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Nuclear Theory

New submissions

[ total of 21 entries: 1-21 ]
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New submissions for Tue, 20 Mar 18

[1]  arXiv:1803.06434 [pdf]
Title: Probable Decay Modes at Limits of Nuclear Stability of the Superheavy Nuclei
Authors: M. Bhuyan
Comments: 17 Pages, 03 Figures and 02 Tables
Journal-ref: Phys. Atm. Nucl. 81, (2018) 15
Subjects: Nuclear Theory (nucl-th)

The modes of decay for the even-even isotopes of superheavy nuclei of Z = 118 and 120 with neutron number $160 \leq N \leq 204$ are investigated in the framework of the axially deformed relativistic mean field model. The asymmetry parameter $\eta$ and the relative neutron-proton asymmetry of the surface to the center ($R_{\eta}$) are estimated from the ground state density distributions of the nucleus. We analyze the resulting asymmetry parameter $\eta$ and the relative neutron-proton asymmetry $R_{\eta}$ of the density play a crucial role in the mode(s) of decay and its half-life. Moreover, the excess neutron richness on the surface facets a superheavy nucleus for $\beta^-$ decays.

[2]  arXiv:1803.06522 [pdf, ps, other]
Title: Fragment Distribution in Reactions of $^{78,86}$Kr+$^{181}$Ta
Subjects: Nuclear Theory (nucl-th)

Within the framework of the isospin-dependent quantum molecular dynamics model along with the GEMINI model, the reaction of $^{86}$Kr+$^{181}$Ta at 80,120 and 160 MeV/nucleon and the reaction of $^{78}$Kr+$^{181}$Ta at 160 MeV/nucleon are studied, and the production cross sections of the generated fragments are calculated. More intermediate and large mass fragments can be produced in the reaction with a large range of impact parameter. The production cross sections of nuclei such as the isotopes of Si and P generally decrease with the increasing incident energy. The isotopes near the neutron drip line are produced more in the neutron-rich system $^{86}$Kr+$^{181}$Ta.

[3]  arXiv:1803.06633 [pdf, ps, other]
Title: Constraints on the inner boundary of a neutron star crust with applications on slow rotating neutron stars
Comments: 23 pages, 7 figures, 5 tables
Subjects: Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)

We systematically study the symmetry energy effects of the transition density $n_{\rm t}$ and the transition pressure $P_{\rm t}$ around the crust-core interface of a neutron star in the framework of the dynamical and the thermodynamical method respectively. We employ both the parabolic approximation and the full expansion, for the definition of the symmetry energy. We use various theoretical nuclear models, which are suitable for reproducing the bulk properties of nuclear matter at low densities, close to saturation density as well as the maximum observational neutron star mass. Firstly we derive and present an approximation for the transition pressure $P_{\rm t}$ and crustal mass $M_{\rm crust}$. Secondly, we explore the effects of the Equation of State (EoS) on a few astrophysical applications which are sensitive to the values of $n_{\rm t}$ and $P_{\rm t}$ including neutron star oscillation frequencies, thermal relaxation of the crust, crustal fraction of the moment of inertia and the r-mode instability window of a rotating neutron star. We found that the above quantities are sensitive mainly on the applied approximation for the symmetry energy (confirming previous results). Furthermore, an additional sensitivity also exists, depending on the used method (dynamical or thermodynamical). The above findings lead us to claim that the determination of the $n_{\rm t}$ and $P_{\rm t}$ must be reliable and accurate before they are used to constrain relevant neutron star properties.

