Bulletin of the American Physical Society
APS April Meeting 2018
Volume 63, Number 4
Saturday–Tuesday, April 14–17, 2018; Columbus, Ohio
Session H12: Computational Issues and Few-Nucleon Systems |
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Sponsoring Units: GFB Chair: Lucas Platter, University of Tennessee Room: A222-223 |
Sunday, April 15, 2018 10:45AM - 10:57AM |
H12.00001: Physics of celestial scale dumbbells Leonardo Golubovic, Steven Knudsen The physics of manmade celestial scale objects, such as Space Elevators connecting the Earth with outer space, has recently attracted increased attention of diverse researchers. In this study we address basic physics of celestial scale dumbbells such as the Analemma Tower suspended from an asteroid orbiting the Earth (Clouds AO, 2017). Celestial dumbbells involve two large masses (top and bottom) connected by strings. The two masses move geosynchronously with the Earth, with the bottom mass remaining close to the Earth and the top mass moving above the Earth's geosynchronous satellite orbit. Appealing examples of celestial scale dumbbells are untied Rotating Space Elevators [S. Knudsen, S. and L. Golubovic (2015). Physics of untied rotating space elevators. \quad European Physical Journal Plus 130, 243.]. Celestial scale dumbbells exhibit rich and interesting nonlinear dynamics caused by instabilities of dumbbell geosynchronous motion discussed in this study. We point out that celestial scale dumbbells are physically feasible (in terms of nowadays available materials strengths) on dwarf planets in the main asteroid belt of the Solar system such as Ceres. [Preview Abstract] |
Sunday, April 15, 2018 10:57AM - 11:09AM |
H12.00002: A realistic three-dimensional calculation of relativistic nucleon-nucleon interactions Mohammadreza Hadizadeh, Mahdi Radin The matrix elements of relativistic nucleon-nucleon interaction are calculated directly in terms of momentum vectors, without using a partial wave decomposition. The quadratic operator relation between the relativistic and non-relativistic nucleon-nucleon ($NN$) interactions is formulated in momentum-helicity basis states. The non-linear relation leads to a single integral equation for total $NN$ spin $s=0$ and two coupled integral equations for $s=1$, which are solved by the iteration method. The input for the calculations are non-relativistic nucleon-nucleon interactions and two different models of realistic $NN$ interactions, i.e. Bonn-B and AV18, are used. The numerical tests indicate that the $NN$ observables calculated by the relativistic $NN$ interactions are preserved with high accuracy. [Preview Abstract] |
Sunday, April 15, 2018 11:09AM - 11:21AM |
H12.00003: Renormalization of Inverse Power Law Potentials Daniel Odell, Lucas Platter Inverse power law potentials of the form $1/r^n$ play a central role in nuclear and atomic physics. For $n \ge 2$, their singularity requires an additional boundary condition to solve the 2-body system. I will present the results of examining the renormalization process for these highly singular potentials in the 3-body sector. The results are focused on two particular scenarios. First, I will address the renormalization of the $1/r^3$ potential as it represents the most singular term of the one-pion-exchange potential. I will discuss the necessity of a 3-body force in the 2 and 3-body sectors, basing my conclusions on calculations of bound state and scattering observables. Second, I will discuss the renormalization of van der Waals systems. These systems exhibit universal properties known to exist for a large scattering length which I will also address. [Preview Abstract] |
Sunday, April 15, 2018 11:21AM - 11:33AM |
