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Nuclear Theory·nucl-th

Friday·January 8, 2016

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 01

    Explicit inclusion of nonlocality in (d,p) transfer reactions

    L.J. Titus · F.M. Nunes · G. Potel

    Background: Traditionally, nucleon-nucleus optical potentials are made local for convenience. In recent work we studied the effects of including nonlocal interactions explicitly in the final state for (d,p) reactions, within the distorted wave Born approximation. Purpose: Our goal in this work is to develop an improved formalism for nonlocal interactions that includes deuteron breakup and to use it to study the effects of including nonlocal interactions in transfer (d,p) reactions, in both the deuteron and the proton channel. Method: We extend the finite-range adiabatic distorted wave approximation to include nonlocal nucleon optical potentials. We apply our method to (d,p) reactions on 16O, 40Ca, 48Ca, 126Sn, 132Sn, and 208Pb at 10, 20 and 50 MeV. Results: We find that nonlocality in the deuteron scattering state reduces the amplitude of the wave function in the nuclear interior, and shifts the wave function outward. In many cases, this has the effect of increasing the transfer cross section at the first peak of the angular distributions. This increase was most significant for heavy targets and for reactions at high energies. Conclusions: Our systematic study shows that, if only local optical potentials are used in the analysis of experimental (d,p) transfer cross sections, the extracted spectroscopic factors may be incorrect by up to 40% due to the local approximation.

    nucl-thPRC(2016)·45 citations
  2. 02

    Pairing in high-density neutron matter including short- and long-range correlations

    D. Ding · A. Rios · H. Dussan · W. H. Dickhoff · S. J. Witte · A. Carbone · A. Polls

    Pairing gaps in neutron matter need to be computed in a wide range of densities to address open questions in neutron star phenomenology. Traditionally, the Bardeen-Cooper-Schrieffer approach has been used to compute gaps from bare nucleon-nucleon interactions. Here, we incorporate the influence of short- and long-range correlations in the pairing gaps. Short-range correlations are treated including the appropriate fragmentation of single-particle states, and substantially suppress the gaps. Long-range correlations dress the pairing interaction via density and spin modes, and provide a relatively small correction. We use different interactions, some with three-body forces, as a starting point to control for any systematic effects. Results are relevant for neutron-star cooling scenarios, in particular in view of the recent observational data on Cassiopeia A.

    nucl-thPRC(2016)·102 citations
  3. 03

    Comparisons of electric charge and axial charge meson cloud distributions in the PCQM

    X. Y. Liu🇹🇭 · K. Khosonthongkee🇹🇭 · A. Limphirat🇹🇭 · Y. Yan🇹🇭

    The meson cloud distributions in -space are extracted from the nucleon electromagnetic and axial form factors which are derived in the perturbative chiral quark model. The theoretical results indicate that the electric charge and axial charge distributions of the three-quark core are the same, the magnetic charge distributions of the meson cloud and three-quark core are more or less in the same region and peak at distances of around 2 , but the axial charge meson cloud distributes mainly inside the three-quark core.

    ↳ hep-phnucl-thSci.Rep.(2017)·5 citations
  4. 04

    Strangeness Production in AA and pp Collisions

    P.Castorina🇮🇹 · H.Satz🇩🇪

    Boost-invariant hadron production in high energy collisions occurs in causally disconnected regions of finite space-time size. As a result, globally conserved quantum numbers (charge, strangeness, baryon number) are conserved locally in spatially restricted correlation clusters. Their size is determined by two time scales: the equilibration time specifying the formation of a quark-gluon plasma, and the hadronization time, specifying the onset of confinement. The expected values for these scales provide the theoretical basis for the suppression observed for strangeness production in elementary interactions (, ) below LHC energies. In contrast, the space-time superposition of individual collisions in high energy heavy ion interactions leads to higher energy densities, resulting in much later hadronization and hence much larger hadronization volumes. This largely removes the causality constraints and results in an ideal hadronic resonance gas in full chemical equilibrium. In the present paper, we determine the collision energies needed for that; we also estimate when collisions reach comparable hadronization volumes and thus determine when strangeness suppression should disappear there as well.

    ↳ hep-phnucl-thEPJA(2016)·10 citations
  5. 05

    How big are the smallest drops of quark-gluon plasma?

    Paul M. Chesler🇺🇸

    Using holographic duality, we present results for both head-on and off-center collisions of Gaussian shock waves in strongly coupled supersymmetric Yang-Mills theory. The shock waves superficially resemble Lorentz contracted colliding protons. The collisions results in the formation of a plasma whose evolution is well described by viscous hydrodynamics. The size of the produced droplet is where is the effective temperature, which is the characteristic microscopic scale in strongly coupled plasma. These results demonstrate the applicability of hydrodynamics to microscopically small systems and bolster the notion that hydrodynamics can be applied to heavy-light ion collisions as well as some proton-proton collisions.

    ↳ hep-thgr-qchep-phnucl-thJHEP(2016)·75 citations
  6. 06

    Probing the Small- Gluon Tomography in Correlated Hard Diffractive Dijet Production in DIS

    Yoshitaka Hatta🇯🇵 · Bo-Wen Xiao🇺🇸 · Feng Yuan🇺🇸

    We investigate the close connection between the quantum phase space Wigner distribution of small- gluons and the color dipole scattering amplitude, and propose to study it experimentally in the hard diffractive dijet production at the planned electron-ion collider. The angular correlation between the nucleon recoiled momentum and the dijet transverse momentum will probe the nontrivial correlation in the phase space Wigner distribution. This experimental study will not only provide us with three-dimensional tomographic pictures of gluons inside high energy proton, but also give a unique and interesting signal for the small- dynamics with QCD evolution effects.

    ↳ hep-phnucl-thPRL(2016)·206 citations
  7. 07

    Direct Evaluation of the Quark Content of Nucleons from Lattice QCD at the Physical Point

    A. Abdel-Rehim (The Cyprus Inst.)🇨🇾 · C. Alexandrou (Univ. of Cyprus and The Cyprus Inst.)🇨🇾 · M. Constantinou (The Cyprus Inst.)🇨🇾 · K. Hadjiyiannakou (Univ. of Cyprus and The Cyprus Inst.)🇨🇾 · K. Jansen (DESY-Zeuthen)🇩🇪 · Ch. Kallidonis (The Cyprus Inst.)🇨🇾 · G.Koutsou (The Cyprus Inst.)🇨🇾 · A. Vaquero Aviles-Casco (INFN, Milan)🇮🇹

    We evaluate the light, strange and charm scalar content of the nucleon using one lattice QCD ensemble generated with two degenerate light quarks with mass fixed to their physical value. We use improved techniques to evaluate the disconnected quark loops to sufficient accuracy to determine the strange and charm nucleon -terms. in addition to the light quark content . We find = MeV = MeV and = MeV, where the first error is statistical and the second is the systematic error due to the determination of the lattice spacing, the assessment of finite volume and residual excited state effects.

    ↳ hep-lathep-phnucl-exnucl-thPRL(2016)·143 citations

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first authorsco-authorsvia INSPIRE