Nuclear Theory·nucl-th

Friday·July 15, 2016

17 papers—9 primary·8 cross-listed

01
[Submitted on 14 Jul 2016]
Radiative proton capture cross sections in the mass range $40 - 55$
Dipti Chakraborty · Saumi Dutta · G. Gangopadhyay · Abhijit Bhattacharyya
Proton capture cross sections in the energy range of astrophysical interest for mass region 40-54 have been calculated in the Hauser-Feshbach formalism with reaction code TALYS1.6. The density dependent M3Y effective nucleon-nucleon interaction folded with target radial matter densities from relativistic mean field approach is used to obtain the semi-microscopic optical potential. A definite normalization of potential-well depths has been used over the entire mass region. The $(p, γ)$ rates of some reactions, important in the astrophysical scenario, are calculated using the potential in the relevant mass region.
Comments:
9 pages, 6 figures, accepted for publication in the journal Physical Review C
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1607.03986 [pdf]
PRC(2016)·2 citations
02
[Submitted on 14 Jul 2016]
Spectra and elliptic flow of (multi-)strange hadrons at RHIC and LHC within viscous hydrodynamics+hadron cascade hybrid model
Xiangrong Zhu🇨🇳
Using the (2+1)-dimensional ultrarelativistic viscous hydrodynamics+hadron cascade, VISHNU, hybrid model, we study the $p_{T}$ -spectra and elliptic flow of $Λ$ , $Ξ$ , and $Ω$ in Au+Au collisions at $s_{N N}$ =200 GeV and in Pb+Pb collisions at $s_{N N}$ =2.76 TeV. Comparing our model results with the data measurements, we find that the VISHNU model gives general descriptions of the measurements of these strange and multi-strange hadrons at several centrality classes at RHIC and LHC. Mass ordering of elliptic flow $v_{2}$ among $π$ , $K$ , $p$ , $Λ$ , $Ξ$ , and $Ω$ are further investigated and discussed at the two collision systems. We find, at both RHIC and LHC, the $v_{2}$ mass ordering among $π$ , $K$ , $p$ , and $Ω$ are fairly reproduced within the VISHNU hybrid model, and more improvements are needed to implement for well describing the $v_{2}$ mass ordering among $p$ , $Λ$ , and $Ξ$ .
Comments:
revise the draft according to the reviewers` comments, 7 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.04003 [pdf]
Adv.High Energy Phys.(2016)·7 citations
03
[Submitted on 14 Jul 2016]
$Δ$ (1232) effects in density-dependent relativistic Hartree-Fock theory and neutron stars
Zhen-Yu Zhu🇨🇳 · Ang Li🇨🇳 · Jin-Niu Hu🇨🇳 · Hiroyuki Sagawa🇯🇵
The density-dependent relativistic Hartree-Fock (DDRHF) theory is extended to include $Δ$ -isobars for the study of dense nuclear matter and neutron stars. To this end, we solve the Rarita-Schwinger equation for spin-3/2 particle. Both the direct and exchange terms of the $Δ$ -isobars' self-energies are evaluated in details. In comparison with the relativistic mean field theory (Hartree approximation), a weaker parameter dependence is found for DDRHF. An early appearance of $Δ$ -isobars is recognized at $ρ_{B} \sim 0.27$ fm $^{- 3}$ , comparable with that of hyperons. Also, we find that the $Δ$ -isobars' softening of the equation of state is found to be mainly due to the reduced Fock contributions from the coupling of the isoscalar mesons, while the pion contributions are found negligibly small. We finally conclude that with typical parameter sets, neutron stars with $Δ$ -isobars in their interiors could be as heavy as the two massive pulsars whose masses are precisely measured, with slightly smaller radii than normal neutron stars.
