E835 at FNAL: Charmonium Spectroscopy in pˉp\bar p p Annihilations

I present preliminary results on the search for $h_c$ in its $\eta_c\gamma$ and $J/\psi\pi^0$ decay modes. We observe an excess of \eta_c\gamma$events near 3526 MeV that has a probability${\cal P} \sim 0.001$to arise from background fluctations. The resonance parameters are$M=3525.8 \pm 0.2 \pm 0.2 $MeV,$\Gamma\leq$1 MeV, and$10.6\pm 3.7\pm3.4(br) < \Gamma_{\bar{p}p}B_{\eta_c\gamma} < 12.8\pm 4.8\pm4.5(br) $eV. We find no event excess within the search region in the$J/\psi\pi^0$ mode.Comment: Presented at the 6th International Conference on Hyperons, Charm and Beauty Hadrons (BEACH 2004), Chicago(Il), June 27-July 3,200

Precision measurements of the total and partial widths of the psi(2S) charmonium meson with a new complementary-scan technique in antiproton-proton annihilations

We present new precision measurements of the psi(2S) total and partial widths from excitation curves obtained in antiproton-proton annihilations by Fermilab experiment E835 at the Antiproton Accumulator in the year 2000. A new technique of complementary scans was developed to study narrow resonances with stochastically cooled antiproton beams. The technique relies on precise revolution-frequency and orbit-length measurements, while making the analysis of the excitation curve almost independent of machine lattice parameters. We study the psi(2S) meson through the processes pbar p -> e+ e- and pbar p -> J/psi + X -> e+ e- + X. We measure the width to be Gamma = 290 +- 25(sta) +- 4(sys) keV and the combination of partial widths Gamma_e+e- * Gamma_pbarp / Gamma = 579 +- 38(sta) +- 36(sys) meV, which represent the most precise measurements to date.Comment: 17 pages, 3 figures, 3 tables. Final manuscript accepted for publication in Phys. Lett. B. Parts of the text slightly expanded or rearranged; results are unchange

Residue from vacuum ultraviolet irradiation of benzene ices: Insights into the physical structure of astrophysical dust

We have irradiated benzene ices deposited at 4 K on a cold, interstellar dust analog with vacuum ultraviolet (9 eV) irradiation for periods lasting from several hours to nearly a day, after which the irradiated ice was warmed to room temperature. Vacuum ultraviolet photoabsorption spectra of the aromatic residue left at room temperature were recorded and showed the synthesis of benzene derivatives. The residue was also imaged using an electron microscope and revealed crystals of various sizes and shapes. The result of our experiments suggests such geometrically shaped dust particles may be a key component of interstellar dust

Infrared attenuation due to phase change from amorphous to crystalline observed in astrochemical propargyl ether ices

Astrochemical ices are known to undergo morphological changes, from amorphous to crystalline, upon warming the ice from lower (10 K) to higher temperatures. Phase changes are mostly identified by the observation of significant changes in the InfraRed (IR) spectrum, where the IR bands that are broad in the amorphous phase are narrower and split when the ice turns crystalline. To-date all the molecules that are studied under astrochemical conditions are observed to follow such a behaviour without significant attenuation in the IR wavelength. However, in this paper we report a new observation when propargyl ether ($C_3H_3OC_3H_3$) is warmed from the amorphous phase, at 10 K, through the phase transition temperature of 170 K, the crystalline ice being found to strongly attenuate IR photons at the mid-IR wavelengths

Gravitational Lensing by Black Holes

We review the theoretical aspects of gravitational lensing by black holes, and discuss the perspectives for realistic observations. We will first treat lensing by spherically symmetric black holes, in which the formation of infinite sequences of higher order images emerges in the clearest way. We will then consider the effects of the spin of the black hole, with the formation of giant higher order caustics and multiple images. Finally, we will consider the perspectives for observations of black hole lensing, from the detection of secondary images of stellar sources and spots on the accretion disk to the interpretation of iron K-lines and direct imaging of the shadow of the black hole.Comment: Invited article for the GRG special issue on lensing (P. Jetzer, Y. Mellier and V. Perlick Eds.). 31 pages, 12 figure

Surveillance of emerging drugs of abuse in Hong Kong: Validation of an analytical tool

© 2015, Hong Kong Academy of Medicine Press. All rights reserved. Objective: To validate a locally developed chromatography-based method to monitor emerging drugs of abuse whilst performing regular drug testing in abusers. Design: Cross-sectional study. Setting: Eleven regional hospitals, seven social service units, and a tertiary level clinical toxicology laboratory in Hong Kong. Participants: A total of 972 drug abusers and high-risk individuals were recruited from acute, rehabilitation, and high-risk settings between 1 November 2011 and 31 July 2013. A subset of the participants was of South Asian ethnicity. In total, 2000 urine or hair specimens were collected. Main outcome measures: Proof of concept that surveillance of emerging drugs of abuse can be performed whilst conducting routine drug of abuse testing in patients. Results: The method was successfully applied to 2000 samples with three emerging drugs of abuse detected in five samples: PMMA (paramethoxymethamphetamine), TFMPP [1-(3-trifluoromethylphenyl)piperazine], and methcathinone. The method also detected conventional drugs of abuse, with codeine, methadone, heroin, methamphetamine, and ketamine being the most frequently detected drugs. Other findings included the observation that South Asians had significantly higher rates of using opiates such as heroin, methadone, and codeine; and that ketamine and cocaine had significantly higher detection rates in acute subjects compared with the rehabilitation population. Conclusions: This locally developed analytical method is a valid tool for simultaneous surveillance of emerging drugs of abuse and routine drug monitoring of patients at minimal additional cost and effort. Continued, proactive surveillance and early identification of emerging drugs will facilitate prompt clinical, social, and legislative management.Link_to_subscribed_fulltex

Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02