210000982
Probing the equation of state of neutron-rich matter with intermediate energy heavy-ion collisions
Nuclear reactions induced by stable and/or radioactive neutronrich nuclei provide the opportunity to pin down the equation of state of neutron-rich matter, especially the density (ρ) dependence of its isospin-dependent part, i.e., the nuclear symmetry energy Esym. A conservative constraint, 32(ρ/ρ0) 0.7 < Esym(ρ) < 32(ρ/ρ0) , around the nuclear matter saturation density ρ0 has recently been obtained from the isospin diffusion data in intermediate energy heavy-ion collisions. We review this exciting result and discuss its consequences and implications on nuclear effective interactions, radii and cooling mechanisms of neutron stars.
54036055
Nucleon-nucleon cross sections in neutron-rich matter and isospin transport in heavy-ion reactions at intermediate energies
Nucleon-nucleon (NN) cross sections are evaluated in neutron-rich matter using a scaling model according to density, momentum, and isospin dependent nucleon effective masses. It is found that the in-medium NN cross sections are not only reduced but also have a different isospin dependence compared with the free-space ones. Because of the neutron-proton effective mass splitting the difference between nn and pp scattering cross sections increases with the increasing isospin asymmetry of the medium. Within the transport model IBUU04, the in-medium NN cross sections are found to influence significantly the isospin transport in heavy-ion reactions. With the in-medium NN cross sections, a symmetry energy of ${E}_{\mathrm{sym}}(\ensuremath{\rho})\ensuremath{\approx}31.6(\ensuremath{\rho}/{\ensuremath{\rho}}_{0}){}^{0.69}$ was found most acceptable compared with both the MSU isospin diffusion data and the presently acceptable neutron-skin thickness in $^{208}\mathrm{Pb}$. The isospin dependent part ${K}_{\mathrm{asy}}({\ensuremath{\rho}}_{0})$ of isobaric nuclear incompressibility was further narrowed down to $\ensuremath{-}500\ifmmode\pm\else\textpm\fi{}50$ MeV. The possibility of determining simultaneously the in-medium NN cross sections and the symmetry energy was also studied. The proton transverse flow, or even better the combined transverse flow of neutrons and protons, can be used as a probe of the in-medium NN cross sections without much hindrance from the uncertainties of the symmetry energy.
119234702
TRITON-3HE RELATIVE AND DIFFERENTIAL FLOWS AND THE HIGH DENSITY BEHAVIOR OF NUCLEAR SYMMETRY ENERGY
Using a transport model coupled with a phase-space coalescence after-burner we study the triton-3He relative and differential transverse flows in semi-central 132Sn + 124Sn reactions at a beam energy of 400 MeV/nucleon. We find that the triton-3He pairs carry interesting information about the density dependence of the nuclear symmetry energy. The t-3He relative flow can be used as a particularly powerful probe of the high-density behavior of the nuclear symmetry energy.
15375821
Rapidity and system size dependence of anisotropic flows in relativistic heavy ion collisions
We report results from a multiphase transport (AMPT) model on the rapidity and system size dependence of charged hadron anisotropic flows in nuclear collisions at the Relativistic Heavy Ion Collider (RHIC).
15108148
Systematic study of the pi(-)/pi(+) ratio in heavy-ion collisions with the same neutron/proton ratio but different masses
National Natural Science Foundation of China 10675148 
10635080 
10575071 
10675082 
MOE of China NCET-05-0392 
Shanghai Rising-Star Program 06QA14024 
SEM of China 
National Basic Research Program of China 2007CB815004 
US National Science Foundation PHY-0652548 
PHY-0757839 
Research Corporation 7123 
Texas Coordinating Board of Higher Education 0035650004- 2007
120983580
Isospin dependent Pauli blocking and nucleon mean free path in isospin-asymmetric nuclear matter
122248926
Simulation study of beam-beam effects
The Beijing Electron-Positron Collider (BEPC) will be upgraded to BEPCII, and the luminosity will be about 100 times higher. We developed a three-dimensional strong-strong PIC code to study the beam-beam effects in BEPCII. The transportation through the arc is the same as that in Hirata's weak-strong code. The beam-beam force is computed directly by solving the Poisson equation using the Fourier analysis and cyclic reduction method, and the boundary potential is computed by circular convolution. The finite bunch length effect is included by longitudinal slices. An interpolation scheme is used to reduce the required slice number in simulations. The standard message passing interface is used to parallelize the code. The computing time increases linearly with (n+1), where n is the slice number. The calculated luminosity of BEPCII at the design working point is similar to 50% of the design value. The best area in the tune space is near (0.505,0.57) according to the survey, where the luminosity is similar to 80% of the design.
137374294
Preliminary Lattice Design of the SSRF Storage Ring
119238467
Orientability of loop processes in relative locality
Inspired by recent results of unusual properties of loop processes in relative locality, we introduce a way to classify loops in the case of kappa-Poincare momentum space. We show that the notion of orientability is deeply connected to a few essential properties of loop processes. Nonorientable loops have "effective curvature", which explicitly breaks translation symmetry, and can lead to a breaking of causality and global momentum conservation. Orientable loops, on the other hand, are "flat." Causality and global momentum conservation are all well preserved in this kind of loops. We comment that the nontrivial classical loops in relative locality might be understood as dual effects from general relativity, and some physical implications are discussed.
119289860
P-wave quarkonium decays to meson pairs
A bstractThe processes of p-wave Quarkonium exclusive decays to two mesons are investigated, in which the final state vector mesons with various polarizations are considered separately. In the calculation, the initial heavy quarkonia are treated in the framework of non-relativistic quantum chromodynamics, whereas for light mesons, the light cone distribution amplitudes up to twist-3 are employed. It turns out that the higher twist contribution is significant and provides a possible explanation for the observation of the hadron helicity selection rule violated processes χc1→ φφ, ωω by the BESIII collaboration in recently. We also evaluate the χb1→ J/ψJ/ψ process and find that its branching ratio is big enough to be measured at the B-factories.