[4]  arXiv:1803.06695 [pdf, other]
Title: Vortex-like solutions and internal structures of covariant ideal magnetohydrodynamics
Subjects: Nuclear Theory (nucl-th); High Energy Physics - Phenomenology (hep-ph)

We discuss a manifestly covariant formulation of ideal relativistic magnetohydrodynamics, which has been recently used in astrophysical and heavy-ion contexts, and compare it to other similar frameworks. We show that the covariant equations allow for stationary vortex-like solutions that represent generalizations of the perfect-fluid solutions describing systems in global equilibrium with rotation. Such solutions are further used to demonstrate that inhomogeneous Maxwell equations, implicitly included in the covariant framework, may generate very large electric charge densities. This suggests that solutions of the covariant formulation may violate in some cases the assumptions of standard ideal magnetohydrodynamics. Furthermore, we show that the flow four-vector and conserved currents obtained in the covariant approach are usually not related to each other, which hinders kinetic-theory interpretation of the obtained results.

[5]  arXiv:1803.06729 [pdf, other]
Title: Polar polarization: a new method for polarimetry analysis
Authors: D. Izraeli (1), I. Mardor (1,2), E.O. Cohen (1), M. Duer (1), T.Y. Izraeli (3), I. Korover (1,4), J. Lichtenstadt (1), E. Piasetzky (1) ((1) School of Physics and Astronomy, Tel Aviv University, Tel Aviv 6997801, Israel., (2) Soreq NRC, Yavne 81800, Israel., (3) Guardian Optical Technologies, Derech Hashalom 7, Tel Aviv 6789208, Israel., (4) Department of Physics, NRCN, P.O. Box 9001, Beer-Sheva 8419001, Israel.)
Subjects: Nuclear Theory (nucl-th); High Energy Physics - Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)

We present a novel analysis method for measurements of polarization transferred in $A(\vec{e},e'\vec{N})$ experiments, which can be applied to other kinds of polarization measurements as well. In this method the polarization transfer components are presented in spherical coordinates using an efficient likelihood numerical maximization based on an analytic derivation. We also propose a formalism that accounts for multi-parameter models, and which yields a smooth and continuous representation of the data (rather than using standard binning). Applying this method on simulated data generates results with reduced statistical and systematic uncertainties and enables revealing physical information that is lost in standard binning of the data. The obtained results can be compared easily to theoretical models and other measurements. Furthermore, CPU time is significantly reduced using this method.

[6]  arXiv:1803.06758 [pdf, ps, other]
Title: Impact of the $^7$Be($α, γ$)$^{11}$C reaction on the primordial abundance of $^7$Li
Comments: 15 pages and 2 figures
Subjects: Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Nuclear Experiment (nucl-ex)

We calculate the radiative capture cross section for $^7$Be($\alpha, \gamma$)$^{11}$C and its reaction rate for the big bang nucleosynthesis. The impact of this reaction on the primordial $^7$Li abundance is revised with the assumption of a narrow resonance in the low energy region. We show that such a resonance is unlikely to emerge within a two-body potential model. Taking the existence of this resonance for granted, we show that a small shift of its energy to a location right below the previously suggested value of $E_r=270$ KeV, with a narrow width of 160 eV, can modify substantially the $^7$Li abundance and solve the cosmological lithium puzzle.

[7]  arXiv:1803.06761 [pdf, other]
Title: Hadron-Quark Combustion as a Nonlinear, Dynamical System
Comments: 8 pages, 2 figures
Journal-ref: Universe, 4(3), 51 (2018)
Subjects: Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)

The hadron-quark combustion front is a system that couples various processes, such as chemical reactions, hydrodynamics, diffusion, and neutrino transport. Previous numerical work has shown that this system is very nonlinear, and can be very sensitive to some of these processes. In these proceedings, we contextualize the hadron-quark combustion as a nonlinear system, subject to dramatic feedback triggered by leptonic weak decays and neutrino transport.

[8]  arXiv:1803.06828 [pdf, ps, other]
Title: Multipole Modes for Triaxially Deformed Superfluid Nuclei
Comments: 4 pages, 2 figures, accepted for publication in Proceedings of Ito International Research Center (IIRC) Symposium "Perspectives of the Physics of Nuclear Structure" (JPS Proc. Conf.)
Subjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)

To study shape fluctuations of nuclei in transitional regions, the collective Hamiltonian method has often been employed. We intend to construct the quadrupole collective Hamiltonian with the collective inertial functions given by the local quasiparticle random-phase approximation (QRPA) based on the Skyrme energy density functional. For this purpose, we first construct a practical framework of Skyrme QRPA for triaxial nuclear shapes with the finite amplitude method (FAM). We show quadrupole strength functions for a triaxial superfluid nucleus $^{188}$Os and the Thouless-Valatin rotational moment of inertia by the local FAM-QRPA for $^{106}$Pd.

