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Hafner, A.

Publications and source records attributed to Hafner, A..

At least 73 records · Page 4
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DOE OSTI2016

Determination of the number of J/ψ events with inclusive J/ψ decays

A measurement of the number of J/ψ events collected with the BESIII detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be (223.7 ± 1.4) × 10 6 , which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESIII software. The number of J/ψ events taken in 2012 is determined to be (1086.9 ± 6.0) × 10 6 . In total, the number of J/ψ events collected with the BESIII detector is measured to be (1310.6 ± 7.0) × 10 6 , where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2016

Search for a muonic dark force at BaBar

Many models of physics beyond the standard model predict the existence of new Abelian forces with new gauge bosons mediating interactions between "dark sectors" and the standard model. We report a search for a dark boson Z' coupling only to the second and third generations of leptons in the reaction e+e-→μ+μ-Z',Z'→μ+μ- using 514 fb -1 of data collected by the BABAR experiment. No significant signal is observed for Z' masses in the range 0.212-10 GeV. Lastly, limits on the coupling parameter g' as low as 7×10 -4 are derived, leading to improvements in the bounds compared to those previously derived from neutrino experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Tests of C P T symmetry in B 0 - B ¯ 0 mixing and in B 0 → c c ¯ K 0 decays

Here, using the eight time dependences e- Γt (1 + C i cos Δmt + S i sin Δmt) for the decays Y(4S)→B 0 $\bar{B}$ 0 →f j f k , with the decay into a flavor-specific state f j = ± X before or after the decay into a CP eigenstate f k =c$\bar{c}$ K S,L , as measured by the BABAR experiment, we determine the three CPT-sensitive parameters Re(z) and Im(z) in B 0 $\bar{B}$ 0 mixing and |$\bar{A}$/A| in B 0 →c$\bar{c}$ K 0 decays. We find Im(z) = 0.010 ± 0.030 ± 0.013, Re(z) = -0.065 ± 0.028 ± 0.014, and |$\bar{A}$/A|=0.999±0.023±0.01, in agreement with CPT symmetry.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Improved measurement of the absolute branching fraction of $D^{+}\rightarrow \bar{K}^0 \mu ^{+}\nu _{\mu }$

Here, by analyzing 2.93 fb -1 of data collected at √s = 3.773 GeV with the BESIII detector, we measure the absolute branching fraction B(D + → K¯ 0 μ + ν μ ) = (8.72 ± 0.07 stat. ± 0.18 sys. )%, which is consistent with previous measurements within uncertainties but with significantly improved precision. Combining the Particle Data Group values of B(D 0 → K - μ + ν μ ), B(D + → K¯ 0 e + ν e ), and the lifetimes of the D 0 and D + mesons with the value of B(D + → K¯ 0 μ + ν μ ) measured in this work, we determine the following ratios of partial widths: Γ(D 0 → K - μ + ν μ )/Γ(D + → K¯ 0 μ + ν μ ) = 0.963 ± 0.044 and Γ(D + → K¯ 0 μ + ν μ )/Γ(D + → K¯ 0 e + ν e ) = 0.988 ± 0.033.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of the neutral D meson mixing parameters in a time-dependent amplitude analysis of the D 0 → π + π - π 0 decay

Here we perform the first measurement on the D 0 -D 0 mixing parameters using a time-dependent amplitude analysis of the decay D 0 →π + π - π 0 . The data were recorded with the BABAR detector at center-of-mass energies at and near the $Y$(4S) resonance, and correspond to an integrated luminosity of approximately 468.1 fb -1 . The neutral D meson candidates are selected from D*(2010) + →D 0 π$+\atop{s}$ decays where the flavor at the production is identified by the charge of the low-momentum pion, π$+\atop{s}$. The measured mixing parameters are x=(1.5±1.2±0.6)% and y=(0.2±0.9±0.5)%, where the quoted uncertainties are statistical and systematic, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurements of the center-of-mass energies at BESIII via the di-muon process

From 2011 to 2014, the BESIII experiment collected about 5 fb -1 data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing the di-muon process e + e - → γ ISR/FSR μ + μ - , the center-of-mass energies of the data samples are measured with a precision of 0.8 MeV. The center-of-mass energy is found to be stable for most of the time during data taking.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