Nuclear Theory·nucl-th

Thursday·April 28, 2016

8 papers—5 primary·3 cross-listed

01
Delta(1232) contribution to real photon radiative corrections for elastic electron-proton scattering
R. E. Gerasimov🇷🇺 · V. S. Fadin🇷🇺
Here we consider a contribution of Delta(1232) resonance to real photon radiative corrections for elastic $e p$ -scattering. The effect is found to be small for past experiments to study unpolarized cross section as well as for the recent VEPP-3 experiment to investigate two-photon exchange effects by precision measurement of $e^{\pm} p$ -scattering cross sections ratio.
nucl-thhep-phJ.Phys.G(2016)·15 citations
02
Thermodynamic Properties of a Nucleon under the Generalized Symmetric Woods-Saxon Potential in Flourine 17 Isotope
B.C. Lütfüoğlu · M. Erdogan
The exact analytical solution of the Schrödinger equation for a generalized symmetrical Woods-Saxon potential are examined for a nucleon in Fluorine 17 nucleus for bound and quasi-bound states in one dimension. The wave functions imply that the nucleon is completely confined within the nucleus, i.e., no decay probability for bound states, while tunneling probabilities arise for the quasi-bound state. We have calculated the temperature dependent Helmholtz free energies, the internal energies, the entropies and the specific heat capacities of the system. It is shown that, when the quasi-bound state is included, the internal energy and entropy increase, while the Helmholtz energy decreases at high temperatures. Very high excitation temperatures imply that the nucleus does not tend to release a nucleon. The calculated quasi bound state energy is in reasonable agreement with the experimental data on the cumulative fission energy issued by IAEA.
nucl-thANADOLU UNIVERSITY JOURNAL OF SCIENCE AND…·1 citation
03
Physical and unphysical solutions of random-phase approximation equation
H. Nakada
Properties of solutions of the RPA equation is reanalyzed mathematically, which is defined as a generalized eigenvalue problem of the stability matrix $S$ with the norm matrix $N = diag. (1, - 1)$ . As well as physical solutions, unphysical solutions are examined in detail, with taking the possibility of Jordan blocks of the matrix $N S$ into consideration. Two types of duality of eigenvectors and basis vectors of the Jordan blocks are pointed out and explored, which disclose many basic properties of the RPA solutions.
nucl-thquant-phPTEP(2016)·8 citations
04
Shell structure from nuclear observables
I. Bentley · Y. Colon Rodrıguez · S. Cunningham · A. Aprahamian
The appearance and disappearance of shells and subshells are determined using a previously introduced method of structural analysis. This work extends the approach and applies it to protons, in addition to neutrons, in an attempt to provide a more complete understanding of shell structure in nuclei. Experimental observables including the mean-square charge radius, as well as other spectroscopic and mass related quantities are analyzed for extrema. This analysis also uses differential observables among adjacent even-even nuclei to serve as the derivatives for these quantities of interest. Local extrema in these quantities indicate shell structure and the lack of local extrema indicate missing shell closures. The shell structure of low-mass nuclei is inconsistent likely as a consequence of the single-particle structure. Additionally, multiple shell features occurring in midshell regions are determined by combining information from two or more observables. Our results near stability complement previous observations further out.
nucl-thPRC(2016)·13 citations
05
Nuclear Matrix Elements for Tests of Local Lorentz Invariance Violation
B. A. Brown🇺🇸 · G. F. Bertsch🇺🇸 · L. M. Robledo🇪🇸 · M. V. Romalis🇺🇸 · V. Zelevinsky🇺🇸
The nuclear matrix elements for the momentum quadrupole operator are important for the interpretation of precision atomic physics experiments that search for violations of local Lorentz and CPT symmetry and for new spin-dependent forces. We use the configuration-interaction nuclear shell model and self-consistent mean field theory to calculate these matrix elements in $^{21}$ Ne, $^{23}$ Na, $^{131}$ Xe, $^{173}$ Yb and $^{201}$ Hg. These are the first microscopic calculations of the nuclear matrix elements for the momentum quadrupole tensor that go beyond the single-particle estimate. We show that they are strongly suppressed by the many-body correlations, in contrast to the well known enhancement of the spatial quadrupole nuclear matrix elements.
nucl-thPRL(2017)·20 citations
06
Protophobic Fifth Force Interpretation of the Observed Anomaly in $^{8}$ Be Nuclear Transitions
Jonathan L. Feng🇺🇸 · Bartosz Fornal🇺🇸 · Iftah Galon🇺🇸 · Susan Gardner🇺🇸 · Jordan Smolinsky🇺🇸 · Tim M. P. Tait🇺🇸 · Philip Tanedo🇺🇸
Recently a 6.8 $σ$ anomaly has been reported in the opening angle and invariant mass distributions of $e^{+} e^{-}$ pairs produced in $^{8} Be$ nuclear transitions. The data are explained by a 17 MeV vector gauge boson $X$ that is produced in the decay of an excited state to the ground state, $^{8} Be^{*} \to^{8} Be X$ , and then decays through $X \to e^{+} e^{-}$ . The $X$ boson mediates a fifth force with a characteristic range of 12 fm and has milli-charged couplings to up and down quarks and electrons, and a proton coupling that is suppressed relative to neutrons. The protophobic $X$ boson may also alleviate the current 3.6 $σ$ discrepancy between the predicted and measured values of the muon's anomalous magnetic moment.
↳ hep-phhep-exnucl-exnucl-thPRL(2016)·301 citations
07
Helicity and nuclear $β$ decay correlations
Ran Hong🇺🇸 · Matthew G. Sternberg🇺🇸 · Alejandro García🇺🇸
We present simple derivations of nuclear $β$ -decay correlations with an emphasis on the special role of helicity. This provides a good opportunity to teach students about helicity and chirality in particle physics through exercises using simple aspects of quantum mechanics. In addition, this paper serves as an introduction to nuclear $β$ -decay correlations from both a theoretical and experimental vantage. This article can be used to introduce students to ongoing experiments searching for hints of new physics in the low-energy precision frontier.
↳ physics.ed-phnucl-thAm.J.Phys.(2017)·6 citations
08
An implementation of hybrid parallel CUDA code for the hyperonic nuclear forces
Hidekatsu Nemura · for HAL QCD Collaboration
We present our recent effort to develop a GPGPU program to calculate 52 channels of the Nambu-Bethe-Salpeter (NBS) wave functions in order to study the baryon interactions, from nucleon-nucleon to $Ξ - Ξ$ , from lattice QCD. We adopt CUDA programming to perform the multi-GPU execution on a hybrid parallel programming with MPI and OpenMP. Effective baryon block algorithm is briefly outlined, which calculates efficaciously a large number of NBS wave functions at a time, and three CUDA kernel programs are implemented to materialize the effective baryon block algorithm using GPUs on the single-program multiple-data (SPMD) programming model. In order to parallelize multiple GPUs, we take both two approaches by dividing the time dimension and by dividing the spatial dimensions. Performances are measured using HA-PACS supercomputer in University of Tsukuba, which includes NVIDIA M2090 and NVIDIA K20X GPUs. Strong scaling and weak scaling measured by using both M2090 and K20X GPUs are presented. We find distinct difference between the M2090 and the K20X in the sustained performance measurement of particular kernel executions which utilize the cudaStream objects.
↳ hep-latnucl-thPoS(2016)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE