125 research outputs found
Ordered bicontinuous double-diamond morphology in subsaturation nuclear matter
We propose to identify the new "intermediate" morphology in subsaturation
nuclear matter observed in a recent quantum molecular dynamics simulation with
the ordered bicontinuous double-diamond structure known in block copolymers. We
estimate its energy density by incorporating the normalized area-volume
relation given in a literature into the nuclear liquid drop model. The
resulting energy density is higher than the other five known morphologies.Comment: 4 pages, 4 figures, published in Phys. Rev.
Solvable few-body quantum problems
This work is devoted to the study of some exactly solvable quantum problems
of four, five and six bodies moving on the line. We solve completely the
corresponding stationary Schr\"odinger equation for these systems confined in
an harmonic trap, and interacting pairwise, in clusters of two and three
particles, by two-body inverse square Calogero potential. Both translationaly
and non-translationaly invariant multi-body potentials are added. In each case,
the full solutions are provided, namely the normalized regular eigensolutions
and the eigenenergies spectrum. The irregular solutions are also studied. We
discuss the domains of coupling constants for which these irregular solutions
are square integrable. The case of a "Coulomb-type" confinement is investigated
only for the bound states of the four-body systems.Comment: 23 page
A Generalized Uhlenbeck and Beth Formula for the Third Cluster Coefficient
Relatively recently (A. Amaya-Tapia, S. Y. Larsen and M. Lassaut. Ann. Phys.,
vol. 306 (2011) 406), we presented a formula for the evaluation of the third
Bose fugacity coefficient - leading to the third virial coefficient - in terms
of three-body eigenphase shifts, for particles subject to repulsive forces. An
analytical calculation for a 1-dim. model, for which the result is known,
confirmed the validity of this approach. We now extend the formalism to
particles with attractive forces, and therefore must allow for the possibility
that the particles have bound states. We thus obtain a true generalization of
the famous formula of Uhlenbeck and Beth (G.E. Uhlenbeck and E. Beth. Physica,
vol. 3 (1936) 729; E. Beth and G.E. Uhlenbeck. ibid, vol.4 (1937) 915) (and of
Gropper (L. Gropper. Phys. Rev. vol. 50 (1936) 963; ibid vol. 51 (1937) 1108))
for the second virial. We illustrate our formalism by a calculation, in an
adiabatic approximation, of the third cluster in one dimension, using McGuire's
model as in our previous paper, but with attractive forces. The inclusion of
three-body bound states is trivial; taking into account states having
asymptotically two particles bound, and one free, is not.Comment: 38 pages, 6 figure
Cluster Expansion of Cold Alpha Matter Energy
In the cluster expansion framework of Bose liquids we calculate analytical
expressions of the two-body, three-body and four-body diagrams contributing to
the g.s. energy of an infinite system of neutral alpha-particles at
zero-temperature, interacting via the strong nuclear forces exclusively. This
is analytically tractable by assuming a density dependent two-body correlation
function of Gaussian type. For the alpha-alpha potential we adopt the
phenomenological Ali-Bodmer interaction and semi-microscopic potentials
obtained from the Gogny force parametrizations. We show that under such
assumptions we achieve a rapid convergence in the cluster expansion, the
four-body contributions to the energy being smaller than the two-body and
three-body contributions by at least an order of magnitude.Comment: 22 pages, 13 figure
Piecewise constant potentials and discrete ambiguities
This work is devoted to the study of discrete ambiguities. For parametrized
potentials, they arise when the parameters are fitted to a finite number of
phase-shifts. It generates phase equivalent potentials. Such equivalence was
suggested to be due to the modulo uncertainty inherent to phase
determinations. We show that a different class of phase-equivalent potentials
exists. To this aim, use is made of piecewise constant potentials, the
intervals of which are defined by the zeros of their regular solutions of the
Schr\"odinger equation. We give a classification of the ambiguities in terms of
indices which include the difference between exact phase modulo and the
numbering of the wave function zeros.Comment: 26 pages Subject: Mathematical Physics math-p
Ising analogue to compact-star matter
By constructing an Ising analogue of compact-star matter at sub-saturation
density we explored the effect of Coulomb frustration on the nuclear liquid-gas
phase transition. Our conclusions is twofold. First, the range of temperatures
where inhomogeneous phases form expands with increasing Coulomb-field strength.
Second, within the approximation of uniform electron distribution, the limiting
point upon which the phase-coexistence region ends does not exhibit any
critical behaviour. Possible astrophysics consequences and thermodynamical
connections are discussed.Comment: 4 pages, 3 figure
European protection of agricultural products and foodstuffs in the new EU member countries : the example of collaboration between France and Slovenia
The objective of this article is to present the main results of an advising and assisting program, which took place in years 2001 until 2003, and which involved the Slovenian Ministry for Agriculture and two French institutions, French Agency for Standardization and National Institute for Designations of Origin. Authors report their experience in implementation of a system for the registration and certification of special agricultural products and foodstuffs in the Republic of Slovenia, in accordance with the quality policy and legislation of the European union (Council Regulations 2081/92 and 2082/92). They highlight the key success factors for an efficient implementation of the registration system for the special agricultural products and foodstuffs in the new EU members
EVROPSKA ZAŠČITA POIMENOVANJ ZA POSEBNE KMETIJSKE PROIZVODE IN ŽIVILA V NOVIH ČLANICAH EU. PRIMER SODELOVANJA MED FRANCIJO IN SLOVENIJO
The objective of this article is to present the main results of an advising and assisting program, which took place in years 2001 until 2003, and which involved the Slovenian Ministry of Agriculture, Forestry and Food and two French institutions, French Agency for Standardization and National Institute for Designations of Origin. Authors report their experience in implementation of a system for the registration and certifi cation of special agricultural products and
foodstuffs in the Republic of Slovenia, in accordance with the quality policy and legislation of the European union (Council Regulations 2081/92 and 2082/92). They highlight the key success factors for an effi cient implementation of the registration system for the special agricultural products and foodstuffs in the new EU members.V članku so predstavljeni glavni rezultati programa Phare, ki je potekal v letih 2001 do 2003 med slovenskim Ministrstvom za kmetijstvo, gozdarstvo in prehrano ter dvema francoskima institucijama, in sicer Agencijo za standardizacijo in inštitutom INAO (nacionalni inštitut za poimenovanja porekla). Avtorji poročajo o izkušnjah pri implementaciji sistema registracije in certifi kacije posebnih kmetijskih proizvodov in živil v Republiki Sloveniji skladno s politiko kakovosti in zakonodajo Evropske unije (Uredba Sveta 2081/92 in 2082/92). Posebej so poudarjeni ključni dejavniki za učinkovito implementacijo sistema zaščite posebnih kmetijskih proizvodov in živil ter uspešnost tovrstne zaščite v novih članicah Evropske unije
The size of two-body weakly bound objects : short versus long range potentials
The variation of the size of two-body objects is investigated, as the
separation energy approaches zero, with both long range potentials and short
range potentials having a repulsive core. It is shown that long range
potentials can also give rise to very extended systems. The asymptotic laws
derived for states with angular momentum l=1,2 differ from the ones obtained
with short range potentials. The sensitivity of the asymptotic laws on the
shape and length of short range potentials defined by two and three parameters
is studied. These ideas as well as the transition from the short to the long
range regime for the l=0 case are illustrated using the Kratzer potential.Comment: 5 pages, 3 figures, submitted to Physical Review Letter
Anyonic Excitations in Fast Rotating Bose Gases Revisited
The role of anyonic excitations in fast rotating harmonically trapped Bose
gases in a fractional Quantum Hall state is examined. Standard Chern-Simons
anyons as well as "non standard" anyons obtained from a statistical interaction
having Maxwell-Chern-Simons dynamics and suitable non minimal coupling to
matter are considered. Their respective ability to stabilize attractive Bose
gases under fast rotation in the thermodynamical limit is studied. Stability
can be obtained for standard anyons while for non standard anyons, stability
requires that the range of the corresponding statistical interaction does not
exceed the typical wavelenght of the atoms.Comment: 5 pages. Improved version to be published in Phys. Rev. A, including
a physical discussion on relevant interactions and scattering regime together
with implication on the nature of statistical interactio
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