118379255
Collective flow of light particles in Au + Au collisions at intermediate energies
The Skyrme potential energy density functional is introduced into the ultrarelativistic quantum molecular dynamics model and the updated version is applied to studying the directed and elliptic flows of light particles (protons, neutrons, deuterons, tritons, ${}^{3}$He, and ${}^{4}$He) in ${}^{197}$Au + ${}^{197}$Au collisions at beam energies 150, 250, and 400 MeV$/$nucleon. The results are compared with the recent FOPI experimental data. It is found that the yields and collective flows of light particles can be described quite well. The influence of the equation of state, medium-modified nucleon-nucleon elastic cross sections (NNECS) and cluster recognition criteria on the directed and elliptic flows is studied in detail. It is found that the flows of light particles are sensitive to the medium-modified NNECS, but not sensitive to the isospin dependent cluster recognition criteria. It seems difficult, however, even with the new data and calculations, to obtain a more accurate constraint on the nuclear incompressibility ${K}_{0}$ than the interval 200\char21{}260 MeV.
124137012
Study of in-medium Delta Delta elastic scattering cross section
121143863
THE DYNAMICAL ISOSPIN EFFECT ON PROTON-INDUCED REACTIONS ON Sn ISOTOPES
In this talk we present a model, Improved Quantum Molecular Dynamics (ImQMD05) model incorporated with a Statistical Decay Model (SDM), to describe intermediate energy proton induced spallation reactions. A good agreement with experimental data of double differential cross sections of emitted neutrons is obtained. We further apply this model to study the isospin effect in proton induced spallation reactions on a series Sn isotope targets. We find that the systematic behavior of the reaction cross sections for Sn isotope targets deviates from the empirical expression obtained by fitting the experimental data for proton induced spallation reactions on target nuclei along β-stability line. The extent of the deviation depends on the density dependence of the symmetry energy strongly. We also find an obvious shift of the elastic scattering angular distribution of emitted protons when the symmetry energy is taken into account for neutron-rich Sn isotope targets and the angle shifted strongly depends on the stiffness of the symmetry energy. The attractive effect of the symmetry potential of target on incident proton directly influences the motion of the incident proton leading to strong isospin effect on the reaction dynamics and thus on these reaction observables. We conclude that the measurement of reaction cross sections and the elastic scattering angular distributions in proton induced spallation reactions on Sn isotopes can provide clear constraint for the density dependence of symmetry energy.
55892113
In-medium NN cross sections determined from stopping and collective flow in intermediate-energy heavy-ion collisions
In-medium nucleon-nucleon scattering cross sections are explored by comparing results of quantum molecular dynamics simulations to data on stopping and on elliptic and directed flow in intermediate-energy heavy-ion collisions. The comparison points to in-medium cross sections which are suppressed at low energies but not at higher energies. Positive correlations are found between the degree of stopping and the magnitudes of elliptic and directed flows. PACS numbers: 25.70.-z, 24.10.Lx, 21.65.+f
119408968
Isospin dependence of nucleon-nucleon elastic cross section
The in-medium neutron-proton, proton-proton (neutron-neutron) scattering cross sections (sigma(np)*, sigma(pp(nn))*) are studied based on QHD-II type Lagangian within the framework of the microscopic transport theory. The results demonstrate that, for free nucleon-nucleon scattering cross sections, the isospin dependence is dominantly caused by the rho meson field. The medium correction of nucleon-nucleon scattering cross sections is also isospin dependent, sigma(np)*, depends on the baryon density weakly and sigma(pp(nn))* depends on the baryon density significantly, which is due to the different effects of the medium correction of nucleon mass and rho meson mass on sigma(np) and sigma(pp(nn)), respectively.
9051613
Mass and isotope dependence of limiting temperatures for hot nuclei
The mass and isotope dependence of limiting temperatures for hot nuclei are investigated. The predicted mass dependence of limiting temperatures is in good agreement with data derived from the caloric curve data. The predicted isotope distribution of limiting temperatures appears to be a parabolic shape and its centroid is not located at the isotope on the beta-stability line (T=0) but at neutron-rich side. Our study shows that the mass and isotope dependence of limiting temperatures depend on the interaction and the form of surface tension and its isospin dependence sensitively.