[9]  arXiv:1803.06897 [pdf, other]
Title: Generic features of the neutron-proton interaction
Comments: 5 pages, 7 figures
Subjects: Nuclear Theory (nucl-th)

We show that fully aligned neutron-proton pairs play a crucial role in the low-energy spectroscopy of nuclei. with valence nucleons in a high-j orbital. Their dominance is valid in nuclei with valence neutrons and protons in different high-j orbitals as well as in N = Z nuclei, where all nucleons occupy the same orbital. We demonstrate analytically this generic feature of the neutron-proton interaction for a variety of systems with four valence nucleons interacting through realistic, effective forces. The dominance of fully aligned neutron-proton pairs results from the combined effect of (i) angular momentum coupling and (ii) basic properties of the neutron-proton interaction.

Cross-lists for Tue, 20 Mar 18

[10]  arXiv:1803.02548 (cross-list from cond-mat.quant-gas) [pdf, ps, other]
Title: Dynamics of first-order quantum phase transitions in extended Bose-Hubbard model: From density wave to superfluid and vice-versa
Comments: 10 pages, 13 figures
Subjects: Quantum Gases (cond-mat.quant-gas); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)

In this paper, we study the nonequilibrium dynamics of the Bose-Hubbard model with the nearest-neighbor repulsion by using time-dependent Gutzwiller (GW) methods. In particular, we vary the hopping parameters in the Hamiltonian as a function of time, and investigate the dynamics of the system from the density wave (DW) to the superfluid (SF) crossing a first-order phase transition and vice-versa. From the DW to SF, we find scaling laws for the correlation length and vortex density with respect to the quench time. This is a reminiscence of the Kibble-Zurek scaling for continuous phase transitions and contradicts the common expectation. On the other hand from the SF to DW, the system evolution depends on the initial SF state. When the initial state is the ground-state obtained by the static GW methods, a coexisting state of the SF and DW domains forms after passing through the critical point. Coherence of the SF order parameter is lost as the system evolves. This is a phenomenon similar to the glass transition in classical systems. Starting from the SF with small local phase fluctuations, the system is getting a large-size DW-domain structure with thin domain walls.

[11]  arXiv:1803.06420 (cross-list from nucl-ex) [pdf, other]
Title: Exclusive vector meson production at an electron-ion collider
Comments: 12 pages, 12 figures and 4 tables
Subjects: Nuclear Experiment (nucl-ex); High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)

Coherent exclusive vector meson electroproduction is a key physics channel at an electron-ion collider. It probes the gluon structure of nuclei over a wide range of $Q^2$, and can be used to measure nuclear shadowing and to search for gluon saturation and/or the colored glass condensate. In this paper, we present calculations of the kinematic distributions for a variety of exclusive vector meson final states: the $\rho$, $\phi$, J/$\psi$, $\psi'$ and the $\Upsilon$ states. The cross-sections for light and $c\overline c$ mesons are large, while $\Upsilon$ states should be produced in moderate numbers at a medium energy EIC (the proposed U.S. designs) and in large numbers at the LHeC. We investigate the acceptances for these states, as a function of detector rapidity coverage. A large-acceptance detector is needed to cover the full range photon-nucleon collision energies produced at an EIC; a forward detector is required to observe vector mesons from the most energetic photon interactions, and thereby probe gluons at the lowest possible Bjorken-$x$ values.

