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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

The diffractive contribution to deep inelastic lepton-proton scattering: Implications for QCD momentum sum rules and parton distributions

The cross section for deep inelastic lepton-proton scattering (DIS) ℓp→ℓ'p'X includes a diffractive deep inelastic (DDIS) contribution ℓp→ℓ'p'X, in which the proton remains intact with a large longitudinal momentum fraction x F greater than 0.9 and small transverse momentum. The DDIS events, which can be identified with Pomeron exchange in the t-channel, account for approximately 10% of all of the DIS events. Thus, when one measures DIS, one automatically includes the leading-twist Bjorken-scaling DDIS events as a contribution to the DIS cross section, whether or not the final-state proton p' is detected. In such events, the missing momentum fraction x p ' ~0.9 carried by the final-state proton p' in the DDIS events could be misidentified with the light-front momentum fraction carried by sea quarks or gluons in the protons' Fock structure. As we shall show in this article, the underlying QCD Pomeron-exchange amplitude which produces the DDIS events does not obey the operator product expansion nor satisfy momentum sum rules. Thus we conclude that the quark and gluon distributions measured in DIS experiments will be misidentified, unless the measurements explicitly exclude the DDIS events and that a correct determination of the parton distribution functions (PDFs) derived from the DIS data requires the explicit subtraction of the DDIS contribution from the full DIS cross section.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Coulomb sum rule for 4 He and 16 O from coupled-cluster theory

We demonstrate the capability of coupled-cluster theory to compute the Coulomb sum rule for the 4 He and 16 O nuclei using interactions from chiral effective field theory. We perform several checks, including a few-body benchmark for 4He. We provide an analysis of the center-of-mass contaminations, which we are able to safely remove. We then compare with other theoretical results and experimental data available in the literature, obtaining a fair agreement. This is a first and necessary step towards initiating a program for computing neutrino-nucleus interactions from first principles in coupled-cluster theory and supporting the experimental long-baseline neutrino program with a state-of-the-art theory that can reach medium-mass nuclei.

6 ≤ A ≤ 19A ≤ 5↗
DOE OSTI2022

Dispersive sum rules in AdS 2

Dispersion relations for S-matrices and CFT correlators translate UV consistency into bounds on IR observables. In this note, we construct dispersive sum rules for 1D CFTs. We use them to prove bounds on higher-derivative couplings in weakly-coupled non-gravitational EFTs in AdS2. At the leading order in the bulk-point limit, the bounds agree with the flat-space result. We compute the leading universal effect of finite AdS radius on the bounds. Along the way, we give an explicit formula for anomalous dimensions in general higher-derivative contact Witten diagrams in AdS 2 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

X-ray Thomson scattering absolute intensity from the f-sum rule in the imaginary-time domain

We present a formally exact and simulation-free approach for the normalization of X-ray Thomson scattering (XRTS) spectra based on the f-sum rule of the imaginary-time correlation function (ITCF). Our method works for any degree of collectivity, over a broad range of temperatures, and is applicable even in nonequilibrium situations. In addition to giving us model-free access to electronic correlations, this new approach opens up the intriguing possibility to extract a plethora of physical properties from the ITCF based on XRTS experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Contribution of nuclear excitation electromagnetic form factors in C 12 and O 16 to the Coulomb sum rule

We report on empirical parametrizations of longitudinal and transverse nuclear excitation electromagnetic form factors in 12 C and 16 O. We extract the contribution of nuclear excitations to the normalized inelastic Coulomb sum rule [S L (q)] as a function of momentum transfer q and find that it is significant (0.29 ± 0.030 at q = 0.22 GeV). The total contributions of nuclear excitations to S L (q) in 12 C and 16 O are found to be equal within uncertainties. Since the cross sections for nuclear excitations are significant, the radiative tails from nuclear excitations should be included in precise calculations of radiative corrections to quasielastic electron scattering at low q and deep-inelastic electron scattering at large energy transfers ν. The parametrizations also serve as a benchmark in testing theoretical modeling of cross sections for excitation of nuclear states in electron and neutrino interactions on nuclear targets at low energies.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2016

Spectral sum rules for confining large-N theories

We consider asymptotically-free four-dimensional large-$N$ gauge theories with massive fermionic and bosonic adjoint matter fields, compactified on squashed three-spheres, and examine their regularized large-$N$ confined-phase spectral sums. The analysis is done in the limit of vanishing ’t Hooft coupling, which is justified by taking the size of the compactification manifold to be small compared to the inverse strong scale Λ ₋1 . We find our results motivate us to conjecture some universal spectral sum rules for these large $N$ gauge theories.

