3,046 research outputs found
Precision calculation for nucleon capture by deuteron with Effective Field Theory
We calculate the cross section for radiative capture of neutron by deuteron
using Effective Field Theory(EFT). The calculation includes
N2LO order and we compare our results with available calculated data below
E=0.2 Mev.Comment: 4 pages, 1 eps figures, oral contribution, 19th European Few-Body
Conference (fb19), Groningen, Netherlands, August 23 - August 27, 2004. To be
published in the proceeding
Neutron-Deuteron System and Photon Polarization Parameter at Thermal Neutron Energies
Effective Field Theory(EFT) is, the unique, model independent and systematic
low-energy version of QCD for processes involving momenta below the pion mass.
A low-energy photo-nuclear observable in three-body systems, photon
polarization parameter at thermal neutron energies is calculated by using
pionless EFT up to next-to-next to leading order(NLO). In order to make a
comparative study of this model, we compared our results for photon
polarization parameter with the realistic Argonne two-nucleon and
Urbana IX or Tucson-Melbourne three-nucleon interactions. Three-body currents
give small but significant contributions to some of the observables in the
neutron-deuteron radiative capture cross section at thermal neutron energies.
In this formalism the three-nucleon forces are needed up to NLO for cut-off
independent results. Our result converges order by order in low energy
expansion and also cut-off independent at this order.Comment: 10 pages, 3 figures, 2 table
Linkage of modules over Cohen-Macaulay rings
Inspired by the works in linkage theory of ideals, the concept of sliding
depth of extension modules is defined to prove the Cohen-Macaulyness of linked
module if the base ring is merely Cohen-Macaulay. Some relations between this
new condition and other module-theory conditions such as G-dimension and
sequentially Cohen-Macaulay are established. By the way several already known
theorems in linkage theory are improved or recovered by new approaches.Comment: 12 Page
Solving Singular Boundary Value Problems Using Daftardar-Jafari Method
In this paper, we apply the suggested iterative method by Daftardar and Jafari hereafter called Daftardar-Jafari method for solving singular boundary value problems. In the implementation of this new method, one does not need the computation of the derivative of the so-called Adomian polynomials. The method is quite efficient and is practically well suited for use in these problems. Two illustrative examples has been presented
Study on Transpiration Rates of Vicia Villocea and Bromus Inermis Species
Ecohydrology is concerned with the interaction between the hydrological and plant processes. Some aspects of the hydrologic cycle, such as transpiration and interception have received little attention owing to difficulties in field measurements. Quantifying the components of water balance for a watershed is crucial for understanding the dominant hydrologic processes occurring in a basin (Flerchinger & Cooley, 2000). Water use by vegetation is controlled by the water uptake by roots, the transfer of liquid water through plants and vapour loss from the leaf surfaces by the opening and closure of the stomata (Roberts, 2000) i.e. transpiration. Comparison of transpiration of rangelands species is a prerequisite for improving range management. The present study is a preliminary comparison in transpiration between two important Iranian rangeland species, viz. the legume, Vicia villocea and the grass, Bromus inermis
Floquet states and optical conductivity of an irradiated two dimensional topological insulator
We study the topology of the Floquet states and time-averaged optical
conductivity of the lattice model of a thin topological insulator subject to a
circularly polarized light using the extended Kubo formalism. Two driving
regimes, the off-resonant and on-resonant, and two models for the occupation of
the Floquet states, the ideal and mean-energy occupation, are considered. In
the ideal occupation, the real part of DC optical Hall conductivity is shown to
be quantized while it is not quantized for the mean energy distribution. The
optical transitions in the Floquet band structure depend strongly on the
occupation and also the optical weight which consequently affect all components
of optical conductivity. At high frequency regime, we present an analytical
calculation of the effective Hamiltonian and also its phase diagram which
depends on the tunneling energy between two surfaces. The topology of the
system shows rich phases when it is irradiated by a weak on-resonant drive
giving rise to emergence of anomalous edge states.Comment: 11 pages, 8 figure
- …