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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Investigating strangeness enhancement in jet and medium via 𝜙⁡(1020) production in 𝑝-Pb collisions at √ s NN = 5.02TeV

This work aims to differentiate strangeness produced from hard processes (jetlike) and softer processes (underlying event) by measuring the angular correlation between a high-momentum trigger hadron (ℎ) acting as a jet proxy and a produced strange hadron [𝜙⁡(1020) meson]. Measuring ℎ−𝜙 correlations at midrapidity in 𝑝-Pb collisions at √ s NN = 5.02TeV as a function of event multiplicity provides insight into the microscopic origin of strangeness enhancement in small collision systems. The jetlike and the underlying-event-like strangeness production are investigated as a function of event multiplicity. They are also compared between a lower and higher momentum region. The evolutions of the per-trigger yields within the near-side (aligned with the trigger hadron) and away-side (in the opposite direction of the trigger hadron) jets are studied separately, allowing for the characterization of two distinct jetlike production regimes. Furthermore, the ℎ−𝜙 correlations within the underlying event give access to a production regime dominated by soft production processes, which can be compared directly to the in-jet production. Comparisons between ℎ−𝜙 and dihadron correlations show that the observed strangeness enhancement is largely driven by the underlying event, where the 𝜙/ℎ ratio is significantly larger than within the jet regions. As multiplicity increases, the fraction of the total 𝜙⁡(1020) yield coming from jets decreases compared to the underlying event production, leading to high-multiplicity events being dominated by the increased strangeness production from the underlying event.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Quantum chromodynamics resolution of the ATOMKI anomaly in 4 He nuclear transitions

Observations of anomalous angular correlations in electron-positron pairs produced from excited states of 4 He, 8 Be, and 12 C nuclei have been suggested as being due to the creation and subsequent decay of a new light particle of mass ~17MeV. In this work, we investigate the possibility that the source of the observed signals is a set of new excitation channels created by the 12-quark hidden-color Fock state within the 4 He nuclear wave function dubbed the “hexadiquark.” We calculate the invariant e + ⁢ e - mass spectrum for the electromagnetic transition from a new excitation of 4 He, estimating its differential and total decay width. We find that we can fit the shape of the anomalous signal with the QCD Fock state at excitation energy E* = 17.9 ± 1MeV and a Gaussian form factor for the electromagnetic decay. We address the physical issues with the fit parameters using properties of the hexadiquark state, in particular the three weakly repulsive 6 C interactions of SU⁡(3) C between diquark pairs. Experimental tests of our model are described in detail. In light of this work, we emphasize the need for independent experimental confirmation or refutation of the ATOMKI results as well as dedicated experiments to search for the proposed new excitations of 4 He and other a-cluster nuclei.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Accessing the gluon GTMD F 1 , 4 in exclusive π 0 production in e p collisions

We demonstrate that the longitudinal single target-spin asymmetry in exclusive π 0 production in e p collisions can give access to the imaginary part of the gluon generalized transverse momentum distribution (GTMD) F 1 , 4 . Such a longitudinal spin asymmetry that results from the Coulomb-nuclear interference effect, leads to a characteristic azimuthal angular correlation of sin 2 ϕ , where ϕ is the azimuthal angle between the scattered lepton transverse momentum and the recoil proton’s transverse momentum. We also present a numerical estimate of the asymmetry for the kinematics accessible at EIC and EicC. Published by the American Physical Society 2024

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Locality in collider tests of quantum mechanics with top quark pairs

Tests of quantum properties of fundamental particles in high energy colliders are starting to appear. Entanglement and Bell inequality violation in top and antitop quark system is of particular interest since top quarks are unstable particles that undergo a cascade decay. We argue for criteria for the spacelike separation between top and antitop quarks at their different decay stages. We considered causal separation at three different instances: at the top quark decay, at the 𝑊 boson decay, and at the lepton/jet contact with the macroscopic apparatus. We showed that the spacelike fraction of events is the smallest, when requiring that both top quarks and 𝑊 bosons decay within the spacelike interval. For high invariant masses, typically required for the Bell inequality violation, this is almost identical to just the top quark decay requirement. We also include an option for the angular correlation of the 𝑏 quarks from top quark decay to be used for the spin correlation measurement. We require that both top quark and 𝑏 hadron decays are spacelike separated. Again, we find that at high invariant masses it is almost identical to just the requirement of spacelike separation between top and antitop quarks. We provide numerical values for our proposed criteria. If such a criterion is satisfied, the system is guaranteed to not be in a causal connection.

Entanglement in field theory↗
DOE OSTI2025

Building the case for forward muon detection at a muon collider

We survey the opportunities offered by the detection of the forward muons that accompany the creation of neutral effective vector bosons at a muon collider, in different kinematic regimes. Vectors with relatively low energy produce the Higgs boson and the extended muon angular coverage enables studies of the Higgs properties, such as the measurement of the inclusive production cross section and the branching ratio to invisible final states. New heavy particles could be produced by vectors of higher energy, through Higgs portal interactions. If the new particles are invisible, the detection of the forward muons is essential in order to search for this scenario. The angular correlations of the forward muons are sensitive to the quantum interference between the vector-boson helicity amplitudes and can be exploited for the characterization of vector-boson scattering and fusion processes. This is illustrated by analyzing the C P properties of the Higgs coupling to the Z boson. Our findings provide a physics case and a set of benchmarks for the design of a dedicated forward muon detector. Published by the American Physical Society 2025

Ruhdorfer, Maximilian (ORCID:0000000288973223)↗
DOE OSTI2022

Pion-Induced Radiative Corrections to Neutron β Decay

In this work, we compute the electromagnetic corrections to neutron β decay using a low-energy hadronic effective field theory. We identify new radiative corrections arising from virtual pions that were missed in previous studies. The largest correction is a percent-level shift in the axial charge of the nucleon proportional to the electromagnetic part of the pion-mass splitting. Smaller corrections, comparable to anticipated experimental precision, impact the β-ν angular correlations and the β asymmetry. We comment on implications of our results for the comparison of the experimentally measured nucleon axial charge with first-principles computations using lattice QCD and on the potential of β decay experiments to constrain beyond-the-standard-model interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

First Evidence of Axial Shape Asymmetry and Configuration Coexistence in Zn 74 : Suggestion for a Northern Extension of the N = 40 Island of Inversion

The excited states of N=44 74 Zn were investigated via γ-ray spectroscopy following 74 Cu β decay. By exploiting γ-γ angular correlation analysis, the 2$_2^+$, 3$_1^+$, 0$_2^+$, and 2$_3^+$ states in 74 Zn were firmly established. The γ-ray branching and E2/M1 mixing ratios for transitions deexciting the 2$_2^+$, 3$_1^+$, and 2$_3^+$ states were measured, allowing for the extraction of relative B(E2) values. In particular, the 2$_3^+$→0$_2^+$ and 2$_3^+$→4$_1^+$ transitions were observed for the first time. Here the results show excellent agreement with new microscopic large-scale shell-model calculations, and are discussed in terms of underlying shapes, as well as the role of neutron excitations across the N=40 gap. Enhanced axial shape asymmetry (triaxiality) is suggested to characterize 74 Zn in its ground state. Furthermore, an excited K=0 band with a significantly larger softness in its shape is identified. A shore of the N=40 "island of inversion" appears to manifest above Z=26, previously thought as its northern limit in the chart of the nuclides.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Measurements of the Elliptic and Triangular Azimuthal Anisotropies in Central He 3 + Au , d + Au and p + Au Collisions at s N N = 200 GeV

The elliptic (v 2 ) and triangular (v 3 ) azimuthal anisotropy coefficients in central 3He + Au, d + Au, and p + Au collisions at $\sqrt{S_{NN}}$ = 200 GeV are measured as a function of transverse momentum (P T ) at midrapidity (|n| < 0.9) via the azimuthal angular correlation between two particles both at |n| < 0.9 while the v 2 (P T ) values depend on the colliding systems, the v 3 (P T ) values are system independent within the uncertainties, suggesting an influence on eccentricity from subnucleonic fluctuations in these small-sized systems. Furthermore, these results also provide stringent constraints for the hydrodynamic modeling of these systems.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Improved Tensor Current Limit from 8 B 𝛽 Decay Including New Recoil-Order Calculations

