• A
  • A
  • A
  • ABC
  • ABC
  • ABC
  • А
  • А
  • А
  • А
  • А
Regular version of the site

Scholars Gain New Data on Heavy Exotic Hadrons

The Belle detector

The Belle detector
www.kek.jp

As part of the Belle experiment, researchers were able to measure the energy dependence of e+e- -> B-anti-B, B-anti-B* and B*-anti-B* reactions in the 10.63 GeV to 11.02 GeV energy range for the first time. The new data will help clarify the nature of the group of exotic Upsilon mesons that have mass in this range. The results of the study were published in the Journal of High Energy Physics. Over 400 researchers have participated in the Belle experiment, including staff members of the HSE International Laboratory of Elementary Particle Physics.

The first Upsilon meson, consisting of b- and anti-b-quarks, was discovered in 1977. Its discovery also coincided with that of the heaviest b-quark, for which the authors of the study—American researchers Leon M. Lederman, Melvin Schwartz and Jack Steinberger—received a Nobel Prize in 1988.

In 2008, researchers discovered that high-energy Upsilon meson states have anomalous properties. The reason for these unexpected properties remains an unanswered question in hadron physics. Theoretical studies agree that there are additional degrees of freedom within these states: a pair comprising a lightweight quark and an anti-quark, or a valent gluon. Such multi-particle bound states are called ‘exotic hadrons’, and until recently, they had not been found. Additional experimental data was needed to distinguish various models of highly excited Upsilon meson structures. This data was collected during the Belle experiment in 2010 and serves as the foundation for the study published in the Journal of High Energy Physics.

The Belle detector was located at the collision point of KEK-B, an electron-positron collider in Japan, with the total beam energy close to 10 GeV. The detector collected data from 1999 to 2010. The main goal of the experiment was to study the properties of B+ and B0 mesons, consisting of a heavy anti-b-quark and one light u- or d-quark. A large number of rare decays of these particles was detected, and differences in the properties of particles and anti-particles (B+ and B-, B0 and anti-B0) were studied in order to uncover the mechanism behind the matter/anti-matter asymmetry of the contemporary universe.

Quarks are elementary particles that form composite particles: baryons and mesons. Quarks have fractional electric charge values and are categorized in pairs in three generations in order of increasing mass: up and down, charm and strange, top and bottom.

A collision between an electron and a positron creates many particles which, in turn, interact or decay. In order to understand the reactions that occur after a particle collision, modern experiments consist of several layers of various detectors. Certain particles are registered and studied in these layers.

The Belle experiment used a silicon detector to determine the interaction point, a drift chamber to track the charged particles, and a caesium iodide-based counter for the photons.

Based on the scan data, the cross-section energy dependence for many reactions was measured. For example, a new heavy Upsilon(10750) meson was observed in the cross-sections of weakly excited Upsilon mesons produced together with a pair of pi+ and pi- mesons. Until recently, only the reactions that make a relatively small contribution to a total cross section were studied. Finally, the cross sections e+e- -> B-anti-B, B-anti-B* and B*-anti-B*, which make the largest contribution to a total cross section, were measured for the first time. This gave the researchers the first full set of data on exotic Upsilon mesons, which allowed several theoretical teams to start working to explain the measurements.

Roman Mizuk, Leading Research Fellow at the International Laboratory of Elementary Particle Physics

The data obtained includes some unexpected discoveries. The cross sections e+e- -> B-anti-B, B-anti-B* and B*-anti-B* demonstrate a complicated dependence on energy, which might provide some important information on the wave functions of exotic meson states. In the future, joint analysis of data on the energy dependence of the cross sections may help to shed light on the question of the structure of Upsilon mesons’ highly excited states.

See also:

HSE Scientists Have Developed a New Model of Electric Double Layer

This new model accounts for a wide range of ion-electrode interactions and predicts a device's ability to store electric charge. The model's theoretical predictions align with the experimental results. Data on the behaviour of the electric double layer (EDL) can aid in the development of more efficient supercapacitors for portable electronics and electric vehicles. The study has been published in ChemPhysChem

HSE Scientist Optimises Solution of Hydrodynamics Problems

Roman Gaydukov, Associate Professor at the MIEM HSE School of Applied Mathematics, has modelled the fluid flow around a rotating disk with small surface irregularities. His solution allows for predicting fluid flow behaviour without the need for powerful supercomputers. The results have been published in Russian Journal of Mathematical Physics.

Physicists from Russia and Brazil Unveil Mystery behind Complex Superconductor Patterns

Scientists at HSE MIEM and MIPT have demonstrated that highly complex spatial structures, similar to the intricate patterns found in nature, can emerge in superconductors. Mathematically, these patterns are described using the Ginzburg–Landau equation at a specific combination of parameters known as the Bogomolny point. The paper has been published in the Journal of Physics: Condensed Matter.

Adhesive Tape Helps Create Innovative THz Photodetector

An international team of researchers, including scientists at HSE University and Moscow Pedagogical State University (MPGU), has developed a novel photodetector composed of a thin superconducting film, capable of detecting weak terahertz (THz) radiation. This discovery holds promise for studying objects in space, developing wireless broadband communication systems, and making advancements in spectroscopy. The study has been published in Nano Letters.

Operation of Cellular Networks Found Similar to Bacteria Growth in Petri Dish

Scientists at the HSE Laboratory for Computational Physics have developed a new model for analysing communication networks that can significantly enhance the speed of mobile communications. To achieve this, the researchers used computational physics methods and phase transition models. It turns out that the functioning of cellular networks is in many ways similar to the growth of surfaces in physics. The study was performed using the HPC cHARISMa cluster at HSE University. The study findings have been published in Frontiers in Physics.

The Saudi Arabian National Team, Medal Winners at the International Physics Olympiad, Trained at HSE University

At the recent International Physics Olympiad (IPhO 2024) in Iran, students from Saudi Arabia achieved the best results in their country's history, winning one silver and three bronze medals. The team from the Kingdom made their first visit to Russia to receive their final training at the HSE Faculty of Physics.

'I've Always Been Keen to Engage in Experiments and Operate Scientific Instruments'

During his early years at university, physicist Ivan Makhov worried that he might be dismissed, but today he is heading a study supported by a grant from the Russian Science Foundation. In this interview with the HSE Young Scientists project, he shares his work experience using a closed-loop cryostat, his dream of conversing with Einstein, and favourite location in his hometown of St Petersburg.

‘Two Interdisciplinary Research Centres Can Create New Synergy between Themselves’

In mid-June 2024, HSE University and the Joint Institute for Nuclear Research in Dubna held a joint working meeting. This meeting was the first under an agreement signed by the research centres in 2024, when HSE University and JINR agreed to jointly participate in experiments of the NICA megascience project, as well as interact in the field of theoretical and mathematical physics, information technology, and personnel training. These issues were the focus of the first working meeting. Details are in the JINR report.

‘I Aspire to Make a Contribution Comparable to Prometheus' Gift to Humanity'

Egor Sedov initially planned to pursue a career in programming but instead became captivated by experimental physics. In this interview with the HSE Young Scientists project, he spoke about the quantum effect and the quantum standard, a scientist's letter from the future, and the magnetic levitation of a frog.

Russian Scientists Pioneer Accurate Mathematical Description of Quantum Dicke Battery

Physicists at HSE University and NUST MISIS have formulated and solved equations for a quantum battery, a device capable of storing energy in the form of light. Their findings will facilitate precise calculations of the capacity, power, and duration required for optimal battery charging. Quantum batteries are expected to improve the performance of solar panels and electric vehicles, while also opening up new avenues for efficient energy transfer. The study has been published in Physical Review A.