Comments:
13 pages, 7 figures, 5 tables, 4 appendixes, Phys. Rev. C (2016) accepted
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1607.04007 [pdf]
PRC(2016)·67 citations
04
[Submitted on 14 Jul 2016]
Production of $ΛΛ$ and $Λ n ˉ$ in central Pb+Pb collisions at $s_{N N}$ =2.76 TeV within a covariant coalescence model
Kai-Jia Sun🇨🇳 · Lie-Wen Chen🇨🇳
We study the production of $ΛΛ$ and $Λ n$ exotic states in central Pb+Pb collisions at $s_{N N} = 2.76$ TeV at LHC via both hadron and quark coalescence within a covariant coalescence model with a blast-wave-like parametrization for the phase-space configurations of constituent particles at freezeout. In the hadron coalescence, the two states are considered as molecular states while they are considered as six-quark states in the quark coalescence.For $Λ n$ , we find that the yields of both molecular and six-quark states are much larger than the experimental upper-limits. For $ΛΛ$ , while the molecule-state yield is much larger than the experimental upper-limits, the six-quark-state yield could be lower than the upper-limits. The higher molecule-state yields are mainly due to the large contribution of short-lived strong resonance decays into (anti-)nucleons and (anti-) $Λ$ which can significantly enhance the molecule-state yields of $ΛΛ$ and $Λ n$ via hadron coalescence. Our results suggest that the current experimental measurement at LHC cannot exclude the existence of the $ΛΛ$ as an exotic six-quark state, and if $ΛΛ$ is a six-quark state, it is then on the brink of being discovered.
Comments:
6 pages, 4 figures, 2 tables. Minor modifications. Accepted version to appear in PRC
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1607.04037 [pdf]
PRC(2016)·14 citations
05
[Submitted on 14 Jul 2016]
Chiral symmetry restoration in heavy-ion collisions at intermediate energies
A. Palmese🇩🇪 · W. Cassing🇩🇪 · E. Seifert🇩🇪 · T. Steinert🇩🇪 · P. Moreau🇩🇪 · E. L. Bratkovskaya🇩🇪
We study the effect of the chiral symmetry restoration (CSR) on heavy-ion collisions observables in the energy range $s_{N N}$ =3-20 GeV within the Parton-Hadron-String Dynamics (PHSD) transport approach. The PHSD includes the deconfinement phase transition as well as essential aspects of CSR in the dense and hot hadronic medium, which are incorporated in the Schwinger mechanism for the hadronic particle production. We adopt different parametrizations of the nuclear equation of state from the non-linear $σ - ω$ model, which enter in the computation of the quark scalar density for the CSR mechanism, in order to estimate the uncertainty in our calculations.
Comments:
22 pages, 19 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1607.04073 [pdf]
PRC(2016)·85 citations
06
[Submitted on 14 Jul 2016]
Universality of nucleon-nucleon short-range correlations: the factorization property of the nuclear wave function, the relative and center-of-mass momentum distributions, and the nuclear contacts
Massimiliano Alvioli🇮🇹 · Claudio Ciofi degli Atti · Hiko Morita
The two-nucleon momentum distributions have been calculated for nuclei up to A=40 and various values of the relative and center-of-mass momenta and angle between them. For complex nuclei a parameter-free linked-cluster expansion, based upon a realistic local two-nucleon interaction of the Argonne family and variational wave function featuring central, tensor, spin and iso-spin correlations, has been used. The obtained results show that: 1) independently of the mass number A, at values of the relative momentum k_rel> 2 fm^{-1} the proton-neutron momentum distributions for back-to-back (BB) nucleons (K_cm=0) exhibit the factorization property n_A^{pn}(k_rel,K_cm=0)=C_A^{pn} n_D(k_rel) n_{cm}^{pn}(K_cm=0), where n_D is the deuteron momentum distribution, n_{cm}^{pn}(K_{cm}=0) the momentum distribution of the c.m. motion of the pair and C_A^{pn} the nuclear contact measuring the number of BB pn pairs with deuteron-like momenta; 2) the values of the proton-neutron nuclear contact C_A^{pn} are obtained in a model-independent way from the ratio n_A^{pn}(k_rel,K_cm=0)/n_D(k_rel) n_{cm}^{pn}(K_cm=0); 3) also the K_cm-integrated pn momentum distributions divided by the deuteron momentum distribution exhibits a constant behavior equal to C_A^{pn}, but only at very high values of k_{rel}> 3.5fm^{-1}, where the relative momentum distribution is entirely governed by BB short-range correlated nucleons; 4) the absolute value of the number of pn and pp short-range correlated pairs is calculated, illustrating that the high values (K_cm>1 fm^{-1}) of the pair c.m. momentum appreciably reduce the dominance of the pn over pp pairs produced by the tensor force when K_cm=0; 5) calculations are in good agreement with the VMC calculations for light nuclei and with available experimental on the processes A(e,e'pn)X and A(e,e'pp)X.
