Nuclear Theory·nucl-th

Wednesday·April 13, 2016

13 papers—10 primary·3 cross-listed

01
[Submitted on 11 Apr 2016]
On the symmetries of the 12C nucleus
J. Cseh · R. Trencsényi
The consequences of some symmetries of the three-alpha system are discussed. In particular, the recent description of the low-energy spectrum of the 12C nucleus in terms of the Algebraic Cluster Model (ACM) is compared to that of the Semimicroscopic Algebraic Cluster Model (SACM). The previous one applies interactions of a D3h geometric symmetry [1], while the latter one has a U(3) multichannel dynamical symmetry, that connects the shell and cluster pictures. The available data is in line with both descriptions.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1604.03123 [pdf]
IJMPE(2018)·11 citations
02
[Submitted on 12 Apr 2016]
Frontiers in Nuclear Astrophysics
Carlos A. Bertulani🇺🇸 · Toshitaka Kajino🇯🇵
The synthesis of nuclei in diverse cosmic scenarios is reviewed, with a summary of the basic concepts involved before a discussion of the current status in each case is made. We review the physics of the early universe, the proton to neutron ratio influence in the observed helium abundance, reaction networks, the formation of elements up to beryllium, the inhomogeneous Big Bang model, and the Big Bang nucleosynthesis constraints on cosmological models. Attention is paid to element production in stars, together with the details of the pp chain, the pp reaction, $^{3}$ He formation and destruction, electron capture on $^{7}$ Be, the importance of $^{8}$ B formation and its relation to solar neutrinos, and neutrino oscillations. Nucleosynthesis in massive stars is also reviewed, with focus on the CNO cycle and its hot companion cycle, the rp-process, triple- $α$ capture, and red giants and AGB stars. The stellar burning of carbon, neon, oxygen, and silicon is presented in a separate section, as well as the slow and rapid nucleon capture processes and the importance of medium modifications due to electrons also for pycnonuclear reactions. The nucleosynthesis in cataclysmic events such as in novae, X-ray bursters and in core-collapse supernovae, the role of neutrinos, and the supernova radioactivity and light-curve is further discussed, as well as the structure of neutron stars and its equation of state. A brief review of the element composition found in cosmic rays is made in the end.
Comments:
88 pages, 10 figures, 613 references, Progress in Particle and Nuclear Physics, 2016
Subjects:
Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
1604.03197 [pdf]
PPNP(2016)·101 citations
03
[Submitted on 12 Apr 2016]
Effects of realistic tensor force on nuclear quadrupole deformation around the shore of the island of inversion
Y. Suzuki · H. Nakada · S. Miyahara
The M3Y-type semi-realistic interaction is applied to deformed nuclei for the first time. The constrained Hartree-Fock calculations assuming axial symmetry are implemented for the $N = 20$ isotones $^{30}$ Ne, $^{32}$ Mg, $^{34}$ Si and the $N = 28$ isotones $^{40}$ Mg, $^{42}$ Si, $^{44}$ S with the M3Y-P6 interaction. The results match the experimental data well. Effects of the realistic tensor force on the nuclear quadrupole deformation are investigated in relation to the loss of the $N = 20$ and $28$ magic numbers. The tensor force is confirmed to favor the deformation for the $N = 28$ nuclei owing to the closure of the $j j$ -shell (\textit{i.e.}, $n 0 f_{7/2}$ ), while favoring the sphericity for the $N = 20$ nuclei owing to the $ℓ s$ -closure of $N = 20$ .
Comments:
containing 12 figures, to be published in PRC
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1604.03202 [pdf]
PRC(2016)·19 citations
04
[Submitted on 12 Apr 2016]
Neutrino Induced 4He Break-up Reaction -- Application of the Maximum Entropy Method in Calculating Nuclear Strength Function
T. Murata · W. Horiuchi · T. Sato · S. X. Nakamura
The maximum entropy method is examined as a new tool for solving the ill-posed inversion problem involved in the Lorentz integral transformation (LIT) method. As an example, we apply the method to the spin-dipole strength function of 4He. We show that the method can be successfully used for inversion of LIT, provided the LIT function is available with a sufficient accuracy.
