Showing papers by "M. S. Alam published in 2015"
TL;DR: The SO2 removal displays a clear dependence on relative humidity for all four alkene-ozone systems confirming a significant reaction for stabilised Criegee intermediates (SCI) with H2O and is consistent with decomposition being a significant, structure dependent, sink in the atmosphere for syn-SCI.
Abstract: The removal of SO2 in the presence of alkene–ozone systems has been studied for ethene, cis-but-2-ene, trans-but-2-ene and 2,3-dimethyl-but-2-ene, as a function of humidity, under atmospheric boundary layer conditions. The SO2 removal displays a clear dependence on relative humidity for all four alkene–ozone systems confirming a significant reaction for stabilised Criegee intermediates (SCI) with H2O. The observed SO2 removal kinetics are consistent with relative rate constants, k(SCI + H2O)/k(SCI + SO2), of 3.3 (±1.1) × 10−5 for CH2OO, 26 (±10) × 10−5 for CH3CHOO derived from cis-but-2-ene, 33 (±10) × 10−5 for CH3CHOO derived from trans-but-2-ene, and 8.7 (±2.5) × 10−5 for (CH3)2COO derived from 2,3-dimethyl-but-2-ene. The relative rate constants for k(SCI decomposition)/k(SCI + SO2) are −2.3 (±3.5) × 1011 cm−3 for CH2OO, 13 (±43) × 1011 cm−3 for CH3CHOO derived from cis-but-2-ene, −14 (±31) × 1011 cm−3 for CH3CHOO derived from trans-but-2-ene and 63 (±14) × 1011 cm−3 for (CH3)2COO. Uncertainties are ±2σ and represent combined systematic and precision components. These values are derived following the approximation that a single SCI is present for each system; a more comprehensive interpretation, explicitly considering the differing reactivity for syn- and anti-SCI conformers, is also presented. This yields values of 3.5 (±3.1) × 10−4 for k(SCI + H2O)/k(SCI + SO2) of anti-CH3CHOO and 1.2 (±1.1) × 1013 for k(SCI decomposition)/k(SCI + SO2) of syn-CH3CHOO. The reaction of the water dimer with CH2OO is also considered, with a derived value for k(CH2OO + (H2O)2)/k(CH2OO + SO2) of 1.4 (±1.8) × 10−2. The observed SO2 removal rate constants, which technically represent upper limits, are consistent with decomposition being a significant, structure dependent, sink in the atmosphere for syn-SCI.
105 citations
TL;DR: In this article, a search for high-mass resonances decaying into tau(+)tau(-) final states using proton-proton collisions at root s = 7 TeV produced by the Large Hadron Collider is presented.
58 citations
TL;DR: In this article, a comparison of averaged diurnal profiles has shown different patterns of behaviour which has been investigated through calculating ratios of concentration at 18:00-21:00 h relative to that at 06:00 -09:00h.
48 citations
TL;DR: Proximity to an oil refinery in Saudi Arabia is associated with prehypertension and increases in PAH and particulate matter exposures, and Urinary total hydroxyphenanthrenes and 1-hydroxypyrene were not associated with cardiovascular outcomes.
48 citations
TL;DR: A search for a neutral, long-lived particle L that is produced in e- e- collisions and decays at a significant distance from the e+ e- interaction point into various flavor combinations of two oppositely charged tracks is presented.
Abstract: We present a search for a neutral, long-lived particle L that is produced in e^+e^− collisions and decays at a significant distance from the e^+e^− interaction point into various flavor combinations of two oppositely charged tracks. The analysis uses an e^+e^− data sample with a luminosity of 489.1 fb^(−1) collected by the BABAR detector at the Υ(4S), Υ(3S), and Υ(2S) resonances and just below the Υ(4S). Fitting the two-track mass distribution in search of a signal peak, we do not observe a significant signal, and set 90% confidence level upper limits on the product of the L production cross section, branching fraction, and reconstruction efficiency for six possible two-body L decay modes as a function of the L mass. The efficiency is given for each final state as a function of the mass, lifetime, and transverse momentum of the candidate, allowing application of the upper limits to any production model. In addition, upper limits are provided on the branching fraction B(B→X_sL), where X_s is a strange hadronic system.
40 citations
TL;DR: The location of the nitrophenol aromatic substitutions was found to be critically important, with the nitrophhenol in the photo-oxidation of 4-methyl catechol not partitioning into the aerosol phase until irradiation had stopped; highlighting the importance of studying SOA formation and evolution at a molecular level.
