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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 667 records · Page 37
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DOE OSTI2011

On Wilson's theory of confinement

According to recent results, the Gell-Mann-Low function {beta}(g) of four-dimensional {phi}{sup 4} theory is nonalternating and has a linear asymptotics at infinity. According to the Bogoliubov and Shirkov classification, it means the possibility of constructing a continuous theory with finite interaction at large distances. This conclusion is in visible contradiction to the lattice results indicating triviality of {phi}{sup 4} theory. This contradiction is resolved by a special character of renormalizability in {phi}{sup 4} theory: to obtain the continuous renormalized theory, there is no need to eliminate a lattice from the bare theory. In fact, such kind of renormalizability is not accidental and can be understood in the framework of Wilson's many-parameter renormalization group. Application of these ideas to QCD shows that Wilson's theory of confinement is not purely illustrative, but has a direct relation to a real situation. As a result, the problem of analytical proof of confinement and a mass gap can be considered solved, at least on the physical level of rigor.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Charm quark system at the physical point of 2+1 flavor lattice QCD

We investigate the charm quark system using the relativistic heavy quark action on 2+1 flavor PACS-CS configurations previously generated on 32{sup 3}x64 lattice. The dynamical up, down, and strange quark masses are set to the physical values by using the technique of reweighting to shift the quark-hopping parameters from the values employed in the configuration generation. At the physical point, the lattice spacing equals a{sup -1}=2.194(10) GeV and the spatial extent L=2.88(1) fm. The charm quark mass is determined by the spin-averaged mass of the 1S charmonium state, from which we obtain m{sub charm}{sup MS}({mu}=m{sub charm}{sup MS})=1.260(1)(6)(35) GeV, where the errors are due to our statistics, scale determination and renormalization factor. An additional systematic error from the heavy quark is of order {alpha}{sub s}{sup 2}f(m{sub Q}a)(a{Lambda}{sub QCD}), f(m{sub Q}a)(a{Lambda}{sub QCD}){sup 2}, which are estimated to be a percent level if the factor f(m{sub Q}a) analytic in m{sub Q}a is of order unity. Our results for the charmed and charmed-strange meson decay constants are f{sub D}=226(6)(1)(5) MeV, f{sub D{sub s}}=257(2)(1)(5) MeV, again up to the heavy quark errors of order {alpha}{sub s}{sup 2}f(m{sub Q}a)(a{Lambda}{sub QCD}), f(m{sub Q}a)(a{Lambda}{sub QCD}){sup 2}. Combined with the CLEO values for the leptonic decay widths, these values yield |V{sub cd}|=0.205(6)(1)(5)(9), |V{sub cs}|=1.00(1)(1)(3)(3), where the last error is because of the experimental uncertainty of the decay widths.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Ultrafast Multiharmonic Plasmon Generation by Optically Dressed Electrons

Interactions between electrons and photons are a source of rich physics from atomic to astronomical scales. Here, we examine a new kind of electron-photon interaction in which an electron, modulated by light, radiates multiple harmonics of plasmons. The emitted plasmons can be femtosecond in duration and nanometer in spatial scale. The extreme subwavelength nature of the plasmons lowers the necessary input light intensity by at least 4 orders of magnitude relative to state-of-the-art strong-field processes involving bound or free electrons. Here, the results presented here reveal a new means of ultrafast (10–1000 fs) interconversion between photonic and plasmonic energy, and a general scheme for generating spatiotemporally shaped ultrashort pulses in optical materials. More generally, our results suggest a route towards realizing analogues of fascinating physical phenomena like nonlinear Compton scattering in plasmonics and nanophotonics with relatively low intensities, slow electrons, and on nanometer length scales.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Shock interacting with a random array of stationary particles underwater

Accurately predicting the force experienced by particles within a random bed during shock traversal is a challenging problem. In this paper, particle-resolved inviscid simulations of shock propagation over randomly distributed beds are performed, with the goal of quantifying the force on individual particles. Water was considered the continuum material, and then results were compared with previous research completed in air and the differences resulting from these different mediums were examined. Simulations were conducted for four different combinations of incident Mach number and bed volume fraction with the particles remaining stationary. Additionally, time-resolved streamwise and transverse force coefficients were calculated for each particle in the bed. It was observed that while the average force coefficient was similar to that of an isolated particle, the force on individual particles was substantially different. An important observation was that the inviscid drag force on some particles remained consistently positive, but others consistently negative even long after the passage of the shock. This persistent force on the particle was attributed to the potential flow fields that result from neighbors' specific locations upstream and downstream. Similar behavior was observed in the transverse force, with particles experiencing sustained force in the same lateral direction. These persistent forces are inviscid quasisteady contributions which with the viscous counterpart will play an essential role in the particle's long-term dispersion if allowed to move in response to the force.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Isospin symmetry violating effects and scattering length extraction from kaon decays

