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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Measurement of the production cross section of prompt $\Xi ^0_{\textrm{c}}$ baryons in p–Pb collisions at $\sqrt{s_{{\textrm{NN}}}}=5.02$ TeV

The transverse momentum (p T ) differential production cross section of the promptly produced charm-strange baryon $\Xi ^0_{\textrm{c}}$ (and its charge conjugate $\Xi ^0_{\textrm{c}}$) is measured at midrapidity via its hadronic decay into π + $\Xi$ – in p–Pb collisions at a centre-of-mass energy per nucleon–nucleon collision $\sqrt{s_{{\textrm{NN}}}}=5.02$ TeV with the ALICE detector at the LHC. The $\Xi ^0_{\textrm{c}}$ nuclear modification factor (R pPb ), calculated from the cross sections in pp and p–Pb collisions, is presented and compared with the R pPb of Λ$^{+}_{c}$ baryons. The ratios between the p T -differential production cross section of $\Xi ^0_{\textrm{c}}$ baryons and those of D 0 mesons and Λ$^{+}_{c}$ baryons are also reported and compared with results at forward and backward rapidity from the LHCb Collaboration. The measurements of the production cross section of prompt $\Xi ^0_{\textrm{c}}$ baryons are compared with a model based on perturbative QCD calculations of charm-quark production cross sections, which includes only cold nuclear matter effects in p–Pb collisions, and underestimates the measurement by a factor of about 50. This discrepancy is reduced when the data is compared with a model that includes string formation beyond leading-colour approximation or in which hadronisation is implemented via quark coalescence. The p T -integrated cross section of prompt $\Xi ^0_{\textrm{c}}$-baryon production at midrapidity extrapolated down to p T = 0 is also reported. These measurements offer insights and constraints for theoretical calculations of the hadronisation process. Additionally, they provide inputs for the calculation of the charm production cross section in p–Pb collisions at midrapidity.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Precision measurement of the B0 meson lifetime using B0→J/ψK∗0 decays with the ATLAS detector

A measurement of the B0$$B^{0}$$ meson lifetime using B0→J/ψK∗0$$ B^{0} \rightarrow J/\psi K^{*0} $$ decays in data from 13 TeV$$\text {TeV}$$ proton–proton collisions with an integrated luminosity of 140fb-1$$ 140~\mathrm {fb^{-1}} $$ recorded by the ATLAS detector at the LHC is presented. The measured effective lifetime is τ=1.5053±0.0012(stat.)±0.0035(syst.)ps.$$ \tau = 1.5053\pm 0.0012~\mathrm {(stat.)} \pm 0.0035~\mathrm {(syst.)~ps}. $$The average decay width extracted from the effective lifetime, using parameters from external sources, is Γd=0.6639±0.0005(stat.)±0.0016(syst.)±0.0038(ext.)ps-1,$$\begin{aligned} \Gamma _d = 0.6639\pm 0.0005~\mathrm {(stat.)} \pm 0.0016~\mathrm {(syst.)}\\ \pm 0.0038~\text {(ext.)} \text {~ps}^{-1}, \end{aligned}$$where the uncertainties are statistical, systematic and from external sources. The earlier ATLAS measurement of Γs$$\Gamma _s$$ in the Bs0→J/ψϕ$$B^{0}_{s} \rightarrow J/\psi \phi $$ decay was used to derive a value for the ratio of the average decay widths Γd$$\Gamma _d$$ and Γs$$\Gamma _s$$ for B0$$B^{0} $$ and Bs0$$B^{0}_{s} $$ mesons respectively, of ΓdΓs=0.9905±0.0022(stat.)±0.0036(syst.)±0.0057(ext.).$$ \frac{\Gamma _d }{\Gamma _s } = 0.9905\pm 0.0022~\text {(stat.)} \pm 0.0036~\text {(syst.)} \pm 0.0057~\text {(ext.)}. $$The measured lifetime, average decay width and decay width ratio are in agreement with theoretical predictions and with measurements by other experiments. This measurement provides the most precise result of the effective lifetime of the B0$$B^{0}$$ meson to date.