H12.00004: Faddeev Calculations for $Nd$ Breakup Scattering within Isospin and Given Charge Formalism: Numerical Stability Vladimir Suslov, Igor Filikhin, Roman Kezerashvili, Branislav Vlahovic The isospin and given charge models are applied for studying the $Nd$ breakup scattering problem based on the configuration space Faddeev equations. The models are differ by the isospin basis used. The given charge formalism allows us to implement charge dependence of $NN$ interaction for phenomenological $s$-wave $NN$ potentials with adjusted parameters to define the spin singlet $nn$, $pp$ and $np$ components. Calculations of the phase shifts, in elasticities and breakup amplitudes are performed for the $nd$ and $pd$ scattering at $E_{lab}$=4.0 and 14.1~MeV for the both models. We study numerical stability of the calculations for both models with relation to known effect of oscillations of break up amplitudes with dependence on asymptotical cutoff parameter. This effect was recently predicted for quadruplet state of $nd$ scattering in [1]. The oscillations affect at numerical solution accuracy. It was found that new approach based on the given charge formalism brings in more stable numerical solution. Preliminary results for realistic AV14 potential are presented. [1] P.A. Belov and S.L. Yakovlev, Physics of Atomic Nuclei, 76, 126-38 (2013). [Preview Abstract] |
Sunday, April 15, 2018 11:33AM - 11:45AM |
H12.00005: Momentum Space Faddeev Calculation of $d+\alpha$ Scattering Jin Lei, Linda Hlophe, Charlotte Elster, Andreas Nogga, Filomena Nunes The ($d$,$p$) reaction constitutes an important tool for extracting nuclear structure information and contributes to the understanding of the dynamics of reactions. For the three body system $n+p+A$, it is advantageous to treat the problem within a Faddeev framework. Here we present phase shifts and angular distributions for $d+\alpha$ elastic scattering below and above the three-body breakup threshold and reaction cross sections up to 30~MeV deuteron kinetic energy and benchmark with calculations in the literature. We will also study the very low energy behavior below the three-body breakup threshold. The interactions in the subsystems are given by multi-rank separable representations based on the Ernst-Shakin-Thaler scheme of the CD-Bonn interaction for the $np$ system and Woods-Saxon forms for the neutron(proton)-$\alpha$ potential, which already are successfully applied in calculating the ground state of $^6$Li\footnote{L. Hlophe, Jin Lei, Ch. Elster, A. Nogga, F.M. Nunes, Phys. Rev. C{\bf 96}, 064003 (2017)}. For the initial work the Coulomb interaction is omitted. However, we note that for taking Coulomb into account without screening, separable interaction must be used in the subsystems. Thus, a careful benchmarking of our approach for scattering is warrented. [Preview Abstract] |
Sunday, April 15, 2018 11:45AM - 11:57AM |
H12.00006: Three body charmed nuclei . Shalva Tsiklauri We study the $\Lambda_{c}$\textit{NN }three-body system by using the $\Lambda _{c}N $effective potential [1] within the method of hyperspherical functions (HF) in momentum representation, using realistic \textit{NN} local potentials. We solve nonrelativistic three-body Schrodinger equation in the framework of the method of HF [2] to find a ground state binding energy and corresponding wave function for the bound states with $J =$ 1$/$2 and 3$/$2 . The bound states energies are obtained for I$=$0: -21.07 MeV ($\Lambda_{c}$\textit{np, J }$\pi =$1/2$^{\mathrm{+}})$ and -21.74 MeV ($\Lambda_{\mathrm{c}}$\textit{np}, $J_{\mathrm{\pi }} \quad =$3/2$+)$, for $I=$1: -9.80 MeV ($\Lambda_{c}$\textit{nn, J}$_{\pi } =$1/2$^{\mathrm{+}})$ , -8.74 MeV ($\Lambda_{\mathrm{c}}$\textit{np}, $J_{\pi } \quad =$1/2$+)$, -6.82 MeV ($\Lambda _{\mathrm{c}}$\textit{pp}, $J_{\pi } \quad =$1/2$+)$, which are in good agreement with previous results obtained for the same potentials using variational method. \begin{enumerate} \item S. Maeda, M. Oka, A. Yokota, E.Hiyama, and Y. Liu, Prog. Theor. Exp. Phys. \textbf{2}, 023D02, (2016) \item R. Ya. Kezerashvili, Sh. M. Tsiklauri, I. N. Filikhin, V. M. Suslov, and B. Vlahovic, J. Phys. G: Nucl. Part. Phys. 43 065104 (2016). \end{enumerate} [Preview Abstract] |
Sunday, April 15, 2018 11:57AM - 12:09PM |
H12.00007: Deuteron Compton Scattering Above Pion Threshold Luke Myers, Bruno Strandberg This work highlights the final Compton scattering data collected at MAX-lab and marks the first time that the deuteron Compton-scattering cross sections have been measured above the pion photoproduction threshold. With the current interest in extracting the neutron polarizabilities from the scattering cross section, and with the sensitivity to the polarizabilities increasing with photon energy, these results could spur new work on the deuteron. The MAX-lab data are found to be consistent with expectations and cross sections obtained from proton Compton scattering. Large uncertainties prevent the extraction of polarizabilities from this data set; however, the method is shown to be viable and will hopefully inspire future work in the super-threshold region. [Preview Abstract] |
