Nuclear Theory·nucl-th

Thursday·October 1, 2015

20 papers—11 primary·9 cross-listed

01
[Submitted on 29 Sept 2015]
Running Masses in the Nucleon and its Resonances
Craig D. Roberts🇺🇸
An overarching scientific challenge for the coming decade is to discover the meaning of confinement, its relationship to dynamical chiral symmetry breaking (DCSB) - the origin of visible mass - and the connection between them. In progressing toward meeting this challenge, significant progress has been made using continuum methods in QCD. For example, a novel understanding of gluon and quark confinement and its consequences has begun to emerge from quantum field theory; a clear picture is being drawn of how hadron masses emerge dynamically in a universe with light quarks; and ground-state hadron wave functions with a direct connection to QCD are becoming available, which reveal that quark-quark correlations are crucial in hadron structure. There is growing experimental support for this body of predictions in both elastic and nucleon-to-resonance-transition form factors.
Comments:
10 pages, 6 figures. Contribution to the proceedings of NSTAR2015, the 10th International Workshop on the Physics of Excited Nucleons, 25-28 May 2015, Suita Campus, Osaka University, Osaka, Japan
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.08952 [pdf]
JPS Conf.Proc.(2016)·5 citations
02
[Submitted on 30 Sept 2015]
Ab initio calculations of reactions with light nuclei
S. Quaglioni (1)🇺🇸 · G. Hupin (2,1)🇫🇷 · A. Calci (3)🇨🇦 · P. Navratil (3)🇨🇦 · R. Roth (4) ((1) LLNL, (2) IN2P3/CNRS, (3) TRIUMF, (4) TU Darmstadt)🇩🇪
An {\em ab initio} (i.e., from first principles) theoretical framework capable of providing a unified description of the structure and low-energy reaction properties of light nuclei is desirable to further our understanding of the fundamental interactions among nucleons, and provide accurate predictions of crucial reaction rates for nuclear astrophysics, fusion-energy research, and other applications. In this contribution we review {\em ab initio} calculations for nucleon and deuterium scattering on light nuclei starting from chiral two- and three-body Hamiltonians, obtained within the framework of the {\em ab initio} no-core shell model with continuum. This is a unified approach to nuclear bound and scattering states, in which square-integrable energy eigenstates of the $A$ -nucleon system are coupled to $(A - a) + a$ target-plus-projectile wave functions in the spirit of the resonating group method to obtain an efficient description of the many-body nuclear dynamics both at short and medium distances and at long ranges.
Comments:
9 pages, 5 figures, proceedings of the 21st International Conference on Few-Body Problems in Physics
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.09009 [pdf]
EPJ Web Conf.(2016)·7 citations
03
[Submitted on 30 Sept 2015]
Nucleon Resonances Near 2 GeV
Jun He🇨🇳
The nucleon resonances near 2 GeV are investigated through the $Σ$ (1385) and $Λ (1520)$ photoproductions within a Regge-plus-resonance approach based on the new experimental data released by the CLAS Collaboration. The $Δ (2000)$ and the $N (2120)$ are found essential to reproduce the experimental data and should be assigned as second $[Δ5/ 2^{+}]$ and third $[N 3/ 2^{-}]$ in the constituent quark model, respectively. A calculation of the binding energy and decay pattern supports that the $N (1875)$ , which is listed in the PDG as the third $N 3/ 2^{-}$ nucleon resonance instead of the $N (2120)$ , is from the $Σ (1385) K$ interaction rather than a three quark state.
Comments:
Talk given at the 10th International Workshop on the Physics of Excited Nucleons (NSTAR2015), Osaka, May 2015
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1509.09025 [pdf]
JPS Conf.Proc.(2016)·1 citation
04
[Submitted on 30 Sept 2015]
On Distributions of Emission Sources and Speed of Sound in Proton-proton (Proton-antiproton) Collisions
Li-Na Gao🇨🇳 · Fu-Hu Liu🇨🇳
The revised (three-source) Landau hydrodynamic model is used in this paper to study the (pseudo)rapidity distributions of charged particles produced in proton-proton and proton-antiproton collisions at high energies. The central source is assumed to contribute with a Gaussian function which covers the rapidity distribution region as wide as possible. The target and projectile sources are assumed to emit isotropically particles in their respective rest frames. The model calculations obtained with a Monte Carlo method are fitted to the experimental data over an energy range from 0.2 to 13 TeV. The values of the squared speed-of-sound parameter in different collisions are then extracted from the width of the rapidity distributions.
