Effect of entrance-channel asymmetry on the isospin dependence of nucleon emission in heavy ion collisions

Using the isospin- and momentum-dependent hadronic transport model IBUU04, we have investigated the influence of the entrance-channel isospin asymmetry on the sensitivity of the pre-equilibrium neutron/proton ratio to symmetry energy in central heavy-ion collisions induced by high-energy radioactive beams. Our analysis and discussion are based on the dynamical simulations of the three isotopic reaction systems 132Sn^124Sn, 124Sn＋l12Sn and 112Sn＋l12Sn which are of the same total proton number but different isospin asymmetry. We find that the kinetic-energy distributions of the pre-equilibrium neutron/proton ratio are quite sensitive to the density-dependence of symmetry energy at incident beam energy E/A =400 MeV, and the sensitivity increases as the isospin asymmetry of the reaction system increases.

Exploring nuclear symmetry energy with isospin dependence in neutron skin thickness of nuclei

We propose an alternative way to constrain the density dependence of the symmetry energy from the neutron skin thickness of nuclei which shows a linear relation to both the isospin asymmetry and the nuclear charge with a form of Z2/3. The relation of the neutron skin thickness to the nuclear charge and isospin asymmetry is systematically studied with the data from antiprotonic atom measurement, and with the extended Thomas-Fermi approach incorporating the Skyrme energy density functional. An obviously linear relationship between the slope parameter L of the nuclear symmetry energy and the isospin asymmetry dependent parameter of the neutron skin thickness can be found, by adopting 70 Skyrme interactions in the calculations. Combining the available experimental data, the constraint of -20 MeV 〈～ L 〈～ 82 MeV on the slope parameter of the symmetry energy is obtained. The Skyrme interactions satisfying the constraint are selected.

Isospin dependent properties of the isotopic chains of Scandium and Titanium nuclei within the relativistic mean-field formalism

Density-dependent nuclear symmetry energy is directly related to iso spin asymmetry for finite and infinite nuclear systems.It is critical to determine the coefficients of symmetry energy and their related observables because they hold great importance in different areas of nuclear physics,such as the analysis of the structure of ground state exotic nuclei and neutron star studies.The ground state bulk properties of Scandium(Z=21) and Titanium(Z=22) nuclei are calculated,such as their nuclear binding energy(B.E.),quadrupole deformation(β_2),two-neutron separation energy(S_(2 n)),differential variation in the two-neutron separation energy(dS_(2 n)),and root-mean-square charge radius(r_(ch)).The iso spin properties,namely the coefficient of nuclear symmetry energy and its components,such as the surface and volume symmetry energy of a finite isotopic chain,from the corresponding quantities of infinite nuclear matter,are also estimated.Finally,we correlate the neutron-skin thickness with the coefficient of symmetry energy and the related observables corresponding to the isotopic chains of these nuclei.The coherent density fluctuation model(CDFM) is used to estimate the iso spin-dependent properties of finite nuclei,such as symmetry energy,surface symmetry energy,and volume symmetry energy,from their corresponding component in infinite nuclear matter.The relativistic mean-field(RMF) formalism with non-linear NL3 and relativistic-Hartree-Bogoliubov theory with density-dependent DD-ME2 interaction parameters are employed in the analysis.The weight function |F(x)|^(2) is estimated using the total density of each nucleus,which in turn is used with the nuclear matter quantities to obtain the effective symmetry energy and its components in finite nuclei.We calculate the ground state bulk properties,such as nuclear binding energy,quadrupole deformation,two-neutron separation energy,differential variation in the two-neutron separation energy,and root-mean-square charge radius,for the Sc-and Ti-isotopic chains using the non-linear NL 3 and density-dependent DD-ME2 parameter sets.Furthermore,the ground state density distributions are used within the CDFM to obtain the effective surface properties,such as symmetry energy and its components,namely volume and surface symmetry energy,for both the parameter sets.The calculated quantities are used to understand the isospin dependent structural properties of finite nuclei near and beyond the drip line,which broadens the scope of discovering new magicity along the isotopic chains.A shape transition is observed from spherical to prolate near N≥44 and N≥40 for the Sc-and Ti-isotopic chains,respectively.Notable signatures of shell and/or sub-shell closures are found for the magic neutron numbers N=20 and 28 for both isotopic chains using the nuclear bulk and isospin quantities.In addition to these,a few shell/sub-shell closure signatures are observed near the drip-line region at N=34 and 50 by following the surface/isospin dependent observables,namely symmetry energy and its component,for both the isotopic chain of odd-A Sc-and even-even Ti-nuclei.

Search for new physics in the B→K^((*))l^+l^- decays at BABAR

Based on a data sample of 384 million BB pairs collected with the BABAR detector at the PEP-Ⅱ asymmetric e ＋ e ￣ storage ring,we measure branching fractions,direct CP,isospin and lepton-flavor asymmetries for the rare decays B → K （＊） l ＋ l￣ in two di-lepton mass bins above and below the J/ψ resonance.For the B → K＊ l ＋ l￣ decay,we also measure the K＊ longitudinal polarization fraction and the di-lepton forwardbackward asymmetry.