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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

SBN-BD: O(10 GeV) Proton Beam Dump at Fermilab’s PIP-II Linac

Proton beam dumps are prolific sources of mesons enabling a powerful technique to search for vector mediator coupling of dark matter to neutral pion and higher mass meson decays. By the end of the decade the PIP-II linac will be delivering up to 1 MW of proton power to the FNAL campus. This includes a significant increase of power to the Booster Neutrino Beamline (BNB) which delivers 8 GeV protons to the Short Baseline Neutrino (SBN) detectors. By building a new dedicated beam dump target station, and using the SBN detectors, a greater than an order of magnitude increase in search sensitivity for dark matter relative to the recent MiniBooNE beam dump search can be achieved. This modest cost upgrade to the BNB would begin testing models of the highly motivated relic density limit predictions and provide novel ways to test explanations of the anomalous excess of low energy events seen by MiniBooNE.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

SBN-BD: $\mathcal{O}$(10 GeV) Proton Beam Dump at Fermilab's PIP-II Linac

Proton beam dumps are prolific sources of mesons enabling a powerful technique to search for vector mediator coupling of dark matter to neutral pion and higher mass meson decays. By the end of the decade the PIP-II linac will be delivering up to 1 MW of proton power to the FNAL campus. This includes a significant increase of power to the Booster Neutrino Beamline (BNB) which delivers 8 GeV protons to the Short Baseline Neutrino (SBN) detectors. By building a new dedicated beam dump target station, and using the SBN detectors, a greater than an order of magnitude increase in search sensitivity for dark matter relative to the recent MiniBooNE beam dump search can be achieved. This modest cost upgrade to the BNB would begin testing models of the highly motivated relic density limit predictions and provide novel ways to test explanations of the anomalous excess of low energy events seen by MiniBooNE.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Relativistic nuclear theory—nucleons and mesons: origin, current status, and trends

The nuclear shell model (NSM) is a fundamental model of nuclear theory. At the initial stage, the NSM was developed on the basis of the Schrödinger equation, in particular because it was not clear which Dirac matrices should be associated with various components of the (relativistic) shell model potential. In the early 1970s, the relativistic version of the NSM with meson fields as its main components was developed on the basis of the Dirac equation. The relativistic nuclear shell model (RNSM) includes meson fields with different space–time transformation properties (scalar, four-vector, etc.) that determine the behavior of the (corresponding) meson fields under Lorentz transformations. This fact directly indicates that nuclear theory should be relativistic and based on the Dirac equation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurement of the beam asymmetry Σ for π 0 and η photoproduction on the proton at E γ = 9 GeV

In this paper, we report measurements of the photon beam asymmetry $\Sigma$ for the reactions $\vec{\gamma}p\to p\pi^0$ and $\vec{\gamma}p\to p\eta $ from the GLUEX experiment using a 9 GeV linearly polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous $\pi^0$ measurements and are the first $\eta$ measurements in this energy regime. Lastly, the results are compared with theoretical predictions based on $t$-channel, quasi-particle exchange and constrain the axial-vector component of the neutral meson production mechanism in these models.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Search for production of an $\Upsilon$(1S) meson in association with a W or Z boson using the full 1.96 TeV $p\bar{p}$ collision data set at CDF

Production of the Υ(1S) meson in association with a vector boson is a rare process in the standard model with a cross section predicted to be below the sensitivity of the Tevatron. Observation of this process could signify contributions not described by the standard model or reveal limitations with the current nonrelativistic quantum-chromodynamic models used to calculate the cross section. We perform a search for this process using the full Run II data set collected by the CDF II detector corresponding to an integrated luminosity of 9.4 fb -1 . Our search considers the Υ→μμ decay and the decay of the W and Z bosons into muons and electrons. Furthermore, in these purely leptonic decay channels, we observe one ΥW candidate with an expected background of 1.2±0.5 events, and one ΥZcandidate with an expected background of 0.1±0.1 events. Both observations are consistent with the predicted background contributions. The resulting upper limits on the cross section for Υ+W/Zproduction are the most sensitive reported from a single experiment and place restrictions on potential contributions from non-standard-model physics.