[12]  arXiv:1803.06779 (cross-list from hep-ph) [pdf, other]
Title: A novel Dual Chiral Density Wave in nuclear matter based on a parity doublet structure
Subjects: High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)

We study the Dual Chiral Density Wave (DCDW) in nuclear matter using a hadronic model with the parity doublet structure. We first extend the ordinary DCDW ansatz so as to incorporate the effect of an explicit chiral symmetry breaking. Then via numerically evaluating and minimizing the effective potential, we determine the phase structure. We find, in addition to the ordinary DCDW phase where the space average of the chiral condensate vanishes, a new DCDW phase (sDCDW) with a nonvanishing space average depending on the value of the chiral invariant mass parameter.

Replacements for Tue, 20 Mar 18

[13]  arXiv:1609.04803 (replaced) [pdf, other]
Title: Hydrodynamic series and hydrodynamization of expanding plasma in kinetic theory
Comments: 6 pages, 2 figures, v2: author added, major rewrite, mysterious off real axis singularities in the Borel plane explained (!), see also arXiv:1802.08225 [nucl-th] by Heller and Svensson; v3: references added, minor improvements in the text, first 426 terms from Eq. (8) included in the submission
Subjects: Nuclear Theory (nucl-th); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th); Fluid Dynamics (physics.flu-dyn)
[14]  arXiv:1703.02675 (replaced) [pdf, ps, other]
Title: Compositeness of hadron resonances in finite volume
Comments: 21 pages, 16 figrues, v3: typos corrected, application to scalar mesons added
Subjects: Nuclear Theory (nucl-th); High Energy Physics - Phenomenology (hep-ph)
[15]  arXiv:1707.06447 (replaced) [pdf, other]
Title: On spinodal points and Lee-Yang edge singularities
Comments: 26 pages, 8 figures; v2: shortened Sec. 4.1 and streamlined arguments/notation in Sec. 4.2, details moved to appendix, added reference 17
Journal-ref: J. Stat. Mech. (2018) 033207
Subjects: High Energy Physics - Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); Nuclear Theory (nucl-th)
[16]  arXiv:1709.04933 (replaced) [pdf, other]
Title: Matching the Quasi Parton Distribution in a Momentum Subtraction Scheme
Comments: 18 pages, 6 figures
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Lattice (hep-lat); Nuclear Theory (nucl-th)
[17]  arXiv:1801.01250 (replaced) [pdf, other]
Title: Examining empirical evidence of the effect of superfluidity on the fusion barrier
Authors: Guillaume Scamps
Comments: 11 pages, 14 figures
Subjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
[18]  arXiv:1801.02295 (replaced) [pdf, other]
Title: Interatomic interaction effects on second-order momentum correlations and Hong-Ou-Mandel interference of double-well-trapped ultracold fermionic atoms
Comments: 18 pages, 8 color figures. A new section V was added; it describes entanglement aspects and the connection to the Hong-Ou-Mandel interference physics. Also the whole range for both repulsive and attractive interparticle interaction is now investigated. For related papers, see this http URL
Subjects: Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
[19]  arXiv:1801.06067 (replaced) [pdf, other]
Title: The radiative corrections to double-Dalitz decays revisited
Comments: 22 pages, 9 figures; minor changes added (results unchanged). Matches the published version in PRD
Journal-ref: Phys.Rev. D97, 056010 (2018)
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Theory (nucl-th)
[20]  arXiv:1802.05416 (replaced) [pdf, ps, other]
Title: Magnetic moments of the lowest-lying singly heavy baryons
Comments: 9 pages. Table III and IV in the previous version were removed. The manuscript has been revised for publication
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Theory (nucl-th)
[21]  arXiv:1803.03259 (replaced) [pdf, other]
Title: A reciprocal formulation of non-exponential radiative transfer. 1: Sketch and motivation
Authors: Eugene d'Eon
Comments: 14 pages, fixed typos, more clarity, notation summary table, tweaked abstract and title
Subjects: Computational Physics (physics.comp-ph); Graphics (cs.GR); Nuclear Theory (nucl-th)
[ total of 21 entries: 1-21 ]
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