The isospin symmetry breaking effects in the charged kaons decays to two or three pions are considered. In semileptonic decay K{sup {+-}} {yields} {pi}{sup +}{pi}{sup -}e{sup {+-}}{nu} (called K{sub e4}) these effects turn out to be crucial for correct extraction of {pi}{pi} scattering lengths. Taking in account electromagnetic interaction between the pions in the final state and isospin symmetry breaking due to different masses of charged and neutral pions allows to adjust the values of scattering lengths obtained from experimental data on K{sub e4} decay and predictions of Chiral Perturbation Theory (ChPT). Final state interactions of pions in the decay K{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup 0}{pi}{sup 0} leading to the anomaly (cusp) in the {pi}{sup 0}{pi}{sup 0} invariant mass distribution in the vicinity of charged pions' threshold are discussed and recent results of accounting of the electromagnetic interaction among charged pions leading to {pi}{sup +}{pi}{sup -} bound states (pioniumatom) just under the charged pions' threshold are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Generalized boost transformations in finite volumes and application to Hamiltonian methods

The investigation of hadron interactions within lattice QCD has been facilitated by the well-known quantisation condition, linking scattering phase shifts to finite-volume energies. Additionally, the ability to utilise systems at finite total boosts has been pivotal in smoothly charting the energy-dependent behaviour of these phase shifts. The existing implementations of the quantization condition at finite boosts rely on momentum transformations between rest and moving frames, defined directly in terms of the energy eigenvalues. This energy dependence is unsuitable in the formulation of a Hamiltonian. In this work, we introduce a novel approach to generalise the three-momentum boost prescription, enabling the incorporation of energy-independent finite-volume Hamiltonians within moving frames. We demonstrate the application of our method through numerical comparisons, employing a phenomenological ππ scattering example.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Search for Higgs and Z Boson Decays to Φ γ with the ATLAS Detector

Here a search for the decays of the Higgs and Z bosons to a $\phi$ meson and a photon is performed with a pp collision data sample corresponding to an integrated luminosity of 2.7 fb -1 collected at $\sqrt{s}$ = 13 TeV with the ATLAS detector at the LHC. No significant excess of events is observed above the background, and 95% confidence level upper limits on the branching fractions of the Higgs and Z boson decays to $\phi$γ of 1.4 × 10 -3 and 8.3 x 10 -6 , respectively, are obtained.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Evaluation of stochastic particle dispersion modeling in turbulent round jets

ODT (one-dimensional turbulence) simulations of particle-carrier gas interactions are performed in the jet flow configuration. Particles with different diameters are injected onto the centerline of a turbulent air jet. The particles are passive and do not impact the fluid phase. Their radial dispersion and axial velocities are obtained as functions of axial position. The time and length scales of the jet are varied through control of the jet exit velocity and nozzle diameter. Dispersion data at long times of flight for the nozzle diameter (7 mm), particle diameters (60 and 90 µm), and Reynolds numbers (10, 000–30, 000) are analyzed to obtain the Lagrangian particle dispersivity. Flow statistics of the ODT particle model are compared to experimental measurements. It is shown that the particle tracking method is capable of yielding Lagrangian prediction of the dispersive transport of particles in a round jet. In this study, three particle-eddy interaction models (Type-I, -C, and -IC) are presented to examine the details of particle dispersion and particle-eddy interaction in jet flow.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Fuzzy topology, quantization and gauge invariance

Quantum space-time with Dodson-Zeeman topological structure is studied. In its framework the states of massive particle m correspond to elements of fuzzy set called fuzzy points. Due to their weak (partial) ordering, m space coordinate x acquires principal uncertainty σ{sub x}. Quantization formalism is derived from consideration of m evolution in fuzzy phase space with minimal number of additional assumptions. Particle’s interactions on fuzzy manifold are studied and shown to be gauge invariant.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Experimental study of pp{eta} dynamics with WASA-at-COSY

To investigate the interaction of {eta}-meson with the nucleons, its production, near the kinematical threshold, in proton-proton collisions has been studied with the WASA detector at COSY storage ring in Juelich, Germany. The data has been taken at beam energy 1400 MeV (corresponding to excess energy (Q = 57 MeV). The {eta}-meson was detected via its 3{pi}{sup 0} decay in nearly 4{pi} detector and two protons were measured in forward direction. The determination of four vectors of both protons and the {eta}-meson in the final state allowed to derive complete kinematical information of the pp{eta}-system. The analysis resulted in 9x10{sup 6} events of {eta}{yields}3{pi}{sup 0} giving total production cross-section (8.87{+-}0.03{sub stat}{+-}2.57{sub sys}){mu}b. The angular distribution of {eta}-meson in the center of mass frame is anisotropic and squared invariant mass distributions for proton-proton and proton-{eta} shows deviation from pure phase space.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Deployment and performance of a Low-Energy-Threshold Skipper-CCD inside a nuclear reactor

