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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
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DOE OSTI2022

Search for single production of a vector-like T quark decaying to a top quark and a Z boson in the final state with jets and missing transverse momentum at $ \sqrt{s} $ = 13 TeV

A search is presented for single production of a vector-like T quark with charge 2/3 e, in the decay channel featuring a top quark and a Z boson, with the top quark decaying hadronically and the Z boson decaying to neutrinos. The search uses data collected by the CMS experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 137 fb -1 recorded at the CERN LHC in 2016–2018. The search is sensitive to a T quark mass between 0.6 and 1.8 TeV with decay widths ranging from negligibly small up to 30% of the T quark mass. Reconstruction strategies for the top quark are based on the degree of Lorentz boosting of its final state. At 95% confidence level, the upper limit on the product of the cross section and branching fraction for a T quark of small decay width varies between 15 and 602 fb, depending on its mass. For a T quark with decay widths between 10 and 30% of its mass, this upper limit ranges between 16 and 836 fb. For most of the studied range, the results provide the best limits to date. This is the first search for single T quark production based on the full Run 2 data set of the LHC.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Search for charged lepton flavor violating decays of $\Upsilon (1S)$

We present a search for the charged lepton-flavor-violating decays Υ(1S) → ℓ ± ℓ' ∓ and radiative charged lepton-flavour-violating decays Υ(1S) → γ ℓ±ℓ'∓ [ℓ,ℓ' = e, μ, τ] using the 158 million Υ(2S) sample collected by the Belle detector at the KEKB collider. This search uses Υ(1S) mesons produced in Υ(2S) → π + π – Υ(1S) transitions. We do not find any significant signal, so we provide upper limits on the branching fractions at the 90% confidence level.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Helicity amplitude analysis of χcJ → ϕϕ

Using (447.9 ± 2.3) million ψ(3686) events collected with the BESIII detector, the decays of χcJ → ΦΦ (J = 0, 1, 2) have been studied via the decay ψ(3686) → γχcJ. The branching fractions of the decays χcJ → ΦΦ (J = 0, 1, 2) are determined to be (8.59 ± 0.27 ± 0.20) × 10-4, (4.26 ± 0.13 ± 0.15) × 10-4, and (12.67 ± 0.28 ± 0.33) × 10-4, respectively, which are the most precise measurements to date. From a helicity amplitude analysis of the process ψ(3686) → γχcJ , χcJ → ΦΦ, Φ → K+K-, the polarization parameters of the χcJ → ΦΦ decays are determined for the first time.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for heavy resonances and quantum black holes in eμ, eτ, and μτ final states in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search is reported for heavy resonances and quantum black holes decaying into eμ, eτ, and μτ final states in proton-proton collision data recorded by the CMS experiment at the CERN LHC during 2016–2018 at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb -1 . The eμ, eτ, and μτ invariant mass spectra are reconstructed, and no evidence is found for physics beyond the standard model. Upper limits are set at 95% confidence level on the product of the cross section and branching fraction for lepton flavor violating signals. Three benchmark signals are studied: resonant τ sneutrino production in R parity violating supersymmetric models, heavy Z' gauge bosons with lepton flavor violating decays, and nonresonant quantum black hole production in models with extra spatial dimensions. Resonant τ sneutrinos are excluded for masses up to 4.2TeV in the eμ channel, 3.7TeV in the eτ channel, and 3.6TeV in the μτ channel. A Z' boson with lepton flavor violating couplings is excluded up to a mass of 5.0TeV in the eμ channel, up to 4.3Te V in the eτ channel, and up to 4.1TeV in the μτ channel. Quantum black holes in the benchmark model are excluded up to the threshold mass of 5.6TeV in the eμ channel, 5.2TeV in the eτ channel, and 5.0TeV in the μτ channel. In addition, model-independent limits are extracted to allow comparisons with other models for the same final states and similar event selection requirements. The results of these searches provide the most stringent limits available from collider experiments for heavy particles that undergo lepton flavor violating decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for long-lived particles decaying to a pair of muons in proton-proton collisions at $ \sqrt{s} $ = 13 TeV

An inclusive search for long-lived exotic particles decaying to a pair of muons is presented. The search uses data collected by the CMS experiment at the CERN LHC in proton-proton collisions at $ \sqrt{s} $ = 13 TeV in 2016 and 2018 and corresponding to an integrated luminosity of 97.6 fb$^{−1}$. The experimental signature is a pair of oppositely charged muons originating from a common secondary vertex spatially separated from the pp interaction point by distances ranging from several hundred μm to several meters. The results are interpreted in the frameworks of the hidden Abelian Higgs model, in which the Higgs boson decays to a pair of long-lived dark photons Z$_{D}$, and of a simplified model, in which long-lived particles are produced in decays of an exotic heavy neutral scalar boson. For the hidden Abelian Higgs model with m(Z$_{D}$) greater than 20 GeV and less than half the mass of the Higgs boson, they provide the best limits to date on the branching fraction of the Higgs boson to dark photons for cτ(Z$_{D}$) (varying with m(Z$_{D}$)) between 0.03 and ≈0.5 mm, and above ≈0.5 m. Our results also yield the best constraints on long-lived particles with masses larger than 10 GeV produced in decays of an exotic scalar boson heavier than the Higgs boson and decaying to a pair of muons.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Measurement of Born cross section of $$ {e}^{+}{e}^{-}\to {\Sigma}^{+}{\overline{\Sigma}}^{-} $$ at center-of-mass energies between 3.510 and 4.951 GeV

Abstract Using 24.1 fb −1 ofe + e − collision data collected with the BESIII detector at the BEPCII collider, the Born cross sections and effective form factors of the$$ {e}^{+}{e}^{-}\to {\Sigma}^{+}{\overline{\Sigma}}^{-} $$ e + e − → Σ + Σ ¯ − reaction are measured. The measurements are performed at center-of-mass energies ranging from 3.510 to 4.951 GeV. No significant evidence for the decay of the charmonium(-like) states,ψ(3770),ψ(4040),ψ(4160),Y(4230),Y(4360),ψ(4415), andY(4660), into a$$ {\Sigma}^{+}{\overline{\Sigma}}^{-} $$ Σ + Σ ¯ − final state is observed. Consequently, upper limits for the products of the branching fractions and the electronic partial widths at the 90% confidence level are reported for these decays.

Physics↗
DOE OSTI2024

Search for ∆S = 2 nonleptonic hyperon decays Ω− → Σ0π− and Ω− → nK−

Abstract Using (27.12 ± 0.14) × 10 8 ψ(3686) events collected by the BESIII detector at the center-of-mass energy of$$ \sqrt{s} $$ s = 3.686 GeV, we search for the first time for two nonleptonic hyperon decays that change strangeness by two units, Ω − → Σ 0 π − and Ω − →nK − . No significant signal is observed. The upper limits on their decay branching fractions are determined to be$$ \mathcal{B} $$ B (Ω − → Σ 0 π − )<5.4 × 10 −4 and$$ \mathcal{B} $$ B (Ω − →nK − )<2.4 × 10 −4 at the 90% confidence level.

Physics↗
DOE OSTI2024

Search for a new resonance decaying into two spin-0 bosons in a final state with two photons and two bottom quarks in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search for a new boson X is presented using CERN LHC proton-proton collision data collected by the CMS experiment at $\sqrt{s}$ = 13 TeV in 2016–2018, and corresponding to an integrated luminosity of 138 fb -1 . The resonance X decays into either a pair of Higgs bosons HH of mass 125 GeV or an H and a new spin-0 boson Y. One H subsequently decays to a pair of photons, and the second H or Y, to a pair of bottom quarks. The explored mass ranges of X are 260–1000 GeV and 300–1000 GeV, for decays to HH and to HY, respectively, with the Y mass range being 90–800 GeV. For a spin-0 X hypothesis, the 95% confidence level upper limit on the product of its production cross section and decay branching fraction is observed to be within 0.90–0.04 fb, depending on the masses of X and Y. The largest deviation from the background-only hypothesis with a local (global) significance of 3.8 (below 2.8) standard deviations is observed for X and Y masses of 650 and 90 GeV, respectively. The limits are interpreted using several models of new physics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Limits on an exotic Higgs decay from a recast ATLAS four-lepton analysis

The ATLAS collaboration, using 139 fb −1 of 13 TeV collisions from the Large Hadron Collider, has placed limits on the decay of a Z boson to three dark photons. We reproduce the results of the ATLAS analysis, and then recast it as a limit on a exotic Higgs decay mode, in which the Higgs boson decays via a pair of intermediate (pseudo)scalars a to four dark photons V (or some other spin-one meson). Across the mass range for m a and m V , we find limits on the exotic Higgs branching fraction BR(H → aa → V V V V ) in the range of 4 × 10 −5 to 1 × 10 −4 .

