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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Search for a Light Sterile Neutrino at Daya Bay

In this study, a search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment’s unique configuration of multiple baselines from six 2.9 GW th nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the 10 - 3 eV 2 < | Δ m 41 2 | < 0.3 eV 2 range. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. The derived limits on sin 2 2 θ 14 cover the 10 - 3 eV 2 ≲ | Δ m 41 2 | ≲ 0.1 eV 2 region, which was largely unexplored.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

A novel approach to the study of conformality in the SU(3) theory with multiple flavors

We investigate the transition between spontaneous chiral symmetry breaking and conformal behavior in the SU(3) theory with multiple fermion flavors. We propose a new strategy for studying this transition. Instead of changing the number of flavors, we lift the mass of a subset of the fermions, keeping the rest of the fermions near the massless chiral limit in order to probe the transition.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Relation between two-point Green’s functions of N=1 SQED with N{sub f} flavors, regularized by higher derivatives, in the three-loop approximation

We verify the identity which relates the two-point Green’s functions of N=1 SQED with N{sub f} flavors, regularized by higher derivatives, by explicit calculations in the three-loop approximation. This identity explains why, in the limit of the vanishing external momentum, the two-point Green’s function of the gauge superfield is given by integrals of double total derivatives in the momentum space. It also makes it possible to exactly derive the NSVZ β-function in all loops if the renormalization group functions are defined in terms of the bare coupling constant. In order to verify the considered identity, we use it to construct integrals giving the three-loop β-function starting from the two-point Green’s functions of matter superfields in the two-loop approximation. Then we demonstrate that the results for these integrals coincide with the sums of the corresponding three-loop supergraphs.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Chiral and deconfinement phase transitions in QED{sub 3} with finite gauge boson mass

Based on the experimental observation that there is a coexisting region between the antiferromagnetic (AF) and d-wave superconducting (dSC) phases, the influences of gauge boson mass m{sub a} on chiral symmetry restoration and deconfinement phase transitions in QED{sub 3} are investigated simultaneously within a unified framework, i.e., Dyson–Schwinger equations. The results show that the chiral symmetry restoration phase transition in the presence of the gauge boson mass m{sub a} is a typical second-order phase transition; the chiral symmetry restoration and deconfinement phase transitions are coincident; the critical number of fermion flavors N{sup c}{sub f} decreases as the gauge boson mass m{sub a} increases, which implies that there exists a boundary that separates the N{sup c}{sub f}–m{sub a} plane into chiral symmetry breaking/confinement region for (N{sup c}{sub f}, m{sub a}) below the boundary and chiral symmetry restoration/deconfinement region for (N{sup c}{sub f}, m{sub a}) above it.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Neutrino Oscillation Processes with a Change of Lepton Flavor in Quantum Field-Theoretical Approach

The oscillating probabilities of lepton flavor changing neutrino oscillation processes, where neutrinos are detected by weak charged-current and neutral-current interactions, are calculated in a quantum field-theoretical approach to neutrino oscillations based on a modification of the Feynman propagator in the momentum representation. The approach is most similar to the standard Feynman diagram technique in the momentum representation. It is found that the oscillating distance-dependent probabilities of detecting an electron in experiments with neutrino production in the muonic decay of π{sup +}-meson and the detection of the produced neutrino by charged-current and neutral-current interactions exactly coincide with the corresponding probabilities calculated in the standard approach.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Interaction of waves with a birefringent medium moving with acceleration

Recent experiments demonstrated that the energy of a neutron traversing an accelerated sample of a refractive medium changes. Later, it was realized that such an accelerated-medium effect (AME) is quite a general phenomenon characteristic of waves and particles of different nature. This paper discusses some special features of the effect for a birefringent medium. In this case, AME shows quite new features. In neutron optics, where birefringence is due to the spin dependence of the refractive index, AME results in a nonstationary state with a precessing spin. In the case of the propagation of a two-flavor neutrino through an accelerated layer of matter, AME affects substantially the ensuing evolution of a neutrino flavor state as it propagates through a free space.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Projection quantum mechanics and neutrino mixing

The theory of neutrino oscillations rests on the assumption, that the interaction basis and the physical (mass) basis of neutrino states are different. Therefore neutrino is produced in a certain welldefined superposition of three mass eigenstates, which propagate separately and may be detected as a different superposition. This is called flavor oscillations. It is, however, not clear why neutrinos behave this way, i.e., what is the underlying mechanism which leads to the production of a superposition of physical states in a single reaction. In this paper we argue, that one of the reasons may be connected with the temporal structure of the process. In order to discuss the role of time in processes on the quantum level, we use a special formulation of the quantum mechanics, which is based on the projection time evolution. We arrive at the conclusion, that for short reaction times the formation of a superposition of states of similar masses is natural.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2017

Single-flavor Abelian mirror symmetry on ℝℙ{sup 2} × S{sup 1}

The superconformal index on ℝℙ{sup 2} × S{sup 1} can be derived exactly by the localization technique and applied to the direct proof of Abelianmirror symmetry. We find two sets of parity conditions compatible with the unorientable property of ℝℙ{sup 2} and then rigorously show two kinds of Abelian mirror symmetry via the index on ℝℙ{sup 2} × S{sup 1}.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Recent STAR results on W production and asymmetry in polarized p-vector + p-vector collisions at √r = 500 GeV

