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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Observation of B$^0_s$ mesons and measurement of the B$^0_s$/B$^+$ yield ratio in PbPb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV

The B$^0_s$ and B$^+$ production yields are measured in PbPb collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The data sample, collected with the CMS detector at the LHC, corresponds to an integrated luminosity of 1.7 nb$^{-1}$. The mesons are reconstructed in the exclusive decay channels B$^0_s$$\to$ J/$\psi(\mu^+\mu^-)\phi($K$^+$K$^-)$ and B$^+$$\to$ J/$\psi(\mu^+\mu^-)$K$^+$. The B$^0_s$ meson is observed with a statistical significance in excess of five standard deviations for the first time in nucleus-nucleus collisions. The measurements are performed as functions of the transverse momentum of the B mesons and of the PbPb collision centrality. The ratio of production yields of B$^0_s$ and B$^+$ is measured and compared to theoretical models that include quark recombination effects.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Measurements with silicon photomultipliers of dose-rate effects in the radiation damage of plastic scintillator tiles in the CMS hadron endcap calorimeter

Measurements are presented of the reduction of signal output due to radiation damage for two types of plastic scintillator tiles used in the hadron endcap (HE) calorimeter of the CMS detector. The tiles were exposed to particles produced in proton-proton (pp) collisions at the CERN LHC with a center-of-mass energy of 13 TeV, corresponding to a delivered luminosity of 50 fb−1. The measurements are based on readout channels of the HE that were instrumented with silicon photomultipliers, and are derived using data from several sources: a laser calibration system, a movable radioactive source, as well as hadrons and muons produced in pp collisions. Results from several irradiation campaigns using 60Co sources are also discussed. The damage is presented as a function of dose rate. Within the range of these measurements, for a fixed dose the damage increases with decreasing dose rate.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Prototype hardware design and testing of the global common module for the global trigger subsystem of the ATLAS phase-II upgrade

We report the High-Luminosity Large Hadron Collider (HL-LHC) will deliver more than ten times the integrated luminosity of the previous runs combined. Meeting its stricter throughput requirements poses new challenges to the Trigger and Data Acquisition (TDAQ) systems of the LHC experiments. Introduced in the framework of the ATLAS experiment’s HL upgrade, the Global Trigger (GT) is a new subsystem which will perform offline-like algorithms on full-granularity calorimeter data. The implementation of the GT’s functionality is firmware-focused and is composed of three layers: multiplexing (or data aggregating), global event processing, and demultiplexing interface to the central trigger processor. Each layer will be composed of several, similar nodes, hosted on replicas of identical hardware, the Global Common Module (GCM), an ATCA front board which is designed to be adopted throughout the entire GT subsystem. This article proceeds from the TWEPP 2021 conference and presents the GCM hardware design, performed in 2020, and focuses on some key results of its extensive testing performed in 2021.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Search for heavy particles in the b -tagged dijet mass distribution with additional b -tagged jets in proton-proton collisions at $\sqrt{s}$ = 13 TeV with the ATLAS experiment

A search optimized for new heavy particles decaying to two b-quarks and produced in association with additional b-quarks is reported. The sensitivity is improved by b-tagging at least one lower-p T jet in addition to the two highest-p T jets. The data used in this search correspond to an integrated luminosity of 103 fb –1 collected with a dedicated trijet trigger during the 2017 and 2018 √s = 13 TeV proton–proton collision runs with the ATLAS detector at the LHC. The search looks for resonant peaks in the b-tagged dijet invariant mass spectrum over a smoothly falling background. The background is estimated with an innovative data-driven method based on orthonormal functions. The observed b-tagged dijet invariant mass spectrum is compatible with the background-only hypothesis. Upper limits at 95% confidence level on a heavy vector-boson production cross section times branching ratio to a pair of b-quarks are derived.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for an axion-like particle with forward proton scattering in association with photon pairs at ATLAS

