D. Vautherin

Pierre and Marie Curie University - Paris 6, Lutetia Parisorum, Île-de-France, France

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Publications (85)225.11 Total impact

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    P. -H. Heenen, H. Flocard, D. Vautherin
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    ABSTRACT: Without Abstract
    01/2006: pages 338-342;
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    Y. Tsue, D. Vautherin, T. Matsui
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    ABSTRACT: Variational method is applied to describe Bose-Einstein condensates (BEC) interacting via a pseudo-potential, taking into account quantum fluctuations around the mean field by the Gaussian approximation. Contributions from the pair-wise scattering by the singular potential should be removed carefully to avoid double countings in the perturbation series in terms of original bare interaction. We show that this procedure removes all dangerous terms which contain divergences.
    03/2003;
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    ABSTRACT: We study the effects of repulsive interactions on the critical density for the Bose-Einstein transition in a homogeneous dilute gas of bosons. First, we point out that the simple mean field approximation produces no change in the critical density, or critical temperature, and discuss the inadequacies of various contradictory results in the literature. Then, both within the frameworks of Ursell operators and of Green's functions, we derive self-consistent equations that include correlations in the system and predict the change of the critical density. We argue that the dominant contribution to this change can be obtained within classical field theory and show that the lowest order correction introduced by interactions is linear in the scattering length, a, with a positive coefficient. Finally, we calculate this coefficient within various approximations, and compare with various recent numerical estimates.
    Physics of Condensed Matter 10/2001; 24(1):107-124. · 1.28 Impact Factor
  • C. Heinemann, D. Vautherin, C. Martin, E. Iancu
    01/2000;
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    C. Heinemann, E. Iancu, C. Martin, D. Vautherin
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    ABSTRACT: For a SU(N) Yang-Mills theory, we present variational calculations using gaussian wave functionals combined with an approximate projection on gauge invariant states. The projection amounts to correcting the energy of the gaussian states by substracting the spurious energy associated with gauge rotations. Based on this improved energy functional, we perform variational calculations of the interaction energy in the presence of external electric and magnetic fields. We verify that the ultraviolet behaviour of our approximation scheme is consistent, as it should, with that expected from perturbation theory. In particular, we recover in this variational framework the standard one-loop beta function, with a transparent interpretation of the screening and anti-screening contributions. Comment: 40 pages, no figures
    Physical review D: Particles and fields 11/1999;
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    ABSTRACT: We show that the critical temperature of a uniform dilute Bose gas must increase linearly with the s-wave scattering length describing the repulsion between the particles. Because of infrared divergences, the magnitude of the shift cannot be obtained from perturbation theory, even in the weak coupling regime; rather, it is proportional to the size of the critical region in momentum space. By means of a self-consistent calculation of the quasiparticle spectrum at low momenta at the transition, we find an estimate of the effect in reasonable agreement with numerical simulations.
    Physical Review Letters 06/1999; · 7.73 Impact Factor
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    J. Navarro, E. S. Hernandez, D. Vautherin
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    ABSTRACT: We present microscopic calculations of neutrino propagation in hot neutron matter above nuclear density within the framework of the Random Phase Approximation . Calculations are performed for non- degenerate neutrinos using various Skyrme effective interactions. We find that for densities just above nuclear density, spin zero sound is present at zero temperature for all Skyrme forces considered. However it disappears rapidly with increasing temperature due to a strong Landau damping. As a result the mean-free path is given, to a good approximation, by the mean field value. Because of the renormalization of the bare mass in the mean field, the medium is more transparent as compared to the free case. We find, in contrast, that at several times nuclear density, a new type of behavior sets in due to the vicinity of a magnetic instability. It produces a strong reduction of the mean free path. The corresponding transition density however occurs in a region where inputs from more realistic calculations are necessary for the construction of a reliable Skyrme type parametrization. Comment: 17 pages, 4 figures
    Physical Review C 01/1999; · 3.72 Impact Factor
