Engineering topics
Gradl, W.
Publications and source records attributed to Gradl, W..
Analysis of $D$ + → $K¯$ 0 $e$ + $ν$ $e$ and $D$ + → $π$ 0 $e$ + $ν$ $e$ semileptonic decays
Using 2.93 fb –1 of data taken at 3.773 GeV with the BESIII detector operated at the BEPCII collider, we study the semileptonic decays D + → K¯ 0 e + ν e and D + → π 0 e + ν e . Here, we measure the absolute decay branching fractions B(D + → K¯ 0 e + ν e ) = (8.60 ± 0.06 ± 0.15) × 10 –2 and B(D + → π 0 e + ν e ) = (3.63 ± 0.08 ± 0.05) × 10 –3 , where the first uncertainties are statistical and the second systematic. We also measure the differential decay rates and study the form factors of these two decays. With the values of |V cs | and |V cd | from Particle Data Group fits assuming CKM unitarity, we obtain the values of the form factors at q 2 = 0, $f$ $^{K}_{+}$(0) = 0.725 ± 0.004 ± 0.012 and $f$ $^{π}_{+}$(0) = 0.622 ± 0.012 ± 0.003. Taking input from recent lattice QCD calculations of these form factors, we determine values of the CKM matrix elements |V cs | = 0.944 ± 0.005 ± 0.015 ± 0.024 and |V cd | = 0.210 ± 0.004 ± 0.001 ± 0.009, where the third uncertainties are theoretical.
Study of J / ψ and ψ ( 3686 ) → Σ ( 1385 ) 0 Σ ¯ ( 1385 ) 0 and Ξ 0 Ξ ¯ 0
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Observation of e + e − → η h c at center-of-mass energies from 4.085 to 4.600 GeV
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First measurement of the polarization observable E and helicity-dependent cross sections in single π 0 photoproduction from quasi-free nucleons
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Evidence for the singly Cabibbo suppressed decay Λ c + → p η and search for Λ c + → p π 0
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Measurement of integrated luminosity and center-of-mass energy of data taken by BESIII at √s = 2.125 GeV*
To study the nature of the state Y (2175), a dedicated data set of e + e – collision data was collected at the center-of-mass energy of 2.125 GeV with the BESIII detector at the BEPCII collider. By analyzing large-angle Bhabha scattering events, the integrated luminosity of this data set is determined to be 108.49±0.02±0.85 pb –1 , where the first uncertainty is statistical and the second one is systematic. In addition, the center-of-mass energy of the data set is determined with radiative dimuon events to be 2126.55±0.03±0.85 MeV, where the first uncertainty is statistical and the second one is systematic.
Measurement of the e + e - → K s 0 K ± π ∓ π 0 and K s 0 K ± π ∓ η cross sections using initial-state radiation
The processes e + e - → K$0\atop{S}$ K ± π ∓ π 0 and e + e - → K$0\atop{S}$ K ± π ∓ η are studied over a continuum of energies from threshold to 4 GeV with the initial-state photon radiation method. Using 454 fb -1 of data collected with the BABAR detector at the SLAC PEP-II storage ring, the first measurements of the cross sections for these processes are obtained. The intermediate resonance structures from K* 0 (Kπ) 0 , K *(892) ± (Kπ) ∓ , and K$0\atop{S}$K ± ρ ∓ are studied. Lastly, the J / ψ is observed in all of these channels, and corresponding branching fractions are measured.
Study of η and η ′ Photoproduction at MAMI
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Helicity-dependent cross sections and double-polarization observable E in η photoproduction from quasifree protons and neutrons
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Dalitz plot analyses of J / ψ → π + π - π 0 , J / ψ → K + K - π 0 , and J / ψ → K s 0 K ± π ∓ produced via e + e - annihilation with initial-state radiation
Here, we study the processes e + e - → γ ISR J/ψ , where J/ψ → π + π - π 0 , J/ψ → K + K - π 0 , and J / ψ → K$0\atop{S}$ K ± π ∓ using a data sample of 519 fb -1 recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e + e - collider at center-of-mass energies at and near the Υ (nS) (n = 2 , 3 , 4) resonances. We measure the ratio of branching fractions R 1 = $B(J/ψ →K^+K^- π^0)\atop{B(J/ψ →π^+π^- π^0)}$ and R 2 = $B(J/ψ →K^0_SK^±π^∓)\atop{B(J/ψ →π^+π^- π^0)}$. We perform Dalitz plot analyses of the three J/ψ decay modes and measure fractions for resonances contributing to the decays. We also analyze the J/ψ → $π^+π^- π^0$ decay using the Veneziano model. We observe structures compatible with the presence of ρ (1450) in all three J/ψ decay modes and measure the relative branching fraction: R (p(1450)) = $Bp(1450)→K^+K^-)\atop{B(p(1450)→π^+π^-)}$ +0.307 ± 0.084 (stat) ± 0.082 (sys).
