Bulletin of the American Physical Society
2008 Annual Meeting of the Division of Nuclear Physics
Volume 53, Number 12
Thursday–Sunday, October 23–26, 2008; Oakland, California
Session EB: Nuclear Theory: Few-Body |
Hide Abstracts |
Chair: Bruce Barrett, University of Arizona Room: Room 208 |
Friday, October 24, 2008 4:00PM - 4:12PM |
EB.00001: Separable Expansions of $V_{low}$ for 2- and 3-Nucleon Systems James Shepard, James McNeil We present an alternative organizational scheme for developing effective theories of 2- and 3-body systems that is systematic, accurate, and efficient with controlled errors. To illustrate our approach we consider the bound state and scattering properties of the $^3S_1$ and $^4S_{3/2}$ 2- and 3-nucleon systems. Our approach combines the computational benefits of using separable potentials with the improved convergence properties of potentials evolved with a renormalization group procedure. Long ago Harms showed that any potential can be expanded in a series of separable terms, but this fact is only useful if the expansion can be truncated at low order. The separable expansion provides an attractive organizational scheme that incorporates finite range effects at the outset in contrast to the familiar effective range theory starting with contact interactions. We show that when applied to a renormalization group-evolved potential, the separable expansion converges rapidly, with accurate results for both 2- and 3-body scattering processes using only two separable terms. [Preview Abstract] |
Friday, October 24, 2008 4:12PM - 4:24PM |
EB.00002: Chiral three-nucleon forces at N3LO Ruprecht Machleidt In recent years, there has been substantial progress in the derivation of nuclear forces from chiral effective field theory. Accurate two-nucleon forces (2NF) have been constructed up to next-to-next-to-next-to-leading order (N3LO) and applied with a fair amount of success. However, chiral three-nucleon forces (3NF) have been used only at N2LO, improving some microscopic predictions, but leaving also several issues, like the ``A{\_}y puzzle'', unresolved. Thus, the 3NF at N3LO is needed for essentially two reasons: for consistency with the 2NF and to (hopefully) improve some critical predictions. I will summarize the current status of the derivation of the 3NF at N3LO and discuss the expectations of their impact on ab initio calculations. [Preview Abstract] |
Friday, October 24, 2008 4:24PM - 4:36PM |
EB.00003: ABSTRACT WITHDRAWN |
Friday, October 24, 2008 4:36PM - 4:48PM |
EB.00004: Faddeev and Glauber Calculations at Intermediate Energies in a Model for n+d Scattering Ch. Elster, T. Lin, W. Gloeckle, S. Jeschonnek Faddeev calculations of three-body scattering in the intermediate energy regime are carried out in a model for n+d scattering. In order to go to higher energies, the Faddeev equation is formulated and directly solved without employing a partial wave decomposition, leading to a three-dimensional integral equation in five variables, from which the cross sections for elastic and breakup scattering as well as differential cross sections are obtained. These same observables are calculated based on the Glauber formulation. The first order Glauber calculation and the Glauber rescattering corrections are compared in detail with the corresponding terms in the Faddeev multiple scattering series for projectile energies between 100 MeV and 2 GeV. [Preview Abstract] |
Friday, October 24, 2008 4:48PM - 5:00PM |
EB.00005: The Transverse Electron Scattering Response Function of $^3$He Edward Tomusiak, Sara Della Monaca, Victor Efros, Avas Khugaev, Winfried Leidemann, Giuseppina Orlandini, Luping Yuan The $^3$He transverse response function $R_T(q,\omega)$ is calculated using the Bonn-RA nucleon-nucleon (NN) potential, the TM' three-body force and the Coulomb potential. Complete final state interactions are taken into account via the Lorentz integral transform technique. The electromagnetic interactions include meson exchange currents plus the usual one-body terms. Since the transverse response is driven by nuclear currents it is important to verify that charge conservation is maintained. A measure of this is obtained from a comparison of the response calculated using i) a Siegert form of the transition operator and additional contributions beyond it and ii) an operator expressed totally in terms of currents. Charge conservation requires i) and ii) give identical results. We show that with a simple OBEP NN-interaction with $\pi$- and $\rho$- exchange and its corresponding meson exchange currents the results are indeed the same. The main goal is in fact to study the contributions of meson exchange currents beyond the Siegert operator for various kinematical regions. Theoretical results will be compared to experimental data in quasi-elastic kinematics at $q$=250,400,500 MeV/c and in the threshold region at q=174 MeV/c. [Preview Abstract] |