A search for forward proton scattering in association with light-by-light scattering mediated by an axion-like particle is presented, using the ATLAS Forward Proton spectrometer to detect scattered protons and the central ATLAS detector to detect pairs of outgoing photons. Proton-proton collision data recorded in 2017 at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV were analysed, corresponding to an integrated luminosity of 14.6 fb –1 . A total of 441 candidate events were selected. A search was made for a narrow resonance in the diphoton mass distribution, corresponding to an axion-like particle (ALP) with mass in the range 150–1600 GeV. No excess is observed above a smooth background. Upper limits on the production cross section of a narrow resonance are set as a function of the mass, and are interpreted as upper limits on the ALP production coupling constant, assuming 100% decay branching ratio into a photon pair. The inferred upper limit on the coupling constant is in the range 0.04–0.09 TeV –1 at 95% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Search for pair production of heavy resonances in final states with a photon and large-radius jets in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search for the pair production of heavy spin-1/2 or spin-3/2 resonances (𝑡*) in proton-proton collisions at $\sqrt{s}$ =13 TeV is presented. Data collected with the CMS detector at the CERN LHC from 2016 to 2018 corresponding to an integrated luminosity of 138 fb −1 are used. The analysis targets benchmark signal scenarios where one 𝑡* decays into a top quark (𝑡) and a photon (𝛾), and the other into a 𝑡 quark and a gluon (𝑔), i.e., 𝑝⁢𝑝 → $𝑡^*\overline{⁢𝑡^*}$ → 𝑡⁢𝑡⁢𝛾⁢𝑔. All-hadronic final states from the 𝑡 pair decay chain are selected using jet substructure techniques. The signal is probed as a function of the 𝑡* candidate mass, which is reconstructed using the photon and a top quark candidate jet. No significant deviation from the background-only hypothesis is found. Observed (expected) upper limits on the signal cross section at 95% confidence level are set, excluding masses of spin-1/2 𝑡* particles below 930 (930) GeV and spin-3/2 𝑡* particles below 1330 (1390) GeV. This analysis marks the first search for heavy resonances in the $𝑡\bar{⁢𝑡}𝛾⁢𝑔$ channel. Exploiting the high-energy photon to reduce the backgrounds, this search achieves sensitivity competitive with 𝑝⁢𝑝 → $𝑡^*\overline{⁢𝑡^*}$ → $𝑡\bar{⁢𝑡}⁢𝑔⁡𝑔$ searches for spin-1/2 𝑡* despite the small expected 𝑡* → 𝑡⁢𝛾 branching fraction.

hadron colliders↗
DOE OSTI2026

Measurement of coherent exclusive J/ψ → μ+μ− production in ultraperipheral Pb+Pb collisions at sNN=5.36 TeV with the ATLAS detector

The ATLAS experiment has performed a measurement of coherent exclusive J/ψ → μ+μ− production in ultraperipheral Pb+Pb collisions at sNN=5.36$$ \sqrt{s_{\textrm{NN}}}=5.36 $$ TeV. The data was recorded at the Large Hadron Collider (LHC) during 2023, and corresponds to an integrated luminosity of 79 μb−1. Exclusive J/ψ candidates were selected with a dedicated track-sensitive trigger based on the ATLAS transition radiation tracker. The analysis involves reconstruction of the dimuon invariant mass based on muon tracks from the inner detector, as the muon transverse momentum range of interest precludes the use of the standard muon reconstruction and identification algorithms. Differential cross sections are measured as a function of J/ψ rapidity and are compared with theoretical predictions. After extrapolation to sNN=5.02$$ \sqrt{s_{\textrm{NN}}}=5.02 $$ TeV, they are also compared with previous measurements performed by other experiments using data from LHC Run 2. While the results agree reasonably well with theoretical predictions, they are in tension with previous Run-2 results for the central rapidity region.

Aad, G↗
DOE OSTI2021

Measurements of WH and ZH production in the $$H \rightarrow b\bar{b}$$ decay channel in pp collisions at $$13\,\text {Te}\text {V}$$ with the ATLAS detector