Higgs properties↗
DOE OSTI2021

Searches for 25 rare and forbidden decays of D + and ${D}_s^{+}$ mesons

A search is performed for rare and forbidden charm decays of the form ${D}_{(s)}^{+}\to {h}^{\pm }{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{\left(\prime \right)\mp } $, where h ± is a pion or kaon and ℓ (')± is an electron or muon. The measurements are performed using proton-proton collision data, corresponding to an integrated luminosity of 1.6 fb –1 , collected by the LHCb experiment in 2016. No evidence is observed for the 25 decay modes that are investigated and 90 % confidence level limits on the branching fractions are set between 1.4 × 10 –8 and 6.4 × 10 –6 . In most cases, these results represent an improvement on existing limits by one to two orders of magnitude.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Search for charged-lepton flavor violation in top quark production and decay in pp collisions at $ \sqrt{s} $ = 13 TeV

Results are presented from a search for charged-lepton flavor violating (CLFV) interactions in top quark production and decay in pp collisions at a center-of-mass energy of 13 TeV. The events are required to contain one oppositely charged electron-muon pair in the final state, along with at least one jet identified as originating from a bottom quark. The data correspond to an integrated luminosity of 138 fb$^{-1}$, collected by the CMS experiment at the LHC. This analysis includes both the production (q → eμt) and decay (t → eμq) modes of the top quark through CLFV interactions, with q referring to a u or c quark. These interactions are parametrized using an effective field theory approach. With no significant excess over the standard model expectation, the results are interpreted in terms of vector-, scalar-, and tensor-like CLFV four-fermion effective interactions. Finally, observed exclusion limits are set at 95% confidence levels on the respective branching fractions of a top quark to an eμ pair and an up (charm) quark of 0.13 × 10$^{-6}$ (1.31 × 10$^{-6}$), 0.07 × 10$^{-6}$ (0.89 × 10$^{-6}$), and 0.25 × 10$^{-6}$ (2.59 × 10$^{-6}$) for vector, scalar, and tensor CLFV interactions, respectively.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for heavy resonances decaying into a Z or W boson and a Higgs boson in final states with leptons and b -jets in 139 fb –1 of pp collisions at $ \sqrt{s} $ = 13 TeV with the ATLAS detector

This article presents a search for new resonances decaying into a Z or W boson and a 125 GeV Higgs boson h, and it targets the $ν\bar{ν}b\bar{b}, l^{+} l^{-} b\bar{b}$, or $ll^{±} νb\bar{b}$ final states, where $\ell$ = e or µ, in proton-proton collisions at $\sqrt{s}$ = 13 TeV. The data used correspond to a total integrated luminosity of 139 fb –1 collected by the ATLAS detector during Run 2 of the LHC at CERN. The search is conducted by examining the reconstructed invariant or transverse mass distributions of Zh or W h candidates for evidence of a localised excess in the mass range from 220 GeV to 5 TeV. No significant excess is observed and 95% confidence-level upper limits between 1.3 pb and 0.3 fb are placed on the production cross section times branching fraction of neutral and charged spin-1 resonances and CP-odd scalar bosons. These limits are converted into constraints on the parameter space of the Heavy Vector Triplet model and the two-Higgs-doublet model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for lepton-flavor-violating τ decays into a lepton and a vector meson using the full Belle data sample

Charged-lepton-flavor-violation is predicted in several new physics scenarios. We update the analysis of τ lepton decays into a light charged lepton (ℓ = e ± or μ ± ) and a vector meson (V 0 = ρ 0 , Φ, ω, K *0 , or $\overline{K}$ *0 ) using 980 fb -1 of data collected with the Belle detector at the KEKB collider. No significant excess of such signal events is observed, and thus 90% credibility level upper limits are set on the τ → ℓV 0 branching fractions in the range of (1.7–4.3) × 10 -8 . These limits are improved by 30% on average from the previous results.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for the lepton-flavour violating decays B 0 → K *0 τ ± μ ∓

A first search for the lepton-flavour violating decays B 0 → K*0 τ ± μ ∓ is presented. The analysis is performed using a sample of proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV between 2011 and 2018, corresponding to an integrated luminosity of 9 fb –1 . No significant signal is observed, and upper limits on the branching fractions are determined to be B (B 0 → K* 0 τ + μ – ) < 1.0(1.2) x 10 –5 and B(B 0 → K* 0 τ – μ + ) < 8.2(9.8) x 10 –6 at the 90% (95%) confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for pair-produced scalar and vector leptoquarks decaying into third-generation quarks and first- or second-generation leptons in $pp$ collisions with the ATLAS detector

A search for pair-produced scalar and vector leptoquarks decaying into quarks and leptons of different generations is presented. It uses the full LHC Run 2 (2015–2018) data set of 139 fb -1 collected with the ATLAS detector in proton–proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV. Scalar leptoquarks with charge -(1/3)$e$ as well as scalar and vector leptoquarks with charge +(2/3)$e$ are considered. All possible decays of the pair-produced leptoquarks into quarks of the third generation ($t, b$) and charged or neutral leptons of the first or second generation ($e, μ, ν$) with exactly one electron or muon in the final state are investigated. No significant deviations from the Standard Model expectation are observed. Upper limits on the production cross-section are provided for eight models as a function of the leptoquark mass and the branching ratio of the leptoquark into the charged or neutral lepton. In addition, lower limits on the leptoquark masses are derived for all models across a range of branching ratios. Two of these models have the goal of providing an explanation for the recent $B$-anomalies. In both models, a vector leptoquark decays into charged and neutral leptons of the second generation with a similar branching fraction. Lower limits of 1980 GeV and 1710 GeV are set on the leptoquark mass for these two models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Search for bosons of an extended Higgs sector in b quark final states in proton-proton collisions at $\sqrt{\textrm{s}}$ = 13 TeV

A search for beyond-the-standard-model neutral Higgs bosons decaying to a pair of bottom quarks, and produced in association with at least one additional bottom quark, is performed with the CMS detector. The data were recorded in proton-proton collisions at a centre-of-mass energy of 13 TeV at the CERN LHC and correspond to an integrated luminosity of 36.7–126.9 fb −1 , depending on the probed mass range. No signal above the standard model background expectation is observed. Upper limits on the production cross section times branching fraction are set for Higgs bosons in the mass range of 125–1800 GeV. The results are interpreted in benchmark scenarios of the minimal supersymmetric standard model, as well as suitable classes of two-Higgs-doublet models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Search for dark matter production in association with bottom quarks and a lepton pair in proton-proton collisions at $\sqrt{s}=13$ TeV

A search is performed for dark matter produced in association with bottom quarks and a pair of electrons or muons in data collected with the CMS detector at the LHC, corresponding to 138 fb −1 of integrated luminosity of proton-proton collisions at a center-of-mass energy of 13 TeV. For the first time at the LHC, the associated production of a bottom quark-antiquark pair and a new heavy neutral Higgs boson (H) that subsequently decays into a leptonically decaying Z boson and a pseudoscalar (a) is explored. The latter acts as a dark matter mediator in the context of the two Higgs doublet model plus a pseudoscalar (2HDM+a). Multivariate techniques that target a wide range of mass configurations for the H and a particles are used. The observations are consistent with the expectations from standard model processes. Upper limits at 95% confidence level are set on the product of cross section and branching fraction of the new particles, ranging from 10 −2 pb for an H mass of 400 GeV to 10 −3 pb for an H mass of 2000 GeV. Constraints on the parameter space of a benchmark 2HDM+a model are derived and compared with expectations in the context of cosmological predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Search for charged Higgs bosons decaying into a top and a bottom quark in the all-jet final state of pp collisions at $ \sqrt{s} $ = 13 TeV

A search for charged Higgs bosons (H$^{±}$) decaying into a top and a bottom quark in the all-jet final state is presented. The analysis uses LHC proton-proton collision data recorded with the CMS detector in 2016 at $ \sqrt{s} $ = 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{−1}$. No significant excess is observed above the expected background. Model-independent upper limits at 95% confidence level are set on the product of the H$^{±}$ production cross section and branching fraction in two scenarios. For production in association with a top quark, limits of 21.3 to 0.007 pb are obtained for H$^{±}$ masses in the range of 0.2 to 3 TeV. Combining this with a search in leptonic final states results in improved limits of 9.25 to 0.005 pb. The complementary s-channel production of an H$^{±}$ is investigated in the mass range of 0.8 to 3 TeV and the corresponding upper limits are 4.5 to 0.023 pb. These results are interpreted using different minimal supersymmetric extensions of the standard model.[graphic not available: see fulltext]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