Friday, October 24, 2008 5:00PM - 5:12PM |
EB.00006: Electromagnetic two-body currents of one- and two- pion range Saori Pastore, Jos\'e Goity, Rocco Schiavilla The nuclear electromagnetic two-body current operator is calculated up to next-to-next-to-leading order in chiral perturbation theory. A number of low-energy electronuclear observables including \textit{np} radiative capture cross section at neutron thermal energies, deuteron magnetic moment and isoscalr and isovector magnetic moments of $^{3}$H and $^{3}$He are calculated. The matrix elements are evaluated using nuclear wave functions obtained from realistic Hamiltonians involving the Argonne $v_{18}$ and CD Bonn two-nucleon and the Urbana IX three-nucleon interactions. [Preview Abstract] |
Friday, October 24, 2008 5:12PM - 5:24PM |
EB.00007: Webb Model of Nuclear Structure and Forces Bill Webb String theory has established that neutrons and protons consist of threesomes of string-like quarks. These threesomes nucleosynthesize to build larger nuclei. This Webb Model differs by postulating that the larger nuclei are also threesomes: threesomes of string-like ring shaped Jumbo Quarks. A threesome of Jumbo Quarks make up every larger nucleus. From this starting point, the Webb Model uses only the forces of gravity and electromagnetics to accurately calculate a large variety of nuclear properties including - fundamental structural shapes and charge arrangements - the size, shape, internal forces and relativistic mass energies of the neutron, proton, deuteron, triton, alpha particle and oxygen - the details of all types of beta decay - the correct slope of the lower end of the nuclear chart - the calculated stability of the 45 smallest stable nuclei and their 59 naturally occurring unstable isotopes - and mathematical confirmation of the magic number 2,8 and 20. This Webb model satisfies the empirical tests of the Scientific Method. The mathematics is simple enough to be confirmed by any scientist without bias. [Preview Abstract] |
Friday, October 24, 2008 5:24PM - 5:36PM |
EB.00008: On the Convergence of Finite Range Expansions in 3-nucleon Systems James Shepard, James McNeil We examine the convergence properties of the Effective Range Expansion based on Effective Theories (ET-ERE) of the 2-nucleon scattering amplitude in 3-nucleon applications in the context of a simple rank-1 separable 2-body potential where the finite range effects can be tracked explicitly. To illustrate the approach in a simple context we consider the bound and scattering properties of the $^{3}$S$_{1}$ and $^{4}$S$_{3/2}$ 2- and 3-nucleon systems. We find that the poor convergence of the 3-nucleon scattering amplitude using the ET-ERE can be traced to its poor account of finite range effects that soften the momentum dependence of the deuteron propagator in the Faddeev kernel. In contrast, a simple separable potential with dipole form factors works remarkably well and forms the leading term of a systematic controlled approximation expansion. [Preview Abstract] |
Friday, October 24, 2008 5:36PM - 5:48PM |
EB.00009: Classical Solution for Low Energy Nuclear Reactions w/o Tunneling Stewart Brekke Low energy nuclear reactions can be explained classically w/o tunneling using nuclear vibration.This equation also explains the proton proton reaction on the sun classically w/o tunneling. An incoming positive charge approaches a vibrating nucleus. If the amplitudes of vibration are equal in all directions, the position of the particle is $r = [(x + AcosX)^2 + (y + AcosY)^2 + (z + AcosZ)^2]^{1/2}$, then $KE =kQ_1Q_2/r$. If the nuclear reaction takes place contacting the nuclear surface, x=AcosX, y=AcosY and z=AcosZ. Substituting and collecting terms with angle X=Y=Z, $r= A(12cos^2X)^{1/2}$. If $cos(max)= 1 or -1, r = 2A(3) ^{1/2}$ with $RMScos = (1/2)^{1/2}$ $ r = A(6)^{1/2}$ and if cos(min) = 0,r=0. Therefore, the nuclear barrier height is a variable dependent upon the amplitude of vibration of the target nucleus with KE needed =$kQ_1Q_2/2A(3)^{1/2}$ minimum, KE needed = infinite, maximum and average KE needed = $kQ_1Q_2/A(6)^{1/2}$. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700