Jackiw-Pi模型的新涡旋解

运用映射拓扑流理论研究了Jackiw-Pi模型中的自对偶方程,得到一个静态的自对偶解满足带有δ函数项的刘维尔方程,从而得到了一个完整的带有拓扑信息的涡旋解,自然给出了磁通量子化.

THEORETICAL STUDY ON pp -> pn pi(+) REACTION AT MEDIUM ENERGIES

The pp -> pn pi(+) reaction is a channel with the largest total cross section for pp collision in COSY/CSR energy region. In this work, we investigate individual contributions from various N* and Delta* resonances with mass up to about 2 GeV for the pp -> pn pi(+) reaction. We extend a resonance model, which can reproduce the observed total cross section quite well, to give theoretical predictions of various differential cross sections for the present reaction at T-p = 2.88 GeV. It could serve as a reference for identifying new physics in the future experiments at HIRFL-CSR.

Combined study of gamma p ->eta p and pi(-)p ->eta n in a chiral constituent quark approach

Within a chiral constituent quark model approach, η-meson production on the proton via electromagnetic and hadron probes is studied. With few parameters, the differential cross section and polarized beam asymmetry for γp → ηp and differential cross section for π − p → ηn processes are calculated and successfully compared with the data in the center-of-mass energy range from threshold up to 2 GeV. The five known resonances S11(1535), S11(1650), P13(1720),D13(1520), and F15(1680) are found to be dominant in the reaction mechanisms in both channels. Possible roles played by new resonances are also investigated; and in the photoproduction channel, significant contribution from S11 and D15 resonances, with masses around 1715 and 2090 MeV, respectively, are deduced. For the so-called missing resonances, no evidence is found within the investigated reactions. The helicity amplitudes and decay widths of N ∗ → πN, ηN are also presented and found to be consistent with the Particle Data Group values.

Proposal for studying N* resonances with the (p)over-barp -> (p)over-barn pi(+) reaction

A theoretical study of the (p) over barp -> (p) over barn pi(+) reaction for antiproton beam energy from 1 to 4 GeV is made by including contributions from various known N* and Delta* resonances. It is found that for the beam energy around 1.5 GeV, the contribution of the Roper resonance N-(1440)* produced by the t-channel sigma exchange dominates over all other contributions. Since such a reaction can be studied in the forthcoming PANDA experiment at the GSI Facility of Antiproton and Ion Research (FAIR), the reaction will be realistically the cleanest place for studying the properties of the Roper resonance and the best place for looking for other "missing" N* resonances with large coupling to N sigma.

Systematic study of the pi(-)/pi(+) ratio in heavy-ion collisions with the same neutron/proton ratio but different masses

A systematic study of the pi(-)/pi(+) ratio in heavy-ion collisions with the same neutron/proton ratio but different masses can help single out effects of the nuclear mean field on pion production. Based on simulations using the IBUU04 transport model, it is found that the pi(-)/pi(+) ratio in head-on collisions of Ca-48 + Ca-48, Sn-124 + Sn-124, and Au-197 + Au-197 at beam energies from 0.25 to 0.6 GeV/nucleon increases with increasing the system size or decreasing the beam energies. A comprehensive analysis of the dynamical isospin fractionation and the pi(-)/pi(+) ratio as well as their time evolution and spatial distributions demonstrates clearly that the pi(-)/pi(+) ratio is an effective probe of the high-density behavior of the nuclear symmetry energy.

Search for signature inversion in the pi i(13/2) circle times upsilon i1(3/2) bands in Au-182,Au-184,Au-186

Search for low-spin signature inversion in the pi i(13/2) circle times nu i(13/2) bands in odd-odd Au-182,Au-184,Au-186 has been conducted through the standard in-beam gamma-spectroscopy techniques. The experiments for Au-182 and 186Au have been performed in the Japan Atomic Energy Agency (JAEA) via the Sm-152(Cl-35,5n)Au-182 and Yb-172(F-19,5n)Au-186 reactions, respectively. A study of Au-184 has been made using a multi-detector array GASP in LNL, Italy, via the Tb-159(Si-29,4n)Au-184 reaction. The pi i(13/2) circle times nu i(13/2) bands in these three nuclei have been identified and extended up to high-spin states. In particular, the inter-band connection between the pi i(13/2) nu i(13/2) band and the ground-state band in 184 Au has been established, leading to a firm spin-and-parity assignment for the pi i(13/2) circle times nu i(13/2) band. The low-spin signature inversion is found in the pi i(13/2) circle times nu i(13/2) bands in Au-182,Au-184,Au-186 according to our spin-assignment and the signature crossing observed at high-spin states.

Topological structure of the many vortices solution in Jackiw-Pi model

By using the gauge potential decomposition, we discuss the self-dual equation and its solution in Jackiw-Pi model. We obtain a new concrete self-dual equation and find relationship between Chern-Simons vortices solution and topological number which is determined by Hopf indices and Brouwer degrees of Psi-mapping. To show the meaning of topological number we give several figures with different topological numbers. In order to investigate the topological properties of many vortices, we use five parameters (two positions, one scale, one phase per vortex and one charge of each vortex) to describe each vortex in many vortices solutions in Jackiw-Pi model. For many vortices, we give three figures with different topological numbers to show the effect of the charge on the many vortices solutions. We also study the quantization of flux of those vortices related to the topological numbers in this case.

New vortex solutions of Jackiw-Pi model

Based on current phi-mapping topological theory, a kind of self-dual equations in Jackiw-Pi model are studied. We first obtain explicit, self-dual solutions that satisfy Liouville equation which contains delta-function. Then we get perfect vortex solutions which reflect the system's internal topological structure, and consequently the quantization of flux.

Topological structure of vortex solution in Jackiw-Pi model

By using phi-mapping method, we discuss the topological structure of the self-duality solution in Jackiw-Pi model in terms of gauge potential decomposition. We set up relationship between Chern-Simons vortex solution and topological number, which is determined by Hopf index and Brouwer degree. We also give the quantization of flux in this case. Then, we study the angular momentum of the vortex, which can be expressed in terms of the flux.

Search for signature inversion in the pi i(13/2)circle times nu i(13/2) bands in Au-182,Au-184,Au-186

Search for low-spin signature inversion in the pi i(13/2) circle times nu i(13/2) bands in odd-odd Au-182,Au-184,Au-186 has been conducted through the standard in-beam gamma-spectroscopy techniques via the Sm-152(Cl-35,5n) Au-182, Yb-172(F-19,5n) (186)An, and Tb-159(Si-29,4n) (184)An reactions, respectively. The pi i(13/2) circle times nu i(13/2) bands in these three nuclei have been identified and extended up to high-spin states. In particular, the inter-band connection between the pi i(13/2) circle times nu i(13/2) band and the ground-state band in Au-184 has been established, leading to a firm spin-and-parity assignment for the pi i(13/2) circle times nu i(13/2) band. The low-spin signature inversion is found in the pi i(13/2) circle times nu i(13/2) bands according to our spin-assignment and-the signature crossing observed at high-spin states.