Nuclear Theory·nucl-th

Wednesday·November 6, 2019

8 papers—1 primary·7 cross-listed

01
[Submitted on 4 Nov 2019]
Sensitivity of one-neutron knockout of halo nuclei to their nuclear structure
Chloë Hebborn · Pierre Capel
Halo nuclei are located far from stability and exhibit a very peculiar structure. Due to their very short lifetime, they are often studied through reactions. Breakup reactions are of particular interest since their cross sections are large for these loosely-bound nuclei. Inclusive measurements of breakup--also called knockout reactions--have even higher statistics. In this proceeding, we study which nuclear-structure information can be inferred from the parallel-momentum distribution of the core of one-neutron halo nuclei after the knockout of its halo neutron. In particular, we analyse the influence of the ground-state wavefunction, the presence of excited states within the halo-nucleus spectrum and resonances in the core-neutron continuum. Our analysis shows that such observables are sensitive to the tail of the ground-state wavefunction. The presence of excited state decreases the breakup strength, and this flux is transferred to the inelastic-scattering channel. This indicates a conservation of the flux within each partial wave. We also show that the parallel-momentum distributions are insensitive to the existence of resonances within the continuum, they can thus be ignored in practice. This independence on the continuum argues that the parallel-momentum distributions are ideal observables to extract very precisely the ANCs of halo nuclei.
Comments:
6 pages, 3 figures, INPC 2019 proceedings
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1911.01489 [pdf]
J.Phys.Conf.Ser.(2020)·2 citations
02
[Submitted on 1 Nov 2019] (cross-list from cond-mat.quant-gas)
Ground-state phase diagram and excitation spectrum of a Bose-Einstein condensate with spin-orbital-angular-momentum coupling
Ke-Ji Chen · Fan Wu · Jianshen Hu · Lianyi He
We investigate the ground-state phase diagram and excitation spectrum of an interacting spinor Bose-Einstein condensate with spin-orbital-angular-momentum (SOAM) coupling realized in recent experiments by introducing atomic Raman transition with a pair of copropagating Laguerre-Gaussian laser beams that carry different orbital angular momenta (OAM) [Chen et al., Phys. Rev. Lett. 121, 113204 (2018) and Zhang et al., Phys. Rev. Lett. 122, 110402 (2019)]. Because of the ground-state degeneracy of the single-particle Hamiltonian at vanishing detuning, several angular-stripe phases, which are superposition of states with different angular quantum numbers, appear in the phase diagram. However, these phases normally exist at small detuning, which makes them hard to be probed in experiments. We show that for a large OAM difference of the laser beams, an asymmetric kind of angular-stripe phase can exist even at large detuning. The excitation spectra in different phases exhibit distinct features: In the angular-stripe phase there exist two gapless bands corresponding to the broken U(1) and rotational symmetries, while in the half-skyrmion phase the gapless band exhibits a roton-like structure. Our predictions of the angular-stripe phases and the low-energy excitations can be examined in recently realized BECs with SOAM coupling.
Comments:
7 pages, 4 figures
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
1911.00255 [pdf]
PRA(2020)·8 citations
03
[Submitted on 4 Nov 2019] (cross-list from hep-ph)
On the effective theory of neutrino-electron and neutrino-quark interactions
Richard J. Hill🇺🇸 · Oleksandr Tomalak🇺🇸
We determine the four Fermi effective theory of neutrino interactions within the Standard Model including one-loop electroweak radiative corrections, in combination with the measured muon lifetime and precision electroweak data. Including two-loop matching and three-loop running corrections, we determine lepton coefficients accounting for all large logarithms through relative order $O (α α_{s})$ and quark coefficients accounting for all large logarithms through $O (α)$ . We present four-fermion coefficients valid in $n_{f} = 3$ and $n_{f} = 4$ flavor quark theories, as well as in the extreme low-energy limit. We relate the coefficients in this limit to neutrino charge radii governing matter effects via forward neutrino scattering on charged particles.
Comments:
18 pages, 1 figure. v2: journal version; minor corrections, references are added
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1911.01493 [pdf]
PLB(2020)·39 citations
04
[Submitted on 5 Nov 2019] (cross-list from hep-ph)
Initial, effective, and kinetic freeze-out temperatures from transverse momentum spectra in high energy proton(deuteron)-nucleus and nucleus-nucleus collisions
Muhammad Waqas🇨🇳 · Fu-Hu Liu🇨🇳
The transverse momentum spectra of charged particles produced in proton(deuteron)-nucleus and nucleus-nucleus collisions at high energies are analyzed by the Hagedorn thermal model and the standard distribution in terms of multi-component. The experimental data measured in central and peripheral gold-gold (Au-Au) and deuteron-gold ( $d$ -Au) collisions by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC), as well as in central and peripheral lead-lead (Pb-Pb) and proton-lead ( $p$ -Pb) collisions by the ALICE Collaboration at the Large Hadron Collider (LHC) are fitted by the two models. The initial, effective, and kinetic freeze-out temperatures are then extracted from the fitting to the transverse momentum spectra. It is shown that the initial temperature is larger than the effective temperature, and the effective temperature is larger than the kinetic freeze-out temperature. The three types of temperatures in central collisions are comparable with those in peripheral collisions, and those at the LHC are comparable with those at the RHIC.
Comments:
17 pages, 8 figures. The European Physical Journal Plus, accepted
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1911.01709 [pdf]
Eur.Phys.J.Plus(2020)·44 citations
05
[Submitted on 5 Nov 2019] (cross-list from nucl-ex)
