A double-well potential model is proposed for the pionic deuterium that enables to calculate the energy split, the potential barrier height and estimate the pion tetrahedron edge length. We propose that pion tetrahedr...A double-well potential model is proposed for the pionic deuterium that enables to calculate the energy split, the potential barrier height and estimate the pion tetrahedron edge length. We propose that pion tetrahedrons, π<sup>Td</sup> = u<sub>d</sub>~</sup>dũ, play a central role in the Yukawa interaction by enabling quark exchange reactions between protons and neutrons by tunneling through a potential barrier. A vacuum polarization Feynman diagram is proposed for the π<sup>Td</sup> having chains of fermion loops for the two valence quarks and anti-quarks connected by gluons. With a higher order vacuum polarization diagram, the d and u quark loops are interleaved and the chiral symmetry is broken dynamically. The proposed π<sup>Td</sup> vacuum polarization integral does not diverge in both the IR and UV limits and vanishes in the limit of an infinite pion tetrahedron condensate. We propose a new Delbruck scattering Feynman diagram that includes d and u quark and anti-quark interleaved loops. We further propose that conversion of gravitons to photons may occur via quark and anti-quark loops that describe the pion tetrahedrons dynamics in the vacuum and may also transfer gravitational waves.展开更多
The fine and hyperfine structures of pionic helium metastable states is calculated within the formalism of the Breit-Pauli Hamiltonian by using the variationally generated wave functions in Hylleraas coordinates.Our r...The fine and hyperfine structures of pionic helium metastable states is calculated within the formalism of the Breit-Pauli Hamiltonian by using the variationally generated wave functions in Hylleraas coordinates.Our results not only verify the existing values of Hori et al.[Phys.Rev.A 89,042515(2014)]for the fine structure of π^(4)He^(+),but also determine the hyperfine structure of π^(3)He^(+).展开更多
The excess pion inside the nucleus could change not only nucleons structure function, but also electron scattering cross section from nuclei. In this paper, we calculate pionic contribution in nuclear structure functi...The excess pion inside the nucleus could change not only nucleons structure function, but also electron scattering cross section from nuclei. In this paper, we calculate pionic contribution in nuclear structure functions of 3He and 3H nuclei and the differential cross sections of electron scattering from these nuclei. At first, we calculate the Fermi motion and binding energy contribution as an important nuclear medium effect in scattering cross sections and then we add pionic contribution to structure functions and differential cross sections of electron scattering from these nuclei that the Fermi motion and binding energy are considered.展开更多
The renormalization of pion-exchange nucleon self-energy in nuclear matter is doneby dispersion relation.The exchange and correlation energies(in the ring approximation)ofpion,σ and ω mesons are derived and used to ...The renormalization of pion-exchange nucleon self-energy in nuclear matter is doneby dispersion relation.The exchange and correlation energies(in the ring approximation)ofpion,σ and ω mesons are derived and used to calculate the binding energy of nuctear matter atzero temperature.We find that the pionic contribution to the binding energy fails to lift the highdensity end of the binding energy curve,that is,the binding energy can not saturate without adensity dependent correction to the σNN and ωNN coupling constants.But the binding energycan saturate in the relativistic Hartree approximation plus the exchange and correlation energiesof л meson.展开更多
A short overview over the ABC phenomenon is given,which is known since 50 years without any satisfactory explanation.On the basis of new exclusive and kinematically complete data obtained with the WASA detector at COS...A short overview over the ABC phenomenon is given,which is known since 50 years without any satisfactory explanation.On the basis of new exclusive and kinematically complete data obtained with the WASA detector at COSY we show that this phenomenon is linked with a resonant energy dependence in the total cross section of isoscalar double-pionic fusion processes.This resonance structure is connected with the baryon-baryon system,in particular with the pn and ΔΔ systems,however,has a mass,which is 90 MeV below the nominal ΔΔ threshold and a width of only 70 MeV,i.e.,five times smaller than expected from a conventional t-channel ΔΔ scenario.展开更多
After summarizing the experimental results and present status of the d^＊（2380） observed at WASA@COSY,two “extreme” models for explaining its structure, a compact hexaquark dominated model and a loose △△＇-D_（1...After summarizing the experimental results and present status of the d^＊（2380） observed at WASA@COSY,two “extreme” models for explaining its structure, a compact hexaquark dominated model and a loose △△＇-D_（12）π model, are briefly discussed, especially the former. By comparing their results with the corresponding data, the differences of the two models are addressed. As a remedy for the latter model, a mixing model and its result are also quoted for a comparison. It is shown that the compact hexaquark dominated structure might be more promising.However, the mixing model is also a possible structure, and more accurate Γ_（d^＊）→NN_π data are needed for confirmation.展开更多