Sunday, April 15, 2018 12:09PM - 12:21PM |
H12.00008: The sensitivity of different $\gamma p$ scattering observables to the proton’s dipole polarisabilities Harald Griesshammer, Judith McGovern, Daniel Phillips I present highlights from our recent analysis of 13 observables in Compton scattering on the proton. Cross sections, asymmetries with polarized beam and/or targets, and polarisation-transfer observables are computed in chiral effective field theory and their sensitivity to the proton’s dipole scalar and spin polarisabilities examined. For photon energies from the pion-production threshold to about 250 MeV multiple asymmetries have significant sensitivity to presently ill-determined combinations of proton spin polarisabilities. We also argue that in this energy range the broad outcomes of our analysis will be replicated in complementary theoretical approaches, e.g., dispersion relations. An interactive Mathematica notebook, including results for the neutron, is available from judith.mcgovern@manchester.ac.uk [Preview Abstract] |
Sunday, April 15, 2018 12:21PM - 12:33PM |
H12.00009: Bremsstrahlung in Low-Energy Lepton-Proton Scattering Pulak Talukdar, Fred Myhrer, Udit Raha We calculate the cross section for the lepton-proton bremsstrahlung process $l+p\to l^\prime +p+\gamma$ in effective field theory. This process corresponds to an undetected background signal for the proposed MUSE experiment at PSI. MUSE is designed to measure elastic scattering of low-energy electrons and muons off a proton target in order to extract a precise value for the proton's r.m.s. radius. We work in the flavor SU(2) version of the Heavy Baryon Chiral Perturbation theory. Lepton mass is systematically included in all our expressions. We use Coulomb gauge, which means that the proton does not radiate at lowest order in our calculation. We show that the commonly used {\it peaking approximation}, which is used to evaluate the {\it radiative tail} for the elastic cross section, is not applicable for muon proton scattering at the low-energy MUSE kinematics. We discuss how the {\it radiative tail} cross section depends on the outgoing lepton's momentum and how the lepton mass crucially influence the shape of the radiative tail originating from the elastic peak. We also correct a misprint in a commonly cited review article. [Preview Abstract] |
Sunday, April 15, 2018 12:33PM - 12:45PM |
H12.00010: Van der Waals and Casimir-Polder Interactions of Hydrogen Atoms in Excited States Chandra Adhikari, Vincent Debierre, Ulrich Jentschura We analyze the long-range interactions between two hydrogen atoms. Provided both atoms are in the ground states, the retardation regime is achieved when the interatomic distance, $R$, is larger than $137a_0$, where $a_0$ is the Bohr radius. However, for an excited atom interacting with the ground state atom, the presence of virtually low lying energy levels accessible by a dipole transition from an excited reference state makes the situation different. For excited reference states, we match the scattering amplitude and effective perturbation Hamiltonian of the system. For $a_0\ll R\ll137a_0$, the nonretarded approximation is valid and the interaction energy takes a $R^{-6}$ functional form. For a higher excited states, we obtain a numerically large van der Waals coefficient, e.g., about 24000 in atomic units for $12S$-$1S$ system. As soon as the interatomic separation satisfies $R\ge137a_0$, the interaction energy does not have only the $R^{-6}$ term, but surprisingly it also has (i) attractive/repulsive oscillatory terms, in addition to (ii) the familiar Casimir-Polder $R^{-7}$ asymptotic. For sufficiently large $R$, the oscillatory term whose magnitude falls off as $R^{-2}$ dominates the Wick-rotated term (the latter describes the retarded Casimir-Polder type of interaction). [Preview Abstract] |
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