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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 505 records · Page 28
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DOE OSTI2013

Measurement of the B -c meson lifetime in the decay B -c →J/ψπ⁻

The lifetime of the B -c meson is measured using 272 exclusive B -c →J/ψ(→μ⁺μ⁻)π⁻ decays reconstructed in data from proton-antiproton collisions corresponding to an integrated luminosity of 6.7 fb⁻¹ recorded by the CDF II detector at the Fermilab Tevatron. The lifetime of the B -c meson is measured to be τ (B -c )=0.452±0.048(stat)±0.027(syst) ps. This is the first measurement of the B -c meson lifetime in a fully reconstructed hadronic channel, and it agrees with previous results and has comparable precision.

Aaltonen, T.↗
DOE OSTI2013

Measurement of the inclusive semileptonic branching fraction B ( B s 0 → X - ℓ + ν ℓ ) at Belle

Here, we report a measurement of the inclusive semileptonic B s 0 branching fraction in a 121 fb - 1 data sample collected near the Υ ( 5 S ) resonance with the Belle detector at the KEKB asymmetric energy e + e - collider. Events with B s 0 ( * ) B ¯ s 0 ( * ) pairs are selected by reconstructing a tag side D s + and identifying a signal side lepton ℓ + ( ℓ = e , μ ) that is required to have the same-sign charge to ensure that both originate from different B s 0 mesons. The B s 0 → X - ℓ + ν ℓ branching fraction is extracted from the ratio of the measured yields of D s + mesons and D s + ℓ + pairs and the known production and branching fractions. The inclusive semileptonic branching fraction is measured to be [ 10.6 ± 0.5 ( stat ) ± 0.7 ( syst ) ] % .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

First measurement of the muon antineutrino double-differential charged-current quasielastic cross section

The largest sample ever recorded of v ¯ μ charged-current quasielastic (CCQE, ν ¯<!-- ¯ --> μ + p → μ + + n ) candidate events is used to produce the minimally model-dependent, flux-integrated double-differential cross section d 2 σ d T μ d c o s θ μ ν ¯<!-- ¯ --> μ for v ¯ μ CCQE for a mineral oil target. This measurement exploits the large statistics of the MiniBooNE antineutrino mode sample and provides the most complete information of this process to date. In order to facilitate historical comparisons, the flux-unfolded total cross section $σ(E_ν)$ and single-differential cross section d dσ Q 2 on both mineral oil and on carbon are also reported. The observed cross section is somewhat higher than the predicted cross section from a model assuming independently acting nucleons in carbon with canonical form factor values. The shape of the data are also discrepant with this model. Finally, these results have implications for intranuclear processes and can help constrain signal and background processes for future neutrino oscillation measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Complementarity between nonstandard Higgs boson searches and precision Higgs boson measurements in the MSSM

Precision measurements of the Higgs boson properties at the LHC provide relevant constraints on possible weak-scale extensions of the Standard Model (SM). In the context of the minimal supersymmetric Standard Model (MSSM) these constraints seem to suggest that all the additional, non-SM-like Higgs bosons should be heavy, with masses larger than about 400 GeV. This article shows that such results do not hold when the theory approaches the conditions for “alignment independent of decoupling,” where the lightest CP-even Higgs boson has SM-like tree-level couplings to fermions and gauge bosons, independently of the nonstandard Higgs boson masses. In addition, the combination of current bounds from direct Higgs boson searches at the LHC, along with the alignment conditions, have a significant impact on the allowed MSSM parameter space yielding light additional Higgs bosons. In particular, after ensuring the correct mass for the lightest CP-even Higgs boson, we find that precision measurements and direct searches are complementary and may soon be able to probe the region of non-SM-like Higgs boson with masses below the top quark pair mass threshold of 350 GeV and low to moderate values of tanβ.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Measurement of the branching fraction of B + → τ + ν τ decays with the semileptonic tagging method

