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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

On baryogenesis from dark matter annihilation

We study in detail the conditions to generate the baryon asymmetry of the universe from the annihilation of dark matter. This scenario requires a low energy mechanism for thermal baryogenesis, hence we first discuss some of these mechanisms together with the specific constraints due to the connection with the dark matter sector. Then we show that, contrary to what stated in previous studies, it is possible to generate the cosmological asymmetry without adding a light sterile dark sector, both in models with violation and with conservation of B−L. In addition, one of the models we propose yields some connection to neutrino masses.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

B hadrons spectroscopy at the D0 experiment

The latest results on B hadron spectroscopy from the DOe experiment at the Tevatron are presented. The mass measuremen of the B{sub c}{sup -} meson in the B{sub c}{sup -}{yields}J/{psi}{pi}{sup -} decay channel, the observation of excited B{sub s} mesons, the first direct observation of the {Xi}{sub b}{sup -} baryon, and the first observation of the {Omega}{sub b}{sup -} baryon.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Ab initio nuclear structure from lattice effective field theory

This proceedings article reviews recent results by the Nuclear Lattice EFT Collaboration on an excited state of the {sup 12}C nucleus known as the Hoyle state. The Hoyle state plays a key role in the production of carbon via the triple-alpha reaction in red giant stars. We discuss the structure of low-lying states of {sup 12}C as well as the dependence of the triple-alpha reaction on the masses of the light quarks.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Competition of Short-Range and Long-Range Mechanisms of Spectral Line Broadening in Emission of Atomic and Molecular Gases

An analogy is shown for broadening the spectral line of atoms in the case of competition between the short-range Doppler broadening mechanism and the long-range impact mechanism in atomic gases, as well as for the absorption band of a molecular gas in the infrared (IR) region of the spectrum, where the longrange part of the spectrum is also determined by the impact mechanism of the broadening. The long-range part in the pedestal region of the absorption band is associated with the distribution of molecules over the rotational states, and, in the range of wings of the absorption band, it is due to a finite time of collisions between emitting and perturbed molecules. The flux of resonant radiation produced by an excited atomic gas is estimated using the concepts of the spectral absorption band and a large optical thickness of the gas. These concepts are used for a molecular gas where, in the framework of the regular model (the Elsasser model), expressions are given for the absorption coefficient related to a specific spectral absorption band, separately in the pedestal region and for wings of the absorption band. As a demonstration of the possibilities of these concepts, the IR flux is calculated on the surface of Venus from its atmosphere, which includes seven vibrational transitions of the carbon dioxide molecule and amounts to 26% of the total flux of IR radiation emitted by the Venus surface. An analysis of the Venus energy balance leads to the conclusion that the main part of IR radiation of the Venus atmosphere falling on its surface is formed by a microscopic dust in the Venus atmosphere. This channel of the Venus energy balance is realized if the mass of a microscopic dust in the Venus atmosphere is seven orders of magnitude less than the mass of atmospheric carbon dioxide.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2011

pp{yields}p{Lambda}K{sup +} reaction in search for the K{sup -}pp state - quest for a kaonic nuclei

The dibaryonic kaonic nuclear bound state, K{sup -}pp is searched by studying an exclusive p+p{yields}p+{Lambda}+K{sup +} process at several beam energies. A signature of the K{sup -}pp is explored in a p+p{yields}X({identical_to}K{sup -}pp)+K{sup +} reaction that follows a decay of the X into p+{Lambda}. We found in a missing-mass {Delta}M(K{sup +}) spectrum and a {Lambda}p invariant-mass M({Lambda}p) spectrum of DISTO data at 2.85 GeV a resonance with M = 2267 MeV/c{sup 2} and {Gamma} = 118 MeV. Those events are found to be associated with a mono energetic kaon. We investigate this resonance as a candidate of the K{sup -}pp further also with a different beam energies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

eA Pion Production at CLAS Aimed at Neutrinos

Preliminary results on semi-inclusive charged pion production in eA collisions at E{sub beam} = 5 GeV/c{sup 2} are presented. The data were collected using the CLAS detector, which is a multipurpose, large acceptance, magnetic spectrometer located in Hall B at the Thomas Jefferson National Accelerator Facility. Distributions in W, Q{sup 2}, p{sub {pi}}, and {theta}{sub {pi}} are shown for data produced using deuterium and carbon targets. Preliminary comparisons with data simulated using the GENIE generator are made. The motivation for this work is to provide distributions useful for tuning the hadronic production models used in extracting results from current and next-generation neutrino oscillation experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Upper bounds on asymmetric dark matter self annihilation cross sections

Most models for asymmetric dark matter allow for dark matter self annihilation processes, which can wash out the asymmetry at temperatures near and below the dark matter mass. We study the coupled set of Boltzmann equations for the symmetric and antisymmetric dark matter number densities, and derive conditions applicable to a large class of models for the absence of a significant wash-out of an asymmetry. These constraints are applied to various existing scenarios. In the case of left- or right-handed sneutrinos, very large electroweak gaugino masses, or very small mixing angles are required.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

Quark matter and meson properties in a Nonlocal SU(3) chiral quark model at finite temperature

We study the finite temperature behavior of light scalar and pseudoscalar meson properties in the context of a three-flavor nonlocal chiral quark model. The model includes mixing with active strangeness degrees of freedom, and takes care of the effect of gauge interactions by coupling the quarks with a background color field. We analyze the chiral restoration and deconfinement transitions, as well as the temperature dependence of meson masses, mixing angles, and decay constants.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

New LHC resonance with mass 750 GeV and the vacuum stability in the Standard Model

