Scientists Test Asymmetry Between Matter and Antimatter
An international team, including scientists from HSE University, has collected and analysed data from dozens of experiments on charm mixing—the process in which an unstable charm meson oscillates between its particle and antiparticle states. These oscillations were observed only four times per thousand decays, fully consistent with the predictions of the Standard Model. This indicates that no signs of new physics have yet been detected in these processes, and if unknown particles do exist, they are likely too heavy to be observed with current equipment. The paper has been published in Physical Review D.
Immediately after the Big Bang, matter and antimatter should have formed in equal amounts and annihilated each other in perfect symmetry. Yet the universe has persisted, made up almost entirely of matter—evidence that this symmetry was somehow broken. The cause remains unknown. The Standard Model, the main theory of particle physics, describes the properties of elementary particles and has been confirmed by numerous experiments, but it does not explain the disappearance of antimatter. To search for answers, physicists study the weak interaction, a process in which particles can transform into their antiparticles and back. These transformations are especially sensitive to symmetry violations, making them a convenient tool for testing the limits of the Standard Model.
UTfit, an international team including researchers from HSE University, has carried out the most comprehensive analysis of these processes to date, combining data from dozens of experiments. This includes new results from the LHCb detector at the Large Hadron Collider and Japan’s Belle II experiment, both of which record rare particle decays under different conditions. The scientists focused on charmed mesons—short-lived particles that can spontaneously transform into their antiparticles and back, making them a useful tool for detecting even the slightest differences between matter and antimatter. If such transformations showed even a tiny asymmetry between particles and antiparticles, it would suggest the existence of previously unknown particles or interactions. To process the data, the researchers used a Bayesian approach with Markov chains, which made it possible to account for both statistical and systematic errors and to combine diverse experiments into a single coherent picture.
The results show that meson-to-antimeson transformations are extremely rare—occurring in only about four out of every thousand decays—and that the difference in decay rates between particles and antiparticles is roughly six per thousand. These values align perfectly with the predictions of the Standard Model. The observed CP violation—the very asymmetry between matter and antimatter—is far too small to account for the disappearance of antimatter from the universe.
However, even when no anomalies are detected, such studies help refine the boundaries within which the Standard Model holds and allow researchers to estimate the possible properties of hypothetical new physics. The analysis indicates that if new particles do exist, they must be so heavy that their effects are almost imperceptible at the current level of precision. In other words, such effects could only appear at energy scales that today’s colliders cannot yet reach.
Denis Derkach
'The heavier a hypothetical particle, the weaker its contribution to observed processes at accessible energies,' explains Denis Derkach, Head of the Laboratory of Methods for Big Data Analysis at the AI and Digital Science Institute of the HSE FCS. 'We combined data from dozens of experiments and found that all results remain consistent with the Standard Model. This suggests that if new physics exists, its particles are so heavy that their influence on these processes is nearly undetectable. Noticing even such faint effects will require further accumulation of data and continued improvements in measurement precision.'
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Economists at HSE University have examined how smokers respond to changes in cigarette prices. When tobacco prices increase, cigarette consumption does not always decline. In fact, spending on tobacco may even rise: according to the researchers, a 1% decrease in cigarette affordability leads to a 0.28% increase in per capita tobacco expenditure. The findings suggest that to reduce smoking rates, tobacco prices must rise faster than household incomes. The study has been published in Voprosy Statistiki.
Biologists Discover Unique Properties of MiR-93-5p MicroRNA in Prostate Cancer
Researchers at the International Laboratory of Microphysiological Systems of the HSE Faculty of Biology and Biotechnology investigated how different isoforms of the same microRNA influence gene function in prostate adenocarcinoma. The study found that in some cases, microRNAs can reinforce each other’s effects by targeting and suppressing the same genes. This finding offers a fresh perspective on the molecular mechanisms underlying tumour development and on the search for disease biomarkers. The results have been published in PeerJ.
HSE Researchers Provide the World’s First Legal Definition of a Digital Ecosystem
Digital ecosystems have evolved from a technological innovation into a fundamental institution of the modern economy over the past few years. According to HSE University’s latest estimates, they account for 8.5% of Russia’s GDP. Previously, no jurisdiction had a statutory definition of what constitutes a digital ecosystem. HSE University researchers have addressed this gap by proposing the first legal concept of a digital ecosystem. Their article, ‘The Digital Ecosystem as a Novel Economic Phenomenon and Legal Concept,’ has been published in the BRICS Law Journal.
HSE Economists Use Search Queries to Forecast Birth Rates
Researchers from the HSE Faculty of Economic Sciences have shown that the accuracy of birth rate forecasts for Russia can be improved by almost 50% by incorporating the dynamics of online search queries related to pregnancy and childbirth into forecasting models. In the best-performing models, the forecasting error fell from 4.6% to 3.2%. The findings have been published in Populations and Economics.
When Looking at Their Own Faces, Men Forget Everything
In an experiment involving 15 healthy men, scientists at HSE University investigated how different phases of the cardiac cycle influence the excitability of the motor cortex when participants viewed either their own photograph or the faces of strangers. The researchers found that when participants looked at their own image, the brain’s response to signals from the heart was weaker, meaning that the influence of cardiac activity on the motor cortex decreased. This finding came contrary to expectations, as self-focused attention was thought to enhance the brain's sensitivity to internal bodily signals. The study has been published in Frontiers in Signal Processing.
HSE Researchers Discover Who Eats Out in Russia—And Why
Around one-third of Russians (31.3%) rarely eat out or buy ready-made meals. The core group of active consumers—those who eat out or purchase prepared food almost every day or several times a week—accounts for only about 9% of the population. These are the findings of a study conducted by the HSE Institute for Social Policy. According to the researchers eating out is no longer a marker of high social status in Russia.
Scientists Model How Interactions Between Societies Can Trigger Chaotic Behaviour
Scientists at HSE MIEM have proposed a mathematical model explaining how interactions between societies can influence their stability. Based on the classical theory of evolutionary games, the study reveals an unexpected effect: even a weak informational influence of one society on another can cause one society to remain stable while the other exhibits chaotic behaviour among its individual members. The study has been published in the International Journal of Bifurcation and Chaos.
Ancient Craniiform Brachiopod: A Newly Discovered Species with a Unique Shell Shape and Lifestyle
Scientists from HSE University, MSU, and Tallinn University of Technology have studied a fossil species of ancient brachiopods that lived in a warm sea in what is now northern Estonia more than 445 million years ago. These ancient brachiopods developed a cup-shaped shell with a protective 'cap' that shielded them from overgrowth by other marine organisms. The study has been published in Palaeogeography, Palaeoclimatology, Palaeoecology.
Scientists Develop Bacterium-Sized Microlaser
An international team of researchers, including scientists from HSE University–St Petersburg, has developed microlasers that emit deep-ultraviolet light at a wavelength of 255 nanometres. The devices operate at room temperature, and the smallest of them measures just two micrometres in diameter—roughly the size of a bacterium. These microlasers could be used in sensors, spectroscopic systems, photonic chips, and communication devices. The paper has been published in Optics & Laser Technology.