This report is a measurement of the branching fraction of B + → τ + ν τ decays using a data sample of 772 × 10 6 B B ¯ pairs, collected at the Υ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e - collider. We reconstruct the accompanying B meson in a semileptonic decay and detect the recoiling B candidate in the decay channel B + → τ + ν τ . We obtain a branching fraction of B ( B + → τ + ν τ ) = [ 1.25 ± 0.28 ( stat . ) ± 0.27 ( syst . ) ] × 10 - 4 . This result is in good agreement with previous measurements and the expectation from the calculation based on the Standard Model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Measurement of the branching ratio of B ¯ → D ( * ) τ - ν ¯ τ relative to B ¯ → D ( * ) ℓ - ν ¯ ℓ decays with hadronic tagging at Belle

In this article we report a measurement of the branching fraction ratios R ( D ( * ) ) of B ¯ → D ( * ) τ - ν ¯ τ relative to B ¯ → D ( * ) ℓ - ν ¯ ℓ (where ℓ = e or μ ) using the full Belle data sample of 772 × 10 6 B B ¯ pairs collected at the Υ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e - collider. The measured values are R ( D ) = 0.375 ± 0.064 ( stat ) ± 0.026 ( syst ) and R ( D * ) = 0.293 ± 0.038 ( stat ) ± 0.015 ( syst ) . The analysis uses hadronic reconstruction of the tag-side B meson and purely leptonic τ decays. The results are consistent with earlier measurements and do not show a significant deviation from the standard model prediction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Inclusive and exclusive measurements of B decays to χ c 1 and χ c 2 at Belle

We report inclusive and exclusive measurements for χ c1 and χ c2 production in B decays. We measure B(B→ χc1 X) = (3.03 ± 0.05(stat) ± 0.24(syst)) × 10 –3 and B(B→χ c2 X) = (0.70 ± 0.06(stat) ± 0.10(syst)) × 10 –3 . For the first time, χ c2 production in exclusive B decays in the modes B 0 →χ c2 π – K + and B + →χ c2 π + π – K + has been observed, along with first evidence for the B + →χ c2 π + K$^{0}_{S}$ decay mode. For χ c1 production, we report the first observation in the B + →χ c1 π + π – K + , B 0 →χ c1 π + π – K$^{0}_{S}$ and B 0 →χ c1 π 0 π – K + decay modes. Using these decay modes, we observe a difference in the production mechanism of χ c2 in comparison to χ c1 in B decays. In addition, we report searches for X(3872) and χ c1 (2P) in the B + →(χ c1 π + π – )K + decay mode. In conclusion, the reported results use 772 × 10 6 BB¯ events collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e – collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of the CKM angle φ 1 in B 0 → D ¯ ( * ) 0 h 0 , D ¯ 0 → K S 0 π + π - decays with time-dependent binned Dalitz plot analysis

Here, we show a measurement of the C P -violation parameter φ 1 obtained in a time-dependent analysis of B 0 → D ¯ ( * ) 0 h 0 decays followed by D ¯ 0 → K S 0 π + π - decay. A model-independent measurement is performed using the binned Dalitz plot technique. The measured value is φ 1 = 11.7 ° ± 7.8 ° ( stat ) ± 2.1 ° ( syst ) . Treating sin 2 φ 1 and cos 2 φ 1 as independent parameters, we obtain sin 2 φ 1 = 0.43 ± 0.27 ( stat ) ± 0.08 ( syst ) and cos 2 φ 1 = 1.06 ± 0.33 ( stat ) - 0.15 + 0.21 ( syst ) . The findings are obtained with a full data sample of 772 × 1 0 6 B B ¯ pairs collected near the Υ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e - collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurement of the branching fraction and C P asymmetry in B 0 → π 0 π 0 decays, and an improved constraint on φ 2

Here, we measure the branching fraction and C P violation asymmetry in the decay B 0 → π 0 π 0 , using a data sample of 752 × 10 6 B B ¯ pairs collected at the Υ ( 4 S ) resonance with the Belle detector at the KEKB e + e - collider. The obtained branching fraction and direct C P asymmetry are B ( B → π 0 π 0 ) = [ 1.31 ± 0.19 ( stat ) ± 0.19 ( syst ) ] × 10 - 6 and A C P = + 0.14 ± 0.36 ( stat ) ± 0.10 ( syst ) , respectively. The signal significance, including the systematic uncertainty, is 6.4 standard deviations. Furthemore, we combine these results with Belle’s earlier measurements of B 0 → π + π - and B ± → π ± π 0 to exclude the C P -violating parameter φ 2 from the range 15.5 ° < φ 2 < 75.0 ° at 95% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Direct-drive measurements of laser-imprint-induced shock velocity nonuniformities [First direct-drive measurements of laser-imprint-induced shock velocity nonuniformities]

Perturbations in the velocity profile of a laser-ablation-driven shock wave seeded by speckle in the spatial beam intensity (i.e., laser imprint) have been measured. Direct measurements of these velocity perturbations were recorded using a two-dimensional high-resolution velocimeter probing plastic material shocked by a 100-ps picket laser pulse from the OMEGA laser system. The measured results for experiments with one, two, and five overlapping beams incident on the target clearly demonstrate a reduction in long-wavelength (>25– μ m) perturbations with an increasing number of overlapping laser beams, consistent with theoretical expectations. Furthermore, these experimental measurements are crucial to validate radiation-hydrodynamics simulations of laser imprint for laser direct drive inertial confinement fusion research since they highlight the significant (factor of 3) underestimation of the level of seeded perturbation when the microphysics processes for initial plasma formation, such as multiphoton ionization are neglected.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2011

Measurement of the B s 0 Lifetime in Fully and Partially Reconstructed B s 0 →D s - (Φπ⁻)X Decays in pp̄ Collisions at √s=1.96 TeV

We present a measurement of the BB s 0 lifetime in fully and partially reconstructed B s 0 →D s - (Φπ⁻)X decays in 1.3 fb⁻¹ collected in pp̄ collisions at √s=1.96 TeV by the CDF II detector at the Fermilab Tevatron. We measure τ(B s 0 )=1.518±0.041(stat)±0.027(syst) ps. The ratio of this result and the world average B⁰ lifetime yields τ(B s 0 )/τ(B⁰)=0.99±0.03, which is in agreement with recent theoretical predictions.

Aaltonen, T.↗
DOE OSTI2012

Measurements of WW and WZ Production in W+jets Final States in pp̄ Collisions

We study WW and WZ production with lνqq (l=e,μ) final states using data collected by the D0 detector at the Fermilab Tevatron Collider corresponding to 4.3 fb⁻¹ of integrated luminosity from pp̄ collisions at √s=1.96 TeV. Assuming the ratio between the production cross sections σ(WW) and σ(WZ) as predicted by the standard model, we measure the total WV (V=W,Z) cross section to be σ(WV)=19.6 +3.2 -3.0 pb and reject the background-only hypothesis at a level of 7.9 standard deviations. We also use b-jet discrimination to separate the WZ component from the dominant WW component. Simultaneously fitting WW and WZ contributions, we measure σ(WW)=15.9 +3.7 -3.2 pb and σ(WZ)=3.3 +4.1 -3.3 pb, which is consistent with the standard model predictions.

Abazov, V. M.↗
DOE OSTI2014

Measurement of the τ -lepton Lifetime at Belle

We report that the lifetime of the τ lepton is measured using the process e + e - → τ + τ - , where both τ leptons decay to 3 π ν τ . The result for the mean lifetime, based on 711 fb - 1 of data collected with the Belle detector at the Y ( 4 S ) resonance and 60 MeV below, is τ = ( 290 . 17 ± 0.53 ( stat ) ± 0.33 ( syst ) ) × 10 - 15 s . The first measurement of the lifetime difference between τ + and τ - is performed. The upper limit on the relative lifetime difference between positive and negative τ leptons is | Δ τ | / τ < 7.0 × 10 - 3 at 90% C.L.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Measurement of the Branching Fraction B ( Λ c + → p K - π + )

In this work, we present the first model-independent measurement of the absolute branching fraction of the Λ c + → p K - π + decay using a data sample of 978 fb - 1 collected with the Belle detector at the KEKB asymmetric-energy e + e - collider. The number of Λ c + baryons is determined by reconstructing the recoiling D ( * ) - p ¯ π + system in events of the type e + e - → D ( * ) - p ¯ π + Λ c + . Lastly, the branching fraction is measured to be B ( Λ c + → p K - π + ) = ( 6.84 ± 0.24 - 0.27 + 0.21 ) % , where the first and second uncertainties are statistical and systematic, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