Search for the $N$ (1685) in $η π$ -Photoproduction
Dominik Werthmüller🇬🇧
The nucleon-like member $N (1685)$ of the speculative baryon antidecuplet denotes one possible explanation for the narrow peak-structure around $W = 1.68$ GeV observed in the total cross section of $η$ -photoproduction off the neutron. If this baryon existed, it would likely to be seen in other reactions as well. While the aforementioned peak, whatever its nature is, was confirmed by several experiments, claims for signatures of the $N (1685)$ in other reactions and observables are mainly made by V. Kuznetsov et al. using GRAAL data. Their latest work suggests signals of both $N (1685)$ charge states in all isospin channels of $η π$ -photoproduction off the proton and neutron. This contribution reports on challenging these claims with data from the A2 at MAMI experiment employing photon beam energies from $E_{γ}$ =1.43-1.58 GeV. The $η π^{0} p$ and $η π^{+} n$ final states produced from a hydrogen target were studied and new analysis cuts were tested in order to enhance a possible signal.
Comments:
Contribution to the proceedings of the 12th International Workshop on the Physics of Excited Nucleons - NSTAR2019, June 10-14, 2019, Bonn, Germany, updated with referee comments
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1911.01754 [pdf]
EPJ Web Conf.(2020)·1 citation
06
[Submitted on 31 Oct 2019] (cross-list from gr-qc)
Variational formulation of compressible hydrodynamics in curved spacetime and symmetry of stress tensor
T. Koide🇧🇷 · T. Kodama🇧🇷
Hydrodynamics of the non-relativistic compressible fluid in the curved spacetime is derived using the generalized framework of the stochastic variational method (SVM) for continuum medium. The fluid-stress tensor of the resultant equation becomes asymmetric for the exchange of the indices, differently from the standard Euclidean one. Its incompressible limit suggests that the viscous term should be represented with the Bochner Laplacian. Moreover the modified Navier-Stokes-Fourier (NSF) equation proposed by Brenner can be considered even in the curved spacetime. To confirm the compatibility with the symmetry principle, SVM is applied to the gauge-invariant Lagrangian of a charged compressible fluid and then the Lorentz force is reproduced as the interaction between the Abelian gauge fields and the viscous charged fluid.
Comments:
23 pages, no figure, discussions, comments and references are added
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
arXiv:
1911.01798 [pdf]
J.Phys.A(2020)·7 citations
07
[Submitted on 2 Nov 2019] (cross-list from physics.data-an)
Unrecognized Sources of Uncertainties (USU) in Experimental Nuclear Data
R. Capote🇦🇹 · S. Badikov · A. Carlson🇺🇸 · I. Duran🇪🇸 · F. Gunsing🇫🇷 · D. Neudecker🇺🇸 · V.G. Pronyaev🇦🇹 · P. Schillebeeckx🇧🇪 · G. Schnabel🇸🇪 · D.L. Smith🇺🇸 · A. Wallner🇦🇺
Evaluated nuclear data uncertainties are often perceived as unrealistic, most often because they are thought to be too small. The impact of this issue in applied nuclear science has been discussed widely in recent years. Commonly suggested causes are: poor estimates of specific error components, neglect of uncertainty correlations, and overlooked known error sources. However, instances have been reported where very careful, objective assessments of all known error sources have been made with realistic error magnitudes and correlations provided, yet the resulting evaluated uncertainties still appear to be inconsistent with observed scatter of predicted mean values. These discrepancies might be attributed to significant unrecognized sources of uncertainty (USU) that limit the accuracy to which these physical quantities can be determined. The objective of our work has been to develop procedures for revealing and including USU estimates in nuclear data evaluations involving experimental input data. We conclude that the presence of USU may be revealed, and estimates of magnitudes made, through quantitative analyses. This paper identifies several specific clues that can be explored by evaluators in identifying the existence of USU. It then describes numerical procedures to generate quantitative estimates of USU magnitudes. Key requirements for these procedures to be viable are that sufficient numbers of data points be available, for statistical reasons, and that additional supporting information about the measurements be provided by the experimenters. Realistic examples are described to illustrate these procedures and demonstrate their outcomes as well as limitations. Our work strongly supports the view that USU is an important issue in nuclear data evaluation, with significant consequences for applications, and that this topic warrants further investigation by the nuclear science community.
Comments:
39 pages, 16 figures, submitted to Nuclear Data Sheets
Subjects:
Data Analysis, Statistics and Probability (physics.data-an); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1911.01825 [pdf]
Nucl.Data Sheets(2020)·22 citations
08
[Submitted on 5 Nov 2019] (cross-list from astro-ph.HE)
Propagation of Electromagnetic Waves in Neutron Star
Sania Saleem · Saeeda Sajjad · Samina Masood
Propagation properties of electromagnetic (EM) waves in the dense medium of neutron star are studied. It is pointed out that EM waves develop a longitudinal component when they propagate in such a dense medium. Renormalization scheme of quantum electrodynamics (QED) is used to investigate the behavior of EM waves in transverse and longitudinal directions. Medium response to EM waves indicates that the electromagnetic properties of the dense material are modified as a result of the interaction of EM waves with the matter. Using QED, expressions for the electromagnetic properties such as electric permittivity, magnetic permeability and the refractive index of dense matter are obtained. The results are applied to a particular star for illustration.
Comments:
5 pages and 6 figures submitted to Journal of Space Technology
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1911.01980 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE