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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 1,351 records · Page 75
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Charm and bottom hadronic form factors with QCD sum rules

We present a brief review of some calculations of form factors and coupling constants in vertices with charm and bottom mesons in the framework of QCD sum rules. We first discuss the motivation for this work, describing possible applications of these form factors to charm and bottom decays processes. We first make a summarize of the QCD sum rules method. We give special attention to the uncertainties of the method introducing by the intrinsic variation of the parameters. Finally we conclude.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Reggeometry of lepton- and hadron-induced reactions

We append a simple Pomeron pole amplitude by t and Q{sup 2}, MV dependencies inspired by geometrical ideas. The experimentally transition from soft to hard dynamics is realized by the introduction of a two-component Pomeron with different Q{sup 2} and M{sub V}-dependent residues. A unified description of deeply virtual Compton scattering (DVCS), of exclusive electroproduction of all vector mesons as well as of elastic pp scattering is suggested.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Hadron structure from lattice QCD

Recent progress in lattice QCD calculations of nucleon structure will be presented. Calculations of nucleon matrix elements and form factors have long been difficult to reconcile with experiment, but with advances in both methodology and computing resources, this situation is improving. Some calculations have produced agreement with experiment for key observables such as the axial charge and electromagnetic form factors, and the improved understanding of systematic errors will help to increase confidence in predictions of unmeasured quantities. The long-omitted disconnected contributions are now seeing considerable attention and some recent calculations of them will be discussed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Hadronic molecules in the heavy baryon spectrum

We study possible baryon molecules in the non-strange heavy baryon spectrum. We include configurations with a heavy-meson and a light baryon. We find several structures, in particular we can understand the Λ{sub c}(2940) as a D*N molecule with J{sup P} = 3/2{sup −} quantum numbers. We also find D{sup (*)}Δ candidates for the recently discovered X{sub c}(3250) resonance.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

A new hadron spectroscopy

Many candidate multiquark mesons, i.e., mesons with substructures that are more complex that the quark-antiquark prescription that is in the textbooks, have recently been observed. Many of the most recently observed candidate states are electrically charged and have the same spin and parity, namely J{sup P} = 1{sup +}. In this talk I give an overview of the current experimental situation with emphasis on some recent results.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Nuclear Material Characterization Using High-Energy X-rays at BNL Synchrotrons: From Reactor Steels and Molten Salts to Large Hadron Collider Novel Materials

New and improved materials, composites, and super-alloys capable of withstanding the anticipated extreme states of fusion reactors, fission reactors (i.e., high-temperature fast reactors) and multi-MW particle accelerators, with the latter facing similarly extreme states to reactors under energetic protons, are continuously sought. Materials structures like improved reactor steels, super-alloys, and novel composites are continuously being explored to help meet both the challenge of the higher-demand environments and longevity under extreme conditions. Greater fluxes of irradiating species (primarily fast neutrons and energetic protons), extreme temperatures, and aggressively corrosive environments make up the new cocktail of operating conditions these materials must withstand. A challenge in characterizing the effects under intense irradiation, high temperatures, and stresses is the establishment of the link between lattice-induced damage and phase transformation under particle irradiation and macroscopic physical properties, which ultimately determine performance in the real environment. With ever increasing irradiation fluxes, dramatic changes in the material properties are expected to occur stemming from the evolution or development of new microstructures.

36 MATERIALS SCIENCE↗
DOE OSTI2013

COOLING OF COMPACT STARS WITH COLOR SUPERCONDUCTING PHASE IN QUARK-HADRON MIXED PHASE

We present a new scenario for the cooling of compact stars considering the central source of Cassiopeia A (Cas A). The Cas A observation shows that the central source is a compact star that has high effective temperature, and it is consistent with the cooling without exotic phases. The observation also gives the mass range of M {>=} 1.5 M {sub Sun }, which may conflict with the current plausible cooling scenario of compact stars. There are some cooled compact stars such as Vela or 3C58, which can barely be explained by the minimal cooling scenario, which includes the neutrino emission by nucleon superfluidity (PBF). Therefore, we invoke the exotic cooling processes, where a heavier star cools faster than lighter one. However, the scenario seems to be inconsistent with the observation of Cas A. Therefore, we present a new cooling scenario to explain the observation of Cas A by constructing models that include a quark color superconducting (CSC) phase with a large energy gap; this phase appears at ultrahigh density regions and reduces neutrino emissivity. In our model, a compact star has a CSC quark core with a low neutrino emissivity surrounded by high emissivity region made by normal quarks. We present cooling curves obtained from the evolutionary calculations of compact stars: while heavier stars cool slowly, and lighter ones indicate the opposite tendency without considering nucleon superfluidity. Furthermore, we show that our scenario is consistent with the recent observations of the effective temperature of Cas A during the last 10 years, including nucleon superfluidity.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

The hadronic origin of the hard gamma-ray spectrum from blazar 1ES 1101-232

The very hard γ-ray spectrum from distant blazars challenges the traditional synchrotron self-Compton (SSC) model, which may indicate that there is a contribution from an additional high-energy component beyond the SSC emission. In this paper, we study the possible origin of the hard γ-ray spectrum from distant blazars. We develop a model to explain the hard γ-ray spectrum from blazar 1ES 1101-232. In the model, the optical and X-ray radiation would come from the synchrotron radiation of primary electrons and secondary pairs and the GeV emission would be produced by the SSC process, however, the hard γ-ray spectrum would originate from the decay of neutral pion produced through proton-photon interactions with the synchrotron radiation photons within the jet. Our model can explain the observed spectral energy distribution of 1ES 1101-232 well, especially the very hard γ-ray spectrum. However, our model requires a very large proton power to efficiently produce the γ-ray through proton-photon interactions.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Pion production momentum loss of cosmic ray hadrons

We present new results on the energy loss rate of high energy protons due to pion production in proton–proton interactions. Our calculations are based on the parameterized pion flux of Kelner et al. Our new results are valid for proton energies in the range of 1 GeV ≪ E⩽10{sup 8} GeV, which enhance the valid energy range by orders of magnitude. With these results one can calculate the energy loss due to pion production for cosmic ray protons from low energies to energies between the knee and ankle.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Instrumental Backgrounds to $t\bar{t}$ and Single Top Production at Hadron Colliders

A number of backgrounds to top-quark production at the LHC and Tevatron experiments are characterized as instrumental: beam related-backgrounds, cosmic ray backgrounds, and backgrounds from non-prompt (or fake) leptons. A number of strategies have been deployed in the experiments to minimize these backgrounds and to estimate their rates. The strategies are applied at the level of the accelerator, the detector apparatus, the first few cuts which are common to many physics analyses, and more refined kinematic cuts. Remaining fake lepton background is estimated using sophisticated data-driven techniques. We present here a survey of the state-of-the-art in the reduction of instrumental backgrounds and also their estimation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Electromagnetic effects on the light hadron spectrum

For some time, the MILC Collaboration has been studying electromagnetic effects on light mesons. These calculations use fully dynamical QCD, but only quenched photons, which suffices to NLO in χPT. That is, the sea quarks are electrically neutral, while the valence quarks carry charge. For the photons we use the non-compact formalism. We have new results with lattice spacing as small as 0.045 fm and a large range of volumes. We consider how well chiral perturbation theory describes these results and the implications for light quark masses.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