arXiv subjects

Song Gao

Publications and source records attributed to Song Gao.

115 records · Page 7Linked to original sources

arXiv2001

Novel Cyano-Bridged 4f-3d Coordination Polymers with a Unique 2D Topological Architecture and Unusual Magnetic Behavior

Cyano-bridged bimetallic hybrid Prussian Blue one- to three-dimensional (1D-3D) coordination polymers based on [M(CN)6]3- (M = Fe, Cr, Mn) have attracted great attention because of their rich and interesting structures and magnetic behaviors. The previous study implies that increasing dimensionality may enhance and improve bulk magnetic properties.Our strategy for the rational synthesis of high-dimensional network is to use a suitable combination of cyanide groups and other bridging ligands. Here, 2,2'-bipyrimidine (bpym) was selected, in preference to 4,4'-bipyrazine and pyrazine, because it is more capable of transmitting magnetic interactions and its bis(chelating) coordination modes facilitate connection between lanthanide ions. Unexpectedly, two novel coordination polymers [NdM(bpym)(H2O)4(CN)6]3H2O (M = Fe 1, Co 2;) were obtained, which have a unique 2D topological architecture, and exhibit unusual magnetic behavior.

cond-mat.mtrl-sci↗

arXiv2001

Observation of an unusual field dependent slow magnetic relaxation and two distinct transitions in a family of new complexes

An unusual field dependent slow magnetic relaxation and two distinct transitions were observed in a family of new rare earth-transition metal complexes, [Ln (bipy) (H$_{2}$O)$_{4}$ M(CN)$_{6}$] $\cdot $1.5 (bipy) $ \cdot $ 4H$_{2}$O (bipy = 2,2'-bipyridine; Ln = Gd$^{3+}$,Y$^{3+}$; M = Fe$ ^{3+}$, Co$^{3+}$). The novel magnetic relaxation, which is quite different from those in normal spin glasses and superparamagnets but very resembles qualitatively those in single-molecule magnet Mn$_{12}$-Ac even if they possess different structures, might be attributed to the presence of frustration that is incrementally unveiled by the external magnetic field. The two distinct transitions in [GdFe] were presumed from DC and AC susceptibility as well as heat capacity measurements.

cond-mat.mtrl-sci↗

arXiv1999

Meson mass modification in strange hadronic matter

We investigate in stable strange hadronic matter (SHM) the modification of the masses of the scalar ($σ$, $σ^*$) and the vector ($ω$, $ϕ$) mesons. The baryon ground state is treated in the relativistic Hartree approximation in the nonlinear $σ$-$ω$ and linear $σ^*$-$ϕ$ model. In stable SHM, the masses of all the mesons reveal considerable reduction due to large vacuum polarization contribution from the hyperons and small density dependent effects caused by larger binding.

nucl-th↗

arXiv1999

$ρ$ meson broadening and dilepton production in heavy ion collisions

The modification of the width of the rho meson due to in-medium decays and collisions is evaluated. In high temperature and/or high density hadronic matter, the collision width is much larger than the one-loop decay width. The large width of the $ρ$ meson in matter seems to be consistent with some current interpretations of the $e^+ e^-$ mass spectra measured at the CERN/SPS.

nucl-th↗

arXiv1999

Rho Meson Broadening in Hot and Dense Hadronic Matter

The modification of the width of rho mesons due to in-medium decays and collisions is evaluated. The decay width is calculated from the imaginary part of the one-loop self-energy at finite temperature. The collision width is related to the cross sections of the $ρ$ + pion and the $ρ$ + nucleon reactions. A calculation based on an effective Lagrangian shows the importance of including the direct $ρπ\toρπ$ scattering which is dominated by the $a_1$ exchange. A large broadening of the spectral function is found, accompanied by a strength suppression at the pole.

nucl-th↗

arXiv1997

Off-shell effects in dilepton production from hot interacting mesons

The production of dielectrons in reactions involving a_1 mesons and pions is studied. We compare results obtained with different phenomenological Lagrangians that have been used in connection with hadronic matter and finite nuclei. We insist on the necessity for those interactions to satisfy known empirical properties of the strong interaction. Large off-shell effects in dielectron production are found and some consequences for the interpretation of heavy ion data are outlined. We also compare with results obtained using experimentally-extracted spectral functions.

nucl-th↗

arXiv1996

Study on $ν_μ$, $ν_τ$ Decays and CP-Non Invariance at Early Epoch of the Universe

We study the $ν_μ$ and $ν_τ$ decays in the early epoch of the universe. If $m_{ν_τ}>2m_e$, there would be a CP asymmetry between $ν_τ\rightarrow e^++e^-+ν_e$ and $\barν_τ \rightarrow e^++e^-+\barν_e$. The resultant CP non-invariance is a function of temperature and density and can reach $10^{-7}$ for a reasonable temperature range, but it is noticed that if $m_{ν_τ}>2m_μ\sim 200$ MeV, the CP non-invariance can be much larger.

hep-ph↗