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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Relic abundance of MeV millicharged particles

The relic abundance of light millicharged particles (MCPs) with the electric charge e′ = 5 × 10{sup –5}e and with the mass slightly below or above the electron mass is calculated. The abundance depends on the mass ratio η = m{sub X}/m{sub e} and for η < 1 can be high enough to allow MCPs to be the cosmological dark matter or to make a noticeable contribution to it. On the other hand, for η ≳ 1 the cosmological energy density of MCPs can be quite low, Ω{sub X}h{sub 0}{sup 2} ≈ 0.02 for scalar MCPs, and Ω{sub X}h{sub 0}{sup 2} ≈ 0.001 for spin 1/2 fermions. But even the lowest value of Ω{sub X}h{sub 0}{sup 2} is in tension with several existing limits on the MCP abundances and parameters. However, these limits have been derived under some natural or reasonable assumptions on the properties of MCPs. If these assumptions are relaxed, a patch in the mass–charge plot of MCPs may appear, permitting them to be dark matter particles.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

SUSY breaking with D term and gauge mediation

We classify supersymmetry breaking models with the F- and U(1) D-term potentials. In addition to the classification in our previous paper [1], we consider the other class where the F-term potential shows runaway behaviors. It is shown that the runaway in the F-term potential can be uplifted by the D-term effect, and supersymmetry breaking is realized. The vacuum in this class has no pseudomoduli and is useful for gauge mediation because gaugino masses are generated at the one-loop order. We provide such an example without the Fayet-Iliopoulous term.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Sneutrino inflation in supersymmetric B - L with inverse seesaw

We have shown that inflation in the supersymmetric B - L extension of the Standard Model can be realized where one of the associated right-handed sneutrinos can provide a non-trivial inflationary trajectory at tree level (hence breaking B - L during inflation). As soon as the inflation ends, the right-handed sneutrino falls into the supersymmetric vacuum, with a vanishing vacuum expectation value, so that B - L symmetry is restored. The B - L gauge symmetry will be radiatively broken at a TeV scale and light neutrino masses are generated through the inverse seesaw mechanism.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Cosmic rays and hadronic interactions

The cosmic ray spectrum extends to particles with energy E{approx} 10{sup 20} eV, that corresponds (assuming that the primary particle is a proton) to a nucleon-nucleon c.m. energy {radical}(s) Asymptotically-Equal-To 430TeV, 50 times higher than the current LHC energy. These very high energy particles can be studied via the observation of the showers they generate in the atmosphere. The interpretation of the data requires therefore the modeling of hadronic interactions in an energy range beyond what can be studied in accelerator experiments. The theoretical problem of estimating the relevant properties of hadronic interactions in this energy range is therefore of central importance for the interpretation of the cosmic ray data. Viceversa, it is in principle possible to obtain information about hadronic interactions from the cosmic ray observations, but this program has to confront the fact that the (freely available) cosmic ray beam has an unknown energy spectrum and an unknown mass composition.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Parity-Violating PVDIS with SoLID

We are planning an experiment at JLab to measure parity-violation in deep inelastic scattering to high precision over a broad kinematic range. The goal of the experiment is to test the Standard Model, search for charge symmetry violation at the quark level, and to search for higher twist effects due to quark-quark interactions. We will also be able to measure the d/u ratio for the nucleon and search for nuclear effects in deep inelastic scattering.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Low Energy Neutrino and Dark Matter Physics with sub-keV Germanium Detectors

A TEXONO collaboration research program on low energy neutrino and dark matter physics is going on at the Kuo-Sheng Neutrino Laboratory (KSNL). Collaboration main goals are to measure the neutrino-nucleus coherent scattering cross section, neutrino magnetic moments, and the searches of WIMP dark matter. To achieve these goals various prototype detectors and their sub-keV background are under study. A threshold of 220 eV was achieved with prototype detectors at the KSNL. New limits were set for WIMPs with mass between 3-6 GeV. Data are being taken with a 500 g Point Contact Germanium detector, where a threshold of {approx}350 eV was demonstrated. A 20 g ULEGe detector is taking data at CJPL in Sichuan, China.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Charm Baryon Results from BaBar

We present experimental results from the BaBar experiment on charm baryon spectroscopy and production studies, including studies of excited cascades produced in charm baryon decays. We review the discovery of new decay modes of known states and searches for predicted states.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Baryons in and beyond the quark-diquark model

We examine the nucleon's electromagnetic form factors in a Poincare-covariant Faddeev framework. The three-quark core contributions to the form factors are obtained by employing a quark-diquark approximation. We implement the self-consistent solution for the quark-photon vertex from its inhomogeneous Bethe-Salpeter equation. We find that the resulting transverse parts which add to the Ball-Chiu vertex have no significant impact on nucleon magnetic moments. The current-quark mass evolution of the form factors agrees with results from lattice QCD.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Electroweak baryogenesis and dark matter from a singlet Higgs

If the Higgs boson H couples to a singlet scalar S via λ{sub m}|H|{sup 2}S{sup 2}, a strong electroweak phase transition can be induced through a large potential barrier that exists already at zero temperature. In this case properties of the phase transition can be computed analytically. We show that electroweak baryogenesis can be achieved using CP violation from a dimension-6 operator that couples S to the top-quark mass, suppressed by a new physics scale that can be well above 1 TeV. Moreover the singlet is a dark matter candidate whose relic density is ∼<3% of the total dark matter density, but which nevertheless interacts strongly enough with nuclei (through Higgs exchange) to be just below the current XENON100 limits. The DM mass is predicted to be in the range 80–160 GeV.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Experimental search for solar hidden photons in the eV energy range using kinetic mixing with photons

We have searched for solar hidden photons in the eV energy range using a dedicated hidden photon detector. The detector consisted of a parabolic mirror with a diameter of 500 mm and a focal length of 1007 mm installed in a vacuum chamber, and a photomultiplier tube at its focal point. The detector was attached to the Tokyo axion helioscope, Sumico which has a mechanism to track the sun. From the result of the measurement, we found no evidence for the existence of hidden photons and set a limit on the photon-hidden photon mixing parameter χ depending on the hidden photon mass m{sub γ'}.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Exploring leptonic CP violation with a Li/B {beta}-beam from CERN to Gran Sasso

We have considered a {beta}-beam setup which tries to leverage at most existing European facilities to boost high-Q ions aiming at a far detector located at L = 732 km in the Gran Sasso Underground Laboratory. The average neutrino energy obtained from {sup 8}Li and {sup 8}B ions boosted at {gamma}-tilde100 is in the range eV - GeV, high enough to use a large iron detector of the MINOS type. We perform, then, a study of the neutrino and antineutrino fluxes needed to observe CP violation and to establish the neutrino mass hierarchy in a significant part of the parameter space.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

The mass splittings of SU(3) baryons within a chiral soliton model

In the framework of a chiral soliton model ({sub {chi}S}M), the complete mass splittings of SU(3) baryons are investigated, the isospin and SU(3) flavor symmetry breaking being simultaneously considered with a 'model-independent approach'. The dynamical quantities appearing in the expressions for the masses are adjusted to the masses of the baryon octet, the decuplet baryon {Sigma}* and the masses of {Theta}{sup +} and N{sup *} as inputs rather than by extracting them from a calculated self-consistent soliton profile. We estimate the masses of the baryon decuplet and antidecuplet without any further adjustable free parameter and it turns out that calculated mass values of the baryon decuplet are in very good agreement with experimental data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Hyperon vector coupling f{sub 1}(0) from 2+1 flavor lattice QCD

We present results for the hyperon vector form factor f{sub 1} for {Xi}{sup 0}{yields}{Sigma}{sup +}l{nu}-bar and {Sigma}{sup -}{yields}nl{nu}-bar semileptonic decays from dynamical lattice QCD with domain-wall quarks. Simulations are performed on the 2+1 flavor gauge configurations generated by the RBC and UKQCD Collaborations with a lattice cutoff of a{sup -1} = 1.7 GeV. Our preliminary results, which are calculated at the lightest sea quark mass (pion mass down to approximately 330 MeV), show that a sign of the second-order correction of SU(3) breaking on hyperon vector coupling f{sub 1}(0) is likely negative.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Inflation from the Higgs field false vacuum with hybrid potential

We have recently suggested [1,2] that Inflation could have started in a local minimum of the Higgs potential at field values of about 10{sup 15}–10{sup 17} GeV, which exists for a narrow band of values of the top quark and Higgs masses and thus gives rise to a prediction on the Higgs mass to be in the range 123–129 GeV, together with a prediction on the the top mass and the cosmological tensor-to-scalar ratio r. Inflation can be achieved provided there is an additional degree of freedom which allows the transition to a radiation era. In [1] we had proposed such field to be a Brans-Dicke scalar. Here we present an alternative possibility with an additional subdominant scalar very weakly coupled to the Higgs, realizing an (inverted) hybrid Inflation scenario. Interestingly, we show that such model has an additional constraint m{sub H} < 125.3±3{sub th}, where 3{sub th} is the present theoretical uncertainty on the Standard Model RGEs. The tensor-to-scalar ratio has to be within the narrow range 10{sup −4}∼<r < 0.007, and values of the scalar spectral index compatible with the observed range can be obtained. Moreover, if we impose the model to have subplanckian field excursion, this selects a narrower range 10{sup −4}∼<r < 0.001 and an upper bound on the Higgs mass of about m{sub H} < 124±3{sub th}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

An independent limit on the axion mass from the variable white dwarf star R548

Pulsating white dwarfs with hydrogen-rich atmospheres, also known as DAV stars, can be used as astrophysical laboratories to constrain the properties of fundamental particles like axions. Comparing the measured cooling rates of these stars with the expected values from theoretical models allows us to search for sources of additional cooling due to the emission of weakly interacting particles. In this paper, we present an independent inference of the mass of the axion using the recent determination of the evolutionary cooling rate of R548, the DAV class prototype. We employ a state-of-the-art code which allows us to perform a detailed asteroseismological fit based on fully evolutionary sequences. Stellar cooling is the solely responsible of the rates of change of period with time (.Π)) for the DAV class. Thus, the inclusion of axion emission in these sequences notably influences the evolutionary timescales, and also the expected pulsational properties of the DAV stars. This allows us to compare the theoretical .Π) values to the corresponding empirical rate of change of period with time of R548 to discern the presence of axion cooling. We found that if the dominant period at 213.13 s in R548 is associated with a pulsation mode trapped in the hydrogen envelope, our models indicate the existence of additional cooling in this pulsating white dwarf, consistent with axions of mass m{sub a}cos {sup 2}β ∼ 17.1 meV at a 2σ confidence level. This determination is in agreement with the value inferred from another well-studied DAV, G117-B15A. We now have two independent and consistent estimates of the mass of the axion obtained from DAVs, although additional studies of other pulsating white dwarfs are needed to confirm this value of the axion mass.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Constraints on the neutrino parameters by future cosmological 21 cm line and precise CMB polarization observations

Observations of the 21 cm line radiation coming from the epoch of reionization have a great capacity to study the cosmological growth of the Universe. Besides, CMB polarization produced by gravitational lensing has a large amount of information about the growth of matter fluctuations at late time. In this paper, we investigate their sensitivities to the impact of neutrino property on the growth of density fluctuations, such as the total neutrino mass, the effective number of neutrino species (extra radiation), and the neutrino mass hierarchy. We show that by combining a precise CMB polarization observation such as Simons Array with a 21 cm line observation such as Square kilometer Array (SKA) phase 1 and a baryon acoustic oscillation observation (Dark Energy Spectroscopic Instrument:DESI) we can measure effects of non-zero neutrino mass on the growth of density fluctuation if the total neutrino mass is larger than 0.1 eV. Additionally, the combinations can strongly improve errors of the bounds on the effective number of neutrino species σ (N{sub ν}) ∼ 0.06−0.09 at 95 % C.L.. Finally, by using SKA phase 2, we can determine the neutrino mass hierarchy at 95 % C.L. if the total neutrino mass is similar to or smaller than 0.1 eV.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

CAUSE OF SPIRAL GALAXY ROTATION RATES: A MASSIVE GRAVITON

We attribute the observed rotational velocity profiles of spiral galaxy disks to a combination of Newtonian and exponential gravitational potentials. We offer a novel, yet perfectly plausible, Lagrangian from which the exponential potential is derived. The exponential potential is defined by two universal constants (corresponding to a coupling constant and a graviton mass) that we determine from our sample of 12 THINGS disks. All velocity profile fits are excellent.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

Radiative corrections to polarization observables in elastic electron-deuteron scattering in leptonic variables

The model-independent QED radiative corrections to polarization observables in elastic scattering of unpolarized and longitudinally polarized electron beams by a deuteron target are calculated in leptonic variables. The experimental setup when the deuteron target is arbitrarily polarized is considered and the procedure for applying the derived results to the vector or tensor polarization of the recoil deuteron is discussed. The calculation is based on taking all essential Feynman diagrams into account, which results in the form of the Drell-Yan representation for the cross section, and the use of the covariant parameterization of the deuteron polarization state. Numerical estimates of the radiative corrections are given in the case where event selection allows undetected particles (photons and electron-positron pairs) and the restriction on the lost invariant mass is used.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