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 OSTI2025

Light and Strange Vector Resonances from Lattice QCD at Physical Quark Masses

We present the first ab initio calculation at physical quark masses of scattering amplitudes describing the lightest pseudoscalar mesons interacting via the strong force in the vector channel. Using lattice quantum chromodynamics, we postdict the defining parameters for two short-lived resonances, the ρ(770) and K*(892) which manifest as complex energy poles in ππ and Kπ scattering amplitudes, respectively. The calculation proceeds by first computing the finite-volume energy spectrum of the two-hadron systems and then determining the amplitudes from the energies using the Lüscher formalism. The error budget includes a data-driven systematic error, obtained by scanning possible fit ranges and fit models to extract the spectrum from Euclidean correlators, as well as the scattering amplitudes from the latter. The final results, obtained by analytically continuing multiple parametrizations into the complex energy plane, are M ρ = 796(5)(50)MeV, Γ ρ = 192(10)(31) MeV, M K* = 893(2)(54) MeV, and Γ K = 51(2)(11) MeV, where the subscript indicates the resonance and M and Γ stand for the mass and width, respectively, and where the first bracket indicates the statistical and the second bracket the systematic uncertainty.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Many-body forces in the equation of state of hyperonic matter

In this work we introduce an extended version of the formalism proposed originally by Taurines et al. that considers the effects of many-body forces simulated by nonlinear self-couplings and meson–meson interaction contributions. In this extended version of the model, we assume that matter is at zero temperature, charge neutral, and in beta-equilibrium, considering that the baryon octet interacts by the exchange of scalar–isoscalar (σ, σ{sup ∗}), vector–isoscalar (ω, ϕ), vector–isovector (ϱ), and scalar–isovector (δ) meson fields. Using nuclear matter properties, we constrain the parameters of the model that describe the intensity of the indirectly density dependent baryon–meson couplings to a small range of possible values. We then investigate asymmetric hyperonic matter properties. We report that the formalism developed in this work is in reasonable agreement with experimental data and also allows for the existence of massive hyperon stars (with more than 2 M{sub ⊙}) with small radii, compatible with astrophysical observations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Hidden-flavor four-quark states in the charm and bottom region

We discuss the spectrum and the internal composition of ground and excited four-quark states in the charm and bottom energy region. To this end we extend previous calculations within the framework of the relativistic four-body Faddeev-Yakubovsky equation to include quantum numbers with J P C = 0 + + , 0 − + , 1 − − , 1 + − and 1 + + and study their internal composition in terms of heavy-light meson pairs, hadroquarkonia and diquark-antidiquark clusters. We observe similar patterns in the charm and bottom energy region with different compositions of the four-quark states depending on J P C quantum numbers. Most notably, we find that all states with C · P = + 1 are dominated by heavy-light meson contributions, whereas for axial-vector states with J P C = 1 + − including the Z c ( 3900 ) we find a much more complicated picture depending on the flavor content. We systematically compare our results for the spectrum with existing experimental results and provide predictions for future analyses. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2015

New vector-like fermions and flavor physics

We study renormalizable extensions of the standard model that contain vector-like fermions in a (single) complex representation of the standard model gauge group. There are 11 models where the vector-like fermions Yukawa couple to the standard model fermions via the Higgs field. These models do not introduce additional fine-tunings. They can lead to, and are constrained by, a number of different flavor-changing processes involving leptons and quarks, as well as direct searches. An interesting feature of the models with strongly interacting vector-like fermions is that constraints from neutral meson mixings (apart from CP violation in $ {K}^0-{\overline{K}}^0 $ mixing) are not sensitive to higher scales than other flavor-changing neutral-current processes. We identify order 1/(4πM) 2 (where M is the vector-like fermion mass) one-loop contributions to the coefficients of the four-quark operators for meson mixing, that are not suppressed by standard model quark masses and/or mixing angles.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

D mesons in a magnetic field

In this paper, we investigate the mass spectra of open heavy flavor mesons in an external constant magnetic field within QCD sum rules. Spectral Ansatze on the phenomenological side are proposed in order to properly take into account mixing effects between the pseudoscalar and vector channels, and the Landau levels of charged mesons. The operator product expansion is implemented up to dimension-5 operators. As a result, we find for neutral D mesons a significant positive mass shift that goes beyond simple mixing effects. In contrast, charged D mesons are further subject to Landau level effects, which together with the mixing effects almost completely saturate the mass shifts obtained in our sum rule analysis.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Modeling QCD for Hadron Physics

We review the approach to modeling soft hadron physics observables based on the Dyson-Schwinger equations of QCD. The focus is on light quark mesons and in particular the pseudoscalar and vector ground states, their decays and electromagnetic couplings. We detail the wide variety of observables that can be correlated by a ladder-rainbow kernel with one infrared parameter fixed to the chiral quark condensate. A recently proposed novel perspective in which the quark condensate is contained within hadrons and not the vacuum is mentioned. The valence quark parton distributions, in the pion and kaon, as measured in the Drell Yan process, are investigated with the same ladder-rainbow truncation of the Dyson-Schwinger and Bethe-Salpeter equations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Exploring Resonance Structures in the Partial-Wave Analysis of ¿p0 Photoproduction at GlueX