Measurements of the Standard Model Higgs boson decaying into a $$b\bar{b}$$ b b ¯ pair and produced in association with a W or Z boson decaying into leptons, using proton–proton collision data collected between 2015 and 2018 by the ATLAS detector, are presented. The measurements use collisions produced by the Large Hadron Collider at a centre-of-mass energy of $$\sqrt{s} = 13\,\text {Te}\text {V}$$ s = 13 Te , corresponding to an integrated luminosity of $$139\,\mathrm {fb}^{-1}$$ 139 fb - 1 . The production of a Higgs boson in association with a W or Z boson is established with observed (expected) significances of 4.0 (4.1) and 5.3 (5.1) standard deviations, respectively. Cross-sections of associated production of a Higgs boson decaying into bottom quark pairs with an electroweak gauge boson, W or Z , decaying into leptons are measured as a function of the gauge boson transverse momentum in kinematic fiducial volumes. The cross-section measurements are all consistent with the Standard Model expectations, and the total uncertainties vary from 30% in the high gauge boson transverse momentum regions to 85% in the low regions. Limits are subsequently set on the parameters of an effective Lagrangian sensitive to modifications of the WH and ZH processes as well as the Higgs boson decay into $$b\bar{b}$$ b b ¯ .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Search for the doubly heavy $ {\Xi}_{bc}^0 $ baryon via decays to D0pK-

A search for the doubly heavy \( {\Xi}_{bc}^0 \) baryon using its decay to the D 0 pK – final state is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment between 2016 and 2018, corresponding to an integrated luminosity of 5.4 fb - 1 . No significant signal is found in the invariant mass range from 6.7 to 7.2 GeV/ c 2 . Upper limits are set at 95% credibility level on the ratio of the \( {\Xi}_{bc}^0 \) production cross-section times its branching fraction to D 0 pK - relative to that of the \( {\Lambda}_b^0\to {D}^0{pK}^{-} \) decay. The limits are set as a function of the \( {\Xi}_{bc}^0 \) mass and lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and in the transverse momentum region from 5 to 25 GeV/ c . Upper limits range from 1 . 7 × 10 - 2 to 3 . 0 × 10 - 1 for the considered \( {\Xi}_{bc}^0 \) mass and lifetime hypotheses.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Type Ia supernova magnitude step from the local dark matter environment

ABSTRACT Residuals in the Hubble diagram at optical wavelengths and host galaxy stellar mass are observed to correlate in type Ia supernovae (SNe Ia) (‘magnitude step’). Among possible progenitor channels for the associated explosions, those based on dark matter (DM) have attracted significant attention, including our recent proposal that ‘normal’ SNe Ia from bare detonations in sub-Chandrasekhar white dwarf stars are triggered by the passage of asteroid-mass primordial black holes (PBHs): the magnitude step could then originate from a brightness dependence on stellar properties, on DM properties, or both. Here, we present a method to estimate the local DM density and velocity dispersion of the environment of SN Ia progenitors. We find a luminosity step of $0.52\pm 0.11\,$ mag corresponding to bins of high versus low DM density in a sample of 222 low-redshift events from The Open Supernova Catalog. We investigate whether the magnitude step can be attributed to local DM properties alone, assuming asteroid-mass PBHs. Given the inverse correlation between SN Ia brightness and PBH mass, an intriguing explanation is a spatially inhomogeneous PBH mass function. If so, a strong mass segregation in the DM density-dependent PBH mass scale is needed to explain the magnitude step. While mass segregation is observed in dense clusters, it is unlikely to be realized on galactic scales. Therefore, if DM consists of asteroid-mass PBHs, the magnitude step is more likely to exist, and dominantly to be attributed to local stellar properties.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Search for new non-resonant phenomena in high-mass dilepton final states with the ATLAS detector

A search for new physics with non-resonant signals in dielectron and dimuon final states in the mass range above 2 TeV is presented. This is the first search for non-resonant signals in dilepton final states at the LHC to use a background estimate from the data. The data, corresponding to an integrated luminosity of 139 fb –1 , were recorded by the ATLAS experiment in proton-proton collisions at a center-of-mass energy of √s = 13 TeV during Run 2 of the Large Hadron Collider. The benchmark signal signature is a two-quark and two-lepton contact interaction, which would enhance the dilepton event rate at the TeV mass scale. To model the contribution from background processes a functional form is fit to the dilepton invariant-mass spectra in data in a mass region below the region of interest. It is then extrapolated to a high-mass signal region to obtain the expected background there. No significant deviation from the expected background is observed in the data. Upper limits at 95% CL on the number of events and the visible cross-section times branching fraction for processes involving new physics are provided. Observed (expected) 95% CL lower limits on the contact interaction energy scale reach 35.8 (37.6) TeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Measurement of the Zγ production cross section and search for anomalous neutral triple gauge couplings in pp collisions at $ \sqrt{s}=13 $ TeV

