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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 397 records · Page 22
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DOE OSTI2010

Nuclear Supersymmetry

The concept of symmetries in physics is briefly reviewed. In the first part of these lecture notes, some of the basic mathematical tools needed for the understanding of symmetries in nature are presented, namely group theory, Lie groups and Lie algebras, and Noether's theorem. In the second part, some applications of symmetries in physics are discussed, ranging from isospin and flavor symmetry to more recent developments involving the interacting boson model and its extension to supersymmetries in nuclear physics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Neutrino Nuclear Responses for Neutrino Studies in Nuclear Femto Laboratories

Fundamental properties of neutrinos and neutrino nuclear interactions are of great interest from particle and astro-nuclear physics view points. They are well studied in nuclear femto laboratories, where neutrino nuclear responses are crucial. Neutrino masses and neutrino natures are studied by neutrino-less double beta decays (0{nu}{beta}{beta}) in nuclei. Here neutrino nuclear responses are required to extract neutrino properties from 0{nu}{beta}{beta} rates. Neutrino nuclear responses are sensitive to nuclear spin isospin correlations and nuclear structures. They are experimentally studied by nuclear probes for charge exchange nuclear reactions, photon EM probes for photo-nuclear reactions, and lepton probes for muon and neutrino capture reactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Self-consistent description of coexistence phenomena in medium mass nuclei

Shape coexistence and mixing, isospin mixing, the competition between neutron-proton and like-nucleon pairing correlations have been identified as the main characteristic features of nuclei near the N = Z line in the A{approx_equal}70 mass region. The self-consistent treatment of exotic phenomena dominated by their interplay represents a challenge for the nuclear many-body models. The realistic description of tiny effects in this mass region aiming to test the fundamental interactions and symmetries as well as the required theoretical predictions concerning the nuclear properties relevant for astrophysical scenarios are still open problems of the low-energy nuclear physics today.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2010

The Dirac-Moshinsky oscillator coupled to an external field and its connection to quantum optics

The Dirac-Moshinsky oscillator is an elegant example of an exactly solvable quantum relativistic model that under certain circumstances can be mapped onto the Jaynes-Cummings model in quantum optics. In this work we show, how to do this in detail. Then we extend it by considering its coupling with an external (isospin) field and find the conditions that maintain solvability. We use this extended system to explore entanglement in relativistic systems and then identify its quantum optical analog: two different atoms interacting with an electromagnetic mode. We show different aspects of entanglement which gain relevance in this last system, which can be used to emulate the former.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2010

Loop Effects in Charmonium Transitions

Within the framework of an effective field theory, I discuss the role of charmed meson loops in isospin and SU(3) violating charmonium transitions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Nucleon resonances from three-hadron interactions

Our study of meson-meson-baryon systems with total strangeness zero revealed that many nucleon resonances can be understood as dynamically generated states of three-hadrons. We considered {pi}{pi}N,{pi}{eta}N,{pi}K{Lambda}, and {pi}K{Sigma} as coupled channels and solved the Fadeev equations. To be precise, the study lead to dynamical generation of N*(1710), N*(2100), {Delta}(1910) along with a new isospin 1/2 resonance around 1920 MeV. In this manuscript I briefly review the formalism we use for three-body calculations and the results obtained for the nucleon resonances.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Effective interactions and long distance symmetries in the Nucleon-Nucleon system

Effective interactions, when defined in a coarse grained sense, such as V{sub lowk} at the scale {Lambda} = 450 MeV, display a remarkable symmetry pattern. Serber symmetry works with high accuracy for spin triplet states. Wigner SU(4) spin-isospin symmetry with nucleons in the fundamental representation works only for even partial waves exactly as predicted by large N{sub c} limit of QCD with accuracy O(1/N{sub c}{sup 2}). This suggests tailoring the very definition of effective interactions to provide a best possible fulfillment of long distance symmetries. With the V{sub lowk} definition Wigner symmetry requires that chiral potentials have low cut-offs {Lambda}{sub {chi}{approx}4}50 MeV. Perturbative saturation of exchanged heavy mesonic resonances does not faithfully display the Serber symmetry pattern.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Improving the K{pi} vector form factor through K{sub l3} constraints

The K{pi} vector form factor, F{sub +}{sup K{pi}}, used to reproduce the Belle spectrum of {tau}{yields}K{pi}{nu}{sub {tau}} decays is described by means of a three-times subtracted dispersion relation also incorporating constraints from K{sub l3} decays. The slope and curvature of F{sub +}{sup K{pi}} are fitted to the data yielding {lambda}{sub +}{sup '} = (25.49{+-}0.31)x10{sup -3} and {lambda}{sub +}{sup ''} (12.22{+-}0.14)x10{sup -4}. The pole parameters of the K*(892){sup {+-}} are found to be m{sub K*(892){sup {+-}}} = 892.0{+-}0.5 MeV and {Gamma}{sub K*(892){sup {+-}}} = 46.5{+-}1.1 MeV. The phase-space integrals relevant for K{sub l3} analyses and the P-wave isospin-1/2 K{pi} phase-shift threshold parameters are also calculated.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Quark fragmentation to pions and kaons in the NJL-jet model

We describe the quark fragmentation functions to pions and kaons in the NJL-jet model and compare the results with empirical parametrizations. By including cascade-like fragmentation processes, the momentum and isospin sum rules can be satisfied naturally without introducing new parameters into the theory. We associate a low energy scale with the NJL model, and perform the Q{sup 2} evolution in leading order. The results are in reasonable agreement with the empirical fragmentation functions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Rethinking the X(3872)

The BaBar analysis which favours 2{sup -+} quantum numbers for the X(3872) implies that it may be none other than the 1 {sup 1}D{sub 2} charmonia state. In that case the isospin breaking in closed flavour modes may be the result of re-scattering from open flavour. However, the observed production cross section in proton-antiproton collisions is much larger than expectations, while the mass of the state, compared to the predictions of a string model, is too large. The {sup 1}D{sub 2} assignment would imply a {sup 3}D{sub 2} partner nearby in mass, which may be the X(3875). In the tetraquark interpretation the 2{sup -+} assignment implies a rich spectrum of partner states, although the X(3872) may be among the few which are narrow enough to be observable. This talk is based in part on ref. [1].

