Search NASA⌕ Search

SEARCH · Search NASA

Results for “section”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,441 records · Page 80
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

When rational sections become cyclic — Gauge enhancement in F-theory via Mordell-Weil torsion

We explore novel gauge enhancements from abelian to non-simply-connected gauge groups in F-theory. Accordingly, we consider complex structure deformations of elliptic fibrations with a Mordell-Weil group of rank one and identify the conditions under which the generating section becomes torsional. In the specific case of Ζ 2 torsion we construct the generic solution to these conditions and show that the associated F-theory compactification exhibits the global gauge group [SU (2) × SU (4) ]/Ζ 2 × SU (2) . The subsolution with gauge group SU (2) /Ζ 2 × SU (2) , for which we provide a global resolution, is related by a further complex structure deformation to a genus-one fibration with a bisection whose Jacobian has a Ζ 2 torsional section. While an analysis of the spectrum on the Jacobian fibration reveals an SU (2) /Ζ 2 × Ζ 2 gauge theory, reproducing this result from the bisection geometry raises some conceptual puzzles about F-theory on genus-one fibrations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Measurement of the inclusive $ \mathrm{t}\overline{\mathrm{t}} $ cross section in pp collisions at $ \sqrt{s}=5.02 $ TeV using final states with at least one charged lepton

The top quark pair production cross section $ \left({\sigma}_{\mathrm{t}\overline{\mathrm{t}}}\right) $ is measured for the first time in pp collisions at a center-of-mass energy of 5.02 TeV. The data were collected by the CMS experiment at the LHC and correspond to an integrated luminosity of 27.4 pb$^{−1}$. The measurement is performed by analyzing events with at least one charged lepton. The measured cross section is $ {\sigma}_{\mathrm{t}\overline{\mathrm{t}}} $ = 69.5 ± 6.1 (stat) ± 5.6 (syst) ± 1.6 (lumi) pb, with a total relative uncertainty of 12%. The result is in agreement with the expectation from the standard model. The impact of the presented measurement on the determination of the gluon distribution function is investigated.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at $ \sqrt{s}=8 $ TeV

Cross sections for the production of a Z boson in association with jets in proton-proton collisions at a centre-of-mass energy of $ \sqrt{s}=8 $ TeV are measured using a data sample collected by the CMS experiment at the LHC corresponding to 19.6 fb$^{−1}$. Differential cross sections are presented as functions of up to three observables that describe the jet kinematics and the jet activity. Correlations between the azimuthal directions and the rapidities of the jets and the Z boson are studied in detail. The predictions of a number of multileg generators with leading or next-to-leading order accuracy are compared with the measurements. The comparison shows the importance of including multi-parton contributions in the matrix elements and the improvement in the predictions when next-to-leading order terms are included.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Measurement of normalized differential $ \mathrm{t}\overline{\mathrm{t}} $ cross sections in the dilepton channel from pp collisions at $ \sqrt{s}=13 $ TeV

Normalized differential cross sections for top quark pair production are measured in the dilepton (e$^{+}$e$^{−}$, μ$^{+}$μ$^{−}$, and μ$^{∓}$e$^{±}$) decay channels in proton-proton collisions at a center-of-mass energy of 13 TeV. The measurements are performed with data corresponding to an integrated luminosity of 2.1 fb$^{−1}$ using the CMS detector at the LHC. The cross sections are measured differentially as a function of the kinematic properties of the leptons, jets from bottom quark hadronization, top quarks, and top quark pairs at the particle and parton levels. The results are compared to several Monte Carlo generators that implement calculations up to next-to-leading order in perturbative quantum chromodynamics interfaced with parton showering, and also to fixed-order theoretical calculations of top quark pair production up to next-to-next-to-leading order.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Measurement of the ratio of cross sections for inclusive isolated-photon production in $pp$ collisions at $ \sqrt{s} $ = 13 and 8 TeV with the ATLAS detector

The ratio of the cross sections for inclusive isolated-photon production in pp collisions at centre-of-mass energies of 13 and 8 TeV is measured using the ATLAS detector at the LHC. The integrated luminosities of the 13 TeV and 8 TeV datasets are 3.2 fb –1 and 20.2 fb –1 , respectively. The ratio is measured as a function of the photon transverse energy in different regions of the photon pseudorapidity. The predictions from next-to-leading-order perturbative QCD calculations are compared with the measured ratio. The experimental systematic uncertainties as well as the uncertainties affecting the predictions are evaluated taking into account the correlations between the two centre-of-mass energies, resulting in a reduction of up to a factor of 2.5 (5) in the experimental (theoretical) systematic uncertainties. The predictions based on several parameterisations of the proton parton distribution functions agree with the data within the reduced experimental and theoretical uncertainties. In addition, this ratio to that of the fiducial cross sections for Z boson production at 13 and 8 TeV using the decay channels Z → e + e – and Z → μ + μ – is made and compared with the theoretical predictions. In this double ratio, a further reduction of the experimental uncertainty is obtained because the uncertainties arising from the luminosity measurement cancel out. The predictions describe the measurements of the double ratio within the theoretical and experimental uncertainties.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Measurement of the inclusive $ \mathrm{t}\overline{\mathrm{t}} $ production cross section in proton-proton collisions at $ \sqrt{s} $ = 5.02 TeV

The top quark pair production cross section is measured in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data were collected in a special LHC low-energy and low-intensity run in 2017, and correspond to an integrated luminosity of 302 pb - 1 . The measurement is performed using events with one electron and one muon of opposite charge, and at least two jets. The measured cross section is 60 . 7 ± 5 . 0 (stat) ± 2 . 8 (syst) ± 1 . 1 (lumi) pb. A combination with the result in the single lepton + jets channel, based on data collected in 2015 at the same center-of-mass energy and corresponding to an integrated luminosity of 27.4 pb - 1 , is then performed. The resulting measured value is 63 . 0 ± 4 . 1 (stat) ± 3 . 0 (syst+lumi) pb, in agreement with the standard model prediction of \( {66.8}_{-3.1}^{+2.9} \) pb.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Measurement of the inclusive $\textrm{t}\overline{\textrm{t}}$ cross section in final states with at least one lepton and additional jets with 302 pb −1 of pp collisions at $\sqrt{\textrm{s}}$ = 5.02 TeV

A measurement of the top quark pair ($ \textrm{t}\overline{\textrm{t}} $) production cross section in proton-proton collisions at a centre-of-mass energy of 5.02 TeV is presented. The data were collected at the LHC in autumn 2017, in dedicated runs with low-energy and low-intensity conditions with respect to the default configuration, and correspond to an integrated luminosity of 302 pb$^{−1}$. The measurement is performed using events with one electron or muon, and multiple jets, at least one of them being identified as originating from a b quark (b tagged). Events are classified based on the number of all reconstructed jets and of b-tagged jets. Multivariate analysis techniques are used to enhance the separation between the signal and backgrounds. The measured cross section is $ 62.5\pm 1.6{\left(\textrm{stat}\right)}_{-2.5}^{+2.6}\left(\textrm{syst}\right)\pm 1.2\left(\textrm{lumi}\right) $ pb. A combination with the result in the dilepton channel based on the same data set yields a value of 62.3 ± 1.5 (stat) ± 2.4 (syst) ± 1.2 (lumi) pb, to be compared with the standard model prediction of $ {69.5}_{-3.7}^{+3.5} $ pb at next-to-next-to-leading order in perturbative quantum chromodynamics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Combination and interpretation of differential Higgs boson production cross sections in proton-proton collisions at $ \sqrt{s}=13 $ TeV

Precision measurements of Higgs boson differential production cross sections are a key tool to probe the properties of the Higgs boson and test the standard model. New physics can affect both Higgs boson production and decay, leading to deviations from the distributions that are expected in the standard model. In this paper, combined measurements of differential spectra in a fiducial region matching the experimental selections are performed, based on analyses of four Higgs boson decay channels (γγ, ZZ$^{(*)}$, WW$^{(*)}$, and ττ) using proton-proton collision data recorded with the CMS detector at $ \sqrt{s}=13 $ TeV, corresponding to an integrated luminosity of 138 fb$^{−1}$. The differential measurements are extrapolated to the full phase space and combined to provide the differential spectra. A measurement of the total Higgs boson production cross section is also performed using the γγ and ZZ decay channels, with a result of $ {53.4}_{-2.9}^{+2.9}{\left(\textrm{stat}\right)}_{-1.8}^{+1.9}\left(\textrm{syst}\right) $ pb, consistent with the standard model prediction of 55.6 ± 2.5 pb. The fiducial measurements are used to compute limits on Higgs boson couplings using the κ-framework and the SM effective field theory.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Measurements of the differential cross sections of the production of Z + jets and $\gamma$ + jets and of Z boson emission collinear with a jet in pp collisions at $ \sqrt{s} $ = 13 TeV

Measurements of the differential cross sections of Z + jets and γ + jets production, and their ratio, are presented as a function of the boson transverse momentum. Measurements are also presented of the angular distribution between the Z boson and the closest jet. The analysis is based on pp collisions at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 35.9 fb$^{−1}$ recorded by the CMS experiment at the LHC. The results, corrected for detector effects, are compared with various theoretical predictions. In general, the predictions at higher orders in perturbation theory show better agreement with the measurements. This work provides the first measurement of the ratio of the differential cross sections of Z + jets and γ + jets production at 13 TeV, as well as the first direct measurement of Z bosons emitted collinearly with a jet.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Measurement of differential t-channel single top (anti)quark production cross-sections at 13 TeV with the ATLAS detector

The production of single top quarks and top antiquarks via the t-channel exchange of a virtual W boson is measured in proton-proton collisions at a centre-of-mass energy of 13 TeV at the Large Hadron Collider. The full Run 2 data sample recorded with the ATLAS detector in the years 2015–2018 is used, corresponding to an integrated luminosity of 140 fb−1. The absolute and normalised production cross-sections are measured differentially as a function of the transverse momentum and absolute rapidity of the top quark and top antiquark. In addition, the ratio of top quark to top antiquark production cross-sections is measured. The measured distributions are compared with next-to-leading-order quantum chromodynamics predictions obtained with different combinations of matrix-element generators, parton-shower programs and proton parton distribution functions, as well as to next-to-next-to-leading-order calculations. Overall, good agreement is observed between the measurements and the theoretical predictions. For most measured distributions, the sensitivity to differences between the predictions is limited by the systematic uncertainties in the measurement. The measured differential distributions are also interpreted in an effective field theory approach to constrain the Wilson-Coefficient CQq3,1$$ {C}_{Qq}^{3,1} $$ associated with a four-quark operator. The interpretation accounts for the effect of the selection efficiency, which is altered significantly by non-zero contributions from CQq3,1$$ {C}_{Qq}^{3,1} $$.

Aad, G↗
DOE OSTI2020

Determination of the strong coupling constant $\alpha_{S}(m_\mathrm{Z})$ from measurements of inclusive W$^\pm$ and Z boson production cross sections in proton-proton collisions at $ \sqrt{\mathrm{s}} $ = 7 and 8 TeV

Twelve measurements of inclusive cross sections of W$^{±}$ and Z boson production, performed in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, are compared with perturbative quantum chromodynamics calculations at next-to-next- to-leading order (NNLO) accuracy obtained with the CT14, HERAPDF2.0, MMHT14, and NNPDF3.0 parton distribution functions (PDFs). Data and theory agree well for all PDF sets, taking into account the experimental and theoretical uncertainties. A novel procedure is employed to extract the strong coupling constant at the Z pole mass from a detailed comparison of all the experimental fiducial cross sections to the corresponding NNLO theoretical predictions, yielding $ {\alpha}_{\mathrm{S}}\left({m}_{\mathrm{Z}}\right)={0.1163}_{-0.0031}^{+0.0024} $ (CT14), $ {0.1072}_{-0.0040}^{+0.0043} $ (HERAPDF2.0), 0.1186 ± 0.0025 (MMHT14), and 0.1147 ± 0.0023 (NNPDF3.0). Using the results obtained with the CT14 and MMHT14 PDFs, which yield the most robust and stable α$_{S}$(m$_{Z}$) extractions, a value $ {\alpha}_{\mathrm{S}}\left({m}_{\mathrm{Z}}\right)={0.1175}_{-0.0028}^{+0.0025} $ is determined.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Measurement of the energy dependence of the e+e- → $ B\overline{B} $, $ B{\overline{B}}^{\ast } $ and $ {B}^{\ast }{\overline{B}}^{\ast } $ exclusive cross sections

We report the first measurement of the exclusive cross sections e + e - → $B\overline{B}$, e + e - → $B{\overline{B}}^{\ast }$, and e + e - → ${B}^{\ast }{\overline{B}}^{\ast }$ in the energy range from 10.63 GeV to 11.02 GeV. The B mesons are fully reconstructed in a large number of hadronic final states and the three channels are identified using a beam-constrained-mass variable. The shapes of the exclusive cross sections show oscillatory behavior with several maxima and minima. The results are obtained using data collected by the Belle experiment at the KEKB asymmetric-energy e + e - collider.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Twist-three cross-sections in deeply virtual Compton scattering

We study the deeply virtual Compton scattering process with both twist-two and twist-three Compton form factors and present our cross-sections formulas with all polarization configurations. While the twist-three contributions are generally assumed to be negligible in the literature due to the kinematical suppression, we compare them with the twist-two ones at typical JLab 6 GeV and 12 GeV kinematics as well as EIC kinematics and show their kinematical suppression explicitly, justifying the leading-twist approximation made in the literature. In addition, we also estimate the twist-three Compton form factors using Wandzura-Wilczek relations and inputs of twist-two generalized parton distributions based on a reggeized spectator model. With those estimated Compton form factors, we analyze the kinematical behavior of twist-two and twist-three cross-sections in a wide range of kinematics, and discuss the optimal regions for separating the leading-twist effects from the higher-twist ones.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Measurement of the Z boson production cross-section in proton-lead collisions at $\sqrt{s_{\textrm{NN}}}$ = 8.16 TeV

This article presents the first measurement of the differential Z-boson production cross-section in the forward region using proton-lead collisions with the LHCb detector. The dataset was collected at a nucleon-nucleon centre-of-mass energy of $\sqrt{s_{NN}}$ = 8.16 TeV in 2016, corresponding to an integrated luminosity of 30.8 nb –1 . The forward-backward ratio and the nuclear modification factors are measured together with the differential cross-section as functions of the Z boson rapidity in the centre-of-mass frame, the transverse momentum of the Z boson and a geometric variable $\phi$*. The results are in good agreement with the predictions from nuclear parton distribution functions, providing strong constraining power at small Bjorken-x.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Cross-section measurements for the production of a Z boson in association with high-transverse-momentum jets in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

Cross-section measurements for a $Z$ boson produced in association with high-transverse-momentum jets ($p_T$ ≥ 100 GeV) and decaying into a charged-lepton pair ($e^+$$e^–$, $µ^+$$µ^–$) are presented. The measurements are performed using proton–proton collisions at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 139 fb –1 collected by the ATLAS experiment at the LHC. Measurements of angular correlations between the $Z$ boson and the closest jet are performed in events with at least one jet with $p_T$ ≥ 500 GeV. Event topologies of particular interest are the collinear emission of a $Z$ boson in dijet events and a boosted $Z$ boson recoiling against a jet. Fiducial cross sections are compared with state-of-the-art theoretical predictions. The data are found to agree with next-to-nextto-leading-order predictions by NNLOjet and with the next-to-leading-order multi-leg generators MadGraph5_aMC@NLO and Sherpa.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Measurement of the $t\overline{t}$ production cross-section in pp collisions at √s = 5.02 TeV with the ATLAS detector

The inclusive top-quark pair tt production cross-section σ tt is measured in proton–proton collisions at a centre-of-mass energy $\sqrt{s}$ = 5.02 TeV, using 257 pb -1 of data collected in 2017 by the ATLAS experiment at the LHC. The $t\overline{t}$ cross-section is measured in both the dilepton and single-lepton final states of the $t\overline{t}$ system and then combined.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Measurement and effective field theory interpretation of the photon-fusion production cross section of a pair of W bosons in proton-proton collisions at $\sqrt{s}=13 $ TeV

This analysis presents an observation of the photon-fusion production of W boson pairs using the CMS detector at the LHC. The total cross section of the W + W − production in photon fusion is measured using proton-proton collision data with an integrated luminosity of 138 fb −1 collected with the CMS detector in 2016–2018 at a center-of-mass energy of $\sqrt{s}=13 $ TeV. Events are selected in the final state with one isolated electron and one isolated muon, and no additional tracks associated with the electron-muon production vertex. The total and fiducial production cross sections are 643$^{+82}_{–78}$ fb and 3.96$^{+0.53}_{–0.51}$ fb, respectively, in agreement with the standard model predictions of 631 ± 126 fb and 3.87 ± 0.77 fb. This agreement enables stringent constraints on anomalous quartic gauge couplings within a dimension-8 effective field theory framework.

Hadron-Hadron Scattering↗
DOE OSTI2018

Measurement of the inelastic proton-proton cross section at $ \sqrt{s}=13 $ TeV

A measurement of the inelastic proton-proton cross section with the CMS detector at a center-of-mass energy of $\sqrt{s} =$ 13 TeV is presented. The analysis is based on events with energy deposits in the forward calorimeters, which cover pseudorapidities of -6.6 $< \eta <$ -3.0 and +3.0 $< \eta <$ +5.2. An inelastic cross section of 68.6 $\pm$ 0.5 (syst) $\pm$ 1.6 (lumi) mb is obtained for events with $M_\mathrm{X} >$ 4.1 GeV and/or $M_\mathrm{Y} >$ 13 GeV, where $M_\mathrm{X}$ and $M_\mathrm{Y}$ are the masses of the diffractive dissociation systems at negative and positive pseudorapidities, respectively. Furthermore, the results are compared with those from other experiments as well as to predictions from high-energy hadron-hadron interaction models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