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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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DOE OSTI2025

Search for a Neutral Gauge Boson with Nonuniversal Fermion Couplings in Vector Boson Fusion Processes in Proton-Proton Collisions at $\sqrt{𝑠}$ = 13 TeV

The first search for a heavy neutral spin-1 gauge boson (𝑍′) with nonuniversal fermion couplings produced via vector boson fusion processes and decaying to tau leptons or 𝑊 bosons is presented. The analysis is performed using LHC data at $\sqrt{𝑠}$ = 13 TeV, collected from 2016 to 2018 with the CMS experiment and corresponding to an integrated luminosity of 138 fb −1 . The data are consistent with the standard model predictions. Upper limits are set on the product of the cross section for production of the 𝑍′ boson and its branching fraction to 𝜏⁢𝜏 or 𝑊⁢𝑊. The presence of a 𝑍′ boson decaying to 𝜏 + ⁢𝜏 − (𝑊 + ⁢𝑊 − ) is excluded for masses up to 2.45(1.60) TeV, depending on the 𝑍′ boson coupling to standard model weak bosons, and assuming a 𝑍′→𝜏 + ⁢𝜏 − (𝑊 + ⁢𝑊 − ) branching fraction of 50%.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Correlation of a Bipolar-Transistor-Based Neutron Displacement Damage Sensor Methodology with Proton Irradiations

For this research, a bipolar-transistor-based sensor technique has been used to compare silicon displacement damage from known and unknown neutron energy spectra generated in nuclear reactor and high-energy-density physics environments. The technique has been shown to yield 1-MeV(Si) equivalent neutron fluence measurements comparable to traditional neutron activation dosimetry. This study significantly extends previous results by evaluating three types of bipolar devices utilized as displacement damage sensors at a nuclear research reactor and at a Pelletron particle accelerator. Ionizing dose effects are compensated for via comparisons with 10-keV x-ray and/or cobalt-60 gamma ray irradiations. Non-ionizing energy loss calculations adequately approximate the correlations between particle-device responses and provide evidence for the use of one particle type to screen the sensitivity of the other.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2014

Studies of the 3D structure of the proton at Jlab

In recent years parton distributions, describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been generalized to account also for transverse degrees of freedom. Two new sets of more general distributions, Transverse Momentum Distributions (TMDs) and Generalized Parton Distributions (GPDs) were introduced to describe transverse momentum and spatial distributions of partons. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive and hard exclusive processes, providing access to TMDs and GPDs, respectively. Studies of TMDs and GPDs are also among the main driving forces of the JLab 12 GeV upgrade project.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Electron efficiency measurements with the ATLAS detector using 2012 LHC proton–proton collision data

This paper describes the algorithms for the reconstruction and identification of electrons in the central region of the ATLAS detector at the Large Hadron Collider (LHC). These algorithms were used for all ATLAS results with electrons in the final state that are based on the 2012 pp collision data produced by the LHC at s = 8 TeV. The efficiency of these algorithms, together with the charge misidentification rate, is measured in data and evaluated in simulated samples using electrons from Z→ ee, Z→ eeγ and J/ ψ→ ee decays. For these efficiency measurements, the full recorded data set, corresponding to an integrated luminosity of 20.3 fb - 1 , is used. Based on a new reconstruction algorithm used in 2012, the electron reconstruction efficiency is 97% for electrons with E T = 15 GeV and 99% at E T = 50 GeV. Combining this with the efficiency of additional selection criteria to reject electrons from background processes or misidentified hadrons, the efficiency to reconstruct and identify electrons at the ATLAS experiment varies from 65 to 95%, depending on the transverse momentum of the electron and background rejection.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Charged-particle multiplicity distributions over a wide pseudorapidity range in proton-proton collisions at $\sqrt{s}=$ = 0.9, 7, and 8 TeV

Here, we present the charged-particle multiplicity distributions over a wide pseudorapidity range (-3.4 <η< 5.0) for pp collisions at $\sqrt{s}=$=0.9,7, and 8 TeV at the LHC. Results are based on information from the Silicon Pixel Detector and the Forward Multiplicity Detector of ALICE, extending the pseudorapidity coverage of the earlier publications and the high-multiplicity reach. The measurements are compared to results from the CMS experiment and to PYTHIA, PHOJET and EPOS LHC event generators, as well as IP-Glasma calculations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

π 0 and η meson production in proton-proton collisions at $\sqrt{s}=8$ TeV

For this, an invariant differential cross section measurement of inclusive π 0 and η meson production at mid-rapidity in pp collisions at $\sqrt{s}=8$ TeV was carried out by the ALICE experiment at the LHC. The spectra of π 0 and η mesons were measured in transverse momentum ranges of 0.3 < p T < 35 GeV/c and 0.5 < p T <35 GeV/c, respectively. Next-to-leading order perturbative QCD calculations using fragmentation functions DSS14 for the π 0 and AESSS for the η overestimate the cross sections of both neutral mesons, although such calculations agree with the measured η/π 0 ratio within uncertainties. The results were also compared with PYTHIA 8.2 predictions for which the Monash 2013 tune yields the best agreement with the measured neutral meson spectra. The measurements confirm a universal behavior of the η/π 0 ratio seen for NA27, PHENIX and ALICE data for pp collisions from $\sqrt{s}=27.5$ GeV to $\sqrt{s}=8$ TeV within experimental uncertainties. A relation between the π 0 and η production cross sections for pp collisions at $\sqrt{s}=8$ TeV is given by m T scaling for p T > 3.5 GeV/c . However, a deviation from this empirical scaling rule is observed for transverse momenta below p T < 3.5 GeV/c in the η/π 0 ratio with a significance of 6.2σ .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Measurement of associated Z + charm production in proton-proton collisions at $\sqrt{s} = $ 8 TeV

A study of the associated production of a $\mathrm{Z} $ boson and a charm quark jet ( $\mathrm{Z} + \mathrm{c} $ ), and a comparison to production with a $\mathrm{b} $ quark jet ( $\mathrm{Z} + \mathrm{b} $ ), in $\mathrm {p}\mathrm {p}$ collisions at a centre-of-mass energy of 8 $\,\text {TeV}$ are presented. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 $\,\text {fb}^{-1}$ , collected with the CMS detector at the CERN LHC. The $\mathrm{Z} $ boson candidates are identified through their decays into pairs of electrons or muons. Jets originating from heavy flavour quarks are identified using semileptonic decays of $\mathrm{c} $ or $\mathrm{b} $ flavoured hadrons and hadronic decays of charm hadrons. The measurements are performed in the kinematic region with two leptons with $p_{\mathrm {T}} ^{\ell } > 20\,\text {GeV} $ , ${|\eta ^{\ell }|} < 2.1$ , $71< m_{\ell \ell } < 111\,\text {GeV} $ , and heavy flavour jets with $p_{\mathrm {T}} ^{\text {jet}} > 25\,\text {GeV} $ and ${|\eta ^{ \text {jet}}|} < 2.5$ . The $\mathrm{Z} + \mathrm{c} $ production cross section is measured to be $\sigma (\mathrm {p}\mathrm {p}\rightarrow \mathrm{Z} + \mathrm{c} + X) \mathcal {B}(\mathrm{Z} \rightarrow \ell ^+\ell ^-) = 8.8 \pm 0.5\,\text {(stat)} \pm 0.6\,\text {(syst)} \,\text {pb} $ . The ratio of the $\mathrm{Z} + \mathrm{c} $ and $\mathrm{Z} + \mathrm{b} $ production cross sections is measured to be $\sigma (\mathrm {p}\mathrm {p}\rightarrow \mathrm{Z} + \mathrm{c} + X)/\sigma (\mathrm {p}\mathrm {p}\rightarrow \mathrm{Z} + \mathrm{b} + X) = 2.0 \pm 0.2\,\text {(stat)} \pm 0.2\,\text {(syst)} $ . The $\mathrm{Z} + \mathrm{c} $ production cross section and the cross section ratio are also measured as a function of the transverse momentum of the $\mathrm{Z} $ boson and of the heavy flavour jet. The measurements are compared with theoretical predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Measurements of ${\Xi }{^-}$ and $\overline{\Xi }{^+}$ production in proton–proton interactions at $\sqrt{s_{NN}}$ = 17.3 $\hbox {Ge}\hbox {V}$ in the NA61/SHINE experiment

The production of $\Xi (1321)^{-}$ and $\overline{\Xi }(1321)^{+}$ hyperons in inelastic $p+p$ interactions is studied in a fixed target experiment at a beam momentum of 158 $\hbox {Ge}\hbox {V}\!/\!c$. Double differential distributions in rapidity ${y}$ and transverse momentum $p_{T}$ are obtained from a sample of 33M inelastic events. They allow to extrapolate the spectra to full phase space and to determine the mean multiplicity of both ${\Xi }{^-}$ and $\overline{\Xi }{^+} $. The rapidity and transverse momentum spectra are compared to transport model predictions. The ${\Xi }{^-} $ mean multiplicity in inelastic $p+p$ interactions at 158 $\hbox {Ge}\hbox {V}\!/\!c$ is used to quantify the strangeness enhancement in A+A collisions at the same centre-of-mass energy per nucleon pair.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Optimisation of large-radius jet reconstruction for the ATLAS detector in 13 TeV proton–proton collisions

Jet substructure has provided new opportunities for searches and measurements at the LHC, and has seen continuous development since the optimization of the large-radius jet definition used by ATLAS was performed during Run 1. A range of new inputs to jet reconstruction, pile-up mitigation techniques and jet grooming algorithms motivate an optimisation of large-radius jet reconstruction for ATLAS. In this paper, this optimisation procedure is presented, and the performance of a wide range of large-radius jet definitions is compared. The relative performance of these jet definitions is assessed using metrics such as their pileup stability, ability to identify hadronically decaying W bosons and top quarks with large transverse momenta. A new type of jet input object, called a ‘unified flow object’ is introduced which combines calorimeter- and inner-detector-based signals in order to achieve optimal performance across a wide kinematic range. Large-radius jet definitions are identified which significantly improve on the current ATLAS baseline definition, and their modelling is studied using pp collisions recorded by the ATLAS detector at √s = 13 TeV

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Search for a heavy vector resonance decaying to a ${\mathrm{Z}}_{\mathrm{}}^{\mathrm{}}$ boson and a Higgs boson in proton-proton collisions at $\sqrt{s} = 13\,\text {Te}\text {V}$

A search is presented for a heavy vector resonance decaying into a Z boson and the standard model Higgs boson, where the Z boson is identified through its leptonic decays to electrons, muons, or neutrinos, and the Higgs boson is identified through its hadronic decays. The search is performed in a Lorentz-boosted regime and is based on data collected from 2016 to 2018 at the CERN LHC, corresponding to an integrated luminosity of 137fb -1 . Upper limits are derived on the production of a narrow heavy resonance Z', and a mass below 3.5 and 3.7TeV is excluded at 95% confidence level in models where the heavy vector boson couples predominantly to fermions and to bosons, respectively. These are the most stringent limits placed on the Heavy Vector Triplet Z' model to date. If the heavy vector boson couples exclusively to standard model bosons, upper limits on the product of the cross section and branching fraction are set between 23 and 0.3fb for a Z' mass between 0.8 and 4.6TeV, respectively. This is the first limit set on a heavy vector boson coupling exclusively to standard model bosons in its production and decay.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Measurements of ${\Xi \left( 1530\right) ^{0}} $ and ${\overline{\Xi }\left( 1530\right) ^{0}} $ production in proton–proton interactions at $\sqrt{s_{NN}}$ = 17.3 $\text{ GeV }$ in the NA61/SHINE experiment

Double-differential yields of ${\Xi \left( 1530\right) ^{0}} $ and ${\overline{\Xi }\left( 1530\right) ^{0}} $ resonances produced in p+p interactions were measured at a laboratory beam momentum of 158 $\text{ GeV }\!/\!c$. This measurement is the first of its kind in p+p interactions below LHC energies. It was performed at the CERN SPS by the NA61/SHINE collaboration. Double-differential distributions in rapidity and transverse momentum were obtained from a sample of $26\times 10^6$ inelastic events. The spectra are extrapolated to full phase space resulting in mean multiplicity of ${\Xi \left( 1530\right) ^{0}} $ ($6.73 \pm 0.25\pm 0.67)\times 10^{-4}$ and ${\overline{\Xi }\left( 1530\right) ^{0}} $ ($2.71 \pm 0.18\pm 0.18)\times 10^{-4}$. The rapidity and transverse momentum spectra and mean multiplicities were compared to predictions of string-hadronic and statistical model calculations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for resonant $WZ$ production in the fully leptonic final state in proton–proton collisions at $\sqrt{s}$= 13 TeV with the ATLAS detector

A search for a $WZ$ resonance, in the fully leptonic final state (electrons or muons), is performed using 139 fb –1 of data collected at a centre-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The results are interpreted in terms of a singly charged Higgs boson of the Georgi–Machacek model, produced by WZ fusion, and of a Heavy Vector Triplet, with the resonance produced by $WZ$ fusion or the Drell–Yan process. No significant excess over the Standard Model prediction is observed and limits are set on the production cross-section times branching ratio as a function of the resonance mass for these processes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