This thesis studies what happens when a photon (¿) collides with a proton (p) and produces a neutral omega (¿) and pion (p0) pair, with a recoiling proton (p'), expressed as ¿p ¿ ¿p0p'. We study this and other reactions to better understand the strong nuclear force; one of the four fundamental forces that govern all the physics of the universe. This force is specifically responsible for the binding and decay of subatomic particles, such as the ones here. While we understand the ¿ and p0, what we are actually interested in is a short-lived unknown particle X that decays via X ¿ ¿p0. There are a multitude of possible particles X can be, and so our focus in this work is to find out what X is by determining its properties from the particles we measure. We do this via an intricate analysis procedure known as “partial-wave analysis”. By analogy, one can think of our particle detector as a buoy, and the particles we want to analyze (X) as pebbles hitting a pond. The waves created by the pebble will move our buoy, giving us information about the pebble that produced the wave. However, when multiple pebbles hit our pond, the waves overlap and interfere with each other. Our buoy only can measure the complicated interfering result of all the waves. To disentangle this, our partial-wave analysis works by modeling this interference pattern so that we may infer the properties of the pebbles (particles) we produced. In this thesis, we review the relevant experimental history in photoproduction and related production mechanisms, as well as the theoretical foundations that motivate our measurement. We describe the methods used to collect our data at the GlueX experiment stationed at the Jefferson Lab accelerator facility in Newport News, Virginia. We then detail the selections we apply to ensure our events are almost exclusively ¿p ¿ ¿p0p'. We cover the intensity model, how we verify its capabilities, and finally present our results together with systematic studies. Our primary result is the detection of a b1(1235) meson interfering with a wide JPC = 1-- vector state, measured via a mass-independent partial-wave analysis. It provides precise experimental results that can be used as input for theoretical models of the reaction, yielding conclusions about the procedures responsible for how our universe behaves at its most basic level.

Scheuer, Kevin [College of William and Mary, Willi↗
DOE OSTI2015

Probing anomalous $ t\overline{t}Z $ interactions with rare meson decays

Anomalous couplings of the Z boson to top quarks are only marginally constrained by direct searches and are still sensitive to new particle dynamics at the TeV scale. Employing an effective field theory approach we consider the dimension-six operators which generate deviations from the standard-model vector and axial-vector interactions. We show that rare B and K meson decays together with electroweak precision observables provide strong constraints on these couplings. In addition, we also consider constraints from t-channel single-top production.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

$D$ meson Semileptonic Decay Form Factors at $q^2 = 0$

We discuss preliminary results for the vector form factors $f_+^{\{\pi,K\}}$ at zero-momentum transfer for the decays $D\to\pi\ell\nu$ and $D\to K \ell\nu$ using MILC's $N_f = 2+1+1$ HISQ ensembles at four lattice spacings, $a \approx 0.042, 0.06, 0.09$, and 0.12 fm, and various HISQ quark masses down to the (degenerate) physical light quark mass. We use the kinematic constraint $f_+(q^2)= f_0(q^2)$ at $q^2 = 0$ to determine the vector form factor from our study of the scalar current, which yields $f_0(0)$. Results are extrapolated to the continuum physical point in the framework of hard pion/kaon SU(3) heavy-meson-staggered $\chi$PT and Symanzik effective theory. Our calculation improves upon the precision achieved in existing lattice-QCD calculations of the vector form factors at $q^2=0$. We show the values of the CKM matrix elements $|V_{cs}|$ and $|V_{cd}|$ that we would obtain using our preliminary results for the form factors together with recent experimental results, and discuss the implications of these values for the second row CKM unitarity.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Symmetry-preserving contact interaction model for heavy-light mesons

We use a symmetry-preserving regularization method of ultraviolet divergences in a vector-vector contact interaction model for low-energy QCD. The contact interaction is a representation of nonperturbative kernels used Dyson-Schwinger and Bethe-Salpeter equations. The regularization method is based on a subtraction scheme that avoids standard steps in the evaluation of divergent integrals that invariably lead to symmetry violation. Aiming at the study of heavy-light mesons, we have implemented the method to the pseudoscalar π and K mesons. We have solved the Dyson-Schwinger equation for the u, d and s quark propagators, and obtained the bound-state Bethe-Salpeter amplitudes in a way that the Ward-Green-Takahashi identities reflecting global symmetries of the model are satisfied for arbitrary routing of the momenta running in loop integrals.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