Aad, G↗
DOE OSTI2025

Multiplicity dependence of ${\Xi }_{\text{c}}^{+}$ and ${\Xi }_{\text{c}}^{0}$ production in pp collisions at $\sqrt{s}=13$ TeV

The first measurement at midrapidity (|y| < 0.5) of the production yield of the strange-charm baryons $Ξ$$^{+}_{c}$ and $Ξ$$^{0}_{c}$ as a function of transverse momentum (p T ) in different charged-particle multiplicity classes in proton-proton collisions at $\sqrt{s}$ = 13 TeV with the ALICE experiment at the LHC is reported. The $Ξ$$^{+}_{c}$ baryon is reconstructed via the $Ξ$$^{+}_{c}$ → $Ξ$ – π + π + decay channel in the range 4 < p T < 12 GeV/c, while the $Ξ$$^{0}_{c}$ baryon is reconstructed via both the $Ξ$$^{0}_{c}$ → $Ξ$ – π + and $Ξ$$^{0}_{c}$ → $Ξ$ – e + ν e decay channels in the range 2 < p T < 12 GeV/c. The baryon-to-meson ($Ξ$$^{0}_{c}$ + /D 0 ) and the baryon-to-baryon ($Ξ$$^{0}_{c}$ + /Λ$^{+}_{c}$) production yield ratios show no significant dependence on multiplicity. In addition, the observed yield ratios are not described by theoretical predictions that model charm-quark fragmentation based on measurements at e + e − and e − p colliders, indicating differences in the charm-baryon production mechanism in pp collisions. A comparison with different event generators and tunings, including different modelling of the hadronisation process, is also discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Search for the 𝐾 𝐿 → 𝜋 0 ⁢$𝜈⁢\bar{𝜈}$ Decay at the J-PARC KOTO Experiment

We performed a search for the 𝐾 𝐿 → 𝜋 0 ⁢$𝜈⁢\bar{𝜈}$ decay using the data taken in 2021 at the J-PARC KOTO experiment. With newly installed counters and new analysis method, the expected background was suppressed to 0.252 ± 0.055 stat ⁢ $^{+0.052}_{{−0.067^{syst}}}$. With a single event sensitivity of (9.33 ± 0.0⁢6 stat ±0.8⁢4 syst ) × 10 −10 , no events were observed in the signal region. An upper limit on the branching fraction for the decay was set to be 2.2 ×10 −9 at the 90% confidence level (C.L.), which improved the previous upper limit from KOTO by a factor of 1.4. With the same data, a search for 𝐾 𝐿 → 𝜋 0 ⁢𝑋 0 was also performed, where 𝑋 0 is an invisible boson with a mass ranging from 1 to 260 MeV/𝑐 2 . For 𝑋 0 with a mass of 135 MeV/𝑐 2 , an upper limit on the branching fraction of 𝐾 𝐿 → 𝜋 0 ⁢𝑋 0 was set to be 1.6 ×10 −9 at the 90% C.L.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

First Double-Differential Cross Section Measurement of Neutral-Current 𝜋 0 Production in Neutrino-Argon Scattering in the MicroBooNE Detector

We report the first double-differential cross section measurement of neutral-current neutral pion (NC⁢𝜋 0 ) production in neutrino-argon scattering, as well as single-differential measurements of the same channel in terms of final states with and without protons. The kinematic variables of interest for these measurements are the 𝜋 0 momentum and the 𝜋 0 scattering angle with respect to the neutrino beam. A total of 4971 candidate NC⁢𝜋 0 events fully contained within the MicroBooNE detector are selected using data collected at a mean neutrino energy of ∼0.8 GeV from 6.4 ×10 20 protons on target from the Booster Neutrino Beam at the Fermi National Accelerator Laboratory. After extensive data-driven model validation to ensure unbiased unfolding, the Wiener-singular-value-decomposition method is used to extract nominal flux-averaged cross sections. The results are compared to predictions from commonly used neutrino event generators, which tend to overpredict the measured NC⁢𝜋 0 cross section, especially in the 0.2–0.5 GeV/c 𝜋 0 momentum range and at forward scattering angles. Events with at least one proton present in the final state are also underestimated. This data will help improve the modeling of NC⁢𝜋 0 production, which represents a major background in measurements of charge-parity violation in the neutrino sector and in searches for new physics beyond the standard model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Optimal Transport for e/$\pi^0$ Particle Classification in LArTPC Neutrino Experiments

