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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 793 records · Page 44
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DOE OSTI2016

Search for a dark vector gauge boson decaying to π + π - using η → π + π - γ decays

In this report, we search for a dark vector gauge boson U ' that couples to quarks in the decay chain D * + → D 0 π + , D 0 → K S 0 η , η → U ' γ , U ' → π + π - . No signal is discovered and we set a mass-dependent limit on the baryonic fine structure constant of 10 - 3 - 10 - 2 in the U ' mass range of 290 to 520 MeV / c 2 . This analysis is based on a data sample of 976 fb - 1 collected by the Belle experiment at the KEKB asymmetric-energy e + e - collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurement of the decays B s 0 → J / ψ Φ ( 1020 ) , B s 0 → J / ψ f 2 ' ( 1525 ) and B s 0 → J / ψ K + K – at Belle

In this paper, we report a measurement of the branching fraction of the decay B s 0 → J / ψ Φ ( 1020 ) , evidence and a branching fraction measurement for B s 0 → J / ψ f 2 ' ( 1525 ) , and the determination of the total B s 0 → J / ψ K + K – branching fraction, including the resonant and non-resonant contributions to the K+K– channel. We also determine the S-wave contribution within the Φ(1020) mass region. The absolute branching fractions are B[ B s 0 → J / ψ Φ ( 1020 ) ] = (1.25 ± 0.07(stat) ± 0.08(syst) ± 0.22(fs)) × 10 –3 , B[ B s 0 → J / ψ f 2 ' ( 1525 ) ] = (0.26 ± 0.06(stat) ± 0.02(syst) ± 0.05(fs)) × 10 –3 and B[ B s 0 → J / ψ K + K – ] = (1.01 ± 0.09(stat) ± 0.10(syst) ± 0.18(fs)) × 10 –3 , where the last systematic error is due to the branching fraction of bb¯→ B$^{(*)}_{s}$B$^{(*)}_{s}$. The branching fraction ratio is found to be B[ B s 0 → J / ψ f 2 ' ( 1525 ) ]/B[ B s 0 → J / ψ Φ ( 1020 ) ] = (21.5 ± 4.9(stat) ± 2.6(syst)). All results are based on a 121.4 fb –1 data sample collected at the Υ(5S) resonance by the Belle experiment at the KEKB asymmetric-energy e + e – collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Light sterile neutrino sensitivity at the nuSTORM facility

A facility that can deliver beams of electron and muon neutrinos from the decay of a stored muon beam has the potential to unambiguously resolve the issue of the evidence for light sterile neutrinos that arises in short-baseline neutrino oscillation experiments and from estimates of the effective number of neutrino flavors from fits to cosmological data. In this paper, we show that the nuSTORM facility, with stored muons of 3.8 GeV/c ± 10%, will be able to carry out a conclusive muon neutrino appearance search for sterile neutrinos and test the LSND and MiniBooNE experimental signals with 10σ sensitivity, even assuming conservative estimates for the systematic uncertainties. This experiment would add greatly to our knowledge of the contribution of light sterile neutrinos to the number of effective neutrino flavors from the abundance of primordial helium production and from constraints on neutrino energy density from the cosmic microwave background. Here, the appearance search is complemented by a simultaneous muon neutrino disappearance analysis that will facilitate tests of various sterile neutrino models.

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 OSTI2017

Search for the 0 - - glueball in Υ ( 1 S ) and Υ ( 2 S ) decays

Here, we report the first search for the J P C = 0 - - glueball in Υ ( 1 S ) and Υ ( 2 S ) decays with data samples of ( 102 ± 2 ) × 1 0 6 and ( 158 ± 4 ) × 1 0 6 events, respectively, collected with the Belle detector. No significant signals are observed in any of the proposed production modes, and the 90% credibility level upper limits on their branching fractions in Υ ( 1 S ) and Υ ( 2 S ) decays are gained. The inclusive branching fractions of the Υ ( 1 S ) and Υ ( 2 S ) decays into final states with a χ c 1 are measured to be B ( Υ ( 1 S ) → χ c 1 + anything ) = ( 1.90 ± 0.43 ( stat ) ± 0.14 ( syst ) ) × 10 - 4 with an improved precision over prior measurements and B ( Υ ( 2 S ) → χ c 1 + anything ) = ( 2.24 ± 0.44 ( stat ) ± 0.20 ( syst ) ) × 10 - 4 for the first time.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Observation of an alternative χ c 0 ( 2 P ) candidate in e + e - → J / ψ D D ¯

IN this work, we perform a full amplitude analysis of the process e + e - → J / ψ D D ¯ , where D refers to either D 0 or D + . A new charmoniumlike state X * ( 3860 ) that decays to D D ¯ is determined with a significance of 6.5 σ . Its mass is ( 3862 - 32 + 26 - 13 + 40 ) MeV / c 2 , and its width is ( 201 - 67 + 154 - 82 + 88 ) MeV . The J P C = 0 + + hypothesis is favored over the 2 + + hypothesis at the level of 2.5 σ . The analysis is based on the 980 fb - 1 data sample collected by the Belle detector at the asymmetric-energy e + e - collider KEKB.