Comments:
22 pages, 17 figures, 4 tables
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1607.04103 [pdf]
PRC(2016)·44 citations
07
[Submitted on 5 Apr 2016]
The self-consistent analysis for sub-barrier fusion enhancement effect in Ca + Ca and Ni + Ni
N.R. Ma · H.M. Jia · C.J. Lin · L. Yang · X.X. Xu · L.J. Sun · F. Yang · Z.D. Wu · H.Q. Zhang · Z.H. Liu · D.X. Wang
The fusion dynamic mechanism of heavy-ions at energies near the Coulomb barrier is complicated and still not very clear up to now. Accordingly, a self-consistent method based on the CCFULL calculations has been developed and applied for an ingoing study of the effect of the positive Q-value neutron transfer (PQNT) channels in this work. The typical experimental fusion data of Ca + Ca and Ni + Ni is analyzed within the unified calculation scheme. The PQNT effect in near-barrier fusion is further confirmed based on the self-consistent analysis and extracted quantitatively.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.04191 [pdf]
CPC(2016)·2 citations
08
[Submitted on 13 Jul 2016]
Very low-energy nucleon + 16O coupled-channel scattering: results with a phenomenological vibrational model
J. P. Svenne · L. Canton · K. Amos · P. R. Fraser · S. Karataglidis · G. Pisent · D. van der Knijff
We employ a collective vibration coupled-channel model to describe the nucleon-16O cluster systems, obtaining low-excitation spectra for 17O and 17F. Bound and resonance states of the compound systems have been deduced, showing good agreement with experimental spectra. Low energy scattering cross sections of neutrons and protons from 16O also have been calculated and the results compare well with available experimental data.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.04199 [pdf]
PRC(2017)·9 citations
09
[Submitted on 14 Jul 2016]
Configuration interaction in symmetry-conserving covariant density functional theory
P. W. Zhao · P. Ring · J. Meng
A new method to calculate spectroscopic properties of deformed nuclei is proposed: configuration interaction on top of projected density functional theory (CI-PDFT). The general concept of this approach is discussed in the framework of covariant density functional theory and its validity is illustrated in an application to the yrast band of the nucleus Cr-54. It is found that the experimentally observed excitation energies for the yrast band in Cr-54 can be well reproduced. In contrast to conventional shell-model calculations, there is no core and only a relatively small number of configurations is sufficient for a satisfying description. No new parameters are necessary, because the effective interaction is derived from an universal density functional given in the literature.
Comments:
7 pages, 3 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1607.04241 [pdf]
PRC(2016)·31 citations
10
[Submitted on 13 Jul 2016] (cross-list from physics.hist-ph)
In memoriam: Dmitri Ivanenko
G. Sardanashvily
Dmitri Ivanenko, professor of Moscow State University, was one of the great theoreticians of XX century, an author of the proton-neutron model of atomic nucleus. In honor of the 110th Year Anniversary.
