Bulletin of the American Physical Society
APS April Meeting 2017
Volume 62, Number 1
Saturday–Tuesday, January 28–31, 2017; Washington, DC
Session J2: Few-Body Systems |
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Sponsoring Units: GFB Chair: Saori Pastore, Los Alamos National Laboratory Room: Maryland B |
Sunday, January 29, 2017 10:45AM - 10:57AM |
J2.00001: The Efimov effect with finite range interactions Lucas Platter Systems of strongly interacting atoms are receiving a lot of attention because of their interesting features in the few- and many-body sector. Strong interactions are frequently obtained in experiment by using a Feshbach resonance to tune the scattering to large values. A striking feature of three-body systems with a large scattering is the emergence of a discrete scaling symmetry that is also known as the Efimov effect. The Efimov effect has been observed through the measurement of loss rates in experiments with ultracold atoms. It is, however, also relevant to nuclear physics where the three-nucleon bound state and some halo nuclei are considered to be examples of Efimov states. Such systems can be modeled conveniently with the zero-range limit, however, in many of such experiments the finite range of the interaction leads to significant corrections that need to be taken into account. I will discuss how a finite effective range can be included in calculations for three-body systems that display the Efimov effect and how this leads to novel universal relations. Applications to experiments with homonuclear and heteronuclear ultracold atomic gases are discussed. [Preview Abstract] |
Sunday, January 29, 2017 10:57AM - 11:09AM |
J2.00002: Three-body recombination in heteronuclear systems at finite temperature with a large positive scattering length Samuel Emmons, Bijaya Acharya, Lucas Platter For an ultracold heteronuclear mixture with a large positive interspecies scattering length and negligible intraspecies scattering length, we determine the three-body recombination rate as a function of collision energy using universal functions of a single scaling variable. We use the zero-range approximation and the Skorniakov$-$Ter-Martirosian equation to calculate these scaling functions for a range of collision energies. Further, we explore the effects that a nonzero temperature has on three-body recombination, as well as the effects of the formation of deep dimers, for experimentally relevant heteronuclear gases such as the $^6$Li-$^{133}$Cs mixture. [Preview Abstract] |
Sunday, January 29, 2017 11:09AM - 11:21AM |
J2.00003: ABSTRACT WITHDRAWN |
Sunday, January 29, 2017 11:21AM - 11:33AM |
J2.00004: Constraining Exotic Weakly-Coupled Long-Range Interactions with Pseudoscalar and Axial Couplings With Unpolarized Data Sheakha Aldaihan, William Michael Snow, Dennis Krause Exotic long-range interactions can be generated by many possible sources beyond the Standard Model. Very stringent constraints exist on spin-independent Yukawa interactions from ultralight scalar or vector bosons. On the contrary, constraints on exotic interactions with spin-dependent pseudoscalar and axial couplings are very weak. The extreme disparity between the limits for these two cases suggests that new limits on spin-dependent couplings could be set by comparing the spin-independent component of two-boson exchange processes involving spin-dependent couplings to existing experimental limits on spin-independent interactions. In this talk we present two examples of physical mechanisms involving spin-dependent couplings which lead to spin-independent interactions and whose analysis can lead to improved constraints. The first involves effects arising from higher order exchange processes and the other makes use of exchanges of pseudoscalar and axial bosons between bound-state systems. [Preview Abstract] |
Sunday, January 29, 2017 11:33AM - 11:45AM |
J2.00005: The saga of the tetraneutron Roman Ya. Kezerashvili In light of a new experiment for the double-charge-exchange reaction $^{4}$He($^{8}$He,$^{8}$Be) at 186 MeV/u [1], which claims an identification of a resonant tetraneutron state we review results of experimental search and theoretical studies within methods of few body physics for a tetraneutron. Particularly, we discuss searches of the tetraneutron using the pion double charge exchange reaction $^{4}$He($\pi^{-}$,$\pi ^{+})^{4}$n, heavy-ion transfer reactions such as $^{7}$Li($^{11}$B,$^{14}$O)$^{4}$n and $^{7}$Li($^{7}$Li,$^{10}$C)$^{4}$n, as well as search of the tetraneutron and multineutrons in fission reactions. We present and review theoretical analyses of the tetraneutron in the framework of various theoretical approaches such as variational methods, the method of Faddeev-Yakubovsky equations, and the method of hyperspherical harmonics within the existing modern two- and three-nucleon interactions. Today there is no unambiguous answer for the existence of the trineutron as a bound or resonance state. This issue will be addressed. [1] K. Kisamori, et al., Phys Rev. Lett. 116, 052501 (2016). [Preview Abstract] |
Sunday, January 29, 2017 11:45AM - 11:57AM |