Comments:
14 pages, 3 figures. Major Changes. Advances in High Energy Physics, in press. arXiv admin note: text overlap with arXiv:1509.08603
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.09034 [pdf]
Adv.High Energy Phys.(2015)·8 citations
05
[Submitted on 30 Sept 2015]
Nuclear Reactions at Intermediate Energies
Radhey Shyam🇮🇳
In the domain of Nuclear reactions at intermediate energies, the QCD coupling constant $α_{s}$ is large enough ( $\sim$ 0.3 - 0.5) to render the perturbative calculational techniques inapplicable. In this regime the quarks are confined into colorless hadrons and it is expected that effective field theories of hadron interactions via exchange of hadrons, provide useful tools to describe such reactions. In this contribution we discuss applications of one such theory, the effective Lagrangian model, in describing the hadronic reactions at intermediate energies whose measurements are the focus of a vast international experimental program.
Comments:
10 pages, 6 figures, Plenary talk presented at NN2015, June 21-26, 2015, Catania, Italy
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.09035 [pdf]
EPJ Web Conf.(2016)·0 citations
06
[Submitted on 30 Sept 2015]
Testing two-nucleon transfer reaction mechanism with elementary modes of excitation in exotic nuclei
R.A. Broglia🇮🇹 · G.Potel🇺🇸 · A. Idini🇫🇮 · F. Barranco🇪🇸 · E. Vigezzi🇮🇹
Nuclear Field Theory of structure and reactions is confronted with observations made on neutron halo dripline nuclei, resulting in the prediction of a novel (symbiotic) mode of nuclear excitation, and on the observation of the virtual effect of the halo phenomenon in the apparently non-halo nucleus $^{7}$ Li. This effect is forced to become real by intervening the virtual process with an external (t,p) field which, combined with accurate predictive abilities concerning the absolute differential cross section, reveals an increase of a factor 2 in the cross section due to the presence of halo ground state correlations, and is essential to reproduce the value of the observed $d σ (^{7}$ Li(t,p) $^{9}$ Li)/d $Ω$ .
Comments:
Submitted to CERN proceedings for the 14th International Conference on Nuclear Reaction mechanisms, Varenna, June 15 - 19, 2015
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.09068 [pdf]
0 citations
07
[Submitted on 30 Sept 2015]
Alpha decay in electron environments of increasing density: from the bare nucleus to compressed matter
Fabio Belloni
The influence of the electron environment on the alpha decay is elucidated. Within the frame of a simple model based on the generalized Thomas-Fermi theory of the atom, it is shown that the increase of the electron density around the parent nucleus drives a mechanism which shortens the lifetime. Numerical results are provided for 144Nd, 154Yb and 210Po. Depending on the nuclide, fractional lifetime reduction relative to the bare nucleus is of the order of 0.1-1% in free ions, neutral atoms and ordinary matter, but may reach up to 10% at matter densities as high as 10^4 g/cm3, in a high-Z matrix. The effect induced by means of state-of-the-art compression techniques, although much smaller than previously found, would however be measurable. The extent of the effect in ultra-high-density stellar environments might become significant and would deserve further investigation.
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1509.09106 [pdf]
EPJA(2016)·7 citations
08
[Submitted on 30 Sept 2015]
Projectile deformation effects in the breakup of $^{37}$ Mg
Shubhchintak (TAMU-Commerce) · R. Chatterjee (IIT-R) · R. Shyam (Saha Inst.)
We study the breakup of $^{37}$ Mg on Pb at 244MeV/u with the recently developed extended theory of Coulomb breakup within the post-form finite range distorted wave Born approximation that includes deformation of the projectile. Comparing our calculated cross section with the available Coulomb breakup data we determine the possible ground state configuration of $^{37}$ Mg.
Comments:
6 pages, 2 figures, Proceedings of the 12th International conference on Nucleus-Nucleus collisions (NN2015), June 21-26, Catania, Italy
