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Nuclear Theory

New submissions

[ total of 13 entries: 1-13 ]
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New submissions for Thu, 21 Sep 17

[1]  arXiv:1709.06644 [pdf, other]
Title: The anisotropic non-equilibrium hydrodynamic attractor
Comments: 25 pages, 7 figures
Subjects: Nuclear Theory (nucl-th); High Energy Physics - Phenomenology (hep-ph)

We determine the dynamical attractors associated with anisotropic hydrodynamics (aHydro) and the DNMR equations for a 0+1d conformal system using kinetic theory in the relaxation time approximation. We compare our results to the non-equilibrium attractor obtained from exact solution of the 0+1d conformal Boltzmann equation, Navier-Stokes theory, and second-order Mueller-Israel-Stewart theory. We demonstrate that the aHydro attractor equation resums an infinite number of terms in the inverse Reynolds number. The resulting resummed aHydro attractor possesses a positive longitudinal to transverse pressure ratio and is virtually indistinguishable from the exact attractor. This suggests that kinetic theory involves not only a resummation in gradients (Knudsen number) but also a novel resummation in inverse Reynolds number. We also demonstrate that the DNMR result provides a better approximation to the exact kinetic theory attractor than Mueller-Israel-Stewart theory. Finally, we introduce a new method for obtaining approximate aHydro equations which relies solely on an expansion in inverse Reynolds number, carry out this expansion to third order, and compare these third-order results to the exact kinetic theory solution.

[2]  arXiv:1709.06699 [pdf, ps, other]
Title: A practical scheme for constructing the minimum weight states of the su(n)-Lipkin model in arbitrary fermion number
Authors: Y. Tsue (1), C. Providencia (2), J. da Providencia (2), M. Yamamura (3) ((1) Kochi Univ., Japan, (2) Univ. de Coimbra, Portugal, (3) Kansai Univ., Japan)
Comments: 11 pages, 6 figures
Subjects: Nuclear Theory (nucl-th)

With the aim of performing an argument supplement to the previous paper by the present authors, in this paper, a practical scheme for constructing the minimum weight states of the su(n)-Lipkin model in arbitrary fermion number is discussed. The idea comes from the following two points : (i) consideration on the property of one-fermion transfer induced by the su(n)-generators in the Lipkin model and (ii) use of the auxiliary su(2)-algebra presented by the present authors. The form obtained under the points (i) and (ii) is simple.

[3]  arXiv:1709.06704 [pdf, ps, other]
Title: The role of the elemental nature of A=3 nuclei in neutron rich nuclei
Comments: 4 pages, 3 figures
Subjects: Nuclear Theory (nucl-th)

The idea of treating the trinucleon systems as elementary entities in the elementary particle model (EPM) as an Effective Field Theory, has been a success in explaining the weak charge-changing processes in nuclei. The EPM results are found to be as good as those obtained from nuclear microscopic models using two- and three-body forces. We extend this concept to investigate the validity of the elemental nature of A=3 nuclei through studies of nuclear structure of neutron rich nuclei. By treating neutron rich nuclei as primarily made up of tritons as its building blocks, we extract one-triton and two-triton separation energies of these nuclei. Calculations have been performed within relativistic mean field (RMF) models with latest interactions. Clear evidence of a new shell structure with well defined predictions of new magic nuclei arise. The most significant and an unambiguous prediction of our model, is the existence of a superheavy nucleus $_{\:\:92}^{276}{\rm U}_{184}$, which due to its small charge Z=92, should be easily accessible to experimental confirmation.

[4]  arXiv:1709.06840 [pdf, other]
Title: Electromagnetic Strength Distributions from the Ab Initio No-Core Shell Model
Comments: 6 pages, 3 figures
Subjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)

We present an ab initio approach for the description of collective excitations and transition strength distributions of arbitrary nuclei up into the sd-shell that based on the No-Core Shell Model in combination with the Lanczos strength-function method. Starting from two- and three-nucleon interactions from chiral effective field theory, we investigate the electric monopole, dipole, and quadrupole response of the even oxygen isotopes from 16-O to 24-O. The method describes the full energy range from low-lying excitations to the giant resonance region and beyond in a unified and consistent framework, including a complete description of fragmentation and fine-structure. This opens unique opportunities for understanding dynamic properties of nuclei from first principles and to further constrain nuclear interactions. We demonstrate the computational efficiency and the robust model-space convergence of our approach and compare to established approximate methods, such as the Random Phase Approximation, shedding new light on their deficiencies.