1/N Expansion↗
DOE OSTI2017

Finite-energy sum rules in eta photoproduction off a nucleon

The reaction ${\gamma}N \to {\eta}N$ is studied in the high-energy regime (with photon lab energies $E_{\gamma}^{\textrm{lab}} > 4$ GeV) using information from the resonance region through the use of finite-energy sum rules (FESR). We illustrate how analyticity allows one to map the t-dependence of the unknown Regge residue functions. As a result, we provide predictions for the energy dependence of the beam asymmetry at high energies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Dynamical correlations and nonequilibrium sum rules in photodoped Hubbard ladders

Using matrix product state techniques we study the nonequilibrium dynamical response of the half-filled Hubbard ladder when subject to an optical pump. Optical pumping offers a way of producing and manipulating new strongly correlated phenomena by suppressing existing magnetic correlations. The ladder allows the effects of pump directionality to be investigated, and compared to a single chain it has strong spin-charge coupling and a fully gapped excitation spectrum, promising different nonequilibrium physics. We compute time-dependent correlations, including the nonequilibrium dynamical structure factors for spin and charge. By deriving a combined spin-charge sum rule that applies both in and out-of-equilibrium, we show that spectral weight is pumped directly from the antiferromagnetic spin response into a low energy 𝜔 ∼ 0 charge response below the Mott gap. The transfer of weight is pump direction dependent: pumping directed along the legs disrupts magnetic correlations more than pumping in the rung-direction, even if the post-pump energy density is similar. The charge correlation length is dramatically enhanced by the pump, whilst the spin correlations are most strongly suppressed at nearest- and next-nearest-neighbor spacings. After the pump the system is in a nonthermal correlated metallic state, with gapless charge excitations and approximately equal spin and charge correlation lengths, emphasizing the importance of treating these degrees of freedom on an equal footing in nonequilibrium systems.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Multiple Magnetorotons and Spectral Sum Rules in Fractional Quantum Hall Systems

We study, numerically, the charge neutral excitations (magnetorotons) in fractional quantum Hall systems, concentrating on the two Jain states near quarter filling, ν = 2/7 and ν = 2/9, and the ν = 1/4 Fermi-liquid state itself. In contrast to the ν = 1/3 states and the Jain states near half filling, on each of the two Jain states ν = 2/7 and ν = 2/9 the graviton spectral densities show two, instead of one, magnetoroton peaks. The magnetorotons have spin 2 and have opposite chiralities in the ν = 2/7 state and the same chirality in the ν = 2/9 state. Here, we also provide a numerical verification of a sum rule relating the guiding center spin s¯ with the spectral densities of the stress tensor.

2-dimensional systems↗
DOE OSTI2015

Communication. Kinetics of scavenging of small, nucleating clusters. First nucleation theorem and sum rules

Despite recent advances in monitoring nucleation from a vapor at close-to-molecular resolution, the identity of the critical cluster, forming the bottleneck for the nucleation process, remains elusive. During past twenty years, the first nucleation theorem has been often used to extract the size of the critical cluster from nucleation rate measurements. However, derivations of the first nucleation theorem invoke certain questionable assumptions that may fail, e.g., in the case of atmospheric new particle formation, including absence of subcritical cluster losses and heterogeneous nucleation on pre-existing nanoparticles. Here we extend the kinetic derivation of the first nucleation theorem to give a general framework to include such processes, yielding sum rules connecting the size dependent particle formation and loss rates to the corresponding loss-free nucleation rate and the apparent critical size from a naïve application of the first nucleation theorem that neglects them.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Two-point sum-rules in three-dimensional Yang-Mills theory

We compute the stress-tensor two-point function in three-dimensional Yang-Mills theory to three-loops in perturbation theory. Using its calculable shape at high momenta, we test the notion that its Borel transform is saturated at low energies by the lowest glueball state(s). This assumption provides relatively stable estimates for the mass of the lightest glueball that we compare with lattice simulations. We also provide estimates for the coupling of the lightest glueball to the stress tensor. Along the way, we comment on the extent that such estimates are non-rigorous. Lastly, we discuss the possibility of applying the sum-rule analysis to two-point functions of higher-spin operators and obtain a crude approximation for the glueball couplings to these operators.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

The QCD axion sum rule

Abstract We demonstrate that the true QCD axion that solves the strong CP problem can be found in all generality outside the customary standard QCD band, with QCD being the sole source of Peccei-Quinn breaking. The essential reason is that the basis of axion-gluon interactions does not need to coincide with the mass basis. Specifically, we consider the case in which the QCD axion field is not the only singlet scalar in Nature but it mixes with other singlet scalars (besides theη′). We determine the exact mathematical condition for an arbitraryN-scalar potential to be Peccei-Quinn invariant. Such potentials provide extra sources of mass for the customary axion without enlarging the Standard Model gauge symmetry. The contribution to the axion mass stemming from the QCD topological susceptibility is shown to be shared then among theNaxion eigenstates through a precise sum rule. Their location can only be displaced to the right of the standard QCD band. We demonstrate that the axion closest to this band can be displaced from it by a factor of$$ \sqrt{N} $$ N at most, and this corresponds to the case in which all axion signals are maximally deviated. Conversely, if one axion is found on the standard QCD band, the other eigenstates will be out of experimental reach. Our results imply that any ALP experiment which finds a signal to the right of the standard QCD axion band can be solving the strong CP problem within QCD, with the associatedN− 1 excitations to be found in an area of parameter space that we determine. We illustrate the results and phenomenology in some particular cases.

Physics↗
DOE OSTI2025

Mass ordering sum rule for the neutrino disappearance channels in T2K, NOvA, and JUNO

We revisit, reformulate, and extend a method for determining the neutrino mass ordering by using precision measurements of the atmospheric Δ m 2 s in both electron and muon neutrino disappearance channels, first proposed by the authors in 2005 [H. Nunokawa , Phys. Rev. D 72, 013009 (2005)]. The mass ordering is a very important outstanding question for our understanding of the elusive neutrino and determination of the mass ordering has consequences to particle physics, nuclear physics, and cosmology. The JUNO reactor experiment will start data taking this year, and the precision of the atmospheric Δ m 2 s from electron antineutrino measurements will improve by a factor of 3 from Daya Bay’s 2.4% to 0.8% within a year. This measurement, when combined with the atmospheric Δ m 2 ’s measurements from T2K and NOvA for muon neutrino disappearance, will contribute substantially to the Δ χ 2 between the two remaining neutrino mass orderings. In this paper we derive for the first time a mass ordering sum rule that can be used to address the possibility that JUNO’s atmospheric Δ m 2 ’s measurement, when combined with other experiments in particular T2K and NOvA, can determine the neutrino mass ordering at the 3 σ confidence level within one year of operation. For a confidence level of 5 σ in a single experiment, we will have to wait until the middle of the next decade when the DUNE experiment is operating.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

The MSR mass and the $ \mathcal{O}\left({\Lambda}_{\mathrm{QCD}}\right) $ renormalon sum rule

Here, we provide a detailed description and analysis of a low-scale short-distance mass scheme, called the MSR mass, that is useful for high-precision top quark mass determinations, but can be applied for any heavy quark Q. In contrast to earlier low-scale short-distance mass schemes, the MSR scheme has a direct connection to the well known MS¯ mass commonly used for high-energy applications, and is determined by heavy quark on-shell self-energy Feynman diagrams. Indeed, the MSR mass scheme can be viewed as the simplest extension of the MS¯mass concept to renormalization scales << mQ. The MSR mass depends on a scale R that can be chosen freely, and its renormalization group evolution has a linear dependence on R, which is known as R-evolution. Using R-evolution for the MSR mass we provide details of the derivation of an analytic expression for the normalization of the $ \mathcal{O}\left({\Lambda}_{\mathrm{QCD}}\right) $ renormalon asymptotic behavior of the pole mass in perturbation theory. This is referred to as the $ \mathcal{O}\left({\Lambda}_{\mathrm{QCD}}\right) $ renormalon sum rule, and can be applied to any perturbative series. The relations of the MSR mass scheme to other low-scale short-distance masses are analyzed as well.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Multi-Higgs doublet models: physical parametrization, sum rules and unitarity bounds

If the scalar sector of the Standard Model is non-minimal, one might expect multiple generations of the hypercharge-1/2 scalar doublet analogous to the generational structure of the fermions. In this work, we examine the structure of a Higgs sector consisting of N Higgs doublets (where N ≥ 2). It is particularly convenient to work in the so-called charged Higgs basis, in which the neutral Higgs vacuum expectation value resides entirely in the first Higgs doublet, and the charged components of remaining N - 1 Higgs doublets are mass-eigenstate fields. We elucidate the interactions of the gauge bosons with the physical Higgs scalars and the Goldstone bosons and show that they are determined by an N × 2N matrix. This matrix depends on (N - 1)(2N - 1) real parameters that are associated with the mixing of the neutral Higgs fields in the charged Higgs basis. Among these parameters, N - 1 are unphysical (and can be removed by rephasing the physical charged Higgs fields), and the remaining 2(N - 1) 2 parameters are physical. We also demonstrate a particularly simple form for the cubic interaction and some of the quartic interactions of the Goldstone bosons with the physical Higgs scalars. These results are applied in the derivation of Higgs coupling sum rules and tree-level unitarity bounds that restrict the size of the quartic scalar couplings. In particular, new applications to three Higgs doublet models with an order-4 CP symmetry and with a Z 3 symmetry, respectively, are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