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Chang, P.

Publications and source records attributed to Chang, P..

124 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Observation of exclusive Υ ( 1 S ) and Υ ( 2 S ) decays into light hadrons

Using samples of 102 million Υ(1S) and 158 million Υ(2S) events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to the threebody final states φK + K, ωπ + π - and K *0 (892)K - π + , and to the two-body Vector-Tensor states (φf' 2 (1525), ωf 2 (1270), ρa 2 (1320) and K *0 (892) $\bar{K}$ *0 2 (1430)) and Axial-vector-Pseudoscalar (K1(1270)+K$-$, K 1 (1400) + K - and b 1 (1235) + π - ) states. Signals are observed for the first time in the Υ(1S) → φK + K - , ωπ + π - , K *0 K - π + , K *0 K *0 2 and Υ(2S) → φK + K - , K *0 K - π + decay modes. Branching fractions are determined for all the processes, while 90% confidence level upper limits are established on the branching fractions for the modes with a statistical significance less than 3σ. The ratios of the branching fractions of Υ(2S) and Υ(1S) decays into the same final state are used to test a perturbative QCD prediction for OZI suppressed bottomonium decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Search for B 0 decays to invisible final states at Belle

We report a search for B0 decays into invisible final states using a data sample of 657×106 B$\bar{B}$B pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB e + e - collider. The signal is identified by fully reconstructing a hadronic decay of the accompanying B meson and requiring no other particles in the event. No significant signal is observed, and we obtain an upper limit of 1.3×10 -4 at the 90% confidence level for the branching fraction of invisible B 0 decay.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

First measurement of Φ₃ with a model-independent Dalitz plot analysis of B ± →DK ± , D→K S ⁰π⁺π⁻ decay

We present the first measurement of the angle Φ₃ of the unitarity triangle using a model-independent Dalitz plot analysis of B ± →DK ± , D→K S ⁰π⁺π⁻ decays. The method uses, as input, measurements of the strong phase of the D→K⁰ S π⁺π⁻ amplitude from the CLEO Collaboration. The result is based on the full data set of 772×106 BB¯¯¯ pairs collected by the Belle experiment at the Υ(4S) resonance. We obtain Φ₃=(77.3 +15.1 –14.9 ±4.1±4.3)° and the suppressed amplitude ratio r B =0.145±0.030±0.010±0.011. Here the first error is statistical, the second is the experimental systematic uncertainty, and the third is the error due to the precision of the strong-phase parameters obtained by CLEO.

Aihara, H.↗
DOE OSTI2012

Observation of New Resonant Structures in γ γ → ω Φ , Φ Φ , and ω ω

The processes γγ --> ωΦ, ΦΦ, and ωω are measured using an 870 fb -1 data sample collected with the Belle detector at the KEKB asymmetric-energy e + e - collider. Production of vector meson pairs is clearly observed and their cross sections are measured for masses that range from threshold to 4.0 GeV. In addition to signals from well established spin-zero and spin-two charmonium states, there are resonant structures below charmonium threshold, which have not been previously observed. We report a spin-parity analysis for the new structures and determine the products of the η c , χ c0 , and χ c2 two-photon decay widths and branching fractions to ωΦ, ΦΦ, and ωω.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Measurement of B⁰→J/ψη (') and constraint on the η-η' mixing angle

We measure the branching fractions of B⁰→J/ψη (') decays with the complete Belle data sample of 772×10⁶ BB¯¯¯ events collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e⁺e⁻ collider. The results for the branching fractions are: B(B⁰→J/ψη)=(12.3± 1.81 1.7 ±0.7)×10⁻⁶ and B(B⁰→J/ψη')<7.4×10⁻⁶ at 90% confidence level. The η-η' mixing angle is constrained to be less than 42.2° at 90% confidence level.

Chang, M.-C.↗
DOE OSTI2012

Measurement of the CP-Violation Parameter sin2Φ 1 with a New Tagging Method at the Υ(5S) Resonance

We report a measurement of the CP-violation parameter sin2Φ 1 at the Υ(5S) resonance using a new tagging method, called “B-π tagging.” In Υ(5S) decays containing a neutral B meson, a charged B, and a charged pion, the neutral B is reconstructed in the J/ψK$0\atop{S}$ CP-eigenstate decay channel. The initial flavor of the neutral B meson at the moment of the Υ(5S) decay is opposite to that of the charged B and may thus be inferred from the charge of the pion without reconstructing the charged B. From the asymmetry between B - π + and B - π - tagged J/ψK$0\atop{S}$ yields, we determine sin2Φ 1 =0.57±0.58(stat)±0.06(syst). The results are based on 121 fb -1 of data recorded by the Belle detector at the KEKB e + e - collider.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Observation of Two Charged Bottomoniumlike Resonances in Υ ( 5 S ) Decays

We report the observation of two narrow structures in the mass spectra of the π±Υ(nS) (n=1, 2, 3) and π±hb(mP) (m=1, 2) pairs that are produced in association with a single charged pion in Υ(5S) decays. The measured masses and widths of the two structures averaged over the five final states are M1=(10 607.2±2.0) MeV/c 2 , Γ 1 =(18.4±2.4) MeV, and M 2 =(10 652.2±1.5) MeV/c 2 , Γ 2 =(11.5±2.2) MeV. The results are obtained with a 121.4 fb -1 data sample collected with the Belle detector in the vicinity of the Υ(5S) resonance at the KEKB asymmetric-energy e+e- collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS2006

Improved Atmospheric Boundary Layer Observations of Tropical Cyclones with the Imaging Wind and Rain Airborne Profiler

The Imaging Wind and Rain Arborne Profilers (IWRAP) is a dual-frequency, conically-scanning Doppler radar that measures high-resolution, dual-polarized, multi-beam C- and Ku-band reflectivity and Doppler velocity profiles of the atmospheric boundary layer (ABL) within the inner core of hurricanes.From the datasets acquired during the 2002 through 20O5 hurricane seasons as part of the ONR Coupled Boundary Layer Air-Sea Transfer (CBLAST) program and the NOAA/NESDIS Ocean Winds and Rain experiments, very high resolution radar observations of hurricanes have been acquired and made available to the CBLAST community. Of particular interest am the ABL wind fields and 3-D structures found within the inner core of hurricanes. As a result of these analysis, a limitation in the ability to retrieve the ABL wind field at very low altitudes was identified. This paper shows how this limitation has been removed and presents initial results demonstrating its new capabilities to derive the ABL wind field within the inner are of hurricanes to much lower altitudes than the ones the original system was capable of.

wind field↗
NASA NTRS2001

Candle Flames in Microgravity

The goal of this work is to study both experimentally and numerically the behavior of a candle flame burning in a microgravity environment. Two space experiments (Shuttle and Mir) have shown the candle flame in microgravity to be small (approximately 1.5 cm diameter), dim blue, and hemispherical. Near steady flames with very long flame lifetimes (up to 45 minutes in some tests) existed for many of the tests. Most of the flames spontaneously oscillated with a period of approximately 1 Hz just prior to extinction). In a previous model of candle flame in microgravity, a porous sphere wetted with liquid fuel simulated the evaporating wick. The sphere, with a temperature equal to the boiling temperature of the fuel, was at the end of an inert cone that had a prescribed temperature. This inert cone produces the quenching effect of the candle wax in the real configuration. Although the computed flame shape resembled that observed in the microgravity experiment, the model was not able to differentiate the effect of wick geometry, e.g., a long vs. a short wick. This paper presents recent developments in the numerical model of the candle flame. The primary focus has been to more realistically account for the actual shape of the candle.

Dietrich, D. L.↗
NASA NTRS2000

Candle Flames in Non-Buoyant Atmospheres

This paper addresses the behavior of a candle flame in a long-duration, quiescent microgravity environment both on the space Shuttle and the Mir Orbiting Station. On the Shuttle, the flames became dim blue after an initial transient where there was significant yellow (presumably soot) in the flame. The flame lifetimes were typically less than 60 seconds. The safety-mandated candlebox that contained the candle flame inhibited oxygen transport to the flame and thus limited the flame lifetime. The flames on the Mir were similar, except that the yellow luminosity persisted longer into the flame lifetime because of a higher initial oxygen concentration, The Mir flames burned for as long as 45 minutes. The difference in the flame lifetime between the Shuttle and Mir flames was primarily the redesigned candlebox that did not inhibit oxygen transport to the flame. In both environments, the flame intensity and the height-to-width ratio gradually decreased as the ambient oxygen content in the sealed chamber slowly decreased. Both sets of experiments showed spontaneous, axisymmetric flame oscillations just prior to extinction. The paper also presents a numerical model of a candle flame. The formulation is two-dimensional and time-dependent in the gas phase with constant specific heats, thermal conductivity and Lewis number (although different species can have different Lewis numbers), one-step finite-rate kinetics, and gas-phase radiative losses from CO2 and H2O. The treatment of the liquid/wick phase assumes that the, fuel evaporates from a constant diameter sphere connected to an inert cone. The model predicts a steady flame with a shape and size quantitatively similar to the Shuttle and Mir flames. The computation predicts that the flame size will increase slightly with increasing ambient oxygen mole fraction. The model also predicts pre-extinction flame oscillations if the rate of decrease in ambient oxygen is small enough, such as that which would occur for a flame burning in a sealed ambient.

Dietrich, D. L.↗