Within the framework of the isospin-dependent transport model, the roles of the reactions N? → NN and πN→ ? are investigated through simulating heavy-ion collisions at 1000 MeV/nucleon. The absorption process N? →...Within the framework of the isospin-dependent transport model, the roles of the reactions N? → NN and πN→ ? are investigated through simulating heavy-ion collisions at 1000 MeV/nucleon. The absorption process N? → NN plays an important role for heavy impact systems and small impact parameters than for light impact systems and large impact parameters. The resorption process πN→ ? is of importance for heavy impact systems and large impact parameters than for light impact systems and small impact parameters. Thus the influences of the reaction N? → N N(πN→ ?) on pion production dynamics can be neglected in heavy-ion collisions for smaller(larger) impact parameters and light systems. It is the reaction πN→ ? that causes the anti-correlation of pions and nucleons in the rapidity dependence of the directed flow.展开更多
Low-energy partial-wave πN scattering data is reexamined with the help of the production representation of partial-wave S matrix, where branch cuts and poles are thoroughly under consideration. The left-hand cut cont...Low-energy partial-wave πN scattering data is reexamined with the help of the production representation of partial-wave S matrix, where branch cuts and poles are thoroughly under consideration. The left-hand cut contribution to the phase shift is determined, with controlled systematic error estimates, by using the results of O(p^3) chiral perturbative amplitudes obtained in the extended-onmass- shell scheme. In Sn and Pu channels, severe discrepancies are observed between the phase shift data and the sum of all known contributions. Statistically satisfactory fits to the data can only be achieved by adding extra poles in the two channels. We find that a Sn resonance pole locates at √zr=(0.895 ±0.081)—(0.164±0.023)i GeV, on the complex s-plane. On the other hand, a Fn virtual pole, as an accompanying partner of the nucleon bound-state pole, locates at √zv=(0.966 ± 0.018) GeV, slightly above the nucleon pole on the real axis below threshold. Physical origin of the two newly established poles is explored to the best of oiir knowledge. It is emphasized that the O(p^3) calculation greatly improves the fit quality comparing with the previous O(p^2) one.展开更多
We report the results of a phase-shift analysis (PSA) of the low-energy π±p elastic-scattering data. Following the method which we had set forth in our previous PSA [1], we first investigate the self-consistency...We report the results of a phase-shift analysis (PSA) of the low-energy π±p elastic-scattering data. Following the method which we had set forth in our previous PSA [1], we first investigate the self-consistency of the low-energy π±p elastic-scattering databases, via two separate analyses of (first) the π+p and (subsequently) the π-p elastic-scattering data. There are two main differences to our previous PSA: 1) we now perform only one test for the acceptance of each data set (based on its contribution to the overall 2) and 2) we adopt a more stringent acceptance criterion in the statistical tests. We show that it is possible to obtain self-consistent databases after removing a very small amount of the data (4.57% of the initial database). We subsequently fit the ETH model [38] to the truncatedπ±p elastic-scattering databases. The model-parameter values show reasonable stability when subjected to different criteria for the rejection of single data points and entire data sets. Our result for the pseudovector πNN coupling constant is 0.0726±0.0014. We extract the scattering lengths and volumes, as well as the s- and p-wave hadronic phase shifts up to T = 100 MeV. Large differences in the s-wave part of the interaction can be seen when comparing our hadronic phase shifts with the current SAID solution (WI08);there is general agreement in the p waves, save for the ~1/21- hadronic phase shift.展开更多
The recently proposed N^(*)(890)1/2^(-)baryon is studied in a flavor SU(3) scheme with K-matrix unitarization,by fitting to low-energy cross section and phase shift data.It is found that N^(*)(890) co-exists with low-...The recently proposed N^(*)(890)1/2^(-)baryon is studied in a flavor SU(3) scheme with K-matrix unitarization,by fitting to low-energy cross section and phase shift data.It is found that N^(*)(890) co-exists with low-lying poles in other channels,which have been extensively discussed in the literature,though they belong to different octets in the SU(3) limit.Hence,the existence of N^(*)(890) is further verified.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.11505150the National Natural Science Foundation of China under Grant No.11405278the Yuncheng University Research Project under Grant No.YQ-2014014
文摘Within the framework of the isospin-dependent transport model, the roles of the reactions N? → NN and πN→ ? are investigated through simulating heavy-ion collisions at 1000 MeV/nucleon. The absorption process N? → NN plays an important role for heavy impact systems and small impact parameters than for light impact systems and large impact parameters. The resorption process πN→ ? is of importance for heavy impact systems and large impact parameters than for light impact systems and small impact parameters. Thus the influences of the reaction N? → N N(πN→ ?) on pion production dynamics can be neglected in heavy-ion collisions for smaller(larger) impact parameters and light systems. It is the reaction πN→ ? that causes the anti-correlation of pions and nucleons in the rapidity dependence of the directed flow.
