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Measurement of the direct photon momentum spectrum in Υ(1S), Υ(2S), and Υ(3S) decays

Physical Review D - Particles, Fields, Gravitation and Cosmology 74:1 (2006)

Authors:

D Besson, S Henderson, TK Pedlar, D Cronin-Hennessy, KY Gao, DT Gong, J Hietala, Y Kubota, T Klein, BW Lang, SZ Li, R Poling, AW Scott, A Smith, S Dobbs, Z Metreveli, KK Seth, A Tomaradze, P Zweber, J Ernst, K Arms, H Severini, DM Asner, SA Dytman, W Love, S Mehrabyan, JA Mueller, V Savinov, Z Li, A Lopez, H Mendez, J Ramirez, GS Huang, DH Miller, V Pavlunin, B Sanghi, IPJ Shipsey, GS Adams, M Cravey, JP Cummings, I Danko, J Napolitano, Q He, H Muramatsu, CS Park, EH Thorndike, TE Coan, YS Gao, F Liu, R Stroynowski, M Artuso, C Boulahouache, S Blusk, J Butt, O Dorjkhaidav, J Li, N Menaa, G Moneti, R Mountain, R Nandakumar, K Randrianarivony, R Redjimi, R Sia, T Skwarnicki, S Stone, JC Wang, K Zhang, SE Csorna, G Bonvicini, D Cinabro, M Dubrovin, A Bornheim, SP Pappas, AJ Weinstein, RA Briere, GP Chen, J Chen, T Ferguson, G Tatishvili, H Vogel, ME Watkins, JL Rosner, NE Adam, JP Alexander, K Berkelman, DG Cassel, V Crede, JE Duboscq, KM Ecklund, R Ehrlich, L Fields, RS Galik, L Gibbons, B Gittelman, R Gray, SW Gray, DL Hartill, BK Heltsley, D Hertz, CD Jones

Abstract:

Using data taken with the CLEO III detector at the Cornell Electron Storage Ring, we have investigated the direct photon spectrum in the decays Υ(1S)→γgg, Υ(2S)→γgg, Υ(3S)→γgg. The latter two of these are first measurements. Our analysis procedures differ from previous ones in the following ways: (a) background estimates (primarily from π0 decays) are based on isospin symmetry rather than a determination of the π0 spectrum, which permits measurement of the Υ(2S) and Υ(3S) direct photon spectra without explicit corrections for π0 backgrounds from, e.g., χbJ states, (b) we estimate the branching fractions with a parametrized functional form (exponential) used for the background, and c) we use the high-statistics sample of Υ(2S)→ππΥ(1S) to obtain a tagged sample of Υ(1S)→γ+X events, for which there are no QED backgrounds. We determine values for the ratio of the inclusive direct photon decay rate to that of the dominant three-gluon decay Υ→ggg(Rγ= B(ggγ)/B(ggg)) to be Rγ(1S)=(2.70±0.01±0.13±0. 24)%, Rγ(2S)=(3.18±0.04±0.22±0.41)%, and Rγ(3S)=(2.72±0.06±0.32±0.37)%, where the errors shown are statistical, systematic, and theoretical model dependent, respectively. Given a value of Q2, one can estimate a value for the strong coupling constant αs(Q2) from Rγ. © 2006 The American Physical Society.

Rapid star formation in the presence of active galactic nuclei

Astrophysical Journal 646:II (2006) L37-L39

Authors:

C Lintott, S Viti

Abstract:

Recent observations reveal galaxies in the early universe (2 < z < 6.4) with large reservoirs of molecular gas and extreme star formation rates. For a very large range of sources, a tight relationship exists between star formation rate and the luminosity of the HCN 7 = 1-0 spectral line, but sources at redshifts of z ∼ 2 and beyond do not follow this trend. The deficit in HCN is conventionally explained by an excess of infrared radiation due to active galactic nuclei (AGNs). We show in this Letter not only that the presence of AGNs cannot account for the excess of IR over molecular luminosity, but also that the observed abundance of HCN is in fact consistent with a population of stars forming from near-primordial gas. © 2006. The American Astronomical Society. All rights reserved.

