Bulletin of the American Physical Society
2012 Fall Meeting of the APS Division of Nuclear Physics
Volume 57, Number 9
Wednesday–Saturday, October 24–27, 2012; Newport Beach, California
Session CF: Nuclear Theory I |
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Chair: Erich Ormand, Lawrence Livermore National Laboratory Room: Garden III |
Thursday, October 25, 2012 8:30AM - 8:42AM |
CF.00001: In-Medium Similarity Renormalization Group with NN and 3N Interactions Heiko Hergert The primary use of the Similarity Renormalization Group (SRG) in nuclear physics is the derivation of effective interactions from underlying realistic vacuum NN and 3N interactions, which have a greatly improved convergence behavior in nuclear many-body calculations. The SRG flow equation formalism has much wider applications, though. In the In-Medium SRG the Hamiltonian is evolved directly in the A-body system (i.e., at finite density). By a suitable choice of generator the ground state is decoupled from particle-hole excitations, and the IMSRG can be considered an ab initio technique for solving the many-body problem. The modest computational effort makes calculations for medium-mass and heavy nuclei feasible. I will give a brief overview of the method, present results for closed-shell nuclei with NN and 3N interactions, and discuss the progress in our effort to generalize the IM-SRG formalism for arbitrary reference states, with the aim of extending our calculations to open-shell nuclei. \\[4pt] References: K. Tsukiyama, S. Bogner, and A. Schwenk, Phys. Rev. Lett. 106, 222502 (2011)\\[0pt] S. Bogner, R. Furnstahl, and A. Schwenk, Prog. Part. Nucl. Phys. 65, 94 (2010) [Preview Abstract] |
Thursday, October 25, 2012 8:42AM - 8:54AM |
CF.00002: Applications of SRG Factorization E.R. Anderson, S.K. Bogner, R.J. Furnstahl, K. Hebeler, H. Hergert, R.J. Perry Recent calculations of nuclear structure make use of the similarity renormalization group to soften the nuclear potential through a series of unitary transformations, which suppress short range correlations.\footnote{E.D. Jurgenson, P. Navr\'atil, and R.J. Furnstahl, Phys. Rev. Lett. \textbf{103}, 082501 (2009).}\(^{,}\)\footnote{E. R. Anderson, S. K. Bogner, R. J. Furnstahl, and R. J. Perry, Phys. Rev. C \textbf{82}, 054001 (2010)} Not only does this lead to a decoupling of scales in the potential, but also simplifications for other operators. One consequence, in particular, is that operator expectation values of high-energy probes in low-energy nuclear states exhibit factorization. As a result, phenomena previously attributed to strong short-range correlations induced by the nucleon-nucleon interaction, such as nuclear scaling and the EMC effect, can now be understood more clearly as a result of low-momentum nuclear structure. Recent results are reported. [Preview Abstract] |
Thursday, October 25, 2012 8:54AM - 9:06AM |
CF.00003: Local Projections of Low Momentum Potentials Kyle Wendt Chiral and renormalized low resolution nucleon-nucleon interactions are inherently nonlocal. This nonlocality inhibits their use with some techniques for solving the quantum many-body problem including quantum monte carlo methods such as Green's Function Monte Carlo and Auxiliary Field Diffusion Monte Carlo. By exploiting simple integral projections, the non-local nuclear two body forces can be separated into a local interaction and non-local residual. This residual is demonstrated to be perturbative at low energy, raising the possibility of using non-local interactions with modern quantum monte carlo methods. [Preview Abstract] |
Thursday, October 25, 2012 9:06AM - 9:18AM |
CF.00004: Angular-momentum- and parity-projected Hartree-Fock in a shell-model basis Joshua Staker, Calvin Johnson We implement projected Hartree-Fock in a shell-model basis and compare against exact numerical results from full space diagonalization in the same single particle space. We consider the accuracy of projected Hartree-Fock for the excited state spectrum, the moment of inertia, and also odd-even staggering. In particular we consider intrinsic states with mixed parity and project out states with good parity. [Preview Abstract] |
