Nuclear Theory·nucl-th

Monday·June 29, 2015

8 papers—6 primary·2 cross-listed

01
Electromagnetic modulation of monochromatic neutrino beams
A. L. Barabanov🇷🇺 · O. A. Titov🇷🇺
A possibility to produce a modulated monochromatic neutrino beam is discussed. Monochromatic neutrinos can be obtained in electron capture by nuclei of atoms or ions, in particular, by nuclei of hydrogen-like ions. It is shown that monochromatic neutrino beam from such hydrogen-like ions with nuclei of non-zero spin can be modulated because of different probabilities of electron capture from hyperfine states. Modulation arises by means of inducing of electromagnetic transitions between the hyperfine states. Requirements for the hydrogen-like ions with necessary properties are discussed. A list of the appropriate nuclei for such ions is presented.
nucl-thhep-phnucl-exEPJA(2015)·5 citations
02
8li(n,g)9li reaction at superlow energies
S. B. Dubovichenko · A. V. Dzhazairov-Kakhramanov
Within the framework of the modified potential cluster model with the state classification of nuclear particles according to Young tableaux the possibility of describing the available experimental data for the total cross sections of the neutron radiative capture on 8Li at thermal and astrophysical energies was considered.
nucl-thApJ(2016)·20 citations
03
A Universal Damping Mechanism of Quantum Vibrations in Deep Sub-Barrier Fusion Reactions
Takatoshi Ichikawa · Kenichi Matsuyanagi
We demonstrate the damping of quantum octupole vibrations near the touching point when two colliding nuclei approach each other in the mass-asymmetric $^{208}$ Pb + $^{16}$ O system, for which the strong fusion hindrance was clearly observed. We, for the first time, apply the random-phase approximation method to the heavy-mass asymmetric di-nuclear system to calculate the transition strength $B$ (E3) as a function of the center-of-mass distance. The obtained $B$ (E3) strengths are substantially damped near the touching point, because the single-particle wave functions of the two nuclei strongly mix with each other and a neck is formed. The energy-weighted sums of $B$ (E3) are also strongly correlated with the damping factor which is phenomenologically introduced in the standard coupled-channel calculations to reproduce the fusion hindrance. This strongly indicates that the damping of the quantum vibrations universally occurs in the deep sub-barrier fusion reactions.
nucl-thPRC(2015)·19 citations
04
Improved parametrization of the unified model for alpha decay and alpha capture
V. Yu. Denisov · O. I. Davidovskaya · I. Yu. Sedykh
The updated data for the ground-state-to-ground-state alpha-transition half-lives in 401 nuclei and the alpha capture cross sections of 40Ca, 44Ca, 59Co, 208Pb and 209Bi are well described in the framework of the unified model for alpha-decay and alpha-capture. The updated values of the alpha decay half-lives, the binding energies of nuclei, the spins of parent and daughter nuclei, and the surface deformation parameters are used for the reevaluation of the model parameters. The data for the ground-state-to-ground-state alpha-decay half-lives are also well described by the empirical relationships.
nucl-thPRC(2015)·96 citations
05
Probing the neutron-skin thickness by photon production from reactions induced by intermediate-energy protons
Gao-Feng Wei🇨🇳
Photon from neutron-proton bremsstrahlung in p+Pb reactions is examined as a potential probe of the neutron-skin thickness in different centralities and at different proton incident energies. It is shown that the best choice of reaction environment is about 140MeV for the incident proton and the 95\%-100\% centrality for the reaction system since the incident proton mainly interacts with neutrons inside the skin of the target and thus leads to different photon production to maximal extent. Moreover, considering two main uncertainties from both photon production probability and nucleon-nucleon cross section in the reaction, I propose to use the ratio of photon production from two reactions to measure the neutron-skin thickness because of its cancellation effects on these uncertainties simultaneously, but the preserved about 13\%-15\% sensitivities on the varied neutron-skin thickness from 0.1 to 0.3fm within the current experimental uncertainty range of the neutron-skin size in $^{208}$ Pb.
nucl-thPRC(2015)·8 citations
06
Origin of the structures observed in $e^{+} e^{-}$ annihilation into multipion states around the $p ˉ p$ threshold
Johann Haidenbauer🇩🇪 · Christoph Hanhart🇩🇪 · Xian-Wei Kang🇩🇪 · Ulf-G. Meißner🇩🇪
We analyze the origin of the structures observed in the reactions $e^{+} e^{-} \to 3 (π^{+} π^{-})$ , $2 (π^{+} π^{-} π^{0})$ , $ω π^{+} π^{-} π^{0}$ , and $e^{+} e^{-} \to 2 (π^{+} π^{-}) π^{0}$ around the antiproton-proton ( $p ˉ p$ ) threshold. We calculate the contribution of the two-step process $e^{+} e^{-} \to N ˉ N \to$ multipions to the total reaction amplitude. The amplitude for $e^{+} e^{-} \to N ˉ N$ is constrained from near-threshold data on the $e^{+} e^{-} \to p ˉ p$ cross section and the one for $N ˉ N \to$ multipions can be likewise fixed from available experimental information, for all those $5 π$ and $6 π$ states. The resulting amplitude for $e^{+} e^{-} \to$ multipions turns out to be large enough to play a role for the considered $e^{+} e^{-}$ annihilation channels and, in three of the four reactions, even allows us to reproduce the data quantitatively near the $N ˉ N$ threshold. The structures seen in the experiments emerges then as a threshold effect due to the opening of the $N ˉ N$ channel.
nucl-thPRD(2015)·43 citations
07
Heavy quarkonia in strong magnetic fields
Claudio Bonati🇮🇹 · Massimo D'Elia🇮🇹 · Andrea Rucci🇮🇹
We investigate the influence of a homogeneus and constant strong external magnetic field on the heavy-meson spectrum. Quarkonium states $c c ˉ$ and $b b ˉ$ are described within a non-relativistic framework and by means of a suitable potential model based on the Cornell parametrization. In particular, in this work we propose a model which takes into account the possible anisotropies emerging at the level of the static quark-antiquark potential, as observed in recent lattice studies. The investigation is perfomed both with and without taking into account the anisotropy of the static potential, in order to better clarify its effects
↳ hep-phhep-latnucl-thPRD(2015)·98 citations
08
Extended Goldberger-Treiman relation obtained in a three-flavor parity doublet model
Hiroki Nishihara🇯🇵 · Masayasu Harada🇯🇵
We study masses and decay widths of positive and negative parity nucleons using a three-flavor parity doublet model, in which we introduce three representations, $[(3, 3 ˉ) \oplus (3 ˉ, 3)]$ , $[(3, 6) \oplus (6, 3)]$ , and $[(8, 1) \oplus (1, 8)]$ of the chiral U $(3)_{L} \times$ U $(3)_{R}$ symmetry. We find an extended version of the Goldberger-Treiman relation among the mass differences and the coupling constants for pionic transitions. This relation leads to an upper bound for the decay width of $N (1440) \to N (939) + π$ independently of the model parameters. We perform the numerical fitting of the model parameters and derive several predictions, which can be tested in future experiments or lattice QCD analysis. Furthermore, when we use the axial coupling of the excited nucleons obtained from lattice QCD analyses as inputs, we find that the ground state nucleon $N (939)$ consists of about 80% of $[(3, 6) \oplus (6, 3)]$ component, and that the chiral invariant mass of $N (939)$ is roughly $500$ -- $800$ MeV.
↳ hep-phnucl-thPRD(2015)·28 citations

Affiliations

first authorsco-authorsvia INSPIRE