invites secondary schools’ top performing students to expand their knowledge in a range of disciplines.

Dr Elena Accomando of the Southampton High Energy Physics theory group has partnered with the University of Pavia to deliver the AoD School of Physics. The institute, which was launched in 2020, is expected to be accessed by hundreds of 16 and 17-year-olds in the coming years.

The AoD consists of monthly online lectures and coordinated group activities that boost learning and engagement between sessions. A week-long summer school hosted by the University of Southampton is being planned to complete the programme.

Dr Accomando says: “At the AoD School of Physics, brilliant and highly motivated students work together to boost their talents by addressing advanced topics that are not part of the standard school curriculum. Our philosophy is to reach a diverse cohort of outstanding minds from state and international schools and give them the opportunity to feed their curiosity, letting it grow in a stimulating environment.”

The AoD School of Physics was opened with a series of lectures on quantum mechanics by Southampton’s Professor Nick Evans. Dr Accomando’s continuing series is taking pupils on an interactive journey through the mysteries of the sub-nuclear world.

Around 50 secondary schools have enrolled in the scheme, providing the opportunity to nominate their best students for selection in the different AoD disciplines. In this first pilot year, the AoD School of Physics has a cohort of 12 Italian school pupils selected from the 87 nominations.

The number of connected secondary schools is projected to reach 5,000 in the coming years, directing hundreds of talented pupils into the AoD physics programme.

Dr Accomando says: “We want to open our doors for talented international students to pursue a challenging, formative path to meet their highest expectations and hopes.”

An international collaboration of theoretical physicists, including Professor Chris Sachrajda from the University of Southampton, has published a new calculation that bolsters efforts to explain of the predominance of matter over antimatter in the universe.

The collaboration, known as RBC-UKQCD, includes scientists from the Brookhaven National Laboratory, CERN (the European particle physics laboratory), Columbia University, the University of Connecticut, the University of Edinburgh, the Massachusetts Institute of Technology, the University of Regensburg as well as Southampton.

Their results, published this month in the journal Physical Review D, have been highlighted as an Editor's Suggestion.

Professor Sachrajda, of the Southampton High Energy Physics theory group, explains: "Our current understanding is that the universe was created with almost equal amounts of matter and antimatter so that a difference between their interactions is required to have tipped the balance to favour matter over antimatter.

"Such tiny differences, called 'CP-violation', are a natural feature of the Standard Model of Particle Physics, and the aim of this project was to compute their effect in the decays of subatomic particles called kaons into two pions. Understanding these decays quantitatively and comparing the predictions with the experimental measurements made two decades ago at CERN and the Fermi National Accelerator Laboratory gives scientists a way to test our understanding of 'direct CP-violation'."

The results proved to be consistent with experimental measurements, thus significantly constraining models of 'new physics' attempting to explain phenomena such as dark matter which require physics beyond the standard model.

Professor Norman Christ, of Columbia University, says: "Any differences in matter and antimatter that have been observed to date are far too weak to explain the predominance of matter found in our current universe. Finding a significant discrepancy between an experimental observation and predictions based on the Standard Model would potentially point the way to new mechanisms of particle interactions that lie beyond our current understanding and which we hope to find to help to explain this imbalance."

To this end, following this pioneering work, the focus in the next two-to-three years will be to significantly improve the precision of the computations with the potential of revealing any sources of matter/antimatter asymmetry lying beyond the current theory's description of our world.

The final result depends on calculations performed in 2012 and 2015 which constituted the theses of Southampton PhD students Dr Elaine Goode and Dr Tadeusz Janowski.

The two pions into which the kaon decays can be in either of two channels; in one the interactions between the two pions are attractive and in the other repulsive. The earlier calculations were of the decays into the repulsive channel and the 2012 paper won the Kenneth Wilson Lattice Award for 'excellence in Lattice Field Theory'. The present calculation studies the decays into the attractive channel which required very significant additional theoretical and computational developments.

The difficulty of the calculation is due to the quarks, the constituents of the kaon and pions, interacting through the strong nuclear force. These strong interactions cannot be computed analytically and so to conquer the challenge the theorists used lattice Quantum Chromodynamics. This technique 'places' the particles on a space-time lattice of three spatial dimensions plus time.

Nevertheless, the computation required integrating 67 million degrees of freedom, performed using cutting-edge supercomputers, located in the USA, Japan as well as in the UK.

Turkish particle physicist Dr Yasar Hicyilmaz will use data from the Large Hadron Collider (LHC) to strengthen Southampton research into high energy particle physics - the characterisation of Dark Matter (DM).

Yasar, from Balikesir University, has been awarded a year-long Fellowship by the Scientific and Technological Research Council of Turkey (TUBITAK), which supports promising Turkish scientists by funding international research collaborations.

He will spend one year within the Southampton High Energy Physics (SHEP) research group and the New Connections between Experiment and Theory (NExT) Institute, working alongside Southampton’s Professor Stefano Moretti who is a member of SHEP and Director of the NExT Institute.

SHEP studies the most elementary constituents of matter, the basic forces by which they interact, and their role in the early Universe to present days. NExT brings together theorists and experimentalists in the process of new physics discovery.

Yasar’s Fellowship research will build on his previous work in searching for ways to discover DM at colliders. He will now use data from the LHC at CERN to explore the characterisation of DM through the theory of Supersymmetry – a supposed symmetry of nature where all elementary particles have a related superparticle with half a spin less, so that bosons and fermions are one and the same.

He said: “I am very excited about gaining this Fellowship as it will allow me to visit a top 100 worldwide University and work within the NExT Institute - a centre of research excellence in the UK. I am hoping that this will enable me to establish ties for the future.

“It will be a big chance for me to improve my knowledge and experience in a scientifically active environment. NExT has a large number of both theoretical and experimental research groups in particle physics, and interacting with these experimentalists will be a great opportunity to learn the processes of data analyses at the LHC and other experiments.

“I am also hoping to benefit from, and gain a deep learning from, the experience of Southampton Physics and Astronomy scientists who work in DM detection collaborations.”

TUBITAK aims to advance science and technology, conduct research and support Turkish researchers, and has awarded Yasar the Fellowship for a year.

Stefano added: “I am delighted that TUBITAK funding will seed a new collaboration between the UK and Turkey that brings together theorists and experimentalists in the process of new physics discovery.

“The work with Yasar will explore the potential of the LHC at CERN to discover DM. This Fellowship is extremely timely as we are at a cross-roads in high energy particle physics with the LHC experiments currently in the crucial position of being able to confirm or disprove Supersymmetry.

“The rapid and accurate interpretation of this data will point the way to a higher level of understanding of the fundamental interactions of matter and forces, as well as possibly paving the way towards an underlying grand unified theory.”