Nuclear Theory·nucl-th

Monday·November 30, 2015

10 papers—4 primary·6 cross-listed

01
Influence of binding energies of electrons on nuclear mass predictions
Jing Tang · Zhong-Ming Niu · Jian-You Guo
Nuclear mass contains a wealth of nuclear structure information, and has been widely employed to extract the nuclear effective interactions. The known nuclear mass is usually extracted from the experimental atomic mass by subtracting the masses of electrons and adding the binding energy of electrons in the atom. However, the binding energies of electrons are sometimes neglected in extracting the known nuclear masses. The influence of binding energies of electrons on nuclear mass predictions are carefully investigated in this work. If the binding energies of electrons are directly subtracted from the theoretical mass predictions, the rms deviations of nuclear mass predictions with respect to the known data are increased by about $200$ keV for nuclei with $Z, N ⩾ 8$ . Furthermore, by using the Coulomb energies between protons to absorb the binding energies of electrons, their influence on the rms deviations is significantly reduced to only about $10$ keV for nuclei with $Z, N ⩾ 8$ . However, the binding energies of electrons are still important for the heavy nuclei, about $150$ keV for nuclei around $Z = 100$ and up to about $500$ keV for nuclei around $Z = 120$ . Therefore, it is necessary to consider the binding energies of electrons to reliably predict the masses of heavy nuclei at an accuracy of hundreds of keV.
nucl-thCPC(2016)·3 citations
02
Multinucleon transfer reaction in time-dependent Hartree-Fock theory
Kazuyuki Sekizawa · Kazuhiro Yabana
Time-dependent Hartree-Fock (TDHF) theory has achieved a remarkable success in describing and understanding nuclear many-body dynamics from nucleons' degrees of freedom. We here report our investigation of multinucleon transfer (MNT) processes employing the TDHF theory. To calculate transfer probabilities for channels specified by the number of protons and neutrons included in reaction products, a particle-number projection (PNP) method has been developed. The PNP method is also used to calculate excitation energies of reaction products. Combined use of the PNP method with a statistical model, we can evaluate MNT cross sections taking account of effects of particle evaporation. Using these methods, we evaluate MNT cross sections for $^{40, 48}$ Ca+ $^{124}$ Sn, $^{40}$ Ca+ $^{208}$ Pb, and $^{58}$ Ni+ $^{208}$ Pb reactions. From systematic analyses, we find that cross sections for channels with a large reaction probability are in good agreement with experimental data. However, the agreement becomes less accurate as the number of transferred nucleons increases. Possible directions to improve the description are discussed.
nucl-thnucl-ex4 citations
03
Isovector and isoscalar dipole excitations in $^{9}$ Be and $^{10}$ Be studied with antisymmetrized molecular dynamics
Yoshiko Kanada-En'yo
Isovector and isoscalar dipole excitations in $^{9}$ Be and $^{10}$ Be are investigated in the framework of antisymmetrized molecular dynamics, in which angular-momentum and parity projections are performed. In the present method, 1p-1h excitations on the ground state and large amplitude $α$ -cluster mode are incorporated. The isovector giant dipole resonance (GDR) in $E > 20$ MeV shows the two peak structure which is understood by the dipole excitation in the 2 $α$ core part with the prolate deformation. Because of valence neutron modes against the $2 α$ core, low-energy E1 resonances appear in $E < 20$ MeV exhausting about $20%$ of the Thomas-Reiche-Kuhn sum rule and $10%$ of the calculated energy-weighted sum. The dipole resonance at $E \sim 15$ MeV in $^{10}$ Be can be interpreted as the parity partner of the ground state having a $^{6}$ He+ $α$ structure and has the remarkable E1 strength because of coherent contribution of two valence neutrons. The ISD strength for some low-energy resonances are significantly enhanced by the coupling with the $α$ -cluster mode. The calculated E1 strength of $^{9}$ Be reasonably describes the global feature of experimental photonuclear cross sections consisting of the low-energy strength in $E < 20$ MeV and the GDR in $E > 20$ MeV.
nucl-thPRC(2016)·26 citations
04
Hybrid Stars using the Quark-Meson Coupling and Proper Time NJL Models
D. L. Whittenbury🇦🇺 · H. H. Matevosyan🇦🇺 · A. W. Thomas🇦🇺
Background: At high density deconfinement of hadronic matter may occur leading to quark matter. The immense densities reached in the inner core of massive neutron stars may be sufficient to facilitate the transition. Purpose: To investigate a crossover transition between two phenomenological models which epitomise QCD in two different regimes, while incorporating the influence of quark degrees of freedom in both. Method: We use the Hartree-Fock quark-meson coupling model and the proper time regularised three flavour NJL model to describe hadronic and quark matter, respectively. Hybrid equations of state are obtained by interpolating the energy density as a function of total baryonic density and calculating the pressure. Results: Equations of state for hadronic, quark and hybrid matter and the resulting mass versus radius curves for hybrid stars are shown, as well as other relevant physical quantities such as species fractions and the speed of sound in matter. Conclusions: The observations of massive neutron stars can certainly be explained within such a construction. However, the so-called thermodynamic correction arising from an interpolation method can have a considerable impact on the equation of state. The interpolation dependency of and physical meaning behind such corrections require further study.