A measurement of the fiducial cross section of the associated production of a Z boson and a high-p$_{T}$ photon, where the Z decays to two neutrinos, and a search for anomalous triple gauge couplings are reported. The results are based on data collected by the CMS experiment at the LHC in proton-proton collisions at $ \sqrt{s}=13 $ TeV during 2016-2018, corresponding to an integrated luminosity of 138 fb$^{−1}$. The fiducial Zγ cross section, where a photon with a p$_{T}$ greater than 225 GeV is produced in association with a Z, and the Z decays to a $ \upnu \overline{\upnu} $ pair $ \left(\mathrm{Z}\left(\upnu \overline{\upnu}\right)\upgamma \right) $, is measured to be $ {23.3}_{-1.3}^{+1.4} $ fb, in agreement, within uncertainties, with the standard model prediction. The differential cross section as a function of the photon p$_{T}$ has been measured and compared with standard model predictions computed at next-to-leading and at next-to-next-to-leading order in perturbative quantum chromodynamics. Constraints have been placed on the presence of anomalous couplings that affect the ZZγ and Zγγ vertex using the p$_{T}$ spectrum of the photons. The observed 95% confidence level intervals for CP-conserving $ {h}_3^{\upgamma} $ and $ {h}_4^{\upgamma} $ are determined to be (−3.4, 3.5)×10$^{−4}$ and (−6.8, 6.8)×10$^{−7}$, and for $ {h}_3^{\mathrm{Z}} $ and $ {h}_4^{\mathrm{Z}} $ they are (−2.2, 2.2)×10$^{−4}$ and (−4.1, 4.2)×10$^{−7}$, respectively. These are the strictest limits to date on $ {h}_3^{\upgamma} $, $ {h}_3^{\mathrm{Z}} $ and $ {h}_4^{\mathrm{Z}} $.[graphic not available: see fulltext]

Hayrapetyan, Aram [Yerevan Phys. Inst.]↗
DOE OSTI2023

Direct C P violation in charmless three-body decays of B ± mesons

Measurements of CP asymmetries in charmless three-body decays of B ± mesons are reported using proton-proton collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.9 fb –1 . The previously observed CP asymmetry in B ± →π ± ⁢K + K – decays is confirmed, and CP asymmetries are observed with a significance of more than five standard deviations in the B ± →π ± π + ⁢π – and B ± →K ± ⁢K + ⁢K – decays, while the CP asymmetry of B ± →K ± ⁢π + ⁢π – decays is confirmed to be compatible with zero. The distributions of these asymmetries are also studied as a function of the three-body phase space and suggest contributions from rescattering and resonance interference processes. An indication of the presence of the decays B ± →π ± ⁢χ c⁢0 ⁡(1⁢P) in both B ± →π ± π + ⁢π – and B ± →π ± ⁢K + ⁢K – decays is observed, as is CP violation involving these amplitudes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Measurement of quark- and gluon-like jet fractions using jet charge in PbPb and pp collisions at 5.02 TeV

The momentum-weighted sum of the electric charges of particles inside a jet, known as jet charge, is sensitive to the electric charge of the particle initiating the parton shower. This paper presents jet charge distributions in $ \sqrt{s_{\mathrm{NN}}} $ = 5.02 TeV lead-lead (PbPb) and proton-proton (pp) collisions recorded with the CMS detector at the LHC. These data correspond to integrated luminosities of 404 μb$^{−1}$ and 27.4 pb$^{−1}$ for PbPb and pp collisions, respectively. Leveraging the sensitivity of the jet charge to fundamental differences in the electric charges of quarks and gluons, the jet charge distributions from simulated events are used as templates to extract the quark- and gluon-like jet fractions from data. The modification of these jet fractions is examined by comparing pp and PbPb data as a function of the overlap of the colliding Pb nuclei (centrality). This measurement tests the color charge dependence of jet energy loss due to interactions with the quark-gluon plasma. No significant modification between different centrality classes and with respect to pp results is observed in the extracted quark- and gluon-like jet fractions.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for a heavy composite Majorana neutrino in events with dilepton signatures from proton-proton collisions at s = 13 TeV

