Nuclear Theory·nucl-th

Monday·June 26, 2017

10 papers—4 primary·6 cross-listed

01
[Submitted on 22 Jun 2017]
Spin-flip doublets of $^{9}$ Be spectrum within a cluster model
I. Filikhin🇺🇸 · V. M. Suslov🇺🇸 · B. Vlahovic🇺🇸
The structure of the $^{9}$ Be low-lying spectrum is studied within the cluster model $α + α + n$ . In the model the total orbital momentum is fixed for each energy level. Thus each level is determined as a member of the spin-flip doublet corresponding to the total orbital momentum ( $L^{π} = 0^{+}, 2^{+}, 4^{+}, 1^{-}, 2^{-}, 3^{-}, 4^{-}$ ) of the system. The Ali-Bodmer potential (model E) is applied for the $α α$ interaction. We employ a local $α n$ potential which was constructed to reproduce the $α - n$ scattering data. The Pauli blocking is simulated by the repulsive core of the $s$ -wave components of these potentials. Configuration space Faddeev equations are used to calculate the energy of the bound state ( $E_{c a l .}$ =-1.493 MeV v.s. $E_{e x p .}$ =-1.5735 MeV) and resonances. A variant of the method of analytical continuation in the coupling constant is applied to calculate the energies of low-lying levels. Available $^{9}$ Be spectral data are satisfactorily reproduced by the proposed model.
Comments:
17 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1706.07481 [pdf]
FIZIKA B (Zagreb) 20 (2011) 3, 189-202·0 citations
02
[Submitted on 22 Jun 2017]
Estimation of M1 scissors mode strength for deformed nuclei in the medium to heavy mass region by statistical Hauser-Feshbach model calculations
M. R. Mumpower · T. Kawano · J. L. Ullmann · M. Krtička · T. M. Sprouse
Radiative neutron capture is an important nuclear reaction whose accurate description is needed for many applications ranging from nuclear technology to nuclear astrophysics. The description of such a process relies on the Hauser-Feshbach theory which requires the nuclear optical potential, level density and $γ$ -strength function as model inputs. It has recently been suggested that the M1 scissors mode may explain discrepancies between theoretical calculations and evaluated data. We explore statistical model calculations with the strength of the M1 scissors mode estimated to be dependent on the nuclear deformation of the compound system. We show that the form of the M1 scissors mode improves the theoretical description of evaluated data and the match to experiment in both the fission product and actinide regions. Since the scissors mode occurs in the range of a few keV $\sim$ a few MeV, it may also impact the neutron capture cross sections of neutron-rich nuclei that participate in the rapid neutron capture process of nucleosynthesis. We comment on the possible impact to nucleosynthesis by evaluating neutron capture rates for neutron-rich nuclei with the M1 scissors mode active.
Comments:
11 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1706.07504 [pdf]
PRC(2017)·54 citations
03
[Submitted on 23 Jun 2017]
Solving the $q^$ puzzle with $x$ and scale dependence
Amit Kumar🇺🇸 · Evan Bianchi🇺🇸 · Jacob Elledge🇺🇸 · Abhijit Majumder🇺🇸 · Guang-You Qin🇺🇸 · Chun Shen🇺🇸
We present here a possible resolution of the jet quenching parameter $q^$ puzzle by exploring the momentum fraction $x$ and scale $Q^{2}$ dependence of $q^$ , in addition to temperature dependence. We explore the momentum broadening of the jet due to Glauber gluon exchange with the quark-gluon plasma (QGP). This has led us to define the momentum fraction $x$ for the partons in the QGP. We also show here, for the first time, possible forms of the parton distribution function (PDF) of the QGP. The QGP-PDF as input in $q^$ has been used to fit the PHENIX and CMS data simultaneously. We observe that the scale evolution of the QGP-PDF and the energy of the jet are the missing ingredients responsible for the enhancement of $q^$ at the same temperature in RHIC collisions compared to LHC collisions.
Comments:
4 pages, 8 figures, talk at conference Quark-Matter 2017
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1706.07547 [pdf]
NPA(2017)·12 citations
04
[Submitted on 23 Jun 2017]
Quantum Monte Carlo calculations of light nuclei with local chiral two- and three-nucleon interactions
J. E. Lynn🇩🇪 · I. Tews🇺🇸 · J. Carlson🇺🇸 · S. Gandolfi🇺🇸 · A. Gezerlis🇨🇦 · K. E. Schmidt🇺🇸 · A. Schwenk🇩🇪
Local chiral effective field theory interactions have recently been developed and used in the context of quantum Monte Carlo few- and many-body methods for nuclear physics. In this work, we go over detailed features of local chiral nucleon-nucleon interactions and examine their effect on properties of the deuteron, paying special attention to the perturbativeness of the expansion. We then turn to three-nucleon interactions, focusing on operator ambiguities and their interplay with regulator effects. We then discuss the nuclear Green's function Monte Carlo method, going over both wave-function correlations and approximations for the two- and three-body propagators. Following this, we present a range of results on light nuclei: Binding energies and distribution functions are contrasted and compared, starting from several different microscopic interactions.
Comments:
21 pages, 14 figures, published version, Editor's Suggestion
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1706.07668 [pdf]
PRC(2017)·99 citations

Affiliations

first authorsco-authorsvia INSPIRE

Spin-flip doublets of 9Be spectrum within a cluster model

Estimation of M1 scissors mode strength for deformed nuclei in the medium to heavy mass region by statistical Hauser-Feshbach model calculations

Solving the q^​ puzzle with x and scale dependence

Quantum Monte Carlo calculations of light nuclei with local chiral two- and three-nucleon interactions

Affiliations

Spin-flip doublets of $^{9}$ Be spectrum within a cluster model

Solving the $q^$ puzzle with $x$ and scale dependence