nucl-thastro-ph.HEPRC(2016)·53 citations
05
Leptons from heavy-quark semileptonic decay in pA collisions within the CGC framework
Hirotsugu Fujii🇯🇵 · Kazuhiro Watanabe🇨🇳
We study single lepton production from semileptonic decays of heavy flavor hadrons ( $D, B \to l$ ) in pp and p $A$ collisions at RHIC and the LHC within the saturation/Color-Glass-Condensate (CGC) framework. Using the gluon distribution function obtained with the dipole amplitude, whose energy dependence is described by the Balitsky-Kovchegov equation with running coupling effect, we compute the transverse-momentum ( $p_{⊥}$ ) spectra of the lepton yields at mid and forward rapidities. We find that a large fraction of leptons at low $p_{⊥}$ stems from the saturation regime of the incoming gluons in the target, especially in p $A$ collisions at the LHC. The resultant $p_{⊥}$ spectra is slightly harder than the data, but the nuclear modification factor seems consistent with the data within some uncertainty. We also update the nuclear modification factors for J/ $ψ$ and $D$ meson at the LHC energy.
↳ hep-phnucl-thNPA(2016)·19 citations
06
Comment on "Evidence for narrow resonant structures at $W \approx$ 1.68 GeV and $W \approx$ 1.72 GeV in real Compton scattering off the proton"
D. Werthmüller🇬🇧 · L. Witthauer🇨🇭 · D.I. Glazier🇬🇧 · B. Krusche🇨🇭
We comment on the statement by Kuznetsov et al. that the structure around W=1.72 GeV seen in the beam asymmetry in Compton scattering off the proton is not observed in the total cross section of $η$ photoproduction on the neutron.
↳ nucl-exhep-exnucl-thPRC(2015)·15 citations
07
Heavy baryons with Strangeness in Soliton Models
H. Weigel🇿🇦 · J.P. Blanckenberg🇿🇦
We present some recent results from soliton model calculations for the spectrum of baryons with a single heavy quark.The model comprises chiral symmetry for light flavors and (approximate) heavy spin-flavor symmetry for the heavy quarks. We focus on flavor symmetry breaking for strangeness degrees of freedom.
↳ hep-phnucl-thInt.J.Mod.Phys.Conf.Ser.(2015)·0 citations
08
Pion Induced Reactions for the Study of Charmed Baryons
Sang-Ho Kim🇰🇷 · Atsushi Hosaka🇯🇵 · Hyun-Chul Kim🇰🇷 · Hiroyuki Noumi🇯🇵
In this talk, we report the study of $π^{-} p \to K^{* 0} Λ$ and $π^{-} p \to D^{*-} Λ_{c}^{+}$ reactions by using an effective Lagrangian method and a hybrid Regge model. The total and differential cross sections for the $K^{* 0} Λ$ production are first calculated and then those for the $D^{*-} Λ_{c}^{+}$ one are estimated. The two models yield different results, each exhibiting specific features. Our prediction for the charm production provides valuable information about the upcoming J-PARC experiment.
↳ hep-phhep-exnucl-exnucl-thJPS Conf.Proc.(2016)·1 citation
09
$U (1)$ current from the AdS/CFT: diffusion, conductivity and causality
Yanyan Bu🇮🇱 · Michael Lublinsky🇮🇱 · Amir Sharon🇮🇱
For a holographically defined finite temperature theory, we derive an off-shell constitutive relation for a global $U (1)$ current driven by a weak external non-dynamical electromagnetic field. The constitutive relation involves an all order gradient expansion resummed into three momenta-dependent transport coefficient functions: diffusion, electric conductivity, and "magnetic" conductivity. These transport functions are first computed analytically in the hydrodynamic limit, up to third order in the derivative expansion, and then numerically for generic values of momenta. We also compute a diffusion memory function, which, as a result of all order gradient resummation, is found to be causal.
↳ hep-thhep-phnucl-thJHEP(2016)·24 citations
10
Drag suppression in anomalous chiral media
Andrey V. Sadofyev🇺🇸 · Yi Yin🇺🇸
We study a heavy impurity moving longitudinal with the direction of an external magnetic field in an anomalous chiral medium. Such system would carry a non-dissipative current of chiral magnetic effect associated with the anomaly. We show, by generalizing Landau's criterion for superfluidity, that the "anomalous component" which gives rise to the anomalous transport will {\it not} contribute to the drag experienced by an impurity. We argue on a very general basis that those systems with a strong magnetic field would exhibit an interesting transport phenomenon -- the motion of the heavy impurity is frictionless, in analogy to the case of a superfluid. We demonstrate and confirm our general results with two complementary examples: weakly coupled chiral fermion gases and strongly interacting chiral liquids.
↳ hep-thcond-mat.mes-hallnucl-thPRD(2016)·31 citations

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