文摘A double-well potential model is proposed for the pionic deuterium that enables to calculate the energy split, the potential barrier height and estimate the pion tetrahedron edge length. We propose that pion tetrahedrons, π<sup>Td</sup> = u<sub>d</sub>~</sup>dũ, play a central role in the Yukawa interaction by enabling quark exchange reactions between protons and neutrons by tunneling through a potential barrier. A vacuum polarization Feynman diagram is proposed for the π<sup>Td</sup> having chains of fermion loops for the two valence quarks and anti-quarks connected by gluons. With a higher order vacuum polarization diagram, the d and u quark loops are interleaved and the chiral symmetry is broken dynamically. The proposed π<sup>Td</sup> vacuum polarization integral does not diverge in both the IR and UV limits and vanishes in the limit of an infinite pion tetrahedron condensate. We propose a new Delbruck scattering Feynman diagram that includes d and u quark and anti-quark interleaved loops. We further propose that conversion of gravitons to photons may occur via quark and anti-quark loops that describe the pion tetrahedrons dynamics in the vacuum and may also transfer gravitational waves.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11974382 and 11474316)the support from NSERC and SHARCnet of Canada
文摘The fine and hyperfine structures of pionic helium metastable states is calculated within the formalism of the Breit-Pauli Hamiltonian by using the variationally generated wave functions in Hylleraas coordinates.Our results not only verify the existing values of Hori et al.[Phys.Rev.A 89,042515(2014)]for the fine structure of π^(4)He^(+),but also determine the hyperfine structure of π^(3)He^(+).
文摘The excess pion inside the nucleus could change not only nucleons structure function, but also electron scattering cross section from nuclei. In this paper, we calculate pionic contribution in nuclear structure functions of 3He and 3H nuclei and the differential cross sections of electron scattering from these nuclei. At first, we calculate the Fermi motion and binding energy contribution as an important nuclear medium effect in scattering cross sections and then we add pionic contribution to structure functions and differential cross sections of electron scattering from these nuclei that the Fermi motion and binding energy are considered.
基金The project supported by the National Natural Scicnce Foundation of China
文摘The renormalization of pion-exchange nucleon self-energy in nuclear matter is doneby dispersion relation.The exchange and correlation energies(in the ring approximation)ofpion,σ and ω mesons are derived and used to calculate the binding energy of nuctear matter atzero temperature.We find that the pionic contribution to the binding energy fails to lift the highdensity end of the binding energy curve,that is,the binding energy can not saturate without adensity dependent correction to the σNN and ωNN coupling constants.But the binding energycan saturate in the relativistic Hartree approximation plus the exchange and correlation energiesof л meson.
基金Supported by BMBF (06TU261,06TU9193)Forschungszentrum Jülich (COSY-FFE)DFG (Europ.Graduiertenkolleg 683)
文摘A short overview over the ABC phenomenon is given,which is known since 50 years without any satisfactory explanation.On the basis of new exclusive and kinematically complete data obtained with the WASA detector at COSY we show that this phenomenon is linked with a resonant energy dependence in the total cross section of isoscalar double-pionic fusion processes.This resonance structure is connected with the baryon-baryon system,in particular with the pn and ΔΔ systems,however,has a mass,which is 90 MeV below the nominal ΔΔ threshold and a width of only 70 MeV,i.e.,five times smaller than expected from a conventional t-channel ΔΔ scenario.
基金Supported by National Natural Science Foundation of China(11475192,11475181,11521505,11565007,11635009)fund provided to the Sino-German CRC 110 “Symmetries and the Emergence of Structure in QCD” project by NSFC(11621131001)+1 种基金the IHEP Innovation Fund(Y4545190Y2)the support of the Youth Innovation Promotion Association of CAS(2015358)
文摘After summarizing the experimental results and present status of the d^＊（2380） observed at WASA@COSY,two “extreme” models for explaining its structure, a compact hexaquark dominated model and a loose △△＇-D_（12）π model, are briefly discussed, especially the former. By comparing their results with the corresponding data, the differences of the two models are addressed. As a remedy for the latter model, a mixing model and its result are also quoted for a comparison. It is shown that the compact hexaquark dominated structure might be more promising.However, the mixing model is also a possible structure, and more accurate Γ_（d^＊）→NN_π data are needed for confirmation.