Results are presented of a search for a heavy Majorana neutrino Image 1 decaying into two same-flavor leptons ℓ (electrons or muons) and a quark-pair jet. A model is considered in which the Image 1 is an excited neutrino in a compositeness scenario. The analysis is performed using a sample of proton-proton collisions at s = 13 TeV recorded by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 138 fb − 1 . The data are found to be in agreement with the standard model prediction. For the process in which the Image 1 is produced in association with a lepton, followed by the decay of the Image 1 to a same-flavor lepton and a quark pair, an upper limit at 95% confidence level on the product of the cross section and branching fraction is obtained as a function of the Image 1 mass Image 2 and the compositeness scale Λ. For this model the data exclude the existence of Image 3 (Image 4) for Image 2 below 6.0 (6.1) TeV, at the limit where Image 2 is equal to Λ. For Image 5, values of Λ less than 20 (23) TeV are excluded. These results represent a considerable improvement in sensitivity, covering a larger parameter space than previous searches in Image 6 collisions at 13 TeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Development of a High Throughput PCIe Card for DAQ System in the ATLAS and DUNE Experiments

In the Run 3 upgrade of ATLAS experiment, the FELIX (Front-End LInk eXchange) system has been prepared as the interface between front-end electronics and common Data Acquisition (DAQ) systems. Based on a PCIe card hosted in commodity server, FELIX's flexibilty makes it has also been adopted by other experiments, such as the Single-Phase ProtoDUNE (Prototype for the Deep Underground Neutrino Experiment), sPHENIX and CBM experiments. The same PCIe based architecture is proposed for use in the ATLAS HL-LHC (High Luminosity Large Hadron Collider) upgrade and the DUNE experiment. To this end, the next generation of FELIX I/O card FLX-801 has been developed. It supports 25+ Gbps high speed fiber optical links and 16-lane Gen4 PCIe interface. There is an on-card DDR4 module to buffer event data for DUNE experiment. This paper reports on the test results for the demonstrator of this next generation card, with which main functions have been successfully evaluated.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Measurement of $Z\gamma \gamma$ production in pp collisions at $\sqrt{s}= 13$ TeV with the ATLAS detector

Cross-sections for the production of a $Z$ boson in association with two photons are measured in proton–proton collisions at a centre-of-mass energy of 13 TeV. The data used correspond to an integrated luminosity of 139 fb -1 recorded by the ATLAS experiment during Run 2 of the LHC. The measurements use the electron and muon decay channels of the $Z$ boson, and a fiducial phase-space region where the photons are not radiated from the leptons. The integrated $Z$($\rightarrow$ $\ell$$\ell$)$\gamma \gamma$ cross-section is measured with a precision of 12% and differential cross-sections are measured as a function of six kinematic variables of the $Z\gamma \gamma$ system. The data are compared with predictions from MC event generators which are accurate to up to next-to-leading order in QCD. The cross-section measurements are used to set limits on the coupling strengths of dimension-8 operators in the framework of an effective field theory.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Self-consistent microscopic calculations for electron captures on nuclei in core-collapse supernovae

Calculations for electron capture rates on nuclei with atomic numbers between 𝑍 = 20 and 𝑍 = 52 are performed in a self-consistent finite-temperature covariant energy density functional theory within the relativistic quasiparticle random-phase approximation. Electron captures on these nuclei contribute most to reducing the electron fraction during the collapse phase of core-collapse supernovae. The rates include contributions from allowed (Gamow-Teller) and first-forbidden (FF) transitions, and it is shown that the latter become dominant at high stellar densities and temperatures. Temperature-dependent effects such as Pauli unblocking and transitions from thermally excited states are also included. The new rates are implemented in a spherically symmetric one-dimensional simulation of the core-collapse phase. The results indicate that the increase in electron capture rates, due to inclusion of FF transitions, leads to reductions of the electron fraction at nuclear saturation density, the peak neutrino luminosity, and enclosed mass at core bounce. The new rates reaffirm that the most relevant nuclei for the deleptonization situate around the 𝑁 = 50 and 82 shell closures, but, compared to previous simulations, nuclei are less proton rich. Here, the new rates developed in this work are available, and will be of benefit to improve the accuracy of multidimensional supernova simulations.

Electron & muon capture↗