In the present talk we show that the correction to the Higgs mass coming from the bound state S of 6 t + 6 t̅ quarks, predicted early by C.D. Froggatt and ourselves, leads to the just borderline of the Standard Model vacuum stability thereby confirming the accuracy of the multiple point principle (principle of degenerate vacua), if a mass of the bound state S coincides with the mass 750 GeV of the new diphoton state recently observed by LHC.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Lepton event rates in neutrino-nucleus DIS

In this work we have studied the nuclear effect in F{sub 2}{sup A}(x) and F{sub 3}{sup A}(x) weak structure functions and calculated {nu}-nucleus cross section using them by taking into account Fermi motion, binding energy, pion and rho meson cloud contributions and shadowing and anti-shadowing effects. The numerical calculations have been performed in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. The results have been compared with the experimental results of NuTeV and CDHSW collaborations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Lattice Calculations of Nucleon Form Factors

We present recent results of calculation of the isovector electromagnetic and axial form factors of the nucleon using lattice QCD with three different lattice actions and pion masses down to m{sub {pi}} > or approx. 300 MeV. Because of the precision of our high-statistics calculations, we can test predictions of baryon chiral perturbation theory for the charge and axial radii of the nucleon. We find that currently available baryon ChPT calculations disagree with our data, indicating that the corresponding effective theory approximations are not valid above m{sub {pi}{approx_equal}3}00 MeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

The CTEQ-JLab global analysis of large-x PDFs

I discuss several corrections to leading twist calculations of nucleon structure functions which are needed to include experimental data at large parton fractional momentum x and at low scales Q{sup 2} in global fits of parton distribution functions. In particular I discuss the results of the CTEQ-JLab global fit, and some work in progress. Topics covered include the interplay of target mass and higher-twist corrections, the importance of nuclear corrections for deuterium target data, and applications to the study of quark-hadron duality. Implications for collider physics are highlighted.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

A resonance interpretation for the nonmonotonic behavior of the {phi} photoproduction cross section near threshold

We study whether the nonmonotonic behavior found in the differential cross section of the {phi}-meson photoproduction near threshold can be described by a resonance. The resonant contribution is evaluated by using an effective Lagrangian approach. We find that, with the assumption of a J{sup P} 3/2{sup -} resonance with mass of 2.10{+-}0.03 GeV and width of 0.465{+-}0.141 GeV, LEPS data can indeed be well described. The ratio of the helicity amplitudes A{sub 1/2}/A{sub 3/2} calculated from the resulting coupling constants differs in sign from that of the known D{sub 13}(2080). We further find that the addition of this postulated resonance can substantially improve the agreement between the existing theoretical predictions and the recent {omega} photoproduction data if a large value of the OZI evading parameter xOZI = 12 is assumed for the resonance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Kaon photoproduction and electroproduction near threshold

We analyze the electromagnetic production of K{sup +}{Lambda} and K{sup 0}{Lambda} near their production thresholds by using isobar models. In the K{sup +}{Lambda} channel we show that the model can nicely describe the available experimental data. In the K{sup 0}{Lambda} channel we demonstrate that the K{sup 0} charge form factor has sizable effects on the longitudinal cross section. By extending the model up to W = 1730 MeV, we are able to observe the existence of the narrow P{sub 11}(J{sup p} = 1/2{sup +}) resonance in the kaon photoproduction process. It is found that the most convincing mass (width) of this resonance is 1650 MeV(5 MeV).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

The weak bound state with the non-zero charge density as the LHC 126.5 GeV state

The self-consistent model of classical field interactions formulated as the counterpart of the quantum electroweak model leads to homogeneous boson ground state solutions in presence of non-zero extended fermionic charge density fluctuations. Two different types of electroweak configurations of fields are analyzed. The first one has non-zero electric and weak charge fluctuations. The second one is electrically uncharged but weakly charged. Both types of configurations have two physically interesting solutions which possess masses equal to 126.67 GeV at the value of the scalar fluctuation potential parameter λ equal to ~0.0652. The spin zero electrically uncharged droplet formed as a result of the decay of the charged one is interpreted as the ~126.5 GeV state found in the Large Hadron Collider (LHC) experiment. (The other two configurations correspond to solutions with masses equal to 123.7 GeV and λ equal to ~0.0498 and thus the algebraic mean of the masses of two central solutions, i.e., 126.67 GeV and 123.7 GeV, is equal to 125.185 GeV.) The problem of a mass of this kind of droplets will be considered on the basis of the phenomenon of the screening of the fluctuation of charges. Their masses are found in the thin wall approximation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Limits of Majorana neutrino mass from combined analysis of data from {sup 76}Ge and {sup 136}Xe neutrinoless double beta decay experiments

We present effective Majorana neutrino mass limits obtained from the joint analysis of the recently published results of {sup 76}Ge and {sup 136}Xe neutrinoless double beta decay (0νββ) experiments, which was carried out by using the Bayesian calculations. Nuclear matrix elements (NMEs) used for the analysis are taken from the works, in which NMEs of {sup 76}Ge and {sup 136}Xe were simultaneously calculated. This reduced systematic errors connected with NME calculation techniques. The new effective Majorana neutrino mass limits less than [85.4–197.0] meV are much closer to the inverse neutrino mass hierarchy region.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Constraints on neutrino masses from future cosmological observations

Constraints on neutrino masses are estimated based on future observations of the cosmic microwave background (CMB) including the B-mode polarization produced by CMB lensing using the Planck satellite, and baryon acoustic oscillations distance scale and the galaxy power spectrum from all-sky galaxy redshift survey in the BigBOSS experiment. We estimate the error in the bound on the total neutrino mass to be Δ∑m{sub v} = 0.012 eV with a 68% confidence level. If the fiducial value of the total neutrino mass is ∑m{sub v} = 0.06 eV, this result implies that the neutrino mass hierarchy must be normal.

79 ASTRONOMY AND ASTROPHYSICS↗