Comments:
9 pages in Science Newsletter, Issue 1 (2014) 16
Subjects:
History and Philosophy of Physics (physics.hist-ph); Nuclear Theory (nucl-th)
arXiv:
1607.03828 [pdf]
0 citations
11
[Submitted on 13 Jul 2016] (cross-list from astro-ph.CO)
The primordial deuterium abundance of the most metal-poor damped Lyman-alpha system
Ryan Cooke (1) · Max Pettini (2,3) · Kenneth M. Nollett (4) · Regina Jorgenson (5,6) · ((1) University of California, Santa Cruz, (2) Institute of Astronomy, University of Cambridge, (3) Kavli Institute for Cosmology, University of Cambridge, (4) San Diego State University, (5) Willamette University, (6) Maria Mitchell Observatory)
We report the discovery and analysis of the most metal-poor damped Lyman-alpha (DLA) system currently known, which also displays the Lyman series absorption lines of neutral deuterium. The average [O/H] abundance of this system is [O/H] = -2.804 +/- 0.015, which includes an absorption component with [O/H] = -3.07 +/- 0.03. Despite the unfortunate blending of many weak D I absorption lines, we report a precise measurement of the deuterium abundance of this system. Using the six highest quality and self-consistently analyzed measures of D/H in DLAs, we report tentative evidence for a subtle decrease of D/H with increasing metallicity. This trend must be confirmed with future high precision D/H measurements spanning a range of metallicity. A weighted mean of these six independent measures provides our best estimate of the primordial abundance of deuterium, 10^5 (D/H)_P = 2.547 +/- 0.033 (log_10 (D/H)_P = -4.5940 +/- 0.0056). We perform a series of detailed Monte Carlo calculations of Big Bang nucleosynthesis (BBN) that incorporate the latest determinations of several key nuclear cross sections, and propagate their associated uncertainty. Combining our measurement of (D/H)_P with these BBN calculations yields an estimate of the cosmic baryon density, 100 Omega_B,0 h^2(BBN) = 2.156 +/- 0.020, if we adopt the most recent theoretical determination of the d(p,gamma)3He reaction rate. This measure of Omega_B,0 h^2 differs by ~2.3 sigma from the Standard Model value estimated from the Planck observations of the cosmic microwave background. Using instead a d(p,gamma)3He reaction rate that is based on the best available experimental cross section data, we estimate 100 Omega_B,0 h^2(BBN) = 2.260 +/- 0.034, which is in somewhat better agreement with the Planck value. Forthcoming measurements of the crucial d(p,gamma)3He cross section may shed further light on this discrepancy.
Comments:
16 pages, 7 figures, Accepted for publication in The Astrophysical Journal
Subjects:
Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); Nuclear Theory (nucl-th)
arXiv:
1607.03900 [pdf]
ApJ(2016)·169 citations
12
[Submitted on 14 Jul 2016] (cross-list from hep-ph)
Unravelling the physical meaning of the Jaffe-Manohar decomposition of the nucleon spin
Masashi Wakamatsu🇯🇵
A general consensus now is that there are two physically inequivalent complete decompositions of the nucleon spin, i.e. the decomposition of the canonical type and that of mechanical type. The well-known Jaffe-Manohar decomposition is of the former type. Unfortunately, there is a wide-spread misbelief that this decomposition matches the partonic picture, which states that motion of quarks in the nucleon is approximately free. In the present monograph, we reveal that this understanding is not necessarily correct and that the Jaffe-Manohar decomposition is not such a decomposition, which natively reflects the intrinsic (or static) orbital angular momentum structure of the nucleon.
Comments:
LaTeX 38pages, 2 eps figures, A slightly modified version to appear Physical Review D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1607.04018 [pdf]
PRD(2016)·12 citations
13
[Submitted on 14 Jul 2016] (cross-list from hep-ph)
Heavy quark production in $p A$ collisions: the double parton scattering contribution
E.R. Cazaroto🇧🇷 · V.P. Goncalves🇸🇪 · F.S. Navarra🇧🇷
In this paper we estimate the double parton scattering (DPS) contribution for the heavy quark production in $p A$ collisions at the LHC. The cross sections for the charm and bottom production are estimated using the dipole approach and taking into account the saturation effects, which are important for high energies and for the scattering with a large nucleus. We compare the DPS contribution with the single parton scattering one and demonstrate that in the case of charm production both are similar in the kinematical range probed by the LHC. Predictions for the rapidity range analysed by the LHCb Collaboration are also presented. Our results indicate that the study of the DPS contribution for the heavy quark production in $pP b$ collisions at the LHC is feasible and can be useful to probe the main assumptions of the approach.
