We discuss the observability of the non-universal bosons Z′ predicted by topcolor-assisted technicolor(TC2) models in the near future high-energy linear e^+e^- collider (LC) experiments via studying its contributions...We discuss the observability of the non-universal bosons Z′ predicted by topcolor-assisted technicolor(TC2) models in the near future high-energy linear e^+e^- collider (LC) experiments via studying its contributions to the processes e^+e^- → bb^- and ττ^-. We find that the signals of the new particle Z′ can be detected by measuring the relative corrections to the cross sections and the ratio of signal over square root of the background S/√B for these two processes in the LC experiments. In most of the parameter space of TC2 models, it is difficult to observe the virtual effects of the Z′ exchange on the forward-backward asymmetries AFB (bb^-) and AFB (ττ^-).展开更多
The influence of the chiral mean field on the K+ in-plane flow in heavy ion collisions at SIS energy is investigated within covariant kaon dynamics. For the kaon mesons inside the nuclear medium a quasi-particle pictu...The influence of the chiral mean field on the K+ in-plane flow in heavy ion collisions at SIS energy is investigated within covariant kaon dynamics. For the kaon mesons inside the nuclear medium a quasi-particle picture including scalar and vector fields is adopted and compared to the standard treatment with a static potential. It is confirmed that a Lorentz force from spatial component of the vector field provides an important contribution to the inmedium kaon dynamics and strongly counterbalances the influence of the vector potential on the K+ in-plane flow. The calculated results show that the new FOPI data can be reasonably described using the Brown & Rho parametrization,which partly takes into account the correction of higher order contributions in the chiral expansion. This indicates that one can abstract the information on the kaon potential in a nuclear medium from the analysis of the K+ in-plane flow.展开更多
文摘We discuss the observability of the non-universal bosons Z′ predicted by topcolor-assisted technicolor(TC2) models in the near future high-energy linear e^+e^- collider (LC) experiments via studying its contributions to the processes e^+e^- → bb^- and ττ^-. We find that the signals of the new particle Z′ can be detected by measuring the relative corrections to the cross sections and the ratio of signal over square root of the background S/√B for these two processes in the LC experiments. In most of the parameter space of TC2 models, it is difficult to observe the virtual effects of the Z′ exchange on the forward-backward asymmetries AFB (bb^-) and AFB (ττ^-).
文摘The influence of the chiral mean field on the K+ in-plane flow in heavy ion collisions at SIS energy is investigated within covariant kaon dynamics. For the kaon mesons inside the nuclear medium a quasi-particle picture including scalar and vector fields is adopted and compared to the standard treatment with a static potential. It is confirmed that a Lorentz force from spatial component of the vector field provides an important contribution to the inmedium kaon dynamics and strongly counterbalances the influence of the vector potential on the K+ in-plane flow. The calculated results show that the new FOPI data can be reasonably described using the Brown & Rho parametrization,which partly takes into account the correction of higher order contributions in the chiral expansion. This indicates that one can abstract the information on the kaon potential in a nuclear medium from the analysis of the K+ in-plane flow.