Comments:
5 pages, 2 figures. Poster presented by TM at the International Workshop on Neutrino-Nucleus Interaction in the Few-GeV Region (NuInt15), Novenber 16-21 2015, Osaka, Japan
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1604.03237 [pdf]
JPS Conf.Proc.(2016)·0 citations
05
[Submitted on 12 Apr 2016]
Estimation of the Shear Viscosity from 3FD Simulations of Au+Au Collisions at $s_{N N} =$ 3.3--39 GeV
Yu. B. Ivanov🇷🇺 · A. A. Soldatov🇷🇺
An effective shear viscosity in central Au+Au collisions is estimated in the range of incident energies 3.3 GeV $\leq s_{N N} \leq$ 39 GeV. The simulations are performed within a three-fluid model employing three different equations of state with and without the deconfinement transition. In order to estimate this effective viscosity, we consider the entropy produced in the 3FD simulations as if it is generated within the conventional one-fluid viscous hydrodynamics. It is found that the effective viscosity within different considered scenarios is very similar at the expansion stage of the collision: as a function of temperature ( $T$ ) the viscosity-to-entropy ratio behaves as $η / s \sim 1/ T^{4}$ ; as a function of net-baryon density ( $n_{B}$ ), $η / s \sim 1/ s$ , i.e. it is mainly determined by the density dependence of the entropy density. The above dependencies take place along the dynamical trajectories of Au+Au collisions. At the final stages of the expansion the $η / s$ values are ranged from $\sim$ 0.05 at highest considered energies to $\sim$ 0.5 at the lowest ones.
Comments:
4 pages, 3 figures, to be published in Eur. Phys. Journ. A
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1604.03261 [pdf]
EPJA(2016)·13 citations
06
[Submitted on 12 Apr 2016]
Meson cloud effects in nucleon resonances at low and intermediate energies
Bojan Golli🇸🇮
We review some results obtained by the Coimbra-Ljubljana collaboration that reveal the important role of the pion cloud in the low- and intermediate-energy nucleon and delta resonances.
Comments:
Talk presented at EEF70, Workshop on Unquenched Hadron Spectroscopy, 1-5 Sept. 2014, Coimbra
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1604.03289 [pdf]
Acta Phys.Polon.Supp.(2015)·0 citations
07
[Submitted on 12 Apr 2016]
Electric multipole response of the halo nucleus $^{6}$ He
Jagjit Singh · L. Fortunato · A. Vitturi · R. Chatterjee
The role of different continuum components in the weakly-bound nucleus $^{6}$ He is studied by coupling unbound spd-waves of $^{5}$ He by means of simple pairing contact-delta interaction. The results of our previous investigations in a model space containing only p-waves, showed the collective nature of the ground state and allowed the calculation of the electric quadrupole transitions. We extend this simple model by including also sd-continuum neutron states and we investigate the electric monopole, dipole and octupole response of the system for transitions to the continuum, discussing the contribution of different configurations.
Comments:
22 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1604.03381 [pdf]
EPJA(2016)·23 citations
08
[Submitted on 12 Apr 2016]
Testing semi-local chiral two-nucleon interaction in selected electroweak processes
R. Skibinski🇵🇱 · J. Golak🇵🇱 · K. Topolnicki🇵🇱 · H. Witala🇵🇱 · E. Epelbaum🇩🇪 · H. Kamada🇩🇪 · H. Krebs🇯🇵 · Ulf-G. Meissner🇩🇪 · A. Nogga🇩🇪
The recently developed semi-local improved chiral nucleon-nucleon interaction is used for the first time to study several electromagnetic and weak processes at energies below the pion production threshold. Cross sections and selected polarization observables for deuteron photodisintegration, nucleon-deuteron radiative capture, three-body $^{3}$ He photodisintegration as well as capture rates for decays of the muonic $^{2}$ H and $^{3}$ He atoms are calculated. The Lippmann-Schwinger and Faddeev equations in momentum space are solved to obtain nuclear states. The electromagnetic current operator is taken as a single nucleon current supplemented by many-body contributions induced via the Siegert theorem. For muon capture processes the nonrelativistic weak current together with the dominant relativistic corrections is used. Our results compare well with experimental data, demonstrating the same quality as is observed for the semi-phenomenological AV18 potential. Compared to the older version of the chiral potential with a nonlocal regularization, a much smaller cut-off dependence is found for the state-of-art chiral local interaction employed in this paper. Finally, estimates of errors due to the truncation of the chiral expansion are given.