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Light scalar susceptibilities and the {pi}{sup 0}-{eta} mixing

We have performed a thermal analysis of the light scalar susceptibilities in the context of SU(3)-Chiral Perturbation Theory to one loop taking into account the QCD source of isospin breaking (IB), i.e corrections coming from m{sub u{ne}}m{sub d}. We find that the value of the connected scalar susceptibility in the infrared regime and below the critical temperature is entirely dominated by the {pi}{sup 0}-{eta} mixing, which leads to model-independent O(Vegr;{sup 0}) corrections, where {epsilon}{approx}m{sub d}-m{sub u}, in the combination {chi}{sub uu}-{chi}{sub ud} of flavour breaking susceptibilities.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Symmetries in nuclei

The use of dynamical symmetries or spectrum generating algebras for the solution of the nuclear many-body problem is reviewed. General notions of symmetry and dynamical symmetry in quantum mechanics are introduced and illustrated with simple examples such as the SO(4) symmetry of the hydrogen atom and the isospin symmetry in nuclei. Two nuclear models, the shell model and the interacting boson model, are reviewed with particular emphasis on their use of group-theoretical techniques.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Interacting boson models for N{approx}Z nuclei

This contribution discusses the use of boson models in the description of N{approx}Z nuclei. A brief review is given of earlier attempts, initiated by Elliott and co-workers, to extend the interacting boson model of Arima and Iachello by the inclusion of neutron-proton s and d bosons with T = 1 (IBM-3) as well as T = 0 (IBM-4). It is argued that for the N{approx}Z nuclei that are currently studied experimentally, a different approach is needed which invokes aligned neutron-proton pairs with angular momentum J = 2j and isospin T = 0. This claim is supported by an analysis of shell-model wave functions in terms of pair states. Results of this alternative version of the interacting boson model are compared with shell-model calculations in the 1g{sub 9/2} shell.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Dynamics Behind the Quark Mass Hierarchy and Electroweak Symmetry breaking

I review the dynamics in a new class of models describing the quark mass hierarchy, suggested recently by Michio Hashimoto and the author. In this class, the dynamics primarily responsible for electroweak symmetry breaking (EWSB) leads to the mass spectrum of quarks with no (or weak) isospin violation. Moreover, the values of these masses are of the order of the observed masses of the down-type quarks. Then, strong (although subcritical) horizontal diagonal interactions for the t quark plus horizontal flavor-changing neutral interactions between different families lead (with no fine tuning) to a realistic quark mass spectrum. In this scenario, many composite Higgs bosons occur. A concrete model with the dynamical EWSB with the fourth family is described in detail.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Exotic modes of excitation and weak interaction rates at finite temperature

The interplay of isospin asymmetry and finite temperature in nuclei plays an important role on properties of nuclear excitations and weak interaction rates in stellar environment. Recently a fully self-consistent microscopic framework, based on Hartree-Fock plus random phase approximation using Skyrme functionals, has been introduced for description of excitations and weak-interaction cross sections at finite temperature. Another self-consistent framework involving nuclei at finite temperature has also been developed within relativistic mean field theory using effective Lagrangians with density dependent meson-nucleon vertex functions. Nuclear excitations are studied using finite temperature random phase approximation for the range of temperatures T = 0-2 MeV, as well as in nuclei far from stability. In the focus of research are the structure properties of exotic modes of excitation (e.g. pygmy dipole resonances) and charge-exchange modes (e.g. Gamow-Teller resonances and forbidden transitions). It is shown that finite temperature effects include novel low-energy multipole excitations and modifications of the Gamow-Teller transition spectra. Using a representative set of Skyrme functionals, as well as covariant energy density functional with DD-ME2 parameterization, both theory frameworks have been applied in calculations of electron-capture cross sections relevant in the stage of supernova precollapse.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

On the nature of the Dipole Pygmy Resonance

The nature of the low-lying dipole states in neutron-rich nuclei, often associated to the Pygmy Dipole Resonance, has been investigated. This has been done by describing them within the Hartree-Fock plus RPA formalism. The analysis shows that they are not of collective nature although many particle-hole configurations participate to their formation. Taking advantage of their strong isospin mixing one can envisage combined reaction processes involving the Coulomb and different mixtures of isoscalar and isovector nuclear interactions in order to provide more hints to unveil the characteristic features of these states.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Gamow-Teller Transitions Starting from T{sub z} = +3/2 Nucleus {sup 45}Sc

Owing to its simplicity and also its nature of spin-isospin ({sigma}{tau}) excitation, Gamow-Teller (GT) transitions play key roles in the studies of nuclear structure as well as astro-nuclear processes. We studied GT transitions starting from {sup 45}Sc in a high-resolution ({sup 3}He,t) charge-exchange reactions at 0 deg. and at an intermediate incoming energy of 140 MeV/nucleon. Individual GT transitions were observed up to high excitation energy of 10 MeV and a concentration of GT strength, a resonance-like structure, was observed at 6.5 MeV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Photopion Physics at the HI{gamma}S Facility

Future photopion experiments at the HI{gamma}S facility are described. It is shown that they will provide accurate tests of ChPT and will be sensitive to isospin breaking dynamics due to the mass difference of the up and down quarks.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