R. Mohammadi

Isfahan University of Technology, Eşfahān, Ostan-e Esfahan, Iran

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Publications (3)0 Total impact

  • Source
    E. Bavarsad, M. Haghighat, R. Mohammadi
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    ABSTRACT: The nucleon-nucleon scattering in a large magnetic background is considered to find its potential to change the neutrino emissivity of the neutron stars. For this purpose we consider the one-pion-exchange approximation to find the NN cross-section in a background field as large as $10^{15}\texttt{G}-10^{18}\texttt{G}$. We show that the NN cross-section in neutron stars with temperatures in the range 0.1-5 \texttt{MeV} can be changed up to the one order of magnitude with respect to the one in the absence of the magnetic field. In the limit of the soft neutrino emission the neutrino emissivity can be written in terms of the NN scattering amplitude therefore the large magnetic fields can dramatically change the neutrino emissivity of the neutron stars as well. Comment: 21 pages, 5 figures, to appear in PRD
    Physical review D: Particles and fields 10/2010;
  • Source
    M. M. Ettefaghi, M. Haghighat, R. Mohammadi
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    ABSTRACT: QED based on -unexpanded noncomutative space-time in contrast with the noncommutative QED based on -expanded U(1) gauge theory via the Seiberg-Witten map is one-loop renormalizable. Meanwhile it suffers from asymptotic freedom that is not in agreement with the experiment. We show that the QED part of the U{sub *}(3)xU{sub *}(1) gauge group as an appropriate gauge group for the noncommutative QED+QCD is not only one-loop renormalizable but also has a function that can be positive, negative and even zero. In fact the function depends on the mixing parameter as a free parameter and it will be equal to its counterpart in the ordinary QED for =0.367.
    Physical review D: Particles and fields 01/2010; 82(10):105017-105017.
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    ABSTRACT: According to the standard cosmology, near the last scattering surface, the photons scattered via Compton scattering are just linearly polarized and then the primordial circular polarization of the CMB photons is zero. In this work we show that CMB polarization acquires a small degree of circular polarization when a background magnetic field is considered or the quantum electrodynamic sector of standard model is extended by Lorentz-noninvariant operators as well as noncommutativity. The existence of circular polarization for the CMB radiation may be verified during future observation programs and it represents a possible new channel for investigating new physics effects. Comment: 28 pages, v3, Phys. Rev. D 81, 084035 (2010)
    Physical review D: Particles and fields 12/2009;

Publication Stats

2 Citations
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  • 2009–2010
    • Isfahan University of Technology
      • Department of Physics
      Eşfahān, Ostan-e Esfahan, Iran