  • J. Navarro, E. S. Hernández, D. Vautherin
    Nuclear Physics A 01/1999; 654(1). · 2.50 Impact Factor
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    Y. Tsue, D. Vautherin, T. Matsui
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    ABSTRACT: Mean field theory for the time evolution of quantum meson fields is studied in terms of the functional Schroedinger picture with a time-dependent Gaussian variational wave functional. We first show that the equations of motion for the variational wavefunctional can be rewritten in a compact form similar to the Hartree-Bogoliubov equations in quantum many-body theory and this result is used to recover the covariance of the theory. We then apply this method to the O(N) model and present analytic solutions of the mean field evolution equations for an N-component scalar field. These solutions correspond to quantum rotations in isospin space and represent generalizations of the classical solutions obtained earlier by Anselm and Ryskin. As compared to classical solutions new effects arise because of the coupling between the average value of the field and its quantum fluctuations. We show how to generalize these solutions to the case of mean field dynamics at finite temperature. The relevance of these solutions for the observation of a coherent collective state or a disoriented chiral condensate in ultra-relativistic nuclear collisions is discussed. Comment: 31 pages, 2 Postscript figures, uses ptptex.sty
    Progress of Theoretical Physics 12/1998; · 2.48 Impact Factor
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    C. Heineman, C. Martin, D. Vautherin, E. Iancu
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    ABSTRACT: Variational calculations using Gaussian wave functionals combined with an approximate projection on gauge invariant states are presented. We find that the energy exhibits a minimum for a wave functional centered around a non vanishing background magnetic field. We show that divergences can be removed by a renormalization of the coupling constant. The resulting expectation value of the gluon condensate is found to be in qualitative agreement with phenomenological estimates.
    03/1998;
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    ABSTRACT: Radii of sodium isotopes have been calculated by using the Hartree-Fock-BCS model and the Generator Coordinate Method (GCM) with different forces. It is found that Hartree-Fock-BCS results present a jump in both neutron and proton radii from 22Na to 23Na. However, configuration mixing calculations performed with the GCM result in a smooth increase of the neutron radius and an almost constant proton radius for the sodium isotopes. We analyze and discuss our results in the light of recent experimental data.
    Physics Letters B 01/1998; · 4.57 Impact Factor
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    D. Vautherin, T. Matsui
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    ABSTRACT: Analytic solutions of the mean field evolution equations for an N-component scalar field with O(N) symmetry are presented. These solutions correspond to rotations in isospin space. They represent generalizations of the classical solutions obtained earlier by Anselm and Ryskin. As compared to classical solutions new effects arise because of the coupling between the average value of the field and quantum fluctuations.
    Physics Letters B 01/1998; · 4.57 Impact Factor
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    ABSTRACT: We present a simple model to calculate energy distributions and multiplicities of the neutrons emitted in the interaction of a high-energy proton with a thick target. It is based on a dEdx formula proposed by Cugnon for the proton energy loss inside nuclear matter and on the assumption that the dissipated energy eventually becomes thermalized. Comparison with the results of existing codes and available data is made. An application to the determination of the sensitivity of multiplicities to various input parameters (e.g. the level density parameter) is described. The model is shown to provide further physical insight into the standard spallation codes.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 12/1997; 400(2):255-266. · 1.14 Impact Factor
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    D. Vautherin, T. Matsui
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    ABSTRACT: We construct asymptotic solutions of the functional Schroedinger equation for a scalar field in the Gaussian approximation at large proper time. These solutions describe the late proper time stages of the expansion of a meson gas with boost invariant boundary conditions. The relevance of these solutions for the formation of a disoriented chiral condensate in ultra relativistic collisions is discussed. Comment: 9 pages, LATEX
    Physical Review D 09/1996; · 4.69 Impact Factor
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    Abdellatif Abada, Dominique Vautherin
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    ABSTRACT: The description of collective motion in nuclei at finite temperature using the framework of the random phase approximation is discussed. We focus on the special case of the isovector response function of hot nuclear matter using various effective Skyrme interactions.