A precision measurement of the 𝛽 + decay of 8 B was performed using the Beta-decay Paul Trap to determine the 𝛽−𝜈 angular correlation coefficient 𝑎 𝛽⁢𝜈 . The experimental results were combined with new ab initio symmetry-adapted no-core shell-model calculations to yield the second-most precise measurement from Gamow-Teller decays, 𝑎 𝛽⁢𝜈 = −0.3345 ± 0.001⁢9 stat ± 0.002⁢1 syst . This value agrees with the standard model value of −1/3 and improves uncertainties in 8 B by nearly a factor of 2. By combining results from 8 B and 8 Li , a tight limit on tensor current coupling to right-handed neutrinos was obtained. A recent global evaluation of all other precision 𝛽 decay studies suggested a nonzero value for right-handed neutrino coupling in contradiction with the standard model at just above 3⁢𝜎. Finally, the present results are of comparable sensitivity and do not support this finding.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Probing the Quark Orbital Angular Momentum at Electron-Ion Colliders Using Exclusive π 0 Production

We propose to detect signals from quark orbital angular momentum (OAM) through exclusive π 0 production in electron- (longitudinally polarized) proton collisions. Our analysis demonstrates that the sin 2 ϕ azimuthal angular correlation between the transverse momentum of the scattered electron and the recoil proton serves as a sensitive probe of quark OAM. Additionally, we present a numerical estimate of the asymmetry associated with this correlation for the kinematics accessible at the Electron-Ion Colliders in the U.S. and China. This study aims to pave the way for the first experimental study of quark OAM in relation to the Jaffe-Manohar spin sum rule. Published by the American Physical Society 2024

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Measurement of the differential $\hbox {t}\overline{\hbox {t}}$ production cross section as a function of the jet mass and extraction of the top quark mass in hadronic decays of boosted top quarks

A measurement of the jet mass distribution in hadronic decays of Lorentz-boosted top quarks is presented. The measurement is performed in the lepton + jets channel of top quark pair production ($\hbox {t}\overline{\hbox {t}}$) events, where the lepton is an electron or muon. The products of the hadronic top quark decay are reconstructed using a single large-radius jet with transverse momentum greater than 400 GeV. The data were collected with the CMS detector at the LHC in proton-proton collisions and correspond to an integrated luminosity of 138 fb -1 . The differential $\hbox {t}\overline{\hbox {t}}$ production cross section as a function of the jet mass is unfolded to the particle level and is used to extract the top quark mass. The jet mass scale is calibrated using the hadronic W boson decay within the large-radius jet. The uncertainties in the modelling of the final state radiation are reduced by studying angular correlations in the jet substructure. These developments lead to a significant increase in precision, and a top quark mass of 173.06 ± 0.84 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Determination of the spins and parities for the $0^+_4$ and $0^+_5$ states in $^{100}Zr$

Two 0 + states at 1294.5 and 1774.0 keV, together with three 2 + and one 4 + levels, were identified or unambiguously spin-parity assigned for the first time in 100 Zr utilizing γ-ray spectroscopy and γ-γ angular correlation techniques with the Gammasphere spectrometer, following the β - decay of neutron-rich, mass separated 100,100m Y isotopes. Comparisons with recent Monte Carlo Shell-Model (MCSM) calculations indicate that these two states are candidates for the bandhead of a sequence in a shape-coexisting spherical minimum predicted to be located around ≈1500 keV. According to the measured relative B(E2) relative transition probabilities, the 0+ 5 state exhibits decay properties which more closely align with those predicted for a spherical shape, while the $0^+_4$ level is suggested to be associated with a weakly-deformed shape similar to one related to the $0^+_2$ state.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Determination of the spins and parities for the $0$$^{+}_{4}$ and $0$$^{+}_{5}$ states in 100 Zr