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 OSTI2014

Evidence for semileptonic B - → p p ¯ ℓ - ν ¯ ℓ decays

Evidence for the semileptonic baryonic decay B - → p p ¯ ℓ - ν ¯ ℓ ( ℓ = e , μ ), based on a data sample of 772 million B B ¯ pairs collected at the Υ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy electron-positron collider is collected. A neural-network based hadronic B -meson tagging method is used in this study. The branching fraction of B - → p p ¯ ℓ - ν ¯ ℓ is measured to be ( 5. 8 - 2.1 + 2.4 (stat) ± 0.9 (syst) ) × 10 - 6 with a significance of 3.2 σ , where lepton universality is assumed. We also estimate the corresponding upper limit: B ( B - → p p ¯ ℓ - ν ¯ ℓ ) < 9.6 × 10 - 6 at the 90% confidence level. This measurement helps constrain the baryonic transition form factor in B decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Reconstruction and Measurement of $\mathcal{O}$(100) MeV Energy Electromagnetic Activity from $\pi^0 \rightarrow \gamma\gamma$ Decays in the MicroBooNE LArTPC

We present results on the reconstruction of electromagnetic (EM) activity from photons produced in charged current νμ interactions with final state π0s. We employ a fully-automated reconstruction chain capable of identifying EM showers of &calO;(100) MeV energy, relying on a combination of traditional reconstruction techniques together with novel machine-learning approaches. These studies demonstrate good energy resolution, and good agreement between data and simulation, relying on the reconstructed invariant π0 mass and other photon distributions for validation. The reconstruction techniques developed are applied to a selection of νμ + Ar → μ + π0 + X candidate events to demonstrate the potential for calorimetric separation of photons from electrons and reconstruction of π0 kinematics.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Invariant-mass and fractional-energy dependence of inclusive production of dihadrons in e + e - annihilation at s = 10.58 GeV

The inclusive cross sections for dihadrons of charged pions and kaons ( e + e - → h h X ) in electron-positron annihilation are observed and reported on. They are obtained as a function of the total fractional energy and invariant mass for any di-hadron combination in the same hemisphere as defined by the thrust event-shape variable and its axis. Since same-hemisphere dihadrons can be assumed to originate predominantly from the same initial parton, di-hadron fragmentation functions are probed. Moreove, these di-hadron fragmentation functions are needed as an unpolarized baseline in order to quantitatively understand related spin-dependent measurements in other processes and to apply them to the extraction of quark transversity distribution functions in the nucleon. The di-hadron cross sections are obtained from a 655 fb - 1 data sample collected at or 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 OSTI2016

Search for the Higgs boson produced in association with a W boson and decaying to four b-quarks via two spin-zero particles in pp collisions at 13 TeV with the ATLAS detector

This paper presents a dedicated search for exotic decays of the Higgs boson to a pair of new spin-zero particles, H→ aa, where the particle a decays to b-quarks and has a mass in the range of 20–60 GeV. The search is performed in events where the Higgs boson is produced in association with a W boson, giving rise to a signature of a lepton (electron or muon), missing transverse momentum, and multiple jets from b-quark decays. The analysis is based on the full dataset of pp collisions at $\sqrt{s}$=13 TeV recorded in 2015 by the ATLAS detector at the CERN Large Hadron Collider, corresponding to an integrated luminosity of 3.2 fb -1 . No significant excess of events above the Standard Model prediction is observed, and a 95% confidence-level upper limit is derived for the product of the production cross section for pp→ WH times the branching ratio for the decay H→ aa→ 4 b. The upper limit ranges from 6.2 pb for an a-boson mass m a = 20 GeV to 1.5 pb for m a =60 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Study of B 0 → ρ + ρ – decays and implications for the CKM angle Φ 2

We present a measurement of the branching fraction and the longitudinal polarization fraction of B 0 → ρ + ρ – decays, as well as the time-dependent CP violating parameters in decays into longitudinally polarized ρ + ρ – pairs with Belle’s final data set of 772 × 10 6 BB¯ pairs, at the Υ(4S) resonance, collected at the asymmetric-energy e + e – collider KEKB. We obtain B(B 0 → ρ + ρ – ) = (28.3 ± 1.5(stat) ± 1.5(syst)) × 10 –6 , f L = 0.988 ± 0.012(stat) ± 0.023(syst), A CP = 0.00 ± 0.10(stat) ± 0.06(syst), S CP = –0.13 ± 0.15(stat) ± 0.05(syst). As a result, we perform an isospin analysis to constrain the Cabibbo-Kobayashi-Maskawa angle Φ 2 and obtain two solutions with Φ 2 = (93.7 ± 10.6)°, being most compatible with other Standard-Model based fits to the data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Study of double parton interactions in diphoton + dijet events in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV

We use a sample of diphoton+dijet events to measure the effective cross section of double parton interactions, which characterizes the area containing the interacting partons in proton-antiproton collisions, and find it to be σeff=19.3±1.4(stat)±7.8(syst) mb. The sample was collected by the D0 detector at the Fermilab Tevatron collider in pp¯ collisions at s=1.96 TeV and corresponds to an integrated luminosity of 8.7 fb-1.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

$B^{0}_{s}$ lifetime measurement in the CP-odd decay channel $B^{0}_{s} \to J/\psi f_{0}(980)$

The lifetime of the Bs0 meson is measured in the decay channel Bs0→J/ψπ+π- with 880≤Mπ+π-≤1080 MeV/c2, which is mainly a CP-odd state and dominated by the f0(980) resonance. In 10.4 fb-1 of data collected with the D0 detector in Run II of the Tevatron, the lifetime of the Bs0 meson is measured to be τ(Bs0)=1.70±0.14(stat)±0.05(syst) ps. Neglecting CP violation in Bs0/B¯s0 mixing, the measurement can be translated into the width of the heavy mass eigenstate of the Bs0, ΓH=0.59±0.05(stat)±0.02(syst) ps-1.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