Comments:
13 pages, 4 figures, 1 table. Revised version to be published in Modern Physics Letters A
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1607.04023 [pdf]
Mod.Phys.Lett.A(2018)·12 citations
14
[Submitted on 14 Jul 2016] (cross-list from hep-lat)
Complex heavy-quark potential and Debye mass in a gluonic medium from lattice QCD
Yannis Burnier🇨🇭 · Alexander Rothkopf🇩🇪
We improve and extend our study of the complex in-medium heavy quark potential and its Debye mass $m_{D}$ in a gluonic medium with a finer scan around the deconfinement transition and newly generated ensembles closer to the thermodynamic limit. On the lattices with larger physical volume, Re[V] shows signs of screening, i.e. a finite $m_{D}$ , only in the deconfined phase, reminiscent of a genuine phase transition. Consistently Im[V] exhibits nonzero values also only above $T_{C}$ . We compare the behavior of Re[V] with the color singlet free-energies that have been used historically to extract the Debye mass. An effective coupling constant is computed to assess the residual influence of the confining part of the potential at $T > 0$ . Our previous finding of a gradual screening of Re[V] around $T_{C}$ on finer lattices is critically reassessed and interpreted to originate from finite volume artifacts that affect the deployed $β = 7$ , $ξ_{b} = 3.5$ parameter set at $N_{s} = 32$ .
Comments:
13 pages, 10 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1607.04049 [pdf]
PRD(2017)·57 citations
15
[Submitted on 14 Jul 2016] (cross-list from hep-ph)
Quark mass dependence of H-dibaryon in $ΛΛ$ scattering
Yasuhiro Yamaguchi🇯🇵 · Tetsuo Hyodo🇯🇵
We study the quark mass dependence of the H-dibaryon in the strangeness $S = - 2$ baryon-baryon scattering. A low-energy effective field theory is used to describe the coupled-channel scattering, in which the quark mass dependence is incorporated so as to reproduce the lattice QCD data by the HAL QCD collaboration in the SU(3) limit. We point out the existence of the Castillejo-Dalitz-Dyson (CDD) pole in the $ΛΛ$ scattering amplitude below the threshold in the SU(3) limit, which may cause the Ramsauer-Townsend effect near the $N Ξ$ threshold at the physical point. The H-dibaryon is unbound at the physical point, and a resonance appears just below the $N Ξ$ threshold. As a consequence of the coupled-channel dynamics, the pole associated with the resonance is not continuously connected to the bound state in the SU(3) limit. Through the extrapolation in quark masses, we show that the unitary limit of the $ΛΛ$ scattering is achieved between the physical point and the SU(3) limit. We discuss the possible realization of the "H-matter" in the unphysical quark mass region.
Comments:
12 pages, 13 figures, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1607.04053 [pdf]
PRC(2016)·25 citations
16
[Submitted on 14 Jul 2016] (cross-list from hep-th)
Multi-Skyrmions with orientational moduli
Fabrizio Canfora🇨🇱 · Gianni Tallarita🇨🇱
We analyze the mechanism of condensation of orientational moduli (as introduced in [25]) on multi-Skyrmionic configurations of the four-dimensional Skyrme model. The present analysis reveals interesting novel features. First of all, the orientational moduli tend to decrease the repulsive interactions between Skyrmions, the effect decreasing with the increase of the Baryon number. Moreover, in the case of a single Skyrmion, the appearance of moduli is energetically favorable if finite volume effects are present. Otherwise, in the usual flat topologically trivial case, it is not. In the low energy theory these solutions can be interpreted as Skyrmions with additional isospin degrees of freedom.
Comments:
19 pages; 5 figures; accepted for publication on Physical Review D
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1607.04140 [pdf]
PRD(2016)·20 citations
17
[Submitted on 14 Jul 2016] (cross-list from hep-ph)
Saturation and geometrical scaling in small systems
Michal Praszalowicz🇵🇱
Saturation and geometrical scaling (GS) of gluon distributions are a consequence of the non-linear evolution equations of QCD. We argue that in pp GS holds for the inelastic cross-section rather than for the multiplicity distributions. We also discuss possible fluctuations of the proton saturation scale in pA collisions at the LHC.
Comments:
6 pages, 4 figures, talk presented at Excited QCD, Costa da Caparica, Portugal, March 6-12, 2016
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1607.04235 [pdf]
Acta Phys.Polon.Supp.(2016)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE