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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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Dependence of the average spatial and energy characteristics of the hadron-lepton cascade on the strong interaction parameters at superhigh energies

A method for calculating the average spatial and energy characteristics of hadron-lepton cascades in the atmosphere is described. The results of calculations for various strong interaction models of primary protons and nuclei are presented. The sensitivity of the experimentally observed extensive air showers (EAS) characteristics to variations of the elementary act parameters is analyzed.

Boyadjian, N. G.↗
DOE OSTI2015

Final Cooling For a High-luminosity High-Energy Lepton Collider

The final cooling system for a high-energy high-luminosity heavy lepton collider requires reduction of the transverse emittance ε t by an order of magnitude to ~0.00003 m (rms, N), while allowing longitudinal emittance ε L to increase to ~0.1m. In the present baseline approach, this is obtained by transverse cooling of low-energy muons within a sequence of high-field solenoids with low-frequency rf systems. Recent studies of such systems are presented. Since the final cooling steps are mostly emittance exchange, a variant form of that final system can be obtained by a round to flat transform in x-y, with transverse slicing of the enlarged flat transverse dimension followed by longitudinal recombination of the sliced bunchlets. Other variants are discussed. More explicit emittance exchange can greatly reduce the cost of a final cooling system.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of summer 2014

This article reports world averages of measurements of $b$-hadron, $c$-hadron, and $\tau$-lepton properties obtained by the Heavy Flavor Averaging Group (HFAG) using results available through summer 2014. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, $CP$ violation parameters, parameters of semileptonic decays and CKM matrix elements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of WW and WZ production in the lepton plus heavy flavor jets final state at CDF

We present the CDF measurement of the diboson WW and WZ production cross section in a final state consistent with leptonic W decay and jets originating from heavy flavor quarks, based on the full Tevatron Run II dataset. The analysis of the di–jet invariant mass spectrum allows the observation of 3.7 sigma evidence for the combined production processes of either WW or WZ bosons. The different heavy flavor decay pattern of the W and Z bosons and the analysis of the secondary–decay vertex properties allow to independently measure the WW and WZ production cross section in a hadronic final state. The measured cross sections are consistent with the standard model predictions and correspond to signal significances of 2.9 and 2.1 sigma for WW and WZ production, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Simulations of Polarization Levels and Spin Tune Biases in High Energy Leptons Storage Rings

The use of resonant depolarization has been suggested for precise beam energy measurements in the 100 km long Future Circular Collider e+e-. The principle behind resonant depolarization is that a vertically polarized beam excited through an oscillating horizontal magnetic field gets depolarized when the excitation frequency is in a given relationship with the beam energy. In this paper the possibility of self- polarized leptons at 45 GeV (Z resonance) and 80 GeV (WW in presence of quadrupole vertical misalignment is investigated.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Combination of the CDF and D0 Effective Leptonic Electroweak Mixing Angles

CDF and D0 have measured the effective leptonic weak mixing angle $sin^2 \theta^{lept}_{eff}$ , using their full Tevatron datasets. This note describes the Tevatron combination of these measurements, and the zfitter standard model-based inference of the on-shell electroweak mixing angle $sin^2 \theta_W$, or equivalently, the W-boson mass. The combination of CDF and D0 results yields: $sin^2 \theta^{lept}_ {eff}$ = 0.23179 ± 0.00035, and $sin^2 \theta_W$ = 0.22356 ± 0.00035, or equivalently, $M_W$(indirect) = 80.351 ± 0.018 GeV/$c^2$.

Source record↗
DOE OSTI2018

B- and D-meson leptonic decay constants and quark masses from four-flavor lattice QCD

We describe a recent lattice-QCD calculation of the leptonic decay constants of heavy-light pseudoscalar mesons containing charm and bottom quarks and of the masses of the up, down, strange, charm, and bottom quarks. Results for these quantities are of the highest precision to date. Calculations use 24 isospin-symmetric ensembles of gauge-field configurations with six different lattice spacings as small as approximately 0.03 fm and several values of the light quark masses down to physical values of the average up- and down-sea-quark masses. We use the highly-improved staggered quark (HISQ) formulation for valence and sea quarks, including the bottom quark. The analysis employs heavy-quark effective theory (HQET). A novel HQET method is used in the determination of the quark masses.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Search for Heavy Neutral Leptons in the MicroBooNE LArTPC

aHeavy Neutral Leptons (HNLs) offer a possible extension of the Standard Model via mixing with the three active neutrino flavours. HNLs with masses between 1 and 493 MeV can be produced from kaon and pion decays in the high-intensity Booster Neutrino Beam. These particles would then travel to the MicroBooNE detector where some fraction would decay in-flight to detectable Standard Model particles. This poster presents work to perform the first search for these particles in a liquid argon TPC. A number of methods are used to distinguish the HNL decays from the neutrino and cosmic ray background including utilising the time of flight of the massive HNL with respect to the active neutrinos. As the first search of its kind in a LArTPC this work pioneers techniques applicable for future large scale searches in the both the full Short Baseline Neutrino program and DUNE.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

A Search for Charged Lepton Flavor Violation in the Mu2e Experiment

The Mu2e experiment will search for the neutrino-less conversion of a muon into an electron in the field of an aluminum nucleus. An observation would be the first signal of charged-lepton flavor violation and de facto evidence for new physics beyond the Standard Model. The clean signature of the conversion process offers an opportunity for a powerful search: Mu2e will probe four orders of magnitude beyond current limits, with real discovery potential over a wide range of well motivated new physics models. This goal requires an integrated system of solenoids that will create the most intense muon beam in the world, and suppression of all possible background sources. The Mu2e components are currently being constructed, with the experiment planned to begin operations in the Fermilab Muon Campus within the next few years.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Measurement of the cross section of top quark pairs produced in association with a Photon in Lepton +Jets events at $\sqrt{s}$ = 13 TeV with full Run II CMS data

The inclusive production cross section of top quark pairs in association with a photon is measured in proton-proton collisions at the LHC with 13 TeV energy using the full RunII data collected by CMS in 2016, 2017, and 2018 with a total corresponding integrated luminosity of 137 fb$^{-1}$. The relative fraction of t$ \bar{t} \gamma$ events normalized to inclusive t$ \bar{t}$ production is measured. The cross section measurement provides important information about the electromagnetic coupling of the standard model top quark and is sensitive to physics beyond the standard model. The analysis is carried out in the in semileptonic decay channel with a well isolated high P$ \_{T}$ lepton (electron and muon), at least four jets out of which at least one must be b-tagged, and an isolated photon. Photons may be emitted from initial state radiation, top quarks, and decay products of top quarks. The fiducial phase space with a photon of transverse momentum $ \ge$ 20 GeV and j\x11$ \eta$ <1.4441 is used. A simultaneous likelihood fit of control regions with the signal region is done to constraint the backgrounds and to extract the t$ \bar{t} \gamma$ cross section. The measurement of the ratio of t$ \bar{t} \gamma$ to t$ \bar{t}$ is $0.02055 \pm 0.00099$ (syst.) $ \pm 0.00099$ (stat.) in $e$ channel , 0.02156 $ \pm$ 0.00068 (syst.) $ \pm$ 0.00068 (stat.) in $ \mu$ channel , and 0.02203 $ \pm$ 0.00064 (syst.) $ \pm$ 0.00064 (stat.) in e + $ \mu$ channel , respectively. The measured inclusive cross section is 3.81 $ \pm$ 0.15 (syst.) $ \pm$ 0.10 (stat.) pb in e channel , 3.87 $ \pm$ 0:11 (syst.) $ \pm$ 0:07 (stat.) pb in $ \mu$ channel , and 3.96 $ \pm$ 0.10 (syst.) $ \pm$ 0.06 (stat.) pb in e + $ \mu$ channel , respectively for full RunII data. The total inclusive cross section with a photon of transverse momentum $ \ge$ 20 GeV is found to be 3.96 $ \pm$ 0.10 (syst.) $ \pm$ 0.06 (stat.) pb with full RunII CMS data. The results are in agreement with the standard model next to leading order prediction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Search for anomalous gauge couplings in semi-leptonic decays of $WW\gamma$ and $WZ\gamma$ in pp collisions at $\sqrt{s} =$ 8 TeV

A study of the Standard Model (SM) three electroweak boson production, $WV\gamma$ where V = W or Z gauge boson, is presented concerning events with a leptonically decaying W boson accompanied by a photon and two or more jets. We are using the full 2012 dataset, of proton-proton collisions at a center-of-mass energy of 8 TeV and an integrated luminosity of 19.3 fb${}^{-1}$, collected by the CMS detector at the Large Hadron Collider (LHC). $WV\gamma$ production final states may be sensitive to anomalous $WW\gamma\gamma$ and $WWZ\gamma$ quartic couplings. In light of the recent discovery of a Higgs-like particle, we investigate, in a model independent way, any deviation of gauge boson couplings with respect to the SM prediction by setting limits on the anomalous quartic gauge couplings (aQGC) for $WW\gamma\gamma$ and $WWZ\gamma$. Upper limits at 95% confidence level are obtained, with and without a form factor.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Search for Higgs Portal Scalars and Heavy Neutral Leptons Decaying in the MicroBooNE Detector

This thesis presents a search for Higgs Portal Scalars (HPS) and Heavy Neutral Leptons (HNL) decaying in the MicroBooNE liquid argon time projection chamber (LArTPC). The measurement was performed using data collected in-time with the Neutrino at the Main Injector (NuMI) beam with a total exposure corresponding to $7.01 \times 10^{20}$ protons on target. Mono-energetic HPS and HNL would be produced from kaons decaying at rest in the NuMI hadron absorber, before travelling ${\sim}100$~m to the MicroBooNE detector where they decay. A single selection and search strategy is used to target decays of HPS to $\mu\mu$ pairs and HNL to $\mu\pi$ pairs. The results are expressed as limits, at the $90\%$ confidence level, on the mixing angles that control the rates of production and decay for each new particle. For the HNL model, upper limits are set on the mixing parameter $\mumix$ in the range [$12.9 \times 10^{-8}$, $0.54 \times 10^{-8}$] for HNL with masses in the region $246$--$385$~MeV. % This represents an order of magnitude increase in sensitivity to the previous MicroBooNE HNL result. For the HPS model, limits on the scalar-Higgs mixing angle $\theta^2$ are set, excluding a region with a lower boundary between [$31.3 \times10^{-9}$, $1.09 \times 10^{-9}$] and an upper boundary between [$2.50 \times 10^{-5}$, $5.05 \times 10^{-9}$] for scalars with a mass of $212$--$275$ MeV. These results set the first constraints in this region of parameter space from a dedicated experimental search for HPS.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Search for Higgs Portal Scalars and Heavy Neutral Leptons Decaying in the MicroBooNE Detector

This thesis presents a search for Higgs Portal Scalars (HPS) and Heavy Neutral Leptons (HNL) decaying in the MicroBooNE liquid argon time projection chamber (LArTPC). The measurement was performed using data collected in-time with the Neutrino at the Main Injector (NuMI) beam with a total exposure corresponding to 7.01x10^20 protons on target. Mono-energetic HPS and HNL would be produced from kaons decaying at rest in the NuMI hadron absorber, before travelling ~100 m to the MicroBooNE detector where they decay. A single selection and search strategy is used to target decays of HPS to muon-muon pairs and HNL to muon-pion pairs. The results are expressed as limits, at the 90% confidence level, on the mixing angles that control the rates of production and decay for each new particle. For the HNL model, upper limits are set on the mixing parameter |U\mu4|^2 in the range [12.9 x 10^-8, 0.54 x 10^-8] for HNL with masses in the region 246 - 385 MeV. For the HPS model, limits on the scalar-Higgs mixing angle \theta^2 are set, excluding a region with a lower boundary between [31.3 x 10^-9, 1.09 x 10^-9] and an upper boundary between [2.50 x 10^-5, 5.05 x 10^-9] for scalars with a mass of 212-275 MeV. These results set the first constraints in this region of parameter space from a dedicated experimental search for HPS.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

DarkNews: a Python-based event generator for heavy neutral lepton production in neutrino-nucleus scattering

We introduce DarkNews, a lightweight Python-based Monte-Carlo generator for beyond-the-Standard-Model neutrino-nucleus scattering. The generator handles the production and decay of heavy neutral leptons via additional vector or scalar mediators, as well as through transition magnetic moments. DarkNews samples pre-computed neutrino-nucleus upscattering cross sections and heavy neutrino decay rates to produce dilepton and single-photon events in accelerator neutrino experiments. We present two case studies with differential distributions for models that can explain the MiniBooNE excess. The aim of this code is to aid the neutrino theory and experimental communities in performing searches and sensitivity studies for new particles produced in neutrino upscattering.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

A Leptonic Model for Neutrino Emission From Active Galactic Nuclei

It is often stated that the observation of high-energy neutrinos from an astrophysical source would constitute a smoking gun for the acceleration of hadronic cosmic rays. Here, we point out that there exists a purely leptonic mechanism to produce TeV-scale neutrinos in astrophysical environments. In particular, very high-energy synchrotron photons can scatter with X-rays, exceeding the threshold for muon-antimuon pair production. When these muons decay, they produce neutrinos without any cosmic-ray protons or nuclei being involved. In order for this mechanism to be efficient, the source in question must produce very high-energy photons which interact in an environment that is dominated by keV-scale radiation. As an example, we consider the active galaxy NGC 1068, which IceCube has recently detected as a source of TeV-scale neutrinos. We find that the neutrino emission observed from this source could potentially be generated through muon pair production for reasonable choices of physical parameters.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

New formulation of target mass corrections in deep-inelastic lepton-nucleon scattering

The description of deep-inelastic lepton-nucleon scattering at finite values of Q2 requires subleading corrections such as those arising from target mass corrections (TMCs) to be accounted for, particularly at large values of the parton momentum fraction x. The standard method of incorporating TMCs via Nachtmann moments of structure functions, constructed from local operators within the operator product expansion, is known to have practical difficulties reproducing the corresponding Cornwall-Norton moments of the structure functions without TMCs. We consider several potential resolutions of this paradox, and discuss consequences for the interpretation of parton distributions at finite values of Q2.

Brown, Matthew D.↗
DOE OSTI2023

A Search for Heavy Neutral Leptons Decaying to Electron-Positron Pairs and Neutral Pions in the MicroBooNE Detector

This thesis presents a search for heavy neutral leptons (HNLs) decaying inside the MicroBooNE detector. The MicroBooNE detector is a liquid-argon time projection chamber located at Fermilab that receives flux from two neutrino beams; the booster neutrino beam (BNB) and the neutrinos at the main injector (NuMI) beam. The search uses data taken when the NuMI beam was on, with a total exposure of $7.01\times10^{20}$ protons on target. HNLs would be produced in kaon decays, and the source of HNLs targeted in this search is kaons decaying at rest in the NuMI hadron absorber. The kinematics of the HNLs produced in this way allow their decays to be distinguished from the majority of beam-neutrino interactions and cosmic-ray activity that constitute the background. Two HNL decay channels are studied, $\nu$\ee and \vpi. Boosted decision trees (BDTs) are trained to separate the simulated HNL decays from the expected background events. The BDT score distributions are used to calculate upper limits on the mixing angle \umusq in the mass range $10\le m_{\rm HNL}\le 245$~MeV. This is the first direct search for HNL decays to the \vpi channel, and the limits provide the most stringent constraints on \umusq in the mass range $35<\mhnl<175$~MeV.

43 PARTICLE ACCELERATORS↗