118549373
THE CROSS SPECTRAL TIME LAG EVOLUTION ALONG BRANCHES IN XTE J1701-462
We investigate the cross spectrum of XTE J1701-462 in various types of neutron star low-mass X-ray binary subclasses during its 2006-2007 outburst. We analyze the relation between the time lags and temporal variabilities. We find that the hard time lags accompany horizontal branch oscillations (HBOs) and the soft time lags dominate the noise in the low frequency range 0.1-10 Hz on HB. In the Cyg-like phase, the time lags decrease on the middle normal branch (NB) from HB/NB vertex to NB/FB vertex, whereas the time lags are roughly invariant in the Sco-like source. We discuss the fact that the Compton upscattering by the corona introduces the soft lag in low-frequency noise. We suggest that the variation of the Comptonization component from the disk emission leads to the HBOs' time lag evolutions along the Z tracks. We also report the rms amplitude spectrum and phase lag spectrum for the normal branch oscillation (NBO). A similar to 160 degrees. phase lag is found. We find that the rms amplitudes of both the Cyg-like and the Sco-like NBOs linearly increase with the photon energy in low energy bands, and drop in the highest energy band.
4046382
Nuclear symmetry potential in the relativistic impulse approximation
Using the relativistic impulse approximation with the Love-Franey NN scattering amplitude developed by Murdock and Horowitz, we investigate the low-energy (100{<=}E{sub kin}{<=}400 MeV) behavior of the nucleon Dirac optical potential, the Schroedinger-equivalent potential, and the nuclear symmetry potential in isospin asymmetric nuclear matter. We find that the nuclear symmetry potential at fixed baryon density decreases with increasing nucleon energy. In particular, the nuclear symmetry potential at saturation density changes from positive to negative values at nucleon kinetic energy of about 200 MeV. Furthermore, the obtained energy and density dependence of the nuclear symmetry potential is consistent with those of the isospin- and momentum-dependent MDI interaction with x=0, which has been found to describe reasonably well both the isospin diffusion data from heavy-ion collisions and the empirical neutron-skin thickness of {sup 208}Pb.
119114677
Progress in CTEQ-TEA PDF analysis
Recent developments in the CTEQ-TEA global QCD analysis are presented. The parton distribution functions CT10-NNLO are described, constructed by comparing data from many experiments to NNLO approximations of QCD. The global analysis of QCD makes use of experimental data from many short-distance scattering processes to construct, within some approximations, universal parton distribution functions (PDFs) for the proton. Then these functions can be used to calculate hadronic cross sections in the Standard Model and other theories. Global analysis and the resulting PDFs are necessary for the interpretation of experimental results at hadron colliders. Recently published PDFs are based on next-to-next-to-leading order (NNLO) approximations for perturbative QCD[1]. Complete calculations for this order of approximation are available for the running coupling s(Q), PDF evolution in Q, matrix elements in deep-inelastic scattering [2] and vector boson production [3]. The CTEQ analysis treats quark-mass eects in the S-ACOT- factorization scheme, which has been recently extended to two-loop, or NNLO, accuracy [4]. Though the NNLO matrix elements are still unknown for some important processes, such as the inclusive jet production in pp=pp collisions, it is important to use NNLO approximations, where available. CTEQ has developed PDFs for general-purpose computations and estimates of PDF-driven uncertainties over many years [5]. The most recent PDFs in this class, named CT10 and CT10W, were published in 2010 [6]. We now present a new family of CTEQ parton distributions, named CT10 NNLO. There are several reasons for publishing them. First, the CT10 NNLO global analysis is based on the NNLO approximation of perturbative QCD, whereas the CT10 and earlier analyses were based on NLO. Second, benchmarking of NLO jet cross sections [7]and DIS cross sections was performed to quantify theoretical uncertainties, and an in-depth study of the treatment of correlated experimental errors has been completed. Third, selection of experimental data sets has been revisited. The new NNLO PDFs are closely related to both CT10 and CT10W NLO PDFs and can be matched to either of two NLO PDF sets when comparing the NLO and NNLO cross sections. In all three cases, only data from pre-LHC experiments were used in the global fit. The same values of the QCD coupling and heavyquark masses as in CT10 NLO were assumed. Some results concerning CT10 NNLO PDFs
59931380
Relativistic energy density functionals: Low-energy collective states ofPu240andEr166
The empirical relativistic density-dependent, point-coupling energy density functional, adjusted exclusively to experimental binding energies of a large set of deformed nuclei with A ≈ 150-180 and A ≈ 230-250, is tested with spectroscopic data for 166 Er and 240 Pu. Starting from constrained self-consistent triaxial relativistic Hartree-Bogoliubov calculations of binding energy maps as functions of the quadrupole deformation in the β-γ plane, excitation spectra and E2 transition probabilities are calculated as solutions of the corresponding microscopic collective Hamiltonian in five dimensions for quadrupole vibrational and rotational degrees of freedom and compared with available data on low-energy collective states.
122278849
Neutron star structure with modern nucleonic three-body forces
We provide convenient parametrizations of the high-density nuclear equation of state obtained within the Brueckner-Hartree-Fock approach using different modern nucleon-nucleon potentials together with compatible microscopic nuclear three-body forces. The corresponding neutron star mass-radius relations are also presented.