Comments:
23 pages, 12 eps figures, improved version accepted to Phys. Rev. C. Note, the title of the manuscript is changed
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1604.03395 [pdf]
PRC(2016)·28 citations
09
[Submitted on 12 Apr 2016]
Charge symmetry breaking in the A=4 hypernuclei
Daniel Gazda🇸🇪 · Avraham Gal🇮🇱
Charge symmetry breaking (CSB) in the $Λ$ -nucleon strong interaction generates a charge dependence of $Λ$ separation energies in mirror hypernuclei, which in the case of the $A = 4$ mirror hypernuclei $0^{+}$ ground states is sizable, $Δ B_{Λ}^{J = 0} \equiv B_{Λ}^{J = 0} (_{Λ}^{4} He) - B_{Λ}^{J = 0} (_{Λ}^{4} H) = 230 \pm 90$ keV, and of opposite sign to that induced by the Coulomb repulsion in light hypernuclei. Recent ab-initio calculations of the ( $_{Λ}^{4} H,_{Λ}^{4} He$ ) mirror hypernuclei $0_{g.s.}^{+}$ and $1_{exc}^{+}$ levels have demonstrated that a $Λ - Σ^{0}$ mixing CSB model due to Dalitz and von Hippel (1964) is capable of reproducing this large value of $Δ B_{Λ}^{J = 0}$ . These calculations are discussed here with emphasis placed on the leading-order chiral EFT hyperon-nucleon strong-interaction Bonn-Juelich potential model used and the no-core shell-model calculational scheme applied. The role of one-pion exchange in producing sizable CSB level splittings in the $A = 4$ mirror hypernuclei is discussed.
Comments:
this v4 version matches the version published in the NPA Special Issue on Recent Progress in Strangeness and Charm in Hadronic and Nuclear Physics, plus (i) an added footnote #4 on OPE CSB contributions, and (ii) an added Appendix A on the present NCSM application to hypernuclei
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1604.03434 [pdf]
NPA(2016)·40 citations
10
[Submitted on 12 Apr 2016]
In-medium covariant propagator of baryons under a strong magnetic field: effect of the intrinsic magnetic moments
R. M. Aguirre🇦🇷 · A. L. De Paoli🇦🇷
We obtain the covariant propagator at finite temperature for interacting baryons immersed in a strong magnetic field. The effect of the intrinsic magnetic moments on the Green function are fully taken into account. We make an expansion in terms of eigenfunctions of a Dirac field, which leads us to a compact form of its propagator. We present some simple applications of these propagators, where the statistical averages of nuclear currents and energy density are evaluated.
Comments:
Matches the published version
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1604.03534 [pdf]
EPJA(2016)·23 citations
11
[Submitted on 12 Apr 2016] (cross-list from hep-ph)
Thoughts on heavy-ion physics in the high luminosity era: the soft sector
Federico Antinori🇮🇹 · Francesco Becattini🇮🇹 · Peter Braun-Munzinger🇩🇪 · Tatsuya Chujo🇯🇵 · Hideki Hamagaki🇯🇵 · John Harris🇬🇧 · Ulrich Heinz🇺🇸 · Boris Hippolyte🇫🇷 · Tetsufumi Hirano🇺🇸 · Barbara Jacak🇺🇸 · Dmitri Kharzeev🇺🇸 · Constantin Loizides🇺🇸 and 19 other authors
This document summarizes thoughts on opportunities in the soft-QCD sector from high-energy nuclear collisions at high luminosities.
