Nuclear Theory·nucl-th

Thursday·September 14, 2017

10 papers—5 primary·5 cross-listed

01
[Submitted on 12 Sept 2017]
RAINIER: A Simulation Tool for Distributions of Excited Nuclear States and Cascade Fluctuations
L. E. Kirsch · L. A. Bernstein
A new code has been developed named RAINIER that simulates the $γ$ -ray decay of discrete and quasi-continuum nuclear levels for a user-specified range of energy, angular momentum, and parity including a realistic treatment of level spacing and transition width fluctuations. A similar program, DICEBOX, uses the Monte Carlo method to simulate level and width fluctuations but is restricted to $γ$ -ray decay from no more than two initial states such as de-excitation following thermal neutron capture. On the other hand, modern reaction codes such as TALYS and EMPIRE populate a wide range of states in the residual nucleus prior to $γ$ -ray decay, but do not go beyond the use of deterministic functions and therefore neglect cascade fluctuations. This combination of capabilities allows RAINIER to be used to determine quasi-continuum properties through comparison with experimental data. Several examples are given that demonstrate how cascade fluctuations influence experimental high-resolution $γ$ -ray spectra from reactions that populate a wide range of initial states.
Comments:
14 pages, 13 figures, Nuclear Instrumentation and Methods A, 2017
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1709.04006 [pdf]
Nucl.Instrum.Meth.A(2018)·22 citations
02
[Submitted on 12 Sept 2017]
Projection of angular momentum via linear algebra
Calvin W. Johnson · Kevin D. O'Mara
Projection of many-body states with good angular momentum from an initial state is usually accomplished by a three-dimensional integral. We show how projection can instead be done by solving a straightforward system of linear equations. We demonstrate the method and give sample applications to $^{48}$ Cr and $^{60}$ Fe in the $p f$ shell. This new projection scheme, which is competitive against the standard numerical quadrature, should also be applicable to other quantum numbers such as isospin and particle number.
Comments:
14 pages, 2 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
1709.04028 [pdf]
PRC(2017)·23 citations
03
[Submitted on 13 Sept 2017]
Algebraic diagrammatic construction formalism with three-body interactions
Francesco Raimondi · Carlo Barbieri
Self-consistent Green's function theory has recently been extended to the basic formalism needed to account for three-body interactions [A. Carbone, A. Cipollone, C. Barbieri, A. Rios, and A. Polls, (Phys. Rev. C 88, 054326 (2013))]. The contribution of three-nucleon forces has so far been included in ab initio calculations on nuclear matter and finite nuclei only as averaged two-nucleon forces. We derive the working equations for all possible two- and three-nucleon terms that enter the expansion of the self-energy up to the third order, thus including the interaction-irreducible (i.e., not averaged) diagrams with three-nucleon forces that have been previously neglected. We employ the algebraic diagrammatic construction up to the third order as an organization scheme for generating a non perturbative self-energy, in which ring (particle-hole) and ladder (particle-particle) diagrams are resummed to all orders. We derive expressions of the static and dynamic self-energy up to the third order, by taking into account the set of diagrams required when either the skeleton or nonskeleton expansions of the single-particle propagator are assumed. A hierarchy of importance among different diagrams is revealed, and a particular emphasis is given to a third-order diagram (see Fig. 2c) that is expected to play a significant role among those featuring an interaction-irreducible three-nucleon force. A consistent formalism to resum at infinite order correlations induced by three-nucleon forces in the self-consistent Green's function theory is now available and ready to be implemented in the many-body solvers.
Comments:
35 pages, 15 figures (significant changes to the text and corrected typos in the text and equations)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1709.04330 [pdf]
PRC(2018)·37 citations
04
[Submitted on 13 Sept 2017]
Towards microscopic studies of survival probabilities of compound superheavy nuclei
Yi Zhu · Junchen Pei
