100150271
Effect of density dependent symmetry energy on fragmentation
The effect of the density dependence of symmetry energy on fragmentation is studied using isospin-dependent quantum molecular dynamics model(IQMD) Model. We have used the reduced isospin-dependent cross-section with soft equation of state to explain the experimental findings for the system 79Au197 + 79Au197 for the full colliding geometry. In addition to that we have tried to study the collective response of the momentum dependent interactions(MDI) and symmetry energy towards the multifragmentation.
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.
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.
120495279
The simulations of Ca-Ca collisions: Binary break-up, onset of multifragmentation and vaporization
The incomplete fusion, onset of multifragmentation and vaporization is studied in Ca-Ca collisions at bombarding energies between 20–1000 A MeV and at impact parameters between b=0 to bmax using quantum molecular dynamics model. We find incomplete fusion events at E/A=20 MeV. The light mass fragment production at a given incident energy does not show any rise and fall with a change in the impact parameter. Whereas, the IMF production at higher energies (≥ 150 A MeV) has a clear rise and fall.
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.
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.
62884347
Some FRW models of accelerating universe with dark energy
The paper deals with a spatially homogeneous and isotropic FRW space-time filled with perfect fluid and dark energy components. The two sources are assumed to interact minimally, and therefore their energy momentum tensors are conserved separately. A special law of variation for the Hubble parameter proposed by Berman (Nuovo Cimento B 74:182, 1983) has been utilized to solve the field equations. The Berman’s law yields two explicit forms of the scale factor governing the FRW space-time and constant values of deceleration parameter. The role of dark energy with variable equation of state parameter has been studied in detail in the evolution of FRW universe. It has been found that dark energy dominates the universe at the present epoch, which is consistent with the observations. The physical behavior of the universe has been discussed in detail.
119337927
Large-eddy simulations of fluid and magnetohydrodynamic turbulence using renormalized parameters
In this paper a procedure for large-eddy simulation (LES) has been devised for fluid and magnetohydrodynamic turbulence in Fourier space using the renormalized parameters. The parameters calculated using field theory have been taken from recent papers by Verma [1,2]. We have carried out LES on 643 grid. These results match quite well with direct numerical simulations of 1283. We show that proper choice of parameter is necessary in LES.
10546536
Instabilities of the small black hole: a view from N = 4 SYM
We compute a one-loop effective action for the constant modes of the scalars and the Polyakov loop matrix of = 4 SYM on S3 at finite temperature and weak 't Hooft coupling. Above a critical temperature, the effective potential develops new unstable directions accompanied by new saddle points which only preserve an SO(5) subgroup of the SO(6) global R-symmetry. We identify this phenomenon as the weak coupling version of the well known Gregory-Laflamme localization instability in the gravity dual of the strongly coupled field theory: The small AdS5 black hole when viewed as a ten dimensional, asymptotically AdS5 × S5 solution smeared on the S5 is unstable to localization on S5. Our effective potential, in a specific Lorentzian continuation, can provide a qualitative holographic description of the decay of the ``topological black hole'' into the AdS bubble of nothing.
59440238
Vacuum structure and flavor symmetry breaking in supersymmetric SO(nc) gauge theories
We determine the vacuum structure and phases of N=1 theories obtained via a 
mass \mu for the adjoint chiral superfield in N=2, SO(n_c) SQCD. For large 
number of flavors these theories have two groups of vacua. The first exhibits 
dynamical breaking of flavor symmetry \USp(2n_f) \to U(n_f) and arises as a 
relevant deformation of a non-trivial superconformal theory. These are in the 
confined phase. The second group, in an IR-free phase with unbroken flavor 
symmetry, is produced from a Coulomb branch singularity with Seiberg's dual 
gauge symmetry. In the large-\mu regime both groups of vacua are well-described 
by dual quarks and mesons, and dynamical symmetry breaking in the first group 
occurs via meson condensation. We follow the description of these vacua from 
weak to strong coupling and demonstrate a nontrivial agreement between the 
phases and the number of vacua in the two regimes. We construct the 
semiclassical monopole flavor multiplets and argue that their multiplicity is 
consistent with the number of N=1 vacua.