APIE TFAISeminaro vadovas: prof. habil. dr. Bronislovas KAULAKYS
Tematika: fizikos krypties disertacijų svarstymas, teorinės fizikos aktualūs klausimai.
Pranešėjų ir klausytojų kontingentas: Lietuvos tizikai teoretikai, doktorantai bei užsienio svečiai.
Detalesnė informacija: tel. 2193254, el. paštas: bronislovas.kaulakys@tfai.vu.lt
Dr. A. Deltuvos (Barselonos universitetas) pranešimas tema: “Four-body collisions in cold atomic gases: manifestation of Efimov physics"
BIRŽELIO 30 d. 11:00 val. Konfucijaus Instituto salėje (432 k.) įvyks Arnoldo Deltuvos pranešimas tema:
"Four-body collisions in cold atomic gases: manifestation of Efimov physics"
Pranešimas vyks anglų kalba, nes turime doktorantą iš užsienio. Pranešimo santrauka yra žemiau.
Kviečiame dalyvauti.
Abstract:
Few-boson systems with resonant interactions, characterized by the two-boson scattering length being much larger than the range of the interaction, show a number of universal properties and correlations between observables. Experimentally these phenomena have been observed in cold atomic gases where the scattering length can be controlled by the magnetic field near Feshbach resonance. Well-known example is the Efimov effect, i.e., the existence of weakly bound three-boson states (Efimov trimers) with discrete scaling symmetry. Furthermore, there are four-boson states (tetramers) associated with each Efimov trimer. However, only the two tetramers associated with the trimer ground state are true bound states that have been studied in detail using standard bound state techniques. All other tetramers are unstable bound states above the boson-trimer threshold. They can be seen as resonances in four-boson collisions; however, due to complexity of the multichannel four-body scattering problem, their properties are far less known. We attack the four-boson scattering problem using exact Alt, Grassberger, and Sandhas four-particle equations for the transition operators that previously were successfully applied to four-nucleon reactions. The equations are solved in momentum-space partial wave representation; however, compared to fermionic system, substantial changes in numerical techniques are needed. Results are obtained for atom-trimer and dimer-dimer scattering and for recombination processes in the four-boson system, i.e., the four-boson recombination into atom plus trimer and dimer-atom-atom recombination into atom plus trimer or dimer plus dimer. Correlations between four-boson scattering observables and two-boson scattering length are studied. Energies and widths of the tetramers are determined.
"Four-body collisions in cold atomic gases: manifestation of Efimov physics"
Pranešimas vyks anglų kalba, nes turime doktorantą iš užsienio. Pranešimo santrauka yra žemiau.
Kviečiame dalyvauti.
Abstract:
Few-boson systems with resonant interactions, characterized by the two-boson scattering length being much larger than the range of the interaction, show a number of universal properties and correlations between observables. Experimentally these phenomena have been observed in cold atomic gases where the scattering length can be controlled by the magnetic field near Feshbach resonance. Well-known example is the Efimov effect, i.e., the existence of weakly bound three-boson states (Efimov trimers) with discrete scaling symmetry. Furthermore, there are four-boson states (tetramers) associated with each Efimov trimer. However, only the two tetramers associated with the trimer ground state are true bound states that have been studied in detail using standard bound state techniques. All other tetramers are unstable bound states above the boson-trimer threshold. They can be seen as resonances in four-boson collisions; however, due to complexity of the multichannel four-body scattering problem, their properties are far less known. We attack the four-boson scattering problem using exact Alt, Grassberger, and Sandhas four-particle equations for the transition operators that previously were successfully applied to four-nucleon reactions. The equations are solved in momentum-space partial wave representation; however, compared to fermionic system, substantial changes in numerical techniques are needed. Results are obtained for atom-trimer and dimer-dimer scattering and for recombination processes in the four-boson system, i.e., the four-boson recombination into atom plus trimer and dimer-atom-atom recombination into atom plus trimer or dimer plus dimer. Correlations between four-boson scattering observables and two-boson scattering length are studied. Energies and widths of the tetramers are determined.
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