Abstract: Secondary organic aerosol (SOA) is well-known to have adverse effects on air quality and human health. However, the dynamic mechanisms occurring during SOA formation and evolution are poorly understood. The time-resolved SOA composition formed during the photo-oxidation of three aromatic compounds, methyl chavicol, toluene and 4-methyl catechol, were investigated at the European Photoreactor. SOA was collected using a particle into liquid sampler and analyzed offline using state-of-the-art mass spectrometry to produce temporal profiles of individual photo-oxidation products. In the photo-oxidation of methyl chavicol, 70 individual compounds were characterized and three distinctive temporal profile shapes were observed. The calculated mass fraction (Ci,aer/COA) of the individual SOA compounds showed either a linear trend (increasing/decreasing) or exponential decay with time. Substituted nitrophenols showed an exponential decay, with the nitro-group on the aromatic ring found to control the formation and l...
40 citations
TL;DR: It is concluded that both respiratory exposure and consumption of chargrilled food are considerable sources of PAH exposure in this population as reflected by concentrations of urinary biomarkers.
35 citations
TL;DR: Concentrations in Jeddah were significantly higher at a sites close to the oil refinery and a site close to a major ring road than at a suburban site to the north of the city, and the partitioning between vapour and particle phases is similar to that in data from China.
34 citations
TL;DR: In this paper, Collins asymmetries in the inclusive process were measured at the center-of-mass energy of 10.6 GeV, using data from the BABAR experiment at the PEP-II B factory at SLAC National Accelerator Center.
Abstract: We present measurements of Collins asymmetries in the inclusive process e^+e^− → h_1h_2X, h_1h_2 = KK, Kπ, ππ, at the center-of-mass energy of 10.6 GeV, using a data sample of 468 fb^(−1) collected by the BABAR experiment at the PEP-II B factory at SLAC National Accelerator Center. Considering hadrons in opposite thrust hemispheres of hadronic events, we observe clear azimuthal asymmetries in the ratio of unlike sign to like sign, and unlike sign to all charged h_1h_2 pairs, which increase with hadron energies. The Kπ asymmetries are similar to those measured for the ππ pairs, whereas those measured for high-energy KK pairs are, in general, larger.
23 citations
TL;DR: In this paper, a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays is reported, where the light neutral hadron h0 is a pi0, eta, or omega meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K 0S omega.
Abstract: We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S omega The measurement is performed combining the final data samples collected at the Y(4S) resonance by the BaBar and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively The data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector We measure the CP asymmetry parameters -eta_f S = +066 +/- 010 (stat) +/- 006 (syst) and C = -002 +/- 007 (stat) +/- 003 (syst) These results correspond to the first observation of CP violation in B0->D(*)CP h0 decays The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 54 standard deviations
16 citations
TL;DR: In this article, the authors measured the charge asymmetry in processes e+ e- --> mu+ mu- gamma and e + e - --> pi+ pi- gamma using 232 fb-1 of data collected with the BABAR detector at center-of-mass energies near 10.58 GeV.
Abstract: Charge asymmetry in processes e+ e- --> mu+ mu- gamma and e+ e- --> pi+ pi- gamma is measured using 232 fb-1 of data collected with the BABAR detector at center-of-mass energies near 10.58 GeV. An observable is introduced and shown to be very robust against detector asymmetries while keeping a large sensitivity to the physical charge asymmetry that results from the interference between initial and final state radiation. The asymmetry is determined as afunction of the invariant mass of the final-state tracks from production threshold to a few GeV/c2. It is compared to the expectation from QED for e+ e- --> mu+ mu- gamma and from theoretical models for e+ e- --> pi+ pi- gamma. A clear interference pattern is observed in e+ e- --> pi+ pi- gamma, particularly in the vicinity of the f_2(1270) resonance. The inferred rate of lowest order FSR production is consistent with the QED expectation for e+ e- --> mu+ mu- gamma, and is negligibly small for e+ e- --> pi+ pi- gamma.
TL;DR: In this paper, a search for the decay Υ(1S)→ γA^0, A^0 → cc[bar] is presented for the CP-odd Higgs boson of the next-to-minimal supersymmetric standard model.