Measurement of higher-order multipole amplitudes in ψ ( 3686 ) → γ χ c 1 , 2 with χ c 1 , 2 → γ J / ψ and search for the transition η c ( 2 S ) → γ J / ψ
Using 106 ×10 6 ψ (3686) events collected with the BESIII detector, we measure multipole amplitudes for the decay ψ (3686) → γχ c1,2 → γγ J/ψ beyond the dominant electric-dipole amplitudes. The normalized magnetic-quadrupole (M2) amplitude for ψ (3686) → γχ c1,2 → γγ J/ψ and the normalized electric-octupole amplitudes for ψ ( 3686 ) → γχ c2 , χ c2 → γJ/ψ are determined. The M2 amplitudes for ψ (3686) → γ χ c1 and χ c1,2 → γ J / ψ are found to differ significantly from zero and are consistent with theoretical predictions. We also obtain the ratios of M2 contributions of ψ ( 3686 ) and J /ψ decays to χ c1,2 , b$1\atop{2}$/ b$2\atop{2}$ = 1.35 ± 0.72 and a$1\atop{2}$/a$2\atop{2}$ = 0.617 ± 0.083 , which agree well with theoretical expectations. By considering the multipole contributions of χ c 1 , 2 , we measure the product branching fractions for the cascade decays ψ ( 3686 ) → γχ c0,1,2 → γγJ/ψ and search for the process η c (2S) → γJ/ψ through ψ ( 3686 ) → γη c (2S). The product branching fraction for ψ (3686) → γχ c0 → γγJ/ψ is 3σ larger than published measurements, while those of ψ (3686) → γχ c1,2 → γγJ/ψ are consistent. In conclusion, no significant signal for the decay ψ ( 3686 ) → γη c (2S) → γγJ/ψ is observed, and the upper limit of the product branching fraction at the 90% confidence level is determined.
Measurement of the absolute branching fraction for Λ c + → Λ μ + ν μ
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Measurement of the inclusive electron spectrum from B meson decays and determination of | V u b |
Based on the full BABAR data sample of 466.5 million $B\bar{B}$ pairs, we present measurements of the electron spectrum from semileptonic B meson decays. We fit the inclusive electron spectrum to distinguish Cabibbo-Kobayashi-Maskawa (CKM) suppressed B → X u eν decays from the CKM-favored B → X c eν decays, and from various other backgrounds, and determine the total semileptonic branching fraction B (B → Xeν) = ( 10.34 ± 0.04 stat ± 0.2 6 syst )%, averaged over B ± and B 0 mesons. We determine the spectrum and branching fraction for charmless B → X u eν decays and extract the CKM element | V ub | , by relying on four different QCD calculations based on the heavy quark expansion. While experimentally, the electron momentum region above 2.1 GeV / c is favored, because the background is relatively low, the uncertainties for the theoretical predictions are largest in the region near the kinematic endpoint. Detailed studies to assess the impact of these four predictions on the measurements of the electron spectrum, the branching fraction, and the extraction of the CKM matrix element |V ub | are presented, with the lower limit on the electron momentum varied from 0.8 GeV / c to the kinematic endpoint. We determine |V ub | using each of these different calculations and find, |V ub | = ( 3.794 ± 0.107 exp $+ 0.292\atop{ - 0.219 SF}$ $+ 0.078 \atop{- 0.068 theory}$ ) × 10 - 3 (De Fazio and Neubert), (4.563 ± 0.126 exp $+ 0.230\atop {- 0.208 SF}$ $+ 0.162\atop{- 0.163 theory}$ ) ×10 -3 (Bosch, Lange, Neubert, and Paz), (3.959 ± 0.104 exp $+ 0.164\atop{- 0.154 SF}$ $+ 0.042\atop{ - 0.079 theory}$ ) × 10 -3 (Gambino, Giordano, Ossola, and Uraltsev), (3.848 ± 0.108 exp $+ 0.084\atop{ - 0.070 theory}$) × 10 -3 (dressed gluon exponentiation), where the stated uncertainties refer to the experimental uncertainties of the partial branching fraction measurement, the shape function parameters, and the theoretical calculations.