Separation of electron signals from $\pi^0$ backgrounds is crucial for neutrino oscillation measurements and searches for Beyond Standard Model (BSM) physics in current and future Liquid Argon Time Projection Chamber (LArTPC) experiments. e/$\pi^0$ separation has been a reconstruction challenge since both e and $\pi^0$ present as electromagnetic showers, and often only one out of the two showers produced by $\pi^0$ is reconstructed correctly. This research aims to improve the performance of e/$\pi^0$ separation using optimal transport (OT), by leveraging on the topological differences in the showers produced by the two particles. OT is a method which compares two distributions by finding the most efficient way to transform, or “move” from one to the other. This work uses the MicroBooNE open samples public dataset to test the e/$\pi^0$ separation performance of the method on events which incorporate realistic modeling of LArTPC detector response. Reconstructed 3D energy deposits are projected onto a plane perpendicular to the primary shower, allowing OT to better detect the topological differences between the two types of particles without the need to separately reconstruct all the showers in the events. Different distance metrics for OT are tested and preliminary results on e/$\pi^0$ separation are presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

The DESI DR1 Peculiar Velocity Survey: Global Zero-point and H 0 Constraints

The Dark Energy Spectroscopic Instrument (DESI) in its first Data Release (DR1) already provides more than 100,000 galaxies with relative distance measurements. The primary purpose of this paper is to perform the calibration of the zero-point for the DESI Fundamental Plane and Tully–Fisher relations, which allows us to measure the Hubble constant, H 0 . This sample has a lower statistical uncertainty than any previously used to measure H 0 , and we investigate the systematic uncertainties in absolute calibration that could limit the accuracy of that measurement. We improve upon the DESI Early Data Release Fundamental Plane H 0 measurement by (a) using a group catalog to increase the number of calibrator galaxies and (b) investigating alternative calibrators in the nearby Universe. Our baseline measurement calibrates to the SH0ES/Pantheon+ type Ia supernovae, and finds H 0 = 73.7 ± 0.06 (stat.) ± 1.1 (syst.) km s −1 Mpc −1 . Calibrating to surface brightness fluctuation distances yields a similar H 0 . We explore measurements using other calibrators, but these are currently less precise since the overlap with DESI peculiar velocity tracers is much smaller. In future data releases with an even larger peculiar velocity sample, we plan to calibrate directly to Cepheids and the tip of the red giant branch, which will enable the uncertainty to decrease towards a percent-level measurement of H 0 . This will provide an alternative to supernovae as the Hubble flow sample for H 0 measurements.

Carr, Anthony [Korea Astronomy and Space Science I↗
DOE OSTI2024

Measurement of the cross sections of $$ {e}^{+}{e}^{-}\to {K}^{-}{\overline{\Xi}}^{+}\Lambda /{\Sigma}^0 $$ at center-of-mass energies between 3.510 and 4.914 GeV

Abstract Usinge + e − collision data collected with the BESIII detector at the BEPCII collider at center-of-mass energies between 3.510 and 4.914 GeV, corresponding to an integrated luminosity of 25 fb −1 , we measure the Born cross sections for the process$$ {e}^{+}{e}^{-}\to {K}^{-}{\overline{\Xi}}^{+}\Lambda /{\Sigma}^0 $$ e + e − → K − Ξ ¯ + Λ / Σ 0 at thirty-five energy points with a partial-reconstruction strategy. By fitting the dressed cross sections of$$ {e}^{+}{e}^{-}\to {K}^{-}{\overline{\Xi}}^{+}\Lambda /{\Sigma}^0 $$ e + e − → K − Ξ ¯ + Λ / Σ 0 , evidence for$$ \psi (4160)\to {K}^{-}{\overline{\Xi}}^{+}\Lambda $$ ψ 4160 → K − Ξ ¯ + Λ is found for the first time with a significance of 4.4σ, including systematic uncertainties. No evidence for other possible resonances is found. In addition, the products of electronic partial width and branching fraction for all assumed resonances decaying into$$ {K}^{-}{\overline{\Xi}}^{+}\Lambda /{\Sigma}^0 $$ K − Ξ ¯ + Λ / Σ 0 are determined.