Charge Coupled Devices (CCD) are being used for reactor neutrino experiments and have already demonstrated their potential in constraining new physics models. The prospect of a Skipper-CCD experiment looking for standard and beyond standard model (BSM) physics in a nuclear reactor has been evaluated for different benchmark scenarios. Here, we report the first installation of a 2-g Skipper-CCD inside the containment building of a 2 GW th nuclear power plant and analyze its performance throughout its first 18 months of operation. The sensor was successfully deployed at Atucha II, in Argentina, 12 meters away from the center of the reactor core. We discuss the challenges involved in the commissioning of the detector and present data acquired during reactor ON and reactor OFF periods, with the sensor functioning with a sub-electron readout noise of 0.17 e - . Based on an exposure of 56.8 g day reactor ON and two reactor OFF data sets with a total exposure of 118.1 g day we characterize the system and evaluate the sensitivity to CEvNS. We achieved a background rate of 33 kdru and a low threshold of 45 eV ee . The ongoing efforts to improve sensitivities to CEvNS and BSM interaction are also discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Neutrino nucleus reactions at high energies within the GiBUU model

The GiBUU model, which implements all reaction channels relevant at medium neutrino energy, is used to investigate the neutrino and antineutrino scattering on iron. Results for integrated cross sections are compared with NOMAD and MINOS data. It is shown, that final state interaction can noticeably change the spectra of the outgoing hadrons. Predictions for the Miner{nu}a experiment are made for pion spectra, averaged over NuMI neutrino and antineutrino fluxes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Oscillation degeneracy in non-standard neutrino interactions

The standard theory describing neutrino oscillations only uses the interactions predicted by the Standard Model of particle physics. However, there is plenty of room for non-standard interactions (NSI) to exist. This is because extra interactions are allowed by experimental error bars and even expected at some level from effective theory arguments. This research is focused on examining the phenomenological consequences of the new physics of NSI at large atmospheric neutrino detectors like IceCube DeepCore. Of particular focus are the degeneracies between and within the standard neutrino oscillation parameters and the NSI parameters. These degeneracies will be explored both analytically and numerically, and strategies to lift them will also be discussed. This research is largely based on [1].

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Bootstrapping closed string field theory

The determination of the string vertices of closed string field theory is shown to be a conformal field theory problem solvable by combining insights from Liouville theory, hyperbolic geometry, and conformal bootstrap. We first demonstrate how Strebel differentials arise from hyperbolic string vertices by performing a WKB approximation to the associated Fuchsian equation, which we subsequently use it to derive a Polyakov-like conjecture for Strebel differentials. This result implies that the string vertices are generated by the interactions of n zero momentum tachyons, or equivalently, a certain limit of suitably regularized on-shell Liouville action. We argue that the latter can be related to the interaction of three zero momentum tachyons on a generalized cubic vertex through classical conformal blocks. We test this claim for the quartic vertex and discuss its generalization to higher-string interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Probing internal structure of {Lambda}(1405) in meson-baryon dynamics with chiral symmetry

The internal structure of the resonant {Lambda}(1405) state is investigated based on meson-baryon coupled-channels chiral dynamics, by evaluating density distributions obtained from the form factors of the {Lambda}(1405) state. The form factors are extracted from current-coupled scattering amplitudes in which the current is coupled to the constituent hadrons inside {Lambda}(1405). Using several probe interactions and channel decomposition, we find that the resonant {Lambda}(1405) state is dominantly composed of widely spread K-bar around N, with a small fraction of the escaping {pi}{Sigma} component.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Glimpsing Colour in a World of Black and White

The past 40 years have taught us that nucleons are built of constituents that carry colour charges with interactions governed by Quantum Chromodynamics (QCD). How experiments (past, present and future) at Jefferson Lab probe colourless nuclei to map out these internal colour degrees of freedom is presented. When combined with theoretical calculations, these will paint a picture of how the confinement of quarks and gluons, and the structure of the QCD vacuum, determine the properties of all (light) strongly interacting states.

Pennington, M. R.↗
DOE OSTI2024

Kinematic Imbalance Measurements with Pionless Events at MicroBooNE

MicroBooNE is an 89-ton liquid argon TPC in the Booster Neutrino Beam at Fermilab. This talk will present two recent measurements of kinematic imbalance in CC0pi events with single protons in the final state, using three years of MicroBooNE data. The two measurements focus on kinematic imbalance in the plane transverse to the neutrino beam, and a generalisation that extends the measurement in the longitudinal direction. These data are highly sensitive to the details of the nuclear ground state, and final state interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