2,190 research outputs found
Energetic particle parallel diffusion in a cascading wave turbulence in the foreshock region
International audienceWe study parallel (field-aligned) diffusion of energetic particles in the upstream of the bow shock with test particle simulations. We assume parallel shock geometry of the bow shock, and that MHD wave turbulence convected by the solar wind toward the shock is purely transverse in one-dimensional system with a constant background magnetic field. We use three turbulence models: a homogeneous turbulence, a regular cascade from a large scale to smaller scales, and an inverse cascade from a small scale to larger scales. For the homogeneous model the particle motions along the average field are Brownian motions due to random and isotropic scattering across 90 degree pitch angle. On the other hand, for the two cascade models particle motion is non-Brownian due to coherent and anisotropic pitch angle scattering for finite time scale. The mean free path ?|| calculated by the ensemble average of these particle motions exhibits dependence on the distance from the shock. It also depends on the parameters such as the thermal velocity of the particles, solar wind flow velocity, and a wave turbulence model. For the inverse cascade model, the dependence of ?|| at the shock on the thermal energy is consistent with the hybrid simulation done by Giacalone (2004), but the spatial dependence of ?|| is inconsistent with it
Report on Agri- Reconstruction Project (ARP).
Poster Sessio
DYNAMIC ANALYSIS OF THE EFFECT OF CENTRIFUGAL AND CORlOLlS FORCES IN SWINGING A BAT
This paper reports a dynamic analysis by computer simulation of bat swinging, taking into account inertial forces at the wrist joint, and which consist of centrifugal and Coriolis forces generated from a body turn and internal rotation of the upper limbs. The ideal bat swing generated by optimisation using a mathematical model is also described. Based on the dynamic analysis, it is shown that the inertial forces play an important role in the process of flexion and extension between a bat and the upper limbs during a bat swing, and that the effects of gravity on a bat is much smaller than those from inertial forces. It was also proven from the optimisation that an ideal bat swing, a swing using minimal torque at the wrist, exists
Light dark matter in leptophobic Z' models
Recent experimental results in direct dark matter detection may be
interpreted in terms of a dark matter particle of mass around 10 GeV/c^2. We
show that the required scenario can be realized with a new dark matter particle
charged under an extra abelian gauge boson Z' that couples to quarks but not
leptons. This is possible provided the Z' gauge boson is very light, around
10-20 GeV/c^2 in mass, and the gauge coupling constant is small, alpha' ~
10^(-5). Such scenarios are not constrained by accelerator data
Low-energy quadrupole collectivity of Sn nuclei in self-consistent calculations with semi-realistic interaction
Quadrupole collectivity of the lowest-lying states, focusing on
and , have been investigated for the Sn nuclei
by applying the self-consistent approaches with the semi-realistic interaction
M3Y-P6. Both and are well reproduced by the
spherical Hartree-Fock-Bogolyubov (HFB) plus quasiparticle random-phase
approximation (QRPA) calculations in , without adjustable parameters.
The measured values in the neutron-deficient Sn nuclei cast a puzzle.
In , the spherical HFB\,+\,QRPA calculations give too strong
, opposite to the shell-model predictions within the one major shell.
Via the constrained-HFB (CHFB) calculations, it is found that the
neutron-deficient Sn nuclei are soft against the quadrupole deformation,
accounting for the limited applicability of the HFB\,+\,QRPA approach. In
particular, the potential energy curves (PECs) are almost flat in the range of
in Sn. We confirm that the near
degeneracy of and triggers weak quadrupole deformation
and its balance with the pairing makes PECs flat, which is qualitatively
consistent with a recent shell model result in an extended model space, by the
calculations shifting the single-particle energy spacing and the pairing
strength. These conclusions are supported by the proton-to-neutron ratios of
the transition matrix elements and the reference values of with the
angular-momentum projection on top of the CHFB solutions
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