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1509.09144 [pdf]
EPJ Web Conf.(2016)·1 citation
09
[Submitted on 30 Sept 2015]
Collectivity in small and large amplitude microscopic mean-field dynamic
Denis Lacroix🇫🇷 · Yusuke Tanimura🇫🇷 · Guillaume Scamps🇯🇵
The time-dependent energy density functional with pairing allows to describe a large variety of phenomena from small to large amplitude collective motion. Here, we briefly summarize the recent progresses made in the field using the TD-BCS approach. A focus is made on the mapping of the microscopic mean-field dynamic to the macroscopic dynamic in collective space. A method is developed to extract the collective mass parameter from TD-EDF. Illustration is made on the fission of $^{258}$ Fm. The collective mass and collective momentum associated to quadrupole deformation including non-adiabatic effects is estimated along the TD-EDF path. With these information, the onset of dissipation during fission is discussed.
Comments:
Proceeding of the XXII Nuclear Physics Workshop, Kazimierz, 2015, Poland
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1509.09155 [pdf]
Acta Phys.Polon.Supp.(2015)·1 citation
10
[Submitted on 30 Sept 2015]
Compton Scattering and Nucleon Polarisabilities in Chiral EFT: Update and Future
Harald W. Griesshammer (George Washington U.)🇺🇸 · Judith A. McGovern (U. of Manchester)🇬🇧 · Daniel R. Phillips (Ohio U.)🇺🇸
We review theoretical progress and prospects for determining the nucleon's static dipole polarisabilities from Compton scattering on few-nucleon targets, including new values; see Refs. [1-5] for details and a more thorough bibliography.
Comments:
6 pages LaTeX2e (pdflatex) including 11 figures as .pdf files. First presented by Griesshammer at the 12th Conference on the Intersections of Nuclear and Particle Physics CIPANP2015, 19-24 May 2015, Vail (CO), USA; updated for 22nd International Spin Symposium (SPIN 2016), University of Illinois, Urbana (USA), 26-30 September 2016. Corrected 2 figures, added clarifying text
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.09177 [pdf]
AIP Conf.Proc.(2016)·3 citations
11
[Submitted on 30 Sept 2015]
Symmetry energy of cold nucleonic matter within a relativistic mean field model encapsulating effects of high momentum nucleons induced by short-range correlations
Bao-Jun Cai · Bao-An Li
Significant progress has been made recently in constraining the isospin-dependent parameters characterizing the SRC (short-range correlation)-modified single-nucleon momentum distribution in neutron-rich nucleonic matter using both experimental data and microscopic model calculations. Using the constrained single-nucleon momentum distribution in a nonlinear relativistic mean field (RMF) model, we study the equation of state (EOS) of asymmetric nucleonic matter (ANM), especially the density dependence of nuclear symmetry energy $E_{sym} (ρ)$ . Firstly, as a test of the model, the average nucleon kinetic energy extracted recently from electron-nucleus scattering experiments using a neutron-proton dominance model is well reproduced by the RMF model incorporating effects of the SRC-induced high momentum nucleons, while it is significantly under predicted by the RMF model using a step function for the single-nucleon momentum distribution as in free Fermi gas (FFG) models. Secondly, the kinetic symmetry energy of quasi-nucleons is found to be $E_{sym}^{kin} (ρ_{0}) = - 16.94 \pm 13.66 MeV$ which is dramatically different from the prediction of $E_{sym}^{kin} (ρ_{0}) \approx 12.5$ MeV by FFG models at nuclear matter saturation density $ρ_{0} = 0.16 fm^{- 3}$ . Thirdly, comparing the RMF calculations with and without the high momentum nucleons using two sets of model parameters both reproducing identically all empirically constraints on the EOS of symmetric nuclear matter (SNM) and the symmetry energy of ANM at $ρ_{0}$ , the SRC-modified single-nucleon momentum distribution is found to make the $E_{sym} (ρ)$ more concave around $ρ_{0}$ by softening it significantly at both sub-saturation and supra-saturation densities, leading to an isospin-dependent incompressibility of ANM in better agreement with existing experimental data.
Comments:
New results/discussions/references added. Version accepted by Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
1509.09290 [pdf]
PRC(2016)·78 citations

Affiliations

first authorsco-authorsvia INSPIRE