Comments:
19 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1604.03310 [pdf]
11 citations
12
[Submitted on 12 Apr 2016] (cross-list from nucl-ex)
Isomer shift and magnetic moment of the long-lived 1/2 $^{+}$ isomer in $_{30}^{79}$ Zn $_{49}$ : signature of shape coexistence near $^{78}$ Ni
X.F. Yang🇧🇪 · C. Wraith🇬🇧 · L. Xie🇬🇧 · C. Babcock🇬🇧 · J. Billowes🇬🇧 · M.L. Bissell🇧🇪 · K. Blaum🇩🇪 · B. Cheal🇬🇧 · K.T. Flanagan🇬🇧 · R.F. Garcia Ruiz🇧🇪 · W. Gins🇧🇪 · C. Gorges🇩🇪 and 12 other authors
Collinear laser spectroscopy has been performed on the $_{30}^{79}$ Zn $_{49}$ isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred milliseconds half-life was confirmed, and the nuclear spins and moments of the ground and isomeric states in $^{79}$ Zn as well as the isomer shift were measured. From the observed hyperfine structures, spins $I = 9/2$ and $I = 1/2$ are firmly assigned to the ground and isomeric states. The magnetic moment $μ$ ( $^{79}$ Zn) = $-$ 1.1866(10) $μ_{N}$ , confirms the spin-parity $9/ 2^{+}$ with a $ν g_{9/2}^{- 1}$ shell-model configuration, in excellent agreement with the prediction from large scale shell-model theories. The magnetic moment $μ$ ( $^{79 m}$ Zn) = $-$ 1.0180(12) $μ_{N}$ supports a positive parity for the isomer, with a wave function dominated by a 2h-1p neutron excitation across the $N = 50$ shell gap. The large isomer shift reveals an increase of the intruder isomer mean square charge radius with respect to that of the ground state: $δ ⟨ r_{c}^{2} ⟩^{79, 79 m}$ = +0.204(6) fm $^{2}$ , providing first evidence of shape coexistence.
Comments:
5 pages, 4 figures, 1 table, Accepeted by Phys. Rev. Lett. (2016)
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1604.03316 [pdf]
PRL(2016)·87 citations
13
[Submitted on 12 Apr 2016] (cross-list from physics.comp-ph)
Relativistic hydrodynamics on graphics processing units
Jan Sikorski · Sebastian Cygert · Joanna Porter-Sobieraj · Marcin Słodkowski · Piotr Krzyżanowski · Natalia Książek · Przemysław Duda
Hydrodynamics calculations have been successfully used in studies of the bulk properties of the Quark-Gluon Plasma, particularly of elliptic flow and shear viscosity. However, there are areas (for instance event-by-event simulations for flow fluctuations and higher-order flow harmonics studies) where further advancement is hampered by lack of efficient and precise 3+1D~program. This problem can be solved by using Graphics Processing Unit (GPU) computing, which offers unprecedented increase of the computing power compared to standard CPU simulations. In this work, we present an implementation of 3+1D ideal hydrodynamics simulations on the Graphics Processing Unit using Nvidia CUDA framework. MUSTA-FORCE (MUlti STAge, First ORder CEntral, with a~slope limiter and MUSCL reconstruction) and WENO (Weighted Essentially Non-Oscillating) schemes are employed in the simulations, delivering second (MUSTA-FORCE), fifth and seventh (WENO) order of accuracy. Third order Runge-Kutta scheme was used for integration in the time domain. Our implementation improves the performance by about 2~orders of magnitude compared to a~single threaded program. The algorithm tests of 1+1D~shock tube and 3+1D~simulations with ellipsoidal and Hubble-like expansion are presented.
Comments:
3 pages, 3 figures, SQM2015 proceedings submitted to Journal of Physics: Conference Series (JPCS) - IOP Conference Series
Subjects:
Computational Physics (physics.comp-ph); Nuclear Theory (nucl-th)
arXiv:
1604.03360 [pdf]
J.Phys.Conf.Ser.(2014)·3 citations

Affiliations

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