The microscopic approach of fission rates and neutron emission rates in compound nuclei have been applied to $^{258}$ No and $^{286}$ Cn. The microscopic framework is based on the finite-temperature Skyrme-Hartree-Fock+BCS calculations, in which the fission barriers and mass parameters are self-consistently temperature dependent. The fission rates from low to high temperatures can be obtained based on the imaginary free energy method. The neutron emission rates are obtained with neutron gases at surfaces. Finally the survival probabilities of superheavy nuclei can be calculated microscopically. The microscopic approach has been compared with the widely used statistical models. Generally, there are still large uncertainties in descriptions of fission rates.
Comments:
9 pages,7 figures, accepted for Physica Scripta Special Issue
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1709.04350 [pdf]
Phys.Scripta(2017)·4 citations
05
[Submitted on 12 Sept 2017]
Distillation of scalar exchange by coherent hypernucleus production in antiproton-nucleus collisions
A.B. Larionov🇩🇪 · H. Lenske🇩🇪
The total and angular differential cross sections of the coherent process $p ˉ +^{A} Z \to_{Λ}^{A} (Z - 1) + Λ ˉ$ are evaluated at the beam momenta $1.5 \div 20$ GeV/c within the meson exchange model with bound proton and $Λ$ -hyperon wave functions. It is shown that the shape of the beam momentum dependence of the hypernucleus production cross sections with various discrete $Λ$ states is strongly sensitive to the presence of the scalar $κ$ -meson exchange in the $p ˉ p \to Λ ˉ Λ$ amplitude. This can be used as a clean test of the exchange by scalar $π K$ correlation in coherent $p ˉ A$ reactions.
Comments:
12 pages, 6 figures, accepted in Phys. Lett. B. arXiv admin note: substantial text overlap with arXiv:1703.02073
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1709.04370 [pdf]
PLB(2017)·6 citations
06
[Submitted on 13 Sept 2017] (cross-list from hep-ph)
Prompt photon production and photon-jet correlations at the LHC
M. Klasen🇩🇪 · C. Klein-Bösing🇩🇪 · H. Poppenborg🇩🇪
Next-to-leading order predictions matched to parton showers are compared with recent ATLAS data on inclusive photon production and CMS data on associated photon and jet production in pp and pPb collisions at different centre-of-mass energies of the LHC. We find good agreement and, as expected, considerably reduced scale uncertainties compared to previous theoretical calculations. Predictions are made for the ratio of inclusive photons over decay photons $R_{γ}$ , an important quantity to evaluate the significance of additional photon sources, e.g. thermal radiation from a Quark-Gluon-Plasma, and for distributions in the parton momentum fraction in lead ions $x_{Pb}^{obs}$ , that could be determined by ALICE, ATLAS, CMS and LHCb in ongoing analyses of photon+jet production in pPb collisions at $s_{N N} = 5.02$ TeV. These data should have an important impact on the determination of nuclear effects such as shadowing at low $x$ .
Comments:
20 pages, 13 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1709.04154 [pdf]
JHEP(2018)·33 citations
07
[Submitted on 13 Sept 2017] (cross-list from astro-ph.SR)
Thermonuclear $^{19}$ F( $p$ , $α_{0}$ ) $^{16}$ O reaction rate
J.J. He · I. Lombardo · D. Dell'Aquila · Y. Xu · L.Y. Zhang · W.P. Liu
The thermonuclear $^{19}$ F( $p$ , $α_{0}$ ) $^{16}$ O reaction rate in a temperature region of 0.007--10 GK has been derived by re-evaluating the available experimental data, together with the low-energy theoretical $R$ -matrix extrapolations. Our new rate deviates up to about 30\% compared to the previous ones, although all rates are consistent within the uncertainties. At very low temperature (e.g. 0.01 GK) our reaction rate is about 20\% smaller than the most recently published rate, because of a difference in the low energy extrapolated $S$ -factor and a more accurate estimate of the reduced mass entering in the calculation of the reaction rate. At temperatures above $\sim$ 1 GK, our rate is smaller, for instance, by about 20\% around 1.75 GK, because we have re-evaluated in a meticulous way the previous data (Isoya et al., Nucl. Phys. 7, 116 (1958)). The present interpretation is supported by the direct experimental data. The uncertainties of the present evaluated rate are estimated to be about 20\% in the temperature region below 0.2 GK, which are mainly caused by the lack of low-energy experimental data and the large uncertainties of the existing data. The asymptotic giant branch (AGB) star evolves at temperatures below 0.2 GK, where the $^{19}$ F( $p$ , $α$ ) $^{16}$ O reaction may play a very important role. However, the current accuracy of the reaction rate is insufficient to help to describe, in a careful way, for the fluorine overabundances phenomenon observed in AGB stars. Precise cross section (or $S$ factor) data in the low energy region are therefore mandatory for astrophysical nucleosynthesis studies.
