118711481
Study of elliptical flow at VECC-SCC500 energies
We study the transverse momentum dependence of elliptical flow at VECC energies by using the projectiles having masses lying between 16 and 56 units. The detailed study in this direction will be fruitful for experimentlists.
117335698
Effect of isospin dependent cross-section on nuclear stopping
Nuclear stopping in heavy ion collisions (HIC) has been studied by means of rapidity distribution and asymmetry of nucleon momentum distribution. It is an important quantity in determining the outcome of a reaction. Fen Fu {\it et al.,} \cite{2} calculate both the radial flow and the degree of nuclear stopping in Pb + Pb and Ni + Ni at 0.4, 0.8 and 1.2 GeV/neucleon. They found that the expansion velocity as well as the degree of nuclear stopping are higher in the heavier system at all energies.
118085314
Rapidity distribution dependence of the transition energy in heavy-ion collisions
For the present analysis, simulations are carried out for thousand of events for the reaction of 79Au197 + 79Au197 at semi-central geometry using a hard equation of state. The whole of the analysis is performed for light charged particles (LCP's). The transition from in-plane to out-of-plane is observed only when the mid-rapidity region is included in the rapidity bin otherwise no transition is observed. The transition energy is found to be strongly dependent on the size of the rapidity bin. The transition energy is parameterized with a straight line interpolation.
116891254
Production of light and intermediate mass fragments using various clusterization algorithms
For the present analysis we simulate the reaction 129Xe 54+197Au79 at E=50 MeV/nucleon respectively[3]. This reaction is simulated at different impact parameters using hard equation of state. The stored phase space is then analyzed by using MST, MSTP and MSTB algorithms. MSTB and MSTP identifies the free nucleons as early as possible. In the two cases, a check in the form of binding energy and momentum cut helps to identify the fragments quite early. The normal MST takes quite a long time to identify the stable fragments which are residual of excited fragments.
118406564
Effect of the symmetry energy on nuclear stopping and its relation to the production of light charged fragments
We present a complete systematics (excitation function, impact parameter, system size, isospin asymmetry, and equations of state dependences) of global stopping and fragment production for heavy-ion reactions in the energy range between 50 and 1000 MeV/nucleon in the presence of symmetry energy and an isospin-dependent cross section. It is observed that the degree of stopping depends weakly on the symmetry energy and strongly on the isospin-dependent cross section. However, the symmetry energy and isospin-dependent cross section has an effect of the order of more than 10% on the emission of light charged particles (LCP's). It means that nuclear stopping and LCP's can be used as a tool to get the information of an isospin-dependent cross section. Interestingly, the LCP's emission in the presence of symmetry energy is found to be highly correlated with the global stopping.
119288476
Influence of charge asymmetry and isospin dependent cross-section on nuclear stopping
Using the isospin dependent quantum molecular dynamics model, we study the effect of charge asymmetry and isospin dependent cross-section on nuclear stopping and multiplicity of free nucleons and LMF’s. Simulations were carried out for the reactions 124 Xm + 124 Xm, where m varies from 47 to 59 and for 40 Yn+ 40 Yn, where n varies from 14 to 23. Our study shows that nuclear stopping as well as the production of LMF’s depend strongly on the isospin of the cross-section.
118269503
Suppression of complete fusion in the Li-6 + Sm-144 reaction
Complete fusion excitation function for the 6 Li + 144 Sm reaction has been measured at near barrier energies by the activation technique. Coupled-channel calculations show an enhancement in fusion cross section at energies below the barrier compared to the one-dimensional barrier penetration model calculation, but they overpredict it in the entire energy range compared to the experimental data. Reduced fusion cross sections for the present system at energies normalized to the Coulomb barrier were also found to be systematically lower than those with strongly bound projectiles forming a similar compound nucleus. These two observations conclusively show that the complete fusion cross section, at above barrier energies, is suppressed by ∼32% in the 6 Li + 144 Sm reaction. Reanalyses of existing fusion data for 7 Li + 165 Ho and 7 Li + 159 Tb also show a suppression compared to those with strongly bound projectiles, which contradicts earlier conclusions. The fusion suppression factor seems to exhibit a systematic behavior with respect to the breakup threshold of the projectile and the atomic number of the target nucleus.
116887728
Sensitivity of elliptical flow in intermediate energy heavy-ion collisions
The detailed analysis of excitation function of elliptical flow by taking into account the nature of equation of state, nucleon-nucleon cross sections as well as momentum dependent interactions is performed within Quantum Molecular Dynamics (QMD)model. All the observables are found to sensitive towards the elliptical flow. The transition energy is found to be decrease with increase in the size of the fragment in the presence of static equation of state as well as with large cross sections, while, trend gets opposite when momentum dependent interactions are included. At last, the experimental data is verified with static hard equation of state in the presence of large cross sections.
16129121
Spinning flavor branes and fermion pairing instabilities
We consider probe Dp-branes, p=3,5,7, in global AdS_5 x S^5, rotating along an internal direction in the S^5. These are dual to strongly interacting N=4 SYM on S^3 with massless fundamental flavours, in the presence of an R-symmetry chemical potential for flavour fermions. For massless, "AdS-filling" Dp-brane embeddings at zero temperature, we find an infinite set of threshold values of the chemical potential at which instabilities are triggered. The onset of instability is always preceded by metastability of the zero density state. From the onset values of the chemical potential, we infer that unstable directions favour a homogeneous condensate of a bilinear made from fermion harmonics, or Cooper pairing. We confirm this picture both numerically and analytically. The linearized analysis showing the appearance of instabilities involves a charged scalar in global AdS space coupled to a (large) constant background gauge potential. The resulting frequency space correlator of the fermion bilinear at strong coupling displays poles in the upper half plane. In contrast, the correlator at zero coupling exhibits Pauli blocking due to occupation of states below the Fermi level, but no instabilities. The end-point of the strong coupling instability is not visible in our setup.
120764089
Bianchi Type-I Space-Time with Variable Cosmological Constant
A spatially homogeneous and anisotropic Bianchi type-I perfect fluid model is considered with variable cosmological constant. Einstein’s field equations are solved by using a law of variation for mean Hubble’s parameter, which is related to average scale factor and that yields a constant value of deceleration parameter. An exact and singular Bianchi-I model is presented, where the cosmological constant remains positive and decreases with the cosmic time. It is found that the solutions are consistent with the recent observations of type Ia supernovae. A detailed study of physical and kinematical properties of the model is carried out.
1526631
Magnetically induced electronic ferroelectricity in half-doped manganites.
Using a joint approach of density functional theory and model calculations, we demonstrate that a prototypical charge ordered half-doped manganite La1/2Ca1/2MnO3 is multiferroic. The combination of a peculiar charge-orbital ordering and a tendency to form spin dimers breaks the inversion symmetry and leads to a ferroelectric ground state with a polarization up to several microC/cm2. The presence of improper ferroelectricity does not depend on the hotly debated structural details of this material: in the Zener-polaron structure we find a similar ferroelectric response with a large polarization of purely magnetic origin.