Abstract: A search is presented for the decay Υ(1S)→ γA^0, A^0 → cc[bar], where A^0 is a candidate for the CP-odd Higgs boson of the next-to-minimal supersymmetric standard model. The search is based on data collected with the BABAR detector at the Υ(2S) resonance. A sample of Υ(1S) mesons is selected via the decay Υ(2S)→π + π − Υ(1S). The A^0 → cc[bar] decay is identified through the reconstruction of hadronic D^0, D^+, and D^∗ (2010)^+ meson decays. No significant signal is observed. The measured 90% confidence-level upper limits on the product branching fraction B(Υ(1S) → γA^0 ) × B(A^0 → cc[bar] ) range from 7.4×10^(−5) to 2.4×10^(−3) for A^0 masses from 4.00 to 8.95 GeV/c^2 and 9.10 to 9.25 GeV/c^2, where the region between 8.95 and 9.10 GeV/c^2 is excluded because of background from Υ(2S) → γχ_(bJ) (1P), χ_(bJ) (1P) → γΥ(1S) decays.
TL;DR: In this article, the authors measured the e^+e^− → K^+K^− cross section and charged-kaon electromagnetic form factor in the center of mass energy range (E) from 2.6 to 8.0 GeV using the initial-state radiation technique with an undetected photon.
Abstract: The e^+e^− → K^+K^− cross section and charged-kaon electromagnetic form factor are measured in the e^+e^− center-of-mass energy range (E) from 2.6 to 8.0 GeV using the initial-state radiation technique with an undetected photon. The study is performed using 469 fb^(−1) of data collected with the BABAR detector at the PEP-II2 e^+e^− collider at center-of-mass energies near 10.6 GeV. The form factor is found to decrease with energy faster than 1/E^2 and approaches the asymptotic QCD prediction. Production of the K^+K^− final state through the J/ψ and ψ(2S) intermediate states is observed. The results for the kaon form factor are used together with data from other experiments to perform a model-independent determination of the relative phases between electromagnetic (single-photon) and strong amplitudes in J/ψ and ψ(2S) → K^+K^− decays. The values of the branching fractions measured in the reaction e^+e^− → K^+K^− are shifted relative to their true values due to interference between resonant and nonresonant amplitudes. The values of these shifts are determined to be about ±5% for the J/ψ meson and ±15% for the ψ(2S) meson.
Posted Content•
TL;DR: The results correspond to the first observation of CP violation in B[over ¯] 0→D_{CP}^{(*)}h^{0} decays, and the hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.
Abstract: We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S omega. The measurement is performed combining the final data samples collected at the Y(4S) resonance by the BaBar and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector. We measure the CP asymmetry parameters -eta_f S = +0.66 +/- 0.10 (stat.) +/- 0.06 (syst.) and C = -0.02 +/- 0.07 (stat.) +/- 0.03 (syst.). These results correspond to the first observation of CP violation in B0->D(*)CP h0 decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.
Journal Article•
TL;DR: In this paper, the authors present a survey of the state-of-the-art work in this area, including the following: A. J. Hohenberger, A. Roudeau, T. T. Hoenebeck, E. Röhrken, R. R. Holden, D. M. Lynch, H. H. Choi, M. S. Kim, H H. Lee, G. So, A A. Kravchenko, A R. Kordchenko, S. A. Serednyakov, Yu.
