Measurement of magnetic and electric dipole moments of neutral charmed and beauty baryons based on the effect of depolarisation of their spin in crystals

  • Viktor V. Tikhomirov Institute for Nuclear Problems, Belarusian State University, 11 Babrujskaja Street, Minsk 220006, Belarus

Abstract

The search and measurement of magnetic and electric dipole moments of elementary particles allows us to determine the structure of the latter and to obtain data on fundamental interactions. At present, preparations are underway for experiments to measure the magnetic and electric dipole moments of charmed and beauty baryons, which become possible during their birth with an energy of the order of a teraelectronvolt or more, at the Large Hadron Collider and even larger projected accelerators. The measurement of magnetic and electric dipole moments is based on their dependence on changes in particle polarisation in a magnetic or electric field. The problem is that even at the energies under consideration, the particle decay length is measured in centimetres and the necessary change in their polarisation can be achieved only in an intense crystal field significantly exceeding any fields obtained in the laboratory. In the case of positively charged particles, such measurements are based on the spin rotation effect under channelling conditions in a bent crystal. Since the channelling effect cannot be used in the case of both neutral and negatively charged particles, it remains to apply the spin depolarisation effect, which exists in amorphous matter and is additionally enhanced in crystals. In order to quantitatively describe this effect, the article finds a relationship between the magnetic and electric dipole moments of a neutral spin particle and the square of the longitudinal polarisation acquired by it when moving at a small angle to one of the main crystalline directions. This calculation forms the basis for a method for measuring the magnetic and electric dipole moments of neutral charmed and beauty baryons, using the effect of coherent amplification of the action of atomic fields on them in crystals. The work also details the procedure for such measurements, based on recording the direction of emission of one of the decay products relative to the plane normal to the momentum in the rest frame of the decaying particle. Estimates have been made showing that the minimum number of particles required to measure the magnetic dipole moment of a neutral charmed omega baryon at the Large Hadron Collider will be of the order of 104, and at colliders designed for energies of the order of 50 TeV, less than 103.

Author Biography

Viktor V. Tikhomirov, Institute for Nuclear Problems, Belarusian State University, 11 Babrujskaja Street, Minsk 220006, Belarus

doctor of science (physics and mathematics), full professor; chief researcher at the sectoral laboratory of radiation safety

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Published
2025-02-11
Keywords: magnetic dipole moment, electric dipole moment, neutral particles, charmed baryons, beauty baryons, crystals, channelling, spin, depolarisation, high energies, teraelectronvolt, Large Hadron Collider
Supporting Agencies The author expresses gratitude to professor V. G. Baryshevsky for introducing his ideas and valuable discussions over 45 years, professor I. D. Feranchuk for advice regarding this article and many years of help and support, as well as PhD (physics and mathematics) S. L. Cherkas for useful discussions.
How to Cite
Tikhomirov, V. V. (2025). Measurement of magnetic and electric dipole moments of neutral charmed and beauty baryons based on the effect of depolarisation of their spin in crystals. Journal of the Belarusian State University. Physics, 1, 4-16. Retrieved from https://journals.bsu.by/index.php/physics/article/view/6847
Issue
No 1 (2025): Journal of the Belarusian State University. Physics
Section
Atomic Nucleus and Elementary Particle Physics

Copyright (c) 2025 Journal of the Belarusian State University. Physics

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