Two 0 + states at 1294.5 and 1774.0 keV, together with three 2 + and one 4 + levels, were identified or unambiguously spin-parity assigned for the first time in 100 Zr utilizing γ-ray spectroscopy and γ-γ angular correlation techniques with the Gammasphere spectrometer, following the β¯ decay of neutron-rich, mass separated 100,100m Y isotopes. Comparisons with recent Monte Carlo Shell-Model (MCSM) calculations indicate that these two states are candidates for the bandhead of a sequence in a shape-coexisting spherical minimum predicted to be located around ≈1500 keV. According to the measured relative B(E2) relative transition probabilities, the $0$$^{+}_{5}$ state exhibits decay properties which more closely align with those predicted for a spherical shape, while the $0$$^{+}_{4}$ level is suggested to be associated with a weakly-deformed shape similar to one related to the $0$$^{+}_{2}$ state.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

The St. Benedict Facility: Probing Fundamental Symmetries through Mixed Mirror $β$-Decays

Precise measurements of nuclear beta decays provide a unique insight into the Standard Model due to their connection to the electroweak interaction. These decays help constrain the unitarity or non-unitarity of the Cabibbo–Kobayashi–Maskawa (CKM) quark mixing matrix, and can uniquely probe the existence of exotic scalar or tensor currents. Of these decays, superallowed mixed mirror transitions have been the least well-studied, in part due to the absence of data on their Fermi to Gamow-Teller mixing ratios ($ρ$). At the Nuclear Science Laboratory (NSL) at the University of Notre Dame, the Superallowed Transition Beta-Neutrino Decay Ion Coincidence Trap (St. Benedict) is being constructed to determine the ρ for various mirror decays via a measurement of the beta–neutrino angular correlation parameter ($α_{βν}$) to a relative precision of 0.5%. In this work, we present an overview of the St. Benedict facility and the impact it will have on various Beyond the Standard Model studies, including an expanded sensitivity study of $ρ$ for various mirror nuclei accessible to the facility. A feasibility evaluation is also presented that indicates the measurement goals for many mirror nuclei, which are currently attainable in a week of radioactive beam delivery at the NSL.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Properties of the Top Quark

Recent measurements of the properties of the top quark at the CERN Large Hadron Collider are discussed. The results were measured for single and top quark pair production in their final states, including jets with either one or two leptons or only in hadronic final states. Top quark properties include angular correlations, top quark spin correlations, mass, and width. When looking towards the future, top quark properties open new and even interdisciplinary avenues for probing quantum information science.

top precision frontier↗
DOE OSTI2025

Potential absence of observed π2 linear-chain structures in 14O via 10C(α,α) resonances scattering

Background: The preference for light nuclear systems to coagulate into -particle clusters has been well-studied. The possibility of a linear chain configuration of -particles would allow for a new way to study this phenomenon. Purpose: A rotational band of states in C has been claimed showing a linear chain structure. The mirror system, O, has been studied here to examine how this linear chain structure is affected by replacing the valence neutrons with protons. Method: A beam of C was incident into a chamber filled with He:CO gas with the tracks recorded inside the TexAT Time Projection Chamber and the recoil -particles detected by a silicon detector array to measure the cross section. Results: The experimental cross section was compared with previous studies and fit using R-Matrix theory with the previously-observed O states being transformed to the C using mirror symmetry. The measured cross section does not replicate the claimed states, with the predicted cross section exceeding that observed at several energies and angles. Conclusion: A series of possibilities are highlighted with the most likely being that the originally-seen C states did not constitute a rotational band with a potentially incorrect spin assignment due to the limitations of the angular correlation method with non-zero spin particles. The work highlights the difficulties in measuring broad resonances corresponding to a linear chain state in a high level density.

Bishop, J.↗
NASA NTRS1972

Radiative pion capture by C12.

The energy spectrum of neutrons from radiative pion capture by carbon is investigated. Radiative pion capture is identified by coincidence of a stop signal and a signal from one of six lead-glass gamma detectors when negative pions traverse a beam telescope and are stopped in a carbon target. The energy of the neutrons is measured using the time interval between a stop signal coincident with a gamma-counter signal and a signal from a liquid-oscillator neutron counter. Asymmetry in the neutron-photon angular correlation increases with neutron energy and is accounted for by direct neutron emission.

Lam, W. C.↗