Rapid Star Formation in the Presence of Active Galactic Nuclei

Astrophys.J. 646 (2006) L37-L40

Authors:

C Lintott, S Viti

Abstract:

Recent observations reveal galaxies in the early Universe (2

Sinfoni integral field spectroscopy of z ∼ 2 UV-selected galaxies: Rotation curves and dynamical evolution

Astrophysical Journal 645:2 I (2006) 1062-1075

Authors:

NM Förster Schreiber, R Genzei, MD Lehnert, N Bouché, A Verma, DK Erb, AE Shapley, CC Steidel, R Davies, D Lutz, N Nesvadba, LJ Tacconi, F Eisenhauer, R Abuter, A Gilbert, S Gillessen, A Sternberg

Abstract:

We present ∼0″5 resolution near-infrared integral field spectroscopy of the Hα line emission of 14 z ∼ 2 UV-selected BM/BX galaxies, obtained with SINFONI at the ESO Very Large Telescope. The average Hα half-light radius is r1/2 ≈4 h70-1 kpc, and line emission is detected over ≳20 h70-1 kpc in several sources. In nine galaxies, we detect spatially resolved velocity gradients, from 40 to 410 km s-1 over ∼10 h70 -1 kpc. The kinematics of the larger systems are generally consistent with orbital motions. Four galaxies are well described by rotating clumpy disks, and we extracted rotation curves out to radii ≳10 h 70-1 kpc. One or two galaxies exhibit signatures more consistent with mergers. Analyzing all 14 galaxies in the framework of rotating disks, we infer mean inclination- and beam-corrected maximum circular velocities of vc ∼ 180 ± 90 km s-1 and dynamical masses from ∼0.5 to 25 × 1010 h70-1 M ⊙ within r1/2- The specific angular momenta of our BM/BX galaxies are similar to those of local late-type galaxies. Moreover, the specific angular momenta of their baryons are comparable to those of their dark matter halos. Extrapolating from the average vc at 10 h 70-1 kpc, the virial mass of the typical halo of a galaxy in our sample is 1011.7±0.5 h70-1 M ⊙. Kinematic modeling of the three best cases implies a ratio of vc to local velocity dispersion vc/σ ∼ 2-4 and, accordingly, a large geometric thickness. We argue that this suggests a mass accretion (alternatively, gas exhaustion) timescale of ∼500 Myr. We also argue that if our BM/BX galaxies were initially gas-rich, their clumpy disks would subsequently lose their angular momentum and form compact bulges on a timescale of ∼1 Gyr. © 2006. The American Astronomical Socieity. All rights reserved.

Measurement of the Bc+ meson lifetime using the decay mode Bc+ --> J/Psie+nue.

Phys Rev Lett 97:1 (2006) 012002

Authors:

A Abulencia, D Acosta, J Adelman, T Affolder, T Akimoto, MG Albrow, D Ambrose, S Amerio, D Amidei, A Anastassov, K Anikeev, A Annovi, J Antos, M Aoki, G Apollinari, J-F Arguin, T Arisawa, A Artikov, W Ashmanskas, A Attal, F Azfar, P Azzi-Bacchetta, P Azzurri, N Bacchetta, H Bachacou, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, S Baroiant, V Bartsch, G Bauer, F Bedeschi, S Behari, S Belforte, G Bellettini, J Bellinger, A Belloni, E Ben Haim, D Benjamin, A Beretvas, J Beringer, T Berry, A Bhatti, M Binkley, D Bisello, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, A Bolshov, D Bortoletto, J Boudreau, A Boveia, B Brau, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, K Burkett, G Busetto, P Bussey, KL Byrum, S Cabrera, M Campanelli, M Campbell, F Canelli, A Canepa, D Carlsmith, R Carosi, S Carron, M Casarsa, A Castro, P Catastini, D Cauz, M Cavalli-Sforza, A Cerri, L Cerrito, SH Chang, J Chapman, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, I Cho, K Cho, D Chokheli, JP Chou, PH Chu, SH Chuang, K Chung, WH Chung, YS Chung, M Ciljak, CI Ciobanu, MA Ciocci, A Clark, D Clark, M Coca, G Compostella, ME Convery, J Conway, B Cooper, K Copic, M Cordelli, G Cortiana, F Cresciolo, A Cruz, C Cuenca Almenar, J Cuevas, R Culbertson, D Cyr, S DaRonco, S D'Auria, M D'Onofrio, D Dagenhart, P de Barbaro, S De Cecco, A Deisher, G De Lentdecker, M Dell'Orso, F Delli Paoli, S Demers, L Demortier, J Deng, M Deninno, D De Pedis, PF Derwent, T Devlin, C Dionisi, JR Dittmann, P DiTuro, C Dörr, S Donati, M Donega, P Dong, J Donini, T Dorigo, S Dube, K Ebina, J Efron, J Ehlers, R Erbacher, D Errede, S Errede, R Eusebi, HC Fang, S Farrington, I Fedorko, WT Fedorko, RG Feild, M Feindt, JP Fernandez, R Field, G Flanagan, LR Flores-Castillo, A Foland, S Forrester, GW Foster, M Franklin, JC Freeman, I Furic, M Gallinaro, J Galyardt, JE Garcia, M Garcia Sciveres, AF Garfinkel, C Gay, H Gerberich, D Gerdes, S Giagu, P Giannetti, A Gibson, K Gibson, C Ginsburg, N Giokaris, K Giolo, M Giordani, P Giromini, M Giunta, G Giurgiu, V Glagolev, D Glenzinski, M Gold, N Goldschmidt, J Goldstein, G Gomez, G Gomez-Ceballos, M Goncharov, O González, I Gorelov, AT Goshaw, Y Gotra, K Goulianos, A Gresele, M Griffiths, S Grinstein, C Grosso-Pilcher, RC Group, U Grundler, J Guimaraes da Costa, Z Gunay-Unalan, C Haber, SR Hahn, K Hahn, E Halkiadakis, A Hamilton, B-Y Han, JY Han, R Handler, F Happacher, K Hara, M Hare, S Harper, RF Harr, RM Harris, K Hatakeyama, J Hauser, C Hays, A Heijboer, B Heinemann, J Heinrich, M Herndon, D Hidas, CS Hill, D Hirschbuehl, A Hocker, A Holloway, S Hou, M Houlden, S-C Hsu, BT Huffman, RE Hughes, J Huston, J Incandela, G Introzzi, M Iori, Y Ishizawa, A Ivanov, B Iyutin, E James, D Jang, B Jayatilaka, D Jeans, H Jensen, EJ Jeon, S Jindariani, M Jones, KK Joo, SY Jun, TR Junk, T Kamon, J Kang, PE Karchin, Y Kato, Y Kemp, R Kephart, U Kerzel, V Khotilovich, B Kilminster, DH Kim, HS Kim, JE Kim, MJ Kim, SB Kim, SH Kim, YK Kim, L Kirsch, S Klimenko, M Klute, B Knuteson, BR Ko, H Kobayashi, K Kondo, DJ Kong, J Konigsberg, A Korytov, AV Kotwal, A Kovalev, A Kraan, J Kraus, I Kravchenko, M Kreps, J Kroll, N Krumnack, M Kruse, V Krutelyov, SE Kuhlmann, Y Kusakabe, S Kwang, AT Laasanen, S Lai, S Lami, S Lammel, M Lancaster, RL Lander, K Lannon, A Lath, G Latino, I Lazzizzera, T LeCompte, J Lee, J Lee, YJ Lee, SW Lee, R Lefèvre, N Leonardo, S Leone, S Levy, JD Lewis, C Lin, CS Lin, M Lindgren, E Lipeles, TM Liss, A Lister, DO Litvintsev, T Liu, NS Lockyer, A Loginov, M Loreti, P Loverre, R-S Lu, D Lucchesi, P Lujan, P Lukens, G Lungu, L Lyons, J Lys, R Lysak, E Lytken, P Mack, D MacQueen, R Madrak, K Maeshima, T Maki, P Maksimovic, S Malde, G Manca, F Margaroli, R Marginean, C Marino, A Martin, V Martin, M Martínez, T Maruyama, H Matsunaga, ME Mattson, R Mazini, P Mazzanti, KS McFarland, P McIntyre, R McNulty, A Mehta, S Menzemer, A Menzione, P Merkel, C Mesropian, A Messina, M von der Mey, T Miao, N Miladinovic, J Miles, R Miller, JS Miller, C Mills, M Milnik, R Miquel, A Mitra, G Mitselmakher, A Miyamoto, N Moggi, B Mohr, R Moore, M Morello, P Movilla Fernandez, J Mülmenstädt, A Mukherjee, Th Muller, R Mumford, P Murat, J Nachtman, J Naganoma, S Nahn, I Nakano, A Napier, D Naumov, V Necula, C Neu, MS Neubauer, J Nielsen, T Nigmanov, L Nodulman, O Norniella, E Nurse, T Ogawa, SH Oh, YD Oh, T Okusawa, R Oldeman, R Orava, K Osterberg, C Pagliarone, E Palencia, R Paoletti, V Papadimitriou, AA Paramonov, B Parks, S Pashapour, J Patrick, G Pauletta, M Paulini, C Paus, DE Pellett, A Penzo, TJ Phillips, G Piacentino, J Piedra, L Pinera, K Pitts, C Plager, L Pondrom, X Portell, O Poukhov, N Pounder, F Prakoshyn, A Pronko, J Proudfoot, F Ptohos, G Punzi, J Pursley, J Rademacker, A Rahaman, A Rakitin, S Rappoccio, F Ratnikov, B Reisert, V Rekovic, N van Remortel, P Renton, M Rescigno, S Richter, F Rimondi, L Ristori, WJ Robertson, A Robson, T Rodrigo, E Rogers, S Rolli, R Roser, M Rossi, R Rossin, C Rott, A Ruiz, J Russ, V Rusu, H Saarikko, S Sabik, A Safonov, WK Sakumoto, G Salamanna, O Saltó, D Saltzberg, C Sanchez, L Santi, S Sarkar, L Sartori, K Sato, P Savard, A Savoy-Navarro, T Scheidle, P Schlabach, EE Schmidt, MP Schmidt, M Schmitt, T Schwarz, L Scodellaro, AL Scott, A Scribano, F Scuri, A Sedov, S Seidel, Y Seiya, A Semenov, L Sexton-Kennedy, I Sfiligoi, MD Shapiro, T Shears, PF Shepard, D Sherman, M Shimojima, M Shochet, Y Shon, I Shreyber, A Sidoti, P Sinervo, A Sisakyan, J Sjolin, A Skiba, AJ Slaughter, K Sliwa, JR Smith, FD Snider, R Snihur, M Soderberg, A Soha, S Somalwar, V Sorin, J Spalding, M Spezziga, F Spinella, T Spreitzer, P Squillacioti, M Stanitzki, A Staveris-Polykalas, R St Denis, B Stelzer, O Stelzer-Chilton, D Stentz, J Strologas, D Stuart, JS Suh, A Sukhanov, K Sumorok, H Sun, T Suzuki, A Taffard, R Takashima, Y Takeuchi, K Takikawa, M Tanaka, R Tanaka, N Tanimoto, M Tecchio, PK Teng, K Terashi, S Tether, J Thom, AS Thompson, E Thomson, P Tipton, V Tiwari, S Tkaczyk, D Toback, S Tokar, K Tollefson, T Tomura, D Tonelli, M Tönnesmann, S Torre, D Torretta, S Tourneur, W Trischuk, R Tsuchiya, S Tsuno, N Turini, F Ukegawa, T Unverhau, S Uozumi, D Usynin, A Vaiciulis, S Vallecorsa, A Varganov, E Vataga, G Velev, G Veramendi, V Veszpremi, R Vidal, I Vila, R Vilar, T Vine, I Vollrath, I Volobouev, G Volpi, F Würthwein, P Wagner, RG Wagner, RL Wagner, W Wagner, R Wallny, T Walter, Z Wan, SM Wang, A Warburton, S Waschke, D Waters, WC Wester, B Whitehouse, D Whiteson, AB Wicklund, E Wicklund, G Williams, HH Williams, P Wilson, BL Winer, P Wittich, S Wolbers, C Wolfe, T Wright, X Wu, SM Wynne, A Yagil, K Yamamoto, J Yamaoka, T Yamashita, C Yang, UK Yang, YC Yang, WM Yao, GP Yeh, J Yoh, K Yorita, T Yoshida, GB Yu, I Yu, SS Yu, JC Yun, L Zanello, A Zanetti, I Zaw, F Zetti, X Zhang, J Zhou, S Zucchelli, CDF Collaboration

Abstract:

We present a measurement of the Bc+ meson lifetime in the decay mode Bc+ --> J/Psie+nue using the Collider Detector at Fermilab II detector at the Fermilab Tevatron Collider. From a sample of about of 360 pb(-1) of pp collisions at square root of s = 1.96 TeV, we reconstruct J/Psie+ pairs with invariant mass in the kinematically allowed range 4< M(J/Psie) < 6 GeV/c2. A fit to the decay-length distribution of 238 signal events yields a measured Bc+ meson lifetime of 0.463(-0.065)(+0.073)(stat) +/- 0.036(syst) ps.