Physics↗
DOE OSTI2026

Probing late-stage hadronic interactions at high baryon density via $K^{⁎0}$ production in the RHIC beam energy scan program

A precision measurement of the $K^{⁎0}$ meson yield is reported in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 14.6, 19.6, and 27 GeV using the high-statistics data sample collected by the STAR experiment during the Beam Energy Scan II (BES-II) program at RHIC. The transeverse momentum (p T )-integrated yield ratios $\large{(}K^{⁎0} + \overline{K^{⁎0}}\large{)}/(K^+ + K^{-})$ in central collisions show a suppression relative to peripheral collisions at the (1.7–3.6) σ level, while a thermal model without final-stage rescattering overpredicts this ratio with a deviation of (6.9–8.2) σ. These results indicate a loss of the measured $K^{⁎0}$ signal in central collisions due to re-scattering of its hadronic decay products in the hadronic phase. The p T -integrated yield of charged kaons exhibits an approximate scaling with charged-particle multiplicity, independent of collision energy and system size. A similar trend is observed for the short-lived $K^{⁎0}$ resonance, although significant deviations emerge at lower energies. At BES energies, the $K^{⁎0}/K$ ratio shows stronger suppression than at the highest RHIC and LHC energies within a given multiplicity bin, particularly in central and mid-central collisions. This behavior is consistent with changes in the effective hadronic interaction cross section and is supported by transport model calculations, which indicate dominant meson–baryon interactions at lower energies and meson–meson interactions at higher energies.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Measurements of the branching fractions of the P -wave charmonium spin-singlet state h c ( P 1 1 ) → h + h − π 0 / η

Based on ( 2712.4 ± 14.3 ) × 10 6 ψ ( 3686 ) events, we investigate four hadronic decay modes of the P -wave charmonium spin-singlet state h c ( 1 P 1 ) → h + h − π 0 / η ( h = π or K ) via the process ψ ( 3686 ) → π 0 h c at BESIII. The h c → π + π − π 0 decay is observed with a significance of 9.6 σ after taking into account systematic uncertainties. Evidences for h c → K + K − π 0 and h c → K + K − η are found with significances of 3.5 σ and 3.3 σ , respectively, after considering the systematic uncertainties. The branching fractions of these decays are measured to be B ( h c → π + π − π 0 ) = ( 1.36 ± 0.16 ± 0.14 ) × 10 − 3 , B ( h c → K + K − π 0 ) = ( 3.26 ± 0.84 ± 0.36 ) × 10 − 4 , and B ( h c → K + K − η ) = ( 3.13 ± 1.08 ± 0.38 ) × 10 − 4 , where the first uncertainties are statistical and the second are systematic. No significant signal of h c → π + π − η is found, and the upper limit of its decay branching fraction is determined to be B ( h c → π + π − η ) < 4.0 × 10 − 4 at the 90% confidence level. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Improved measurement of the semileptonic decay D s + → K 0 e + ν e

Analyzing e + e − collision data corresponding to an integrated luminosity of 7.33 fb − 1 collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we measure the branching fraction of the semileptonic decay D s + → K 0 e + ν e to be ( 2.98 ± 0.2 3 stat ± 0.1 2 syst ) × 10 − 3 . Based on fit to the partial decay rates in various q 2 intervals, the product value of D s + → K 0 hadronic form factor and Cabibbo-Kobayashi-Maskawa element is measured to be f + K 0 ( 0 ) | V c d | = 0.143 ± 0.01 1 stat ± 0.00 3 syst . With | V c d | = 0.22486 ± 0.00067 as an input, the hadronic form factor is evaluated to be f + K 0 ( 0 ) = 0.636 ± 0.04 9 stat ± 0.01 3 syst . The branching fraction and form factor measurements are factors of 1.6 and 1.7 more precise than the previous world averages, respectively. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
NASA NTRS1973

One- and multi-component models of the upper photosphere based on molecular spectra. I - The violet system of CN /0, 0/

Spectroheliograms taken in the CN (0, 0) violet band near 3883 A show very small scale network and cell structures with high contrast. The bandhead itself, which is a broad feature due to overlap of several CN lines, allows the diagnostic simplicity of a continuum since motions, magnetic fields, and broadening mechanisms are unimportant. We have obtained spectroheliograms in the bandhead and center-to-limb photoelectric spectra of CN (0, 0) at Kitt Peak National Observatory. From the photoelectric spectra and a detailed analysis of the formation of the CN (0, 0) spectrum we derive a best-fit one-component upper photospheric model differing from that of the HSRA and recommend a change in solar carbon abundance from the HSRA value.

