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Nuclear Theory·nucl-th

Thursday·January 22, 2015

6 papers—1 primary·5 cross-listed

All6Primary1Cross-lists5
  1. 01

    Pairing versus quarteting coherence length

    Doru S. Delion · Virgil V. Baran

    We systematically analyse the coherence length in even-even nuclei. The pairing coherence length in the spin-singlet channel for the effective density dependent delta (DDD) and Gaussian interaction is estimated. We consider in our calculations bound states as well as narrow resonances. It turns out that the pairing gaps given by the DDD interaction are similar to those of the Gaussian potential if one renormalizes the radial width to the nuclear radius. The correlations induced by the pairing interaction have in all considered cases a long range character inside the nucleus and decrease towards the surface. The mean coherence length is larger than the geometrical radius for light nuclei and approaches this value for heavy nuclei. The effect of the temperature and states in continuum is investigated. Strong shell effects are evidenced, especially for protons. We generalize this concept to quartets by considering similar relations, but between proton and neutron pairs. The quartet coherence length has a similar shape, but with larger values on the nuclear surface. We evidence the important role of proton-neutron correlations by estimating the so-called alpha coherence length, which takes into account the overlap with the proton-neutron part of the -particle wave function. It turns out that it does not depend on the nuclear size and has a value comparable to the free -particle radius. We have shown that pairing correlations are mainly concentrated inside the nucleus, while quarteting correlations are connected to the nuclear surface.

    nucl-thPRC(2015)·3 citations
  2. 02

    The LPM effect in sequential bremsstrahlung

    Peter Arnold🇺🇸 · Shahin Iqbal🇺🇸

    The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. We analyze the case when the coherence lengths of two consecutive splitting processes overlap, which is important for understanding corrections to standard treatments of the LPM effect in QCD. Previous authors have analyzed this problem in the case of overlapping double bremsstrahlung where at least one of the bremsstrahlung gluons is soft. Here we show how to generalize to include the case where both splittings are hard. A number of techniques must be developed, and so in this paper we simplify by (i) restricting attention to a subset of the interference effects, which we call the "crossed" diagrams, and (ii) working in the large- limit. We first develop some general formulas that could in principle be implemented numerically (with substantial difficulty). To make more analytic progress, we then focus on the case of a thick, homogeneous medium and make the multiple scattering approximation (also known as the or harmonic approximation) appropriate at high energy. We show that the differential rate for overlapping double bremsstrahlung of gluons with momentum fractions and can then be reduced to the calculation of a 1-dimensional integral, which we perform numerically. [Though this paper is unfortunately long, our introduction is enough for getting the gist of the method.]

    ↳ hep-phnucl-thJHEP(2015)·76 citations
  3. 03

    Transverse Wobbling in Pr

    J.T. Matta🇺🇸 · U. Garg🇺🇸 · W. Li🇺🇸 · S. Frauendorf🇺🇸 · A.D. Ayangeakaa🇺🇸 · D. Patel🇺🇸 · K.W. Schlax🇮🇳 · R. Palit🇮🇳 · S. Saha🇮🇳 · J. Sethi🇮🇳 · T. Trivedi🇮🇳 · S.S. Ghugre🇺🇸 and 18 other authors

    A pair of transverse wobbling bands has been observed in the nucleus Pr. The wobbling is characterized by =1, E2 transitions between the bands, and a decrease in the wobbling energy confirms its transverse nature. Additionally, a transition from transverse wobbling to a three-quasiparticle band comprised of strong magnetic dipole transitions is observed. These observations conform well to results from calculations with the Tilted Axis Cranking (TAC) model and the Quasiparticle Triaxial Rotor (QTR) Model.

    ↳ nucl-exnucl-thPRL(2015)·111 citations
  4. 04

    Strong and coupling constants in QCD

    K. Azizi🇹🇷 · Y. Sarac🇹🇷 · H. Sundu🇹🇷

    We study the strong interactions among the heavy bottom spin--1/2 baryon, nucleon and meson as well as the heavy charmed spin--1/2 baryon, nucleon and meson in the context of QCD sum rules. We calculate the corresponding strong coupling form factors defining these vertices by using a three point correlation function. We obtain the numerical values of the corresponding strong coupling constants via the most prominent structure entering the calculations.

    ↳ hep-phnucl-thNPA(2015)·18 citations
  5. 05

    Three-body recombination of two-component cold atomic gases into deep dimers in an optical model

    M. Mikkelsen · A. S. Jensen · D. V. Fedorov · N. T. Zinner

    We consider three-body recombination into deep dimers in a mass-imbalanced two-component atomic gas. We use an optical model where a phenomenological imaginary potential is added to the lowest adiabatic hyper-spherical potential. The consequent imaginary part of the energy eigenvalue corresponds to the decay rate or recombination probability of the three-body system. The method is formulated in details and the relevant qualitative features are discussed as functions of scattering lengths and masses. We use zero-range model in analyses of recent recombination data. The dominating scattering length is usually related to the non-equal two-body systems. We account for temperature smearing which tends to wipe out the higher-lying Efimov peaks. The range and the strength of the imaginary potential determine positions and shapes of the Efimov peaks as well as the absolute value of the recombination rate. The Efimov scaling between recombination peaks is calculated and shown to depend on both scattering lengths. Recombination is predicted to be largest for heavy-heavy-light systems. Universal properties of the optical parameters are indicated. We compare to available experiments and find in general very satisfactory agreement.

    ↳ cond-mat.quant-gasnucl-thphysics.atom-phquant-phJ.Phys.B(2015)·7 citations
  6. 06

    Constraining the nuclear matter equation of state around twice saturation density

    A. Le Fèvre🇩🇪 · Y. Leifels🇩🇪 · W. Reisdorf🇩🇪 · J. Aichelin🇫🇷 · Ch. Hartnack🇫🇷

    Using FOPI data on elliptic flow in Au+Au collisions between 0.4 and 1.5A GeV we extract constraints for the equation of state (EOS) of compressed symmetric nuclear matter using the transport code IQMD by introducing an observable describing the evolution of the size of the elliptic flow as a function of rapidity. This observable is sensitive to the nuclear EOS and a robust tool to constrain the compressibility of nuclear matter up to 2 .

    ↳ nucl-exnucl-thNPA(2016)·201 citations

Affiliations

first authorsco-authorsvia INSPIRE