The production of W± bosons in longitudinally polarized proton + proton collisions at RHIC is a unique way to study the flavor-dependent spin structure of the proton, since at leading order it couples directly and exclusively to specific quark flavor pairings: u+ d-bar →W{sup +} and u-bar +d→W{sup −}. Measurement of the longitudinal single-spin asymmetry of the electron decay daughters in W production is sensitive to the polarizations of the quarks involved. Results: from the first proton-proton collisions at √r = 500 GeV in 2009 are presented, along with a discussion of the forward-rapidity tracking upgrade.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

A new forward spectrometer for PHENIX

In the last decade PHENIX has accessed via longitudinal double spin asymmetries the gluon helicity inside the proton, started probing flavor dependent valence and sea quark helicity distributions and started to explore the proton transverse spin structure. A major upgrade is planned for the next decade that will provide an increased acceptance and additional tracking and electromagnetic plus hadronic calorimetry in the forward region. Here, the layout of the new forward detector system will be discussed, together with the new insights in the proton spin structure that the new forward PHENIX spectrometer will provide.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Flavor dependent azimuthal asymmetries in unpolarized semi-inclusive DIS at HERMES

The azimuthal cosϕ{sub h} and cos2ϕ{sub h} modulations of the distribution of hadrons produced in unpolarized semi-inclusive deep-inelastic scattering of electrons and positrons off hydrogen and deuterium targets have been measured in the hermes experiment. For the first time these modulations were determined in a 4-Dimensional kinematic space for positively and negatively charged pions and kaons separately, as well as for unidentified hadrons. These azimuthal dependences are sensitive to the transverse motion and polarization of the quarks within the nucleon via, e.g., the Cahn, Boer-Mulders and Collins effects.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Prospects of the search for neutrino bursts from supernovae with Baksan large volume scintillation detector

Observing a high-statistics neutrino signal from the supernova explosions in the Galaxy is a major goal of low-energy neutrino astronomy. The prospects for detecting all flavors of neutrinos and antineutrinos from the core-collapse supernova (ccSN) in operating and forthcoming large liquid scintillation detectors (LLSD) are widely discussed now. One of proposed LLSD is Baksan Large Volume Scintillation Detector (BLVSD). This detector will be installed at the Baksan Neutrino Observatory (BNO) of the Institute for Nuclear Research, Russian Academy of Sciences, at a depth of 4800 m.w.e. Low-energy neutrino astronomy is one of the main lines of research of the BLVSD.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

SUSY-Like Relation in Evolution of Gluon and Quark Jet Multiplicities

We show the new relationship [1] between the anomalous dimensions, resummed through next-to-next-to-leading-logarithmic order, in the Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) evolution equations for the first Mellin moments D{sub q,g}(μ{sup 2}) of the quark and gluon fragmentation functions, which correspond to the average hadron multiplicities in jets initiated by quarks and gluons, respectively. This relationship, which is independent of the number of quark flavors, strongly improves previous treatments by allowing for an exact solution of the evolution equations. So far, such relationships have only been known from supersymmetric QCD.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Inclusive muon and $B$ quark production cross-sections in $p \bar{p}$ collisions at $\sqrt{s}$ = 1.8-TeV

We have calculated the double and triple differential cross sections for electron ejection with energy of 14.6 eV in single ionization of H2 by 75 keV proton impact. A molecular version of the continuum distorted wave-eikonal initial state approach is applied, where the interaction between the projectile and the residual molecular ion is considered more properly than in previous applications of the method. For triple differential cross sections, the present results are in better agreement with the experimental data than those of other descriptions when large momentum transfer values are considered. For double differential cross sections the experimental data are reproduced quite well for both coherent and incoherent proton beams.

DIFFERENTIAL CROSS SECTIONS↗
DOE OSTI2014

Research in theoretical nuclear and neutrino physics. Final report

The main focus of the research supported by the nuclear theory grant DE-FG02-04ER41319 was on studying parton dynamics in high-energy heavy ion collisions, perturbative approach to charm production and its contribution to atmospheric neutrinos, application of AdS/CFT approach to QCD, neutrino signals of dark mattter annihilation in the Sun and on novel processes that take place in dense stellar medium and their role in stellar collapse, in particular the effect of new neutrino interactions on neutrino flavor conversion in Supernovae. We present final technical report on projects completed under the grant.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2016

Research and Development for the Mu2e Extinction Monitor

Mu2e is a planned experiment to search for flavor-violating conversion from a muon to an electron. The experiment will use a pulsed 8 GeV proton beam to produce muons which will then stop in an aluminum target. Mu2e will search for the $\mu^- + Al \rightarrow e^- + Al$ process. For Mu2e, an extinction rate of 10$^{-10}$ is required to reduce the backgrounds to an acceptable level. Extinction is the ratio of the amount of protons striking the production target between beam pulses to the number striking it during the beam pulse. One of the backgrounds, off-target interactions, was simulated using G4beamline and Fermilab's Grid setup to confirm that an extinction rate of 10$^{-10}$ is possible. The extinction level will be measured by the extinction monitor which will include scintillation counters read out by photomultiplier tubes. In order to build a beam time profile, low fake responses (after pulses) are needed in the photomultiplier tubes. This thesis determines the best combination of resistors, voltage, and other components that provide the lowest after pulse rate.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Nuclear Matter in 1 + 1 Dimensions

We review the solution of QCD in two spacetime dimensions. Following the analysis of Baluni, for a single flavor, the model can be analyzed using Abelian bosonization. The theory can be analyzed in strong coupling, when the quarks are much lighter than the gauge coupling. In this limit, the theory is given by a Luttinger liquid.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