Abstract: J. P. Lees, V. Poireau, V. Tisserand, E. Grauges, A. Palano, G. Eigen, B. Stugu, D. N. Brown, L. T. Kerth, Yu. G. Kolomensky, M. J. Lee, G. Lynch, H. Koch, T. Schroeder, C. Hearty, T. S. Mattison, J. A. McKenna, R. Y. So, A. Khan, V. E. Blinov, A. R. Buzykaev, V. P. Druzhinin, V. B. Golubev, E. A. Kravchenko, A. P. Onuchin, S. I. Serednyakov, Yu. I. Skovpen, E. P. Solodov, K. Yu. Todyshev, A. J. Lankford, B. Dey, J. W. Gary, O. Long, M. Franco Sevilla, T. M. Hong, D. Kovalskyi, J. D. Richman, C. A. West, A. M. Eisner, W. S. Lockman, W. Panduro Vazquez, B. A. Schumm, A. Seiden, D. S. Chao, C. H. Cheng, B. Echenard, K. T. Flood, D. G. Hitlin, J. Kim, T. S. Miyashita, P. Ongmongkolkul, F. C. Porter, M. Röhrken, R. Andreassen, Z. Huard, B. T. Meadows, B. G. Pushpawela, M. D. Sokoloff, L. Sun, W. T. Ford, J. G. Smith, S. R. Wagner, R. Ayad, W. H. Toki, B. Spaan, D. Bernard, M. Verderi, S. Playfer, D. Bettoni, C. Bozzi, R. Calabrese, G. Cibinetto, E. Fioravanti, I. Garzia, E. Luppi, L. Piemontese, V. Santoro, A. Calcaterra, R. de Sangro, G. Finocchiaro, S. Martellotti, P. Patteri, I. M. Peruzzi, M. Piccolo, A. Zallo, R. Contri, M. R. Monge, S. Passaggio, C. Patrignani, B. Bhuyan, V. Prasad, A. Adametz, U. Uwer, H. M. Lacker, U. Mallik, C. Chen, J. Cochran, S. Prell, H. Ahmed, A. V. Gritsan, N. Arnaud, M. Davier, D. Derkach, G. Grosdidier, F. Le Diberder, A. M. Lutz, B. Malaescu, P. Roudeau, A. Stocchi, L. L. Wang, G. Wormser, D. J. Lange, D. M. Wright, J. P. Coleman, J. R. Fry, E. Gabathuler, D. E. Hutchcroft, D. J. Payne, C. Touramanis, A. J. Bevan, F. Di Lodovico, R. Sacco, G. Cowan, D. N. Brown, C. L. Davis, A. G. Denig, M. Fritsch, W. Gradl, K. Griessinger, A. Hafner, K. R. Schubert, R. J. Barlow, G. D. Lafferty, R. Cenci, B. Hamilton, A. Jawahery, D. A. Roberts, R. Cowan, R. Cheaib, P. M. Patel, S. H. Robertson, N. Neri, F. Palombo, L. Cremaldi, R. Godang, D. J. Summers, M. Simard, P. Taras, G. De Nardo, G. Onorato, C. Sciacca, G. Raven, C. P. Jessop, J. M. LoSecco, K. Honscheid, R. Kass, M. Margoni, M. Morandin, M. Posocco, M. Rotondo, G. Simi, F. Simonetto, R. Stroili, S. Akar, E. Ben-Haim, M. Bomben, G. R. Bonneaud, H. Briand, G. Calderini, J. Chauveau, Ph. Leruste, G. Marchiori, J. Ocariz, M. Biasini, E. Manoni, A. Rossi, C. Angelini, G. Batignani, S. Bettarini, M. Carpinelli, G. Casarosa, M. Chrzaszcz, F. Forti, M. A. Giorgi, A. Lusiani, B. Oberhof, E. Paoloni, M. Rama, G. Rizzo, J. J. Walsh, D. Lopes Pegna, J. Olsen, A. J. S. Smith, F. Anulli, R. Faccini, F. Ferrarotto, F. Ferroni, M. Gaspero, A. Pilloni, G. Piredda, C. Bünger, S. Dittrich, O. Grünberg, M. Hess, T. Leddig, C. Voß, R. Waldi, T. Adye, E. O. Olaiya, F. F. Wilson, S. Emery, G. Vasseur, D. Aston, D. J. Bard, C. Cartaro, M. R. Convery, J. Dorfan, G. P. Dubois-Felsmann, W. Dunwoodie, M. Ebert, R. C. Field, B. G. Fulsom, M. T. Graham, C. Hast, W. R. Innes, P. Kim, D.W. G. S. Leith, S. Luitz, V. Luth, D. B. MacFarlane, D. R. Muller, H. Neal, T. Pulliam, B. N. Ratcliff, A. Roodman, R. H. Schindler, A. Snyder, D. Su, M. K. Sullivan, J. Va’vra, W. J. Wisniewski, H.W. Wulsin, M. V. Purohit, J. R. Wilson, A. Randle-Conde, S. J. Sekula, M. Bellis, P. R. Burchat, E. M. T. Puccio, M. S. Alam, J. A. Ernst, R. Gorodeisky, N. Guttman, D. R. Peimer, A. Soffer, S. M. Spanier, J. L. Ritchie, R. F. Schwitters, J. M. Izen, X. C. Lou, F. Bianchi, F. De Mori, A. Filippi, D. Gamba, L. Lanceri, L. Vitale, F. Martinez-Vidal, A. Oyanguren, J. Albert, Sw. Banerjee, A. Beaulieu, F. U. Bernlochner, H. H. F. Choi, G. J. King, R. Kowalewski, M. J. Lewczuk, T. Lueck, I. M. Nugent, J. M. Roney, R. J. Sobie, N. Tasneem, T. J. Gershon, P. F. Harrison, T. E. Latham, H. R. Band, S. Dasu, Y. Pan, R. Prepost, and S. L. Wu