Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session HD: Nuclear Structure Theory II |
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Sponsoring Units: DNP Chair: Mark Caprio, University of Notre Dame Room: Junior Ballroom C |
Saturday, October 15, 2016 8:30AM - 8:42AM |
HD.00001: Applications of modern chiral interactions in nuclear matter and nuclei Francesca Sammarruca Experimental investigations are in progress, and more are planned for the near future, to set reliable constraints on the isospin asymmetric part of the nuclear equation of state. The latter plays a fundamental role in a broad spectrum of systems and phenomena, including the skins of neutron-rich nuclei and the location of the neutron drip lines. From the theoretical standpoint, microscopic calculations with statistically meaningful uncertainties are essential to guide experiments. We will discuss recent calculations of the nuclear and neutron matter equations of state [1] at different orders of the chiral expansion. We will present applications and discuss the significance of those predictions as a foundation for future studies of convergence of the chiral perturbation series. Anticipating future experiments which may provide reliable information on the weak charge density in nuclei, we discuss the possibility of constraining the size of three-neutron forces in neutron matter. [1] F. Sammarruca, L. Coraggio, J.W. Holt, N. Itaco, R. Machleidt, and L.E. Marcucci, Phys. Rev. C {\bf 91}, 054311 (2015). [Preview Abstract] |
Saturday, October 15, 2016 8:42AM - 8:54AM |
HD.00002: Tracing the evolution of nuclear forces under the similarity renormalization group Calvin Johnson I examine the evolution of nuclear forces under the similarity renormalization group (SRG) using traces of the many-body configuration-space Hamiltonian. Through both analytic and explicit numerical calculations I show that if the SRG generator approximates the diagonal of the Hamiltonian, the primary effect is to shift downward the diagonal matrix elements in the model space, while the off-diagonal elements undergo significantly smaller shifts. Thus the primary effect of SRG on low-lying states is to shift energies downwards, with relatively small changes to the configuration-space wavefunction. This in turn helps us to understand how SRG has been so successful a scheme in renormalizing and softening the nuclear interaction for many-body calculations. [Preview Abstract] |
Saturday, October 15, 2016 8:54AM - 9:06AM |
HD.00003: Operator evolution for knock-out processes Sushant More, Sebastian K\"{o}nig, Richard Furnstahl, Kai Hebeler Renormalization group (RG) methods are used to soften nuclear Hamiltonians and obtain accelerated convergence in nuclear structure calculations. Use of soft Hamiltonians in nuclear reaction calculations pose an apparent challenge, because of the need to consistently transform the operator. We build on our recent work where we showed that effect of operator evolution depends on kinematics. We demonstrate that the RG changes to the operator can be explained from effective field theory principles. We also show that the RG perspective helps us understand the high-momentum factorization of experimental observables. [Preview Abstract] |
Saturday, October 15, 2016 9:06AM - 9:18AM |
HD.00004: Bayesian parameter estimation for chiral effective field theory Sarah Wesolowski, Richard Furnstahl, Daniel Phillips, Natalie Klco The low-energy constants (LECs) of a chiral effective field theory (EFT) interaction in the two-body sector are fit to observable data using a Bayesian parameter estimation framework. By using Bayesian prior probability distributions (pdfs), we quantify relevant physical expectations such as LEC naturalness and include them in the parameter estimation procedure. The final result is a posterior pdf for the LECs, which can be used to propagate uncertainty resulting from the fit to data to the final observable predictions. The posterior pdf also allows an empirical test of operator redundancy and other features of the potential. We compare results of our framework with other fitting procedures, interpreting the underlying assumptions in Bayesian probabilistic language. We also compare results from fitting all partial waves of the interaction simultaneously to cross section data compared to fitting to extracted phase shifts, appropriately accounting for correlations in the data. [Preview Abstract] |
Saturday, October 15, 2016 9:18AM - 9:30AM |
HD.00005: Revisting the Density Matrix Expansion with Regulated Chiral Interactions Alexander Dyhdalo, Richard Furnstahl, Scott Bogner, Nicolas Schunck, Rodrigo Navarro Perez The density matrix expansion provides a general way to map microscopic interactions to a local functional. Previous density matrix expansion formulations added unregulated chiral long-range potentials to a Skyrme-type functional, which accounted for the short-range contributions. We implement the expansion with new coordinate space regulators using the regulator cutoff as a tool to adiabatically turn on finite-range pion interactions. We discuss 'smoking guns' for correct inclusion of 3-body forces, which are implemented in a normal-ordering prescription, and compare to ab initio calculations. [Preview Abstract] |
(Author Not Attending)
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HD.00006: Infrared Extrapolations of Electromagnetic Multipole Moments and Transitions Daniel Odell, Thomas Papenbrock, Lucas Platter Basis truncations introduce systematic errors in observables calculated by representing the nuclear Hamiltonian in finite Hilbert spaces. Recent studies of the infrared convergence of finite basis calculations of energies and radii have led to accurate descriptions of numerical data. I will discuss how these concepts can be applied to the study of bound-state quadrupole moments and transitions as well as multipole transitions between bound-states and the continuum. I will show that good agreement is obtained between analytically derived and numerically computed convergence behavior in finite harmonic oscillator spaces for the nucleon-nucleon system. This opens the way to a more precise understanding of structure and reactions involving heavier nuclei. [Preview Abstract] |
Saturday, October 15, 2016 9:42AM - 9:54AM |
HD.00007: Bayesian analysis of truncation errors in chiral effective field theory J. Melendez, R.J. Furnstahl, N. Klco, D.R. Phillips, S. Wesolowski In the Bayesian approach to effective field theory (EFT) expansions, truncation errors are derived from degree-of-belief (DOB) intervals for EFT predictions. By encoding expectations about the naturalness of EFT expansion coefficients for observables, this framework provides a statistical interpretation of the standard EFT procedure where truncation errors are estimated using the order-by-order convergence of the expansion. We extend and test previous calculations of DOB intervals for chiral EFT observables, examine correlations between contributions at different orders and energies, and explore methods to validate the statistical consistency of the EFT expansion parameter. [Preview Abstract] |
Saturday, October 15, 2016 9:54AM - 10:06AM |
HD.00008: ABSTRACT WITHDRAWN |
Saturday, October 15, 2016 10:06AM - 10:18AM |
HD.00009: ABSTRACT WITHDRAWN |
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