    11/1995;
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    F. L. Braghin, D. Vautherin, A. Abada
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    ABSTRACT: We investigate the role of the effective nucleon-nucleon interaction in the description of giant dipole resonances in hot nuclei. For this purpose we calculate the response function of hot nuclear matter to a small isovector external perturbation using various effective Skyrme interactions. We find that for Skyrme forces with an effective mass close to unity an undamped zero sound mode occurs at zero temperature. This mode gives rise in finite nuclei (calculated via the Steinwedel-Jenssen model) to a resonance whose energy agrees with the observed value. We find that zero sound disappears at a temperature of a few MeV, leaving only a broad peak in the dipole strength. For Skyrme forces with a small value of the effective mass (0.4- 0.5), there is no zero sound at zero temperature but only a weak peak located too high in energy. The strength distribution in this case is nearly independent of temperature and shows small collective effects. The relevance of these results for the saturation of photon multiplicities observed in recent experiments is pointed out.
    Physical Review C 06/1995; · 3.72 Impact Factor
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    Abdellatif Abada, Fabio L. Braghin, Dominique Vautherin
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    ABSTRACT: We calculate the isovector response function of hot nuclear matter using various effective Skyrme interactions. For Skyrme forces with a small effective mass the strength distribution is found to be nearly independent of temperature, and shows little collective effects. In contrast effective forces with an effective mass close to unity produce sizeable collective effects at zero temperature which disappear at temperatures of a few MeV. We discuss the relevance of these results for the saturation of the multiplicity of photons emitted by the giant dipole resonance in hot nuclei beyond $T$=3 MeV observed in recent experiments.
    02/1995;
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    F. Braghin, C. Martin, D. Vautherin
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    ABSTRACT: We consider the functional Schrodinger equation for a self interacting scalar field in an expanding geometry. By performing a time dependent scale transformation on the argument of the field we derive a functional Schrodinger equation whose hamiltonian is time independent but involves a time-odd term associated to a constraint on the expansion current. We study the mean field approximation to this equation and generalize in this case, for interacting fields, the solutions worked out by Bunch and Davies for free fields. Comment: 8 pages, Latex, IPNO/TH 94-39
    Physics Letters B 05/1994; · 4.57 Impact Factor
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    F.L. Braghin, D. Vautherin
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    ABSTRACT: We investigate the response function of hot nuclear matter to a small isovector external field using a simplified Skyrme interaction reproducing the value of the symmetry energy coefficient. We consider values of the momentum transfer corresponding to the dipole oscillation in heavy nuclei. We find that while at zero temperature the particle hole interaction is almost repulsive enough to have a sharp (zero sound type) collective oscillation, such is no longer the case at temperatures of a few MeV. As a result a broadening of the dipole resonance occurs, leading to its quasi disappearance by the time the temperature reaches 5 MeV. The sensitivity of the temperature evolution of the width when modifying the residual interaction strength is also examined.
    Physics Letters B 04/1994; · 4.57 Impact Factor
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    Abdellatif Abada, Dominique Vautherin
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    ABSTRACT: Two phonon-states of alkali-metal clusters (treated as jellium spheres) are calculated by using a method based on a perturbative construction of periodic orbits of the time-dependent mean-field equations. Collective vibrations with various multipolarities in charged $Na^+_{21}$ are considered.
    04/1993;

Publication Stats

3k Citations
225.11 Total Impact Points

Institutions

  • 1998
    • Pierre and Marie Curie University - Paris 6
      Lutetia Parisorum, Île-de-France, France
  • 1989–1991
    • Centro de Estudios y Experimentación de Obras Públicas
      Madrid, Madrid, Spain
  • 1972–1989
    • Massachusetts Institute of Technology
      • Center for Theoretical Physics
      Cambridge, Massachusetts, United States
  • 1983–1986
    • Université Libre de Bruxelles
      • Nuclear Physics and Mathematical Physics Unit
      Brussels, BRU, Belgium
  • 1984–1985
    • Weizmann Institute of Science
      Israel
  • 1972–1984
    • Institut de Physique Nucléaire de Lyon
      Lyons, Rhône-Alpes, France
  • 1970–1976
    • University of Oxford
      Oxford, England, United Kingdom
  • 1975
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France