Thursday, October 25, 2012 9:18AM - 9:30AM |
CF.00005: Giant Dipole Resonance in light and heavy nuclei beyond selfconsistent mean field theory Siegfried Krewald, Nikolay Lyutorovich, Victor Tselyaev, Josef Speth, Frank Gruemmer, Paul-Gerhard Reinhard While bulk properties of stable nuclei are successfully reproduced by mean-field theories employing effective interactions, the dependence of the centroid energy of the electric giant dipole resonance on the nucleon number A is not. This problem is cured by considering many-particle correlations beyond mean-field theory, which we do within a selfconsistent generalization of the {\em Quasiparticle Time Blocking Approximation} [1,2]. The electric giant dipole resonances in $^{16}$O, $^{40}$Ca, and $^{208}$Pb are calculated using two new Skyrme interactions. Perspectives for an extension to effective field theories[3] are discussed.\\[4pt] [1] V. Tselyaev et al., Phys.Rev.C{\bf 75}, 014315(2007).\\[0pt] [2] N. Lyutorovich et al., submitted to Phys.Rev.Lett.\\[0pt] [3] S. Krewald et al., Prog.Part.Nucl.Phys.{\bf 67}, 322(2012). [Preview Abstract] |
Thursday, October 25, 2012 9:30AM - 9:42AM |
CF.00006: Three-nucleon interaction in light ion reactions Guillaume Hupin, Joachim Langhammer, Petr Navratil, Robert Roth, Sofia Quaglioni The fundamental description of both structural properties and reactions of light-nuclei based on nucleon-nucleon and three-nucleon forces derived from first principles is a standing goal in nuclear physics. The {\it ab initio} no-core shell model when combined with the resonating-group method (NCSM/RGM) [1,2] is capable of describing simultaneously both bound and scattering states in light nuclei, and has already produced promising results starting from a two-body Hamiltonian. Using similarity-renormalization-group evolved two- and three-nucleon interactions [2,3], I will present the first applications to light nuclei binary scattering processes when accounting for the chiral EFT two- plus three-nucleon interaction versus the chiral EFT two-nucleon interaction.\\[4pt] [1] S. Quaglioni and P. Navr\'atil, PRL {\bf 101}, 092501 (2008); PRC {\bf 79}, 044606 (2009). [2] P. Navr\'atil and S. Quaglioni, PRC {\bf 83}, 044609 (2011). [3] E. Jurgenson, P. Navr\'atil, and R. J. Furnstahl, PRC {\bf 83}, 034301 (2011). [4] R. Roth, J. Langhammer, A. Calci, S. Binder, and P. Navr\'atil, PRL {\bf 107}, 072501 (2011). [Preview Abstract] |
Thursday, October 25, 2012 9:42AM - 9:54AM |
CF.00007: Radiative Neutron Capture on Carbon-14 and Electromagnetic Form Factors of Carbon-15 Akshay Vaghani, Lakma Fernando, Gautam Rupak We calculate the cross section for radiative neutron capture on carbon-14 using halo effective field theory (EFT). The contributions from the resonant and non-resonant interaction is considered. Interference between these leads to a cross section that deviates from a simple Breit -Wigner resonance form. We compare our results with direct capture and coulomb dissociation data. Finally we calculate the electromagnetic form factors of carbon-15 analytically to next-to-leading order (NLO). This result is also applicable to other $s$-wave spin-$\frac{1}{2}$ halo nuclei such as the ground state of beryllium-11 where we estimate the two-body contribution to the magnetic form factor at NLO. [Preview Abstract] |
Thursday, October 25, 2012 9:54AM - 10:06AM |
CF.00008: Hyperon-Nucleon Interactions from QCD Martin Savage Low-energy neutron-Sigma- interactions determine, in part, the role of the strange quark in dense matter, such as that found in astrophysical environments. The scattering phase shifts for this system are obtained from Lattice QCD calculations, performed at a pion mass of ~ 389 MeV in two large lattice volumes and at one lattice spacing, and are extrapolated to the physical pion mass using effective field theory. The interactions determined from QCD are consistent with those extracted from hyperon-nucleon experimental data within uncertainties. [Preview Abstract] |
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