Cross-lists for Thu, 21 Sep 17

[5]  arXiv:1611.06901 (cross-list from hep-lat) [pdf, other]
Title: Gluon momentum fraction of the nucleon from lattice QCD
Comments: 16 pages, 2 Table, 8 Figures, Version accepted for publication in Phys. Rev. D
Journal-ref: Phys. Rev. D 96, 054503 (2017)
Subjects: High Energy Physics - Lattice (hep-lat); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th); Nuclear Theory (nucl-th)

We perform a direct calculation of the gluon momentum fraction of the nucleon using maximally twisted mass fermion ensembles with $N_f=2+1+1$ flavors at a pion mass of about $370\,\mathrm{MeV}$ and a lattice spacing of $a\approx 0.082\,\mathrm{fm}$ and with $N_f=2$ flavors at the physical pion mass and a lattice spacing of $a\approx 0.093\,\mathrm{fm}$. In the definition of the gluon operator we employ stout smearing to obtain a statistically significant result for the bare matrix elements. In addition, we perform a lattice perturbative calculation including 2 levels of stout smearing to carry out the mixing and the renormalization of the quark and gluon operators. We find, after conversion to the $\overline{\mathrm{MS}}$ scheme at a scale of $2\,\mathrm{GeV}$: $\langle x\rangle^R_g {=} 0.284(23)(23)$ for pion mass of about $370\,\mathrm{MeV}$ and $\langle x\rangle^R_g {=} 0.283(23)(15)$ for the physical pion mass.

Replacements for Thu, 21 Sep 17

[6]  arXiv:1612.05795 (replaced) [pdf, other]
Title: What is the magnetic field distribution for the equation of state of magnetized neutron stars?
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
[7]  arXiv:1702.07620 (replaced) [pdf, ps, other]
Title: Probing QCD critical fluctuations from light nuclei production in relativistic heavy-ion collisions
Comments: 6 pages, 1 figure, 2 tables. Correlations between neutron and proton density fluctuations considered and presentation improved. Accepted version to appear in PLB
Subjects: Nuclear Theory (nucl-th); High Energy Physics - Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
[8]  arXiv:1705.07548 (replaced) [pdf, ps, other]
Title: $K^+$-nucleus elastic scattering revisited from perspective of partial restoration of chiral symmetry
Subjects: Nuclear Theory (nucl-th)
[9]  arXiv:1706.00258 (replaced) [pdf, ps, other]
Title: Toward a systematic strategy for defining power counting in the construction of the energy density functional theory
Comments: 24 pages, 12 figures. Published version
Journal-ref: Phys. Rev. C 96 034318 (2017)
Subjects: Nuclear Theory (nucl-th)
[10]  arXiv:1706.07376 (replaced) [pdf, other]
Title: Regge phenomenology in $π^0$ and $η$ photoproduction
Comments: 11 pages, 10 figures
Journal-ref: Phys. Rev. C 96, 035207 (2017)
Subjects: High Energy Physics - Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
[11]  arXiv:1708.00536 (replaced) [pdf, other]
Title: High-precision $Q_{EC}$-value measurement of the superallowed $β^+$ emitter $^{22}$Mg and an evaluation of the $A=22$ isobaric triplet
Comments: Submitted to Physical Review C
Subjects: Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
[12]  arXiv:1708.04437 (replaced) [pdf, ps, other]
Title: From quark and nucleon correlations to discrete symmetry and clustering in nuclei
Comments: 12 pages, 4 figures. Presented at Int. Symp. "Exotic Nuclei - Exon 2016"
Subjects: Nuclear Theory (nucl-th)
[13]  arXiv:1709.04268 (replaced) [pdf, ps, other]
Title: Strong and radiative decays of the low-lying $S$- and $P$-wave singly heavy baryons
Comments: 19 pages, 8 figures, 10 tables
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Theory (nucl-th)
[ total of 13 entries: 1-13 ]
[ showing up to 2000 entries per page: fewer | more ]

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