Mount, G. H.↗
NASA NTRS1994

High-resolution oscillator strength measurements for the A(v') - X(0) bands of carbon monoxide with 11 less than or equal to v' less than or equal to 14

Band oscillator strengths (f-values) for four bands of the Fourth Positive system (A (1)Pi - Chi(sup 1) Sigma(+)) of CO have been determined from high-resolution (lambda/Delta lambda approximately equal to 150,000) absorption spectra. The bands, (14, 0) through (11, 0), are at wavelengths between 121 and 127 nm. Our f-values for the (11, 0) and (12, 0) bands support those of Chan, Cooper, & Brion (1993), which have been shown to be consistent with observations of CO in the clouds in the line of sight to zeta Oph. Our f-values for the (13, 0) and (14, 0) bands are the first directly measured values for these bands.

Smith, Peter L.↗
NASA NTRS1998

Galaxy Cluster Shapes and Systematic Errors in H_0 as Determined by the Sunyaev-Zel'dovich Effect

Imaging of the Sunyaev-Zeldovich (SZ) effect in galaxy clusters combined with cluster plasma x-ray diagnostics promises to measure the cosmic distance scale to high accuracy. However, projecting the inverse-Compton scattering and x-ray emission along the cluster line-of-sight will introduce systematic error's in the Hubble constant, H_0, because the true shape of the cluster is not known. In this paper we present a study of the systematic errors in the value of H_0, as determined by the x-ray and SZ properties of theoretical samples of triaxial isothermal "beta-model" clusters, caused by projection effects and observer orientation relative to the model clusters' principal axes. We calculate three estimates for H_0 for each cluster, based on their large and small apparent angular core radii, and their arithmetic mean. We average the estimates for H_0 for a sample of 25 clusters and find that the estimates have limited systematic error: the 99.7% confidence intervals for the mean estimated H_0 analyzing the clusters using either their large or mean angular core r;dius are within 14% of the "true" (assumed) value of H_0 (and enclose it), for a triaxial beta model cluster sample possessing a distribution of apparent x-ray cluster ellipticities consistent with that of observed x-ray clusters.

Sulkanen, Martin E.↗
NASA NTRS1998

A Very Hot, High Redshift Cluster of Galaxies: More Trouble for Omega(0) = 1

We have observed the most distant (= 0.829) cluster of galaxies in the Einstein Extended Medium Sensitivity Survey (EMSS), with the ASCA and ROSAT satellites. We find an X-ray temperature of 12.3 (sup +3.1) (sub -2.2)keV for this cluster, and the ROSAT map reveals significant substructure. The high temperature of MS1054-0321 is consistent with both its approximate velocity dispersion, based on the redshifts of 12 cluster members we have obtained at the Keck and the Canada-France-Hawaii telescopes, and with its weak lensing signature. The X-ray temperature of this cluster implies a virial mass approx. 7.4 x 10 (sup 14) h (sup -1) M (circle dot), if the mean matter density in the universe equals the critical value (OMEGA (sub 0) = 1), or larger if OMEGA (sub 0) is less than 1. Finding such a hot, massive cluster in the EMSS is extremely improbable if clusters grew from Gaussian perturbations in an OMEGA (sub 0) = 1 universe. Combining the assumptions that OMEGA (sub 0) = 1 and that the initial perturbations were Gaussian with the observed X-ray temperature function at low redshift, we show that this probability of this cluster occurring in the volume sampled by the EMSS is less than a few times 10 (sup -5). Nor is MS1054-0321 the only hot cluster at high redshift; the only two other z greater than 0.5 EMSS clusters already observed with ASCA also have temperatures exceeding 8 keV. Assuming again that the initial perturbations were Gaussian and OMEGA (sub 0) = 1, we find that each one is improbable at the less than 10 (sup -2) level. These observations, along with the fact that these luminosities and temperatures of the high-z clusters all agree with the low-z L (sub X) - T (sub X) relation, argue strongly that OMEGA (sub 0) less than 1. Otherwise, the initial perturbations must be non-Gaussian, if these clusters' temperatures do indeed reflect their gravitational potentials.