J2.00006: Hard QCD rescattering in few nucleon systems Dhiraj Maheswari, Misak Sargsian The theoretical framework of hard QCD rescattering mechanism (HRM) is extended to calculate the high energy $\gamma ^3He \rightarrow pd$ reaction at $90^0$ center of mass angle. In HRM model , the incoming high energy photon strikes a quark from one of the nucleons in the target which subsequently undergoes hard rescattering with the quarks from the other nucleons generating hard two-body baryonic system in the final state of the reaction. Based on the HRM, a parameter free expression for the differential cross section for the reaction is derived, expressed through the $^3He \rightarrow pd $ transition spectral function, hard $pd \rightarrow pd$ elastic scattering cross section and the effective charge of the quarks being interchanged in the hard rescattering process. The numerical estimates obtained from this expression for the differential cross section are in a good agreement with the data recently obtained at the Jefferson Lab experiment, showing the energy scaling of cross section with an exponent of $s^{-17}$, also consistent with the quark counting rule. The angular and energy dependences of the cross section are also predicted within HRM which are in good agreement with the preliminary data of these distributions. [Preview Abstract] |
Sunday, January 29, 2017 11:57AM - 12:09PM |
J2.00007: On the absence of turbulence in exact solutions of the Navier-Stokes equation and implications of a quantum interpretation of turbulence Amador Muriel There have been several papers published which show exact solutions of the Navier-Stokes equation [ A. Muriel, Results in Physics 1, 2 (2011), A. Muriel, Physics Letters A 378, 2529 (2014), A. Muriel, Results in Physics 12/2015, A. Muriel, Results in Physics 6, 29 (2016)]. None of the solutions admit any possibility of turbulence. It is strongly suggested that the Navier-Stokes equation is not the correct problem definition for turbulence. Yet, by contrast, in a simple example, it s shown that turbulence can result quite directly by using two or more species of fluids. The species are in fact identical atoms with different quantum states, provoking the strong suggestion that a plausible explanation for the origin of turbulence is quantum mechanical [Muriel CFD Letters Vol. 2(3) 2010 ]. This suggestion is heavily supported by actual modern pipe flow experiments [Muriel, Quantum Theory of Turbulence, Harvard Book Store (2011),which may be downloaded from (Muriel, ResearchGate)\textbraceright The most general exact solutions of the Navier-Stokes equation will be displayed. In addition, experiments supporting a quantum interpretation will be reviewed. [Preview Abstract] |
Sunday, January 29, 2017 12:09PM - 12:21PM |
J2.00008: The Generalized Onsager Model and DSMC Simulations of High-Speed Rotating Flow with Swirling Feed Dr. Sahadev Pradhan The generalized Onsager model for the radial boundary layer and of the generalized Carrier-Maslen model for the axial boundary layer at the end-caps in a high-speed rotating cylinder ((S. Pradhan {\&} V. Kumaran, J. Fluid Mech., 2011, vol. 686, pp. 109-159); (V. Kumaran {\&} S. Pradhan, J. Fluid Mech., 2014, vol. 753, pp. 307-359)), are extended to incorporate the angular momentum of the feed gas for a swirling feed for single component gas and binary gas mixture. For a single component gas, the analytical solutions are obtained for the sixth-order generalized Onsager equations for the master potential, and for the fourth-order generalized Carrier-Maslen equation for the velocity potential. In both cases, the equations are linearized in the perturbation to the base flow, which is a solid-body rotation. The equations are restricted to the limit of high Reynolds number and (length/radius) ratio, but there is no limitation on the stratification parameter. The linear operators in the generalized Onsager and generalized Carrier-Maslen equations with swirling feed are still self-adjoint, and so the eigenfunctions form a complete orthogonal basis set. The analytical solutions are compared with direct simulation Monte Carlo (DSMC) simulations. The comparison reveals that the boundary conditions in the simulations and analysis have to be matched with care. When these precautions are taken, there is excellent agreement between analysis and simulations, to within 15{\%}. [Preview Abstract] |
Sunday, January 29, 2017 12:21PM - 12:33PM |
J2.00009: Modeling the Physics of Sliding Objects on Rotating Space Elevators and Other Non-relativistic Strings Leonardo Golubovic, Steven Knudsen We consider general problem of modeling the dynamics of objects sliding on moving strings. We introduce a powerful computational algorithm that can be used to investigate the dynamics of objects sliding along non-relativistic strings. We use the algorithm to numerically explore fundamental physics of sliding climbers on a unique class of dynamical systems, Rotating Space Elevators (RSE) [L. Golubovi\'{c} and S. Knudsen, Europhys. Lett. 86\textbf{\textit{, }}34001 (2009); S. Knudsen and L. Golubovi\'{c}, Eur. Phys. J. Plus 129, 242 (2014), ibid., 130, 243 (2015)]. Objects sliding along RSE strings do not require internal engines or propulsion to be transported from the Earth's surface into outer space. By extensive numerical simulations, we find that sliding climbers may display interesting non-linear dynamics exhibiting both quasi-periodic and chaotic states of motion. While our main interest in this study is in the climber dynamics on RSEs, our results for the dynamics of sliding object are of more general interest. In particular, we designed tools capable of dealing with strongly nonlinear phenomena involving moving strings of any kind, such as the chaotic dynamics of sliding climbers observed in our simulations. [Preview Abstract] |
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