基金the National Natural Science Foundations of China (NSFC) under Contract Nos. 10925522 and 11021092the Spanish Ministerio de Economia y Competitividad (MINECO) and the European Regional Development Fund (ERDF), under contracts FIS2014-51948-C2-1-P, FIS2014-51948- C2-2-P, FIS2017-84038-C2-1-P, FIS2017-84038-C2-2-P, and SEV- 2014-0398the Generalitat Valenciana under contract PROMETEOII/ 2014/0068.
文摘Low-energy partial-wave πN scattering data is reexamined with the help of the production representation of partial-wave S matrix, where branch cuts and poles are thoroughly under consideration. The left-hand cut contribution to the phase shift is determined, with controlled systematic error estimates, by using the results of O(p^3) chiral perturbative amplitudes obtained in the extended-onmass- shell scheme. In Sn and Pu channels, severe discrepancies are observed between the phase shift data and the sum of all known contributions. Statistically satisfactory fits to the data can only be achieved by adding extra poles in the two channels. We find that a Sn resonance pole locates at √zr=(0.895 ±0.081)—(0.164±0.023)i GeV, on the complex s-plane. On the other hand, a Fn virtual pole, as an accompanying partner of the nucleon bound-state pole, locates at √zv=(0.966 ± 0.018) GeV, slightly above the nucleon pole on the real axis below threshold. Physical origin of the two newly established poles is explored to the best of oiir knowledge. It is emphasized that the O(p^3) calculation greatly improves the fit quality comparing with the previous O(p^2) one.
文摘We report the results of a phase-shift analysis (PSA) of the low-energy π±p elastic-scattering data. Following the method which we had set forth in our previous PSA [1], we first investigate the self-consistency of the low-energy π±p elastic-scattering databases, via two separate analyses of (first) the π+p and (subsequently) the π-p elastic-scattering data. There are two main differences to our previous PSA: 1) we now perform only one test for the acceptance of each data set (based on its contribution to the overall 2) and 2) we adopt a more stringent acceptance criterion in the statistical tests. We show that it is possible to obtain self-consistent databases after removing a very small amount of the data (4.57% of the initial database). We subsequently fit the ETH model [38] to the truncatedπ±p elastic-scattering databases. The model-parameter values show reasonable stability when subjected to different criteria for the rejection of single data points and entire data sets. Our result for the pseudovector πNN coupling constant is 0.0726±0.0014. We extract the scattering lengths and volumes, as well as the s- and p-wave hadronic phase shifts up to T = 100 MeV. Large differences in the s-wave part of the interaction can be seen when comparing our hadronic phase shifts with the current SAID solution (WI08);there is general agreement in the p waves, save for the ~1/21- hadronic phase shift.
基金Supported in part by National Nature Science Foundations of China (11975028,10925522)。
文摘The recently proposed N^(*)(890)1/2^(-)baryon is studied in a flavor SU(3) scheme with K-matrix unitarization,by fitting to low-energy cross section and phase shift data.It is found that N^(*)(890) co-exists with low-lying poles in other channels,which have been extensively discussed in the literature,though they belong to different octets in the SU(3) limit.Hence,the existence of N^(*)(890) is further verified.