Donahue, Megan↗
DOE OSTI2025

Evaluating Chemical Kinetics Predictions for Propane Using 3-D and 0-D Models in a Boosted Spark-Ignited Engine

Propane has been shown to be a promising alternative fuel to reduce emissions while simultaneously achieving high efficiencies in medium- and heavy-duty engines. These high-power density applications require boosted engines which, combined with high compression ratio, can lead to auto-ignition and knock. While three-dimensional (3-D) computational fluid dynamics (CFD) models are often used for resolving the complex fluid flow in engines, these models can become computationally expensive when simulating detailed chemical kinetics. Likewise, zero-dimensional (0-D) models are computationally concise enough for kinetics development, but lack any flow-field information which governs the flame propagation processes in spark ignition (SI) engines. This work presents a comprehensive comparison between 3-D and 0-D closed cycle simulations at knocking conditions in a high compression ratio high stroke-to-bore ratio propane engine. In order to initialize the flow-field for the 3-D closed cycle (intake valve closing, (IVC) to exhaust valve opening, (EVO)) simulation, a motored multi-cycle 3-D model was run using Converge to create a map at IVC, reducing the computational time. The map allowed a non-homogeneous 3-D closed cycle simulation to be satisfactorily validated against experiments, while a homogeneous case using only the turbulence field mapping was also simulated, mimicking 0-D modeling. The 3-D simulations were used to prescribe the initial conditions (e.g., IVC thermodynamics, speciation, burn-rate profile) for a 2-zone 0-D SI engine model in Chemkin Pro for both cases. It was found that 2-zone 0-D modeling underpredicted the knock onset timing, likely due to the lack of thermal stratification in the unburned gas region. Future work will carry multi-zone 0-D modeling to capture the fuel auto-ignition in the unburned region.

Douvry-Rabjeau, Julien [Oakland University, Roches↗
DOE OSTI2024

Search for the $ {B}_s^0$ → μ + μ – $\gamma$ decay

A search for the fully reconstructed ${B}_s^0$ → μ + μ – γ decay is performed at the LHCb experiment using proton-proton collisions at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 5.4 fb –1 . No significant signal is found and upper limits on the branching fraction in intervals of the dimuon mass are set ${\displaystyle \begin{array}{cc}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[2{m}_{\mu },1.70\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<7.7\times {10}^{-8},&\ m\left({\mu}^{+}{\mu}^{-}\right)\in \left[\textrm{1.70,2.88}\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[3.92,{m}_{B_s^0}\right]\textrm{GeV}/{c}^2,\end{array}}\\{}$ at 95% confidence level. Additionally, upper limits are set on the branching fraction in the [2m μ , 1.70] GeV/c 2 dimuon mass region excluding the contribution from the intermediate Φ(1020) meson, and in the region combining all dimuon-mass intervals.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

PFOA catalytic reaction mechanisms on zerovalent iron (Fe 0 ): A DFT investigation

In this study, density functional theory (DFT) calculations with dispersion corrections are employed to investigate catalytic reactions of perfluorooctanoic acid (PFOA) onto zerovalent iron (Fe 0 ). The main goal of this investigation is to explain the reaction mechanisms, including bond dissociation energies, activation barriers, and rate-determining steps (RDSs), of PFOA degradation. Additionally, we aim to reveal the catalytic effects of Fe 0 by comparing the reaction energy profile for the degradation of PFOA both in solution (i.e., isolated) and after adsorption on Fe 0 . Along with investigating previously reported pathways, this study proposes a new PFOA degradation pathway on Fe0. Overall, the results revealed that Fe 0 plays a key role in the catalytic degradation of PFOA, significantly affecting the RDSs and increasing defluorination rates. For instance, the activation barrier for the decarboxylation step significantly decreased from 3.08 eV to 1.11 eV over the Fe0 surface, while the activation barrier for F dissociation decreased from ∼5 eV to 0.54 eV. Additionally, the proposed pathway in this study (i.e., successive defluorination) was found to be the most favorable pathway for PFOA degradation on Fe 0 . Taken together, the DFT results are consistent with reported experimental findings and provide critical insights that will help advance the design of catalysts for PFAS degradation.

Catalysis↗