Comments:
11 pages, 13 figures
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1709.04170 [pdf]
CPC(2018)·27 citations
08
[Submitted on 13 Sept 2017] (cross-list from hep-ph)
Strong and radiative decays of the low-lying $S$ - and $P$ -wave singly heavy baryons
Kai-Lei Wang🇨🇳 · Ya-Xiong Yao🇨🇳 · Xian-Hui Zhong🇨🇳 · Qiang Zhao🇨🇳
The strong and radiative decays of the low-lying $S$ - and $P$ -wave $Λ_{c (b)}$ , $Σ_{c (b)}$ , $Ξ_{c (b)}$ , $Ξ_{c (b)}^{'}$ and $Ω_{c (b)}$ baryons are systematically studied in a constituent quark model. We find that the radiative decay mode $Λ_{b}^{0} γ$ could be very useful for us to establish the missing neutral states $Σ_{b}^{0}$ and $Σ_{b}^{* 0}$ . Our calculation shows that most of those missing $λ$ -mode $P$ -wave singly heavy baryons have relatively narrow decay width of less than 30 MeV. Their dominant strong and radiative decay channels can be ideal for searching for their signals in future experiment. Configuration mixings between the $J^{P} = 1/ 2^{-}$ states $∣^{2} P_{λ} \frac{1}{2}^{-} ⟩$ and $∣^{4} P_{λ} \frac{1}{2}^{-} ⟩$ of the $6_{F}$ multiplet are discussed. The $Ξ_{c} (2930)^{0}$ state seems to favor the mixed state $∣ Ξ_{c}^{'} P_{λ} \frac{1}{2}^{-} ⟩_{2}$ with $J^{P} = 1/ 2^{-}$ . The $Σ_{c} (2800)$ resonance may be assigned to $∣ Σ_{c}^{2} P_{λ} \frac{3}{2}^{-} ⟩$ with $J^{P} = 3/ 2^{-}$ or $∣ Σ_{c}^{4} P_{λ} \frac{5}{2}^{-} ⟩$ with $J^{P} = 5/ 2^{-}$ . In general, the excitations of $∣^{2} P_{λ} \frac{3}{2}^{-} ⟩$ and $∣^{4} P_{λ} \frac{5}{2}^{-} ⟩$ of the $6_{F}$ multiplet have similar strong decay properties. In order to to identify them, angular distributions of their decays in either strong decay modes or radiative transitions should be needed.
Comments:
19 pages, 8 figures, 10 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1709.04268 [pdf]
PRD(2017)·146 citations
09
[Submitted on 13 Sept 2017] (cross-list from physics.atom-ph)
Laser-induced electronic bridge for characterization of the $^{229 m} Th \to^{229 g} Th$ nuclear transition with a tunable optical laser
Pavlo V. Bilous · Ekkehard Peik · Adriana Pálffy
An alternative method to determine the excitation energy of the $^{229 m} Th$ isomer via the laser-induced electronic bridge is investigated theoretically. In the presence of an optical or ultra-violet laser at energies that fulfill a two-photon resonance condition, the excited nuclear state can decay by transfering its energy to the electronic shell. A bound electron is then promoted to an excited state by absorption of a laser photon and simultaneous de-excitation of the nucleus. We present calculated rates for the laser-induced electronic bridge process and discuss the experimental requirements for the corresponding setup. Our results show that depending on the actual value of the nuclear transition energy, the rate can be very high, with an enhancement factor compared to the radiative nuclear decay of up to $1 0^{8}$ .
Comments:
11 pages, 3 figures, 4 tables
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th)
arXiv:
1709.04364 [pdf]
New J.Phys.(2018)·19 citations
10
[Submitted on 13 Sept 2017] (cross-list from hep-ph)
Criticality in a Hadron Resonance Gas model with the van der Waals interaction
Subhasis Samanta🇮🇳 · Bedangadas Mohanty🇮🇳
The van der Waals interaction is implemented in a Hadron Resonance Gas model. It is shown that this model can describe Lattice QCD data of different thermodynamical quantities satisfactorily with the van der Waals parameters $a = 1250 \pm 150$ MeV fm $^{3}$ and $r = 0.7 \pm 0.05$ fm. Further, a phase transition is observed in this model with the critical point at temperature, $T = 62.1$ MeV and baryon chemical potential, $μ_{B} = 708$ MeV.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1709.04446 [pdf]
PRC(2018)·52 citations

Affiliations

first authorsco-authorsvia INSPIRE