Improved measurement of branching fractions for ππ transitions among Υ(nS) states
Physical Review D - Particles, Fields, Gravitation and Cosmology 79:1 (2009)
Abstract:
Using samples of (5.93±0.10)×106 Υ(3S) decays and (9.11±0.14)×106 Υ(2S) decays collected with the CLEO detector, we report improved measurements of the following branching fractions: B(Υ(3S)→Υ(1S)π+π-)=(4.46±0.01±0.13)%, B(Υ(2S)→Υ(1S)π+π-)=(18.02±0.02±0.61)%, B(Υ(3S)→Υ(1S)π0π0)=(2.24±0.09±0.11)%, B(Υ(2S)→Υ(1S)π0π0)=(8.43±0.16±0.42)%, and B(Υ(3S)→Υ(2S)π0π0)=(1.82±0.09±0.12)%. In each case, the first uncertainty reported is statistical, while the second is systematic. © 2009 The American Physical Society.J/ψ and ψ(2S) radiative transitions to ηc
Physical Review Letters 102:1 (2009)
Abstract:
Using 2.45×107 ψ(2S) decays collected with the CLEO-c detector at the Cornell Electron Storage Ring we present the most precise measurements of magnetic dipole transitions in the charmonium system. We measure B(ψ(2S)→γηc)=(4.32±0.16±0.60)×10-3, B(J/ψ→γηc)/B(ψ(2S)→γηc)=4.59±0. 23±0.64, and B(J/ψ→γηc)=(1.98±0.09±0.30) %. We observe a distortion in the ηc line shape due to the photon-energy dependence of the magnetic dipole transition rate. We find that measurements of the ηc mass are sensitive to the line shape, suggesting an explanation for the discrepancy between measurements of the ηc mass in radiative transitions and other production mechanisms. © 2009 The American Physical Society.Search for the rare decays B+→μ+μ-K+, B0→μ+μ- K*(892)0, and Bs0→μ+μ- at CDF
Physical Review D - Particles, Fields, Gravitation and Cosmology 79:1 (2009)
Abstract:
We search for b→sμ+μ- transitions in B meson (B+, B0, or Bs0) decays with 924pb-1 of pp̄ collisions at s=1.96TeV collected with the CDF II detector at the Fermilab Tevatron. We find excesses with significances of 4.5, 2.9, and 2.4 standard deviations in the B+→μ+μ-K+, B0→μ+μ-K*(892)0, and Bs0→μ+μ- decay modes, respectively. Using B→J/ψh (h=K+, K*(892)0,) decays as normalization channels, we report branching fractions for the previously observed B+ and B0 decays, B(B+→μ+μ-K+)=(0.59±0.15±0. 04)×10-6, and B(B0→μ+μ-K*(892)0)=(0.81±0. 30±0.10)×10-6, where the first uncertainty is statistical, and the second is systematic. We set an upper limit on the relative branching fraction B(Bs0→μ+μ-)/B(Bs0→J/ψ)<2.6(2.3)×10-3 at the 95(90)% confidence level, which is the most stringent to date. © 2009 The American Physical Society.An 80-kpc Lyα halo around a high-redshift type-2 quasi-stellar object
Monthly Notices of the Royal Astronomical Society 393:1 (2009) 309-316
Abstract:
We announce the discovery of an extended emission-line region associated with a high-redshift type-2 quasi-stellar object (QSO). The halo, which was discovered in our new wide-field narrow-band survey, resides at z = 2.85 in the Spitzer First Look Survey region and is extended over ∼80 kpc. Deep very long baseline interferometry (VLBI) observations imply that approximately 50 per cent of the radio emission is extended on scales >200 pc. The inferred active galactic nuclei (AGN) luminosity is sufficient to ionize the extended halo, and the optical emission is consistent with being triggered coevally with the radio source. The Lyα halo is as luminous as those found around high-redshift radio galaxies; however, the active nucleus is several orders of magnitude less luminous at radio wavelengths than those Fanarof-Riley type II (FRIIs) more commonly associated with extended emission-line regions. AMS05 appears to be a high-redshift analogue to the radio-quiet quasar E1821+643 which is core dominated, but which also exhibits extended Fanarof-Riley type I (FRI)-like structure and contains an optically powerful AGN. We also find evidence for more quiescent kinematics in the Lyα emission line in the outer regions of the halo, reminiscent of the haloes around the more powerful FRIIs. The optical to mid-infrared spectral energy distribution is well described by a combination of an obscured QSO (Lbol ∼ 3.4 ± 0.2 × 1013 L⊙) and a 1.4 Gyr old simple stellar population with mass ∼3.9 ± 0.3 × 10 11 M⊙. © 2009 RAS.An H I view of the on-going assembly of early-type galaxies: Present and future observations
Proceedings of Science 89 (2009)