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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Field Theory of the Fermi Function

The Fermi function F ( Z , E ) accounts for QED corrections to beta decays that are enhanced at either small electron velocity β or large nuclear charge Z . For precision applications, the Fermi function must be combined with other radiative corrections and with scale- and scheme-dependent hadronic matrix elements. We formulate the Fermi function as a field theory object and present a new factorization formula for QED radiative corrections to beta decays. We provide new results for the anomalous dimension of the corresponding effective operator complete through three loops, and resum perturbative logarithms and π enhancements with renormalization-group methods. Our results are important for tests of fundamental physics with precision beta decay and related processes. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Conservative Spin-Magnitude Change in Orbital Evolution in General Relativity

We show that physical scattering observables for compact spinning objects in general relativity can depend on additional degrees of freedom in the spin tensor beyond those described by the spin vector alone. The impulse, spin kick, and leading-order waveforms exhibit such a nontrivial dependence. A signal of this additional structure is the change in the magnitude of the spin vector under conservative Hamiltonian evolution, similar to our previous studies in electrodynamics. These additional degrees of freedom describe dynamical mass multipoles of compact objects and decouple for black holes. We also show that the conservative impulse, spin kick, and change of the additional degrees of freedom are encoded in the eikonal phase.

Classical black holes↗
DOE OSTI2024

Interaction-enhanced nesting in spin-fermion and Fermi-Hubbard models

The spin-fermion (SF) model postulates that the dominant coupling between low-energy fermions in near critical metals is mediated by collective spin fluctuations (paramagnons) peaked at the Néel wave vector, Q N , connecting hot spots on opposite sides of the Fermi surface. It has been argued that strong correlations at hot spots lead to a Fermi surface deformation (FSD) featuring flat regions and increased nesting. This conjecture was confirmed in the perturbative self-consistent calculations when the paramagnon propagator dependence on momentum deviation from Q N is given by χ − 1 ∝ | Δ q | . Using diagrammatic Monte Carlo (diagMC) technique we show that such a dependence holds only at temperatures orders of magnitude smaller than any other energy scale in the problem, indicating that a different mechanism may be at play. Instead, we find that a χ − 1 ∝ | Δ q | 2 dependence yields a robust finite- T scenario for achieving FSD. To link phenomenological and microscopic descriptions, we applied the connected determinant diagMC method to the ( t − t ′ ) Hubbard model and found that at large U / t > 5.5 before the formation of electron and hole pockets (i) the FSD defined as a maximum of the spectral function is not very pronounced; instead, it is the lines of zeros of the renormalized dispersion relation that deforms toward nesting, and (ii) the static spin susceptibility is well described by χ − 1 ∝ | Δ q | 2 . Flat FS regions yield a nontrivial scenario for realizing a non-Fermi liquid state. Published by the American Physical Society 2024

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Single-valued representation of unpolarized and polarized semi-inclusive deep inelastic scattering at next-to-next-to-leading order

We revisit the recently published analytic results for unpolarized and polarized semi-inclusive deep inelastic scattering (SIDIS) at next-to-next-to-leading order (NNLO) in quantum chromodynamics (QCD). These expressions for the hard scattering coefficients contain case distinctions in the kinematic (𝑥,𝑧)-plane, splitting the analytic result into four regions. By reexpressing the coefficient functions in terms of single-valued polylogarithms, we remove these case distinctions and can present a unified result valid across the entire kinematic range of SIDIS. This reduces the length of the overall expressions by 30% to 60%.

Deep inelastic scattering↗
DOE OSTI2023

Lowest-order QED radiative corrections in unpolarized elastic electron–deuteron scattering beyond the ultra-relativistic limit for the proposed deuteron charge radius measurement at Jefferson laboratory

Analogous to the well-known proton charge radius puzzle, a similar puzzle exists for the deuteron charge radius, r d . There are discrepancies observed in the results of r d , measured from electron-deuteron (e - d) scattering experiments, as well as from atomic spectroscopy. In order to help resolve the charge radius puzzle of the deuteron, the PRad collaboration at Jefferson Lab has proposed an experiment for measuring r d , named DRad. This experiment is designed to measure the unpolarized elastic e - d scattering cross section in a low-Q 2 region. To extract the cross section with a high precision, having reliable knowledge of QED radiative corrections is important. Here, in this paper, we present complete numerical calculations of the lowest-order radiative corrections in e - d scattering for the DRad kinematics. The calculations have been performed within a covariant formalism and beyond the ultra-relativistic approximation ($m^2_e$ $\ll$ Q 2 ). Besides, we present a systematic uncertainty on r d arising from higher-order radiative corrections, estimated based on our cross-section results.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1966

Electromagnetic form factor of the neutrino.

Electromagnetic form factors of electron and muon neutrinos evaluated, using intermediate vector- boson theory, noting renormalization induced by electromagnetic interactions

PARTICLE THEORY↗
NASA NTRS1967

The nature of intermolecular forces.

Intermolecular forces theory, considering hydrogen atom interaction through Born- Oppenheimer approximation and variational calculations

ATOMIC COLLISION↗
NASA NTRS1977

On the high correlation between long-term averages of solar wind speed and geomagnetic activity

Six-month and yearly averages of solar-wind speed from 1962 to 1975 are shown to be highly correlated with geomagnetic activity as measured by averages of the Ap index. On the same time scale the correlation between the southward component of the interplanetary magnetic field and geomagnetic activity is poor. Previous studies with hourly averages gave opposite results. The better correlation with the southward component on an hourly time scale is explained by its large variation compared with the relatively constant solar-wind speed. However, on a yearly time scale the magnitude of the variations in both parameters are about the same. This problem can be solved by invoking an energy transfer mechanism which is proportional to the first power of the southward component and a higher power of the solar-wind speed.

Crooker, N. U.↗
NASA NTRS1980

Variations of the solar wind and solar cycle in the last 300 years

The past history of the solar wind and solar cycle, inferred from records of geomagnetics and aurora, is examined. Records show that the solar wind apparently varied in a systematic manner throughout the period from 1770 to 1857 and that the period around 1810 resembled the 1901 minimum geomagnetic disturbance. Results show that the solar wind and hence the Sun changes on a time scale long compared to a solar cycle and short compared to the Maunder minimum. The inclusion of a study on the solar wind and solar cycle variations for the SCADM mission is discussed.

Feynman, J.↗
NASA NTRS1979

Solar wind and magnetosphere interactions

The relationship between the magnetosphere and the solar wind is addressed. It is noted that this interface determines how much of the solar plasma and field energy is transferred to the Earth's environment, and that this coupling not only varies in time, responding to major solar disturbances, but also to small changes in solar wind conditions and interplanetary field directions. It is recommended that the conditions of the solar wind and interplanetary medium be continuously monitored, as well as the state of the magnetosphere. Other recommendations include further study of the geomagnetic tail, tests of Pc 3,4 magnetic pulsations as diagnostics of the solar wind, and tests of kilometric radiation as a remote monitor of the auroral electrojet.

Russell, C. T.↗
NASA NTRS1979

Review of selected geomagnetic activity indices

Magnetic activity indexes are reviewed. Classifications of magnetograms from single observatories and the global range of potential associated with the equivalent currents which could have produced the variations monitored at a large array of recording sides are addressed. Principal magnetic activity indexes discussed include: the auroral electrojet index and its associated indexes (AU, AL and AO) useful for auroral zone studies; the Kp, ap, aa and am indexes which are measures of midlatitude geomagnetic activity; and the Dst index of magnetic activity recorded at low latitudes. It is concluded that geomagnetic activity indexes are useful in studies of the interaction between solar activity, the interplanetary magnetic field and solar wind, the magnetosphere, ring current, field aligned currents, and ionospheric currents.

Allen, J. H.↗
NASA NTRS1981

Propagating substorm injection fronts

It is argued that a series of two-satellite observations leads to a clarification of substorm plasma injection, in which boundary motion plays a major role. Emphasis is put on a type of event characterized by abrupt, dispersionless changes in electron intensity and a coincident perturbation that consists of both a field magnitude increase and a small rotation toward more dipolar orientation. Comparing plasma observations at two points, it is found that in active, preinjection conditions the two most important features of the plasma sheet are: (1) the low-energy convection boundary for near-zero energy particles, determined by the magnitude of the large-scale convection electric field; and (2) the precipitation-flow boundary layer between the hot plasma sheet and the atmospherically contaminated inner plasma sheet.

Moore, T. E.↗
NASA NTRS1980

Operation of SC5 rapid scan particle spectrometer on SCATHA satellite

The SC5 rapid scan particle spectrometer, operating on the SCATHA satellite, is discussed. SC5 in-orbit operation and reduction of electrostatic analyzer (ESA) spectra are addressed. ESA data summaries from ion and electron gun operations are explained. Data from gun operations show how the satellite potential responds and provide information on the various time constants involved.

Hanser, F. A.↗
NASA NTRS1980

Three-dimensional analysis of charging events on days 87 and 114, 1979, from SCATHA

Angular distributions of ions and electrons from the Spacecraft Charging at High Altitudes (SCATHA) were investigated for the floating potential and the differential charging of the spacecraft as deduced from Liouville's theorem. The following was found: (1) short time charging events on the spacecraft are associated with short time increases of the intensity of 10 keV to 1 MeV electrons; (2) short time changes of the spacecraft differential potential are associated with simultaneous short time changes of the spacecraft floating potential; (3) solar UV intensities in penumbra anticorrelate with the spacecraft floating potentials; (4) NASCAP predicts correct forms of sunshade asymmetric surface potentials; (5) certain enhancements of the intensity of energetic ions diminishes the absolute value of the spacecraft surface potential; (6) spacecraft discharging events in times shorter than 20 sec did not change in the spectrum of the energetic plasma; (7) partial discharging of the spacecraft occurred upon entry into a magnetically depleted region; and (8) steady state potentials and transient potentials of duration less than 30 seconds are simulated by the NASCAP code.

Saflekos, N. A.↗
NASA NTRS1980

Disappearance and reappearance of particles of energies 50 keV as seen by P78-2 (SCATHA) near geosynchronous orbit

The nightside particle environment as observed by the AFGL Rapid Scan Particle Detector on SCATHA showing large, sudden simultaneous changes in the fluxes of electrons and protons with energies above 50 keV (dropouts) is considered. An interesting feature of SCATHA dropouts is the quasiperiodic behavior of the particle flux amplitudes which often vary with a period of the order of 15 minutes both during the dropout and after the return. A flux return during eclipse caused a major spacecraft charging event of several kilovolts. The SCATHA observations are compared with those reported for other geosynchronous satellites. In agreement with ATS-5, a marked dependence in the frequency of occurrence due to an effect of the orbit is found. ATS-5 experienced few dropouts during quiet geomagnetic conditions. However, for an L shell greater than seven, SCATHA particle dropouts occur routinely during quiet conditions. Thus, for SCATHA's orbit, both the orbital position and geomagnetic conditions must be taken into account in evaluating the potential hazard of flux returns.

Feynman, J.↗
NASA NTRS1983

Solar wind variations in the 60-100 year period range: A review

The evidence for and against the reality of a solar wind variation in the period range of 60-100 years is reexamined. Six data sets are reviewed; sunspot numbers, geomagnetic variations, two auroral data sets and two (14)C data sets. These data are proxies for several different aspects of the solar wind and the presence or absence of 60-100 year cyclic behavior in a particular data set does not necessarily imply the presence or absence of this variation in other sets. It was concluded that two different analyses of proxy data for a particular characteristic of the heliospheric solar wind yielded conflicting results. This conflict can be resolved only by future research. It is also definitely confirmed that proxy data for the solar wind in the ecliptic at 1 A.U. undergo a periodic variation with a period of approximately 87 years. The average amplitude and phase of this variation as seen in eleven cycles of proxy data are presented.

Feynman, J.↗