118393197
Single-particle dissipation in TDHF studied from a phase-space perspective
N. Loebl, A. S. Umar, J.A. Maruhn, P.-G. Reinhard, P.D. Stevenson, and V. E., Oberacker Institut fuer Theoretische Physik, Universitaet Frankfurt, D-60438 Frankfurt, Germany Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA Institut fuer Theoretische Physik II, Universitaet Erlangen-Nuernberg, D-91058 Erlangen, Germany and Department of Physics, University of Surrey, Guildford, GU2 7XH, UK (Dated: August 30, 2012)
17333676
Isoscalar and Isovector Giant Monopole Resonances from a Continuum Hartree-Fock Method
We motivate and summarise some recent results in the application of formally exact boundary conditions in nuclear time-dependent Hartree-Fock calculations, mak- ing use of Laplace transformations to calculate the values of the wave functions at the boundaries. We have realised the method in the case of giant monopole resonances of spherically-symmetric nuclei, and present strength functions of 16 O and 40 Ca using a sim- plified version of the Skyrme force, showing that no artefacts from discretisation occur as contaminatnts
15719604
Do Skyrme forces that fit nuclear matter work well in finite nuclei
A short list of Skyrme force parameterizations, recently found to have passed a series of constraints relating to nuclear matter properties is analyzed for their ability to reproduce data in ﬁnite nuclei. We analyse binding energies, isotope shifts, neutron skin thicknesses and ﬁssion barriers. We ﬁnd that the subset of forces have no common ability to reproduce(or otherwise)properties of ﬁnite nuclei, despite passing the extensive range of nuclear matter constraints.
14308528
Mass dispersions from giant dipole resonances using the Balian–Vénéroni variational approach
The Balian–Veneroni variational approach has been implemented using a three-dimensional time-dependent Hartree–Fock (TDHF) code with realistic Skyrme interactions and used to investigate the mass dispersions from giant dipole resonances in 32S and 132Sn decaying through particle emission. The fluctuations obtained are shown to be quantitatively larger than the standard TDHF results.
16956676
Continuum time-dependent Hartree-Fock method for giant resonances in spherical nuclei
This paper deals with the solution of the spherically symmetric time-dependent Hartree-Fock approximation applied in the case of nuclear giant monopole resonances in the small and large amplitude regimes. The problem is spatially unbounded as the resonance state is in the continuum. The practical requirement to perform the calculation in a finite-sized spatial region results in a difficulty with the spatial boundary conditions. Here we propose an absorbing boundary condition scheme to handle the conflict. The derivation, via a Laplace transform method, and implementation is described. The accuracy and efficiency of the scheme is tested and the results presented to support the case that they are a effective way of handling the artificial boundary. © 2013 American Physical Society.
122193074
The effect of the tensor force on the predicted stability of superheavy nuclei
The effect of the tensor component of the Skyrme effective nucleon-nucleon interaction on the single-particle structure in superheavy elements is studied. A selection of the available Skyrme forces has been chosen and their predictions for the proton and neutron shell closures investigated. The inclusion of the tensor term with realistic coupling strength parameters leads to a small increase in the spin-orbit splitting between the proton 2f7/2 and 2f5/2 partners, opening the Z=114 shell gap over a wide range of nuclei. The Z=126 shell gap, predicted by these models in the absence of the tensor term, is found to be stongly dependent on neutron number with a Z=138 gap opening for large neutron numbers, having a consequent implication for the synthesis of neutron-rich superheavy elements. The predicted neutron shell structures remain largely unchanged by inclusion of the tensor component.
120598082
The Gaussian Effective Potential. 1. Quantum Mechanics
122752251
Comment on ''An alternative implementation of the 'principle of minimal sensitivity'''
I explain that the difficulties encountered by Wrigley in the preceding paper arise only because he is attempting to find the stationary value of an undefined function.
123093258
QCD and final-state jet measures in leptoproduction
Abstract Various infrared-safe measures of jet-like-ness in leptoproduction are studied in QCD perturbation theory using a general formalism. This quantifies the effects predicted in a previous paper. The nucleon remnants jet is found to be distinctly narrower than the quark jet.
16425949
PHYSICAL MECHANISMS GENERATING SPONTANEOUS SYMMETRY BREAKING AND A HIERARCHY OF SCALES
We discuss the phase transition in (3+1)-dimensional λΦ4 theory from a very physical perspective. The particles of the symmetric phase ("phions") interact via a hard-core repulsion and an induced, long-range -1/r3 attraction. If the phion mass is sufficiently small, the lowest-energy state is not the "empty" state with no phions, but is a state with a nonzero density of phions Bose–Einstein condensed in the zero-momentum mode. The condensate corresponds to the spontaneous-symmetry-breaking vacuum with ≠ 0 and its excitations ("phonons" in atomic physics language) correspond to Higgs particles. The phase transition happens when the phion's physical mass m is still positive; it does not wait until m2 passes through zero and becomes negative. However, at and near the phase transition, m is much, much less than the Higgs mass Mh. This interesting physics coexists with "triviality;" all scattering amplitudes vanish in the continuum limit, but the vacuum condensate becomes infinitely dense. The ratio , which goes to zero in the continuum limit, can be viewed as a measure of nonlocality in the regularized theory. An intricate hierarchy of length scales naturally arises. We speculate about the possible implications of these ideas for gravity and inflation.
14288023
HYDRODYNAMICS OF THE VACUUM
Hydrodynamics is the appropriate "effective theory" for describing any fluid medium at sufficiently long length scales. This paper treats the vacuum as such a medium and derives the corresponding hydrodynamic equations. Unlike a normal medium the vacuum has no linear sound-wave regime; disturbances always "propagate" nonlinearly. For an "empty vacuum" the hydrodynamic equations are familiar ones (shallow water-wave equations) and they describe an experimentally observed phenomenon — the spreading of a clump of zero-temperature atoms into empty space. The "Higgs vacuum" case is much stranger; pressure and energy density, and hence time and space, exchange roles. The speed of sound is formally infinite, rather than zero as in the empty vacuum. Higher-derivative corrections to the vacuum hydrodynamic equations are also considered. In the empty-vacuum case the corrections are of quantum origin and the post-hydrodynamic description corresponds to the Gross–Pitaevskii equation. We conjecture the form of the post-hydrodynamic corrections in the Higgs case. In the (1+1)-dimensional case the equations possess remarkable "soliton" solutions and appear to constitute a new exactly integrable system.