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Search for pair production of scalar top quarks decaying to a τ lepton and a b quark in pp̄ collisions at s=1.96TeV

Physical Review Letters 101:7 (2008)

Authors:

T Aaltonen, J Adelman, T Akimoto, MG Albrow, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, M Aoki, G Apollinari, A Apresyan, T Arisawa, A Artikov, W Ashmanskas, A Attal, A Aurisano, F Azfar, P Azzi-Bacchetta, P Azzurri, N Bacchetta, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, S Baroiant, V Bartsch, G Bauer, PH Beauchemin, F Bedeschi, P Bednar, S Behari, G Bellettini, J Bellinger, A Belloni, D Benjamin, A Beretvas, J Beringer, T Berry, A Bhatti, M Binkley, D Bisello, I Bizjak, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, A Bolshov, D Bortoletto, J Boudreau, A Boveia, B Brau, A Bridgeman, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, K Burkett, G Busetto, P Bussey, A Buzatu, KL Byrum, S Cabrera, M Campanelli, M Campbell, F Canelli, A Canepa, D Carlsmith, R Carosi, S Carrillo, S Carron, B Casal, M Casarsa, A Castro, P Catastini, D Cauz, M Cavalli-Sforza, A Cerri, L Cerrito, SH Chang, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, CI Ciobanu

Abstract:

We search for pair production of supersymmetric top quarks (t1), followed by R-parity violating decay t1→τb with a branching ratio β, using 322pb-1 of pp̄ collisions at s=1.96TeV collected by the upgraded Collider Detector at Fermilab. Two candidate events pass our final selection criteria, consistent with the standard model expectation. We set upper limits on the cross section σ(t1t̄1)×β2 as a function of the top-squark mass m(t1). Assuming β=1, we set a 95% confidence level limit m(t1)>153GeV/c2. The limits are also applicable to the case of a third-generation scalar leptoquark (LQ3) decaying LQ3→τb. © 2008 The American Physical Society.
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Development of lightweight carbon-fiber mirrors for the RICH 1 detector of LHCb

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 593:3 (2008) 624-637

Authors:

GJ Barber, A Braem, NH Brook, W Cameron, C D'Ambrosio, N Harnew, J Imong, K Lessnoff, RN Martin, FCD Metlica, RC Romeo, D Websdale

Abstract:

The design, manufacture and characterization of lightweight carbon-fiber spherical converging mirrors for the RICH 1 Cherenkov detector of the LHCb experiment at CERN are described. The mirrors need to be lightweight to minimize the material for traversing particles and fluorocarbon-compatible to avoid degradation in the C4F10 gas radiator of RICH 1. Four large-sized carbon-fiber mirrors covering a total surface area of ∼ 2 m2 were installed in RICH 1 in July 2007. The mirrors have a radius of curvature of ∼ 2700 mm, a high reflectivity of ∼ 90 % in the 200-600 nm wavelength band, a low areal density of ∼ 5 kg / m2 equivalent to ∼ 1.2 % of a radiation length. Results of the radiation and fluorocarbon testing of the mirror prototypes are also reported. © 2008 Elsevier B.V. All rights reserved.
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Determination of the D0→K+π- relative strong phase using quantum-correlated measurements in e+e-→D0D̄0 at CLEO

Physical Review D - Particles, Fields, Gravitation and Cosmology 78:1 (2008)

Authors:

DM Asner, KW Edwards, P Naik, RA Briere, T Ferguson, G Tatishvili, H Vogel, ME Watkins, JL Rosner, JP Alexander, DG Cassel, JE Duboscq, R Ehrlich, L Fields, L Gibbons, R Gray, SW Gray, DL Hartill, BK Heltsley, D Hertz, CD Jones, J Kandaswamy, DL Kreinick, VE Kuznetsov, H Mahlke-Krüger, D Mohapatra, PUE Onyisi, JR Patterson, D Peterson, D Riley, A Ryd, AJ Sadoff, X Shi, S Stroiney, WM Sun, T Wilksen, SB Athar, R Patel, J Yelton, P Rubin, BI Eisenstein, I Karliner, S Mehrabyan, N Lowrey, M Selen, EJ White, J Wiss, RE Mitchell, MR Shepherd, D Besson, TK Pedlar, D Cronin-Hennessy, KY Gao, J Hietala, Y Kubota, T Klein, BW Lang, R Poling, AW Scott, P Zweber, S Dobbs, Z Metreveli, KK Seth, A Tomaradze, J Libby, A Powell, G Wilkinson, KM Ecklund, W Love, V Savinov, A Lopez, H Mendez, J Ramirez, JY Ge, DH Miller, B Sanghi, IPJ Shipsey, B Xin, GS Adams, M Anderson, JP Cummings, I Danko, D Hu, B Moziak, J Napolitano, Q He, J Insler, H Muramatsu, CS Park, EH Thorndike, F Yang, M Artuso, S Blusk, S Khalil, J Li, R Mountain, S Nisar, K Randrianarivony, N Sultana, T Skwarnicki

Abstract:

We exploit the quantum coherence between pair-produced D0 and D̄0 in ψ(3770) decays to study charm mixing, which is characterized by the parameters x and y, and to make a first determination of the relative strong phase δ between doubly Cabibbo-suppressed D0→K+π- and Cabibbo-favored D̄0→K+π-. We analyze a sample of 1.0×106 D0D̄0 pairs from 281pb-1 of e+e- collision data collected with the CLEO-c detector at Ecm=3.77GeV. By combining CLEO-c measurements with branching fraction input and time-integrated measurements of RM≡(x2+y2)/2 and RWS≡Γ(D0→K+π-)/Γ(D̄0→K+π-) from other experiments, we find cosδ=1.03-0.17+0.31±0.06, where the uncertainties are statistical and systematic, respectively. In addition, by further including external measurements of charm mixing parameters, we obtain an alternate measurement of cosδ=1.10±0.35±0.07, as well as xsinδ=(4.4-1.8+2.7±2.9)×10-3 and δ=(22-12-11+11+9) °. © 2008 The American Physical Society.
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Search for new heavy particles decaying to Z0Z0→eeee in pp̄ collisions at s=1.96TeV

Physical Review D - Particles, Fields, Gravitation and Cosmology 78:1 (2008)

Authors:

T Aaltonen, J Adelman, T Akimoto, MG Albrow, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, M Aoki, G Apollinari, A Apresyan, T Arisawa, A Artikov, W Ashmanskas, A Attal, A Aurisano, F Azfar, P Azzi-Bacchetta, P Azzurri, N Bacchetta, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, S Baroiant, V Bartsch, G Bauer, PH Beauchemin, F Bedeschi, P Bednar, S Behari, G Bellettini, J Bellinger, A Belloni, D Benjamin, A Beretvas, J Beringer, T Berry, A Bhatti, M Binkley, D Bisello, I Bizjak, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, A Bolshov, D Bortoletto, J Boudreau, A Boveia, B Brau, A Bridgeman, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, K Burkett, G Busetto, P Bussey, A Buzatu, KL Byrum, S Cabrera, M Campanelli, M Campbell, F Canelli, A Canepa, D Carlsmith, R Carosi, S Carrillo, S Carron, B Casal, M Casarsa, A Castro, P Catastini, D Cauz, M Cavalli-Sforza, A Cerri, L Cerrito, SH Chang, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, CI Ciobanu

Abstract:

We report the results of a search for the anomalous production of a massive particle decaying to four electrons via two Z0 bosons in 1.1fb-1 of pp̄ collisions at s=1.96TeV collected by the CDF II detector at Fermilab. We employ optimized electron identification criteria to maximize acceptance and efficiency. We estimate the backgrounds in the invariant mass range 500-1000GeV/c2 to be 0.028±0.009(stat)±0.011(syst) events. We observe zero events in this search region. Assuming a Randall-Sundrum graviton production model, we set 95% C.L. limits on σ×BF(G→Z0Z0)<4- 6pb, depending on the graviton mass. © 2008 The American Physical Society.
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Branching fractions for transitions of ψ(2S) to J/ψ

Physical Review D - Particles, Fields, Gravitation and Cosmology 78:1 (2008)

Authors:

H Mendez, JY Ge, DH Miller, IPJ Shipsey, B Xin, GS Adams, M Anderson, JP Cummings, I Danko, D Hu, B Moziak, J Napolitano, Q He, J Insler, H Muramatsu, CS Park, EH Thorndike, F Yang, M Artuso, S Blusk, S Khalil, J Li, R Mountain, S Nisar, K Randrianarivony, N Sultana, T Skwarnicki, S Stone, JC Wang, LM Zhang, G Bonvicini, D Cinabro, M Dubrovin, A Lincoln, P Naik, J Rademacker, DM Asner, KW Edwards, J Reed, RA Briere, T Ferguson, G Tatishvili, H Vogel, ME Watkins, JL Rosner, JP Alexander, DG Cassel, JE Duboscq, R Ehrlich, L Fields, L Gibbons, R Gray, SW Gray, DL Hartill, BK Heltsley, D Hertz, JM Hunt, J Kandaswamy, DL Kreinick, VE Kuznetsov, J Ledoux, H Mahlke-Krüger, D Mohapatra, PUE Onyisi, JR Patterson, D Peterson, D Riley, A Ryd, AJ Sadoff, X Shi, S Stroiney, WM Sun, T Wilksen, SB Athar, R Patel, J Yelton, P Rubin, BI Eisenstein, I Karliner, S Mehrabyan, N Lowrey, M Selen, EJ White, J Wiss, RE Mitchell, MR Shepherd, D Besson, TK Pedlar, D Cronin-Hennessy, KY Gao, J Hietala, Y Kubota, T Klein, BW Lang, R Poling, AW Scott, P Zweber, S Dobbs, Z Metreveli, KK Seth

Abstract:

We report determination of branching fractions for the decays ψ(2S)→h+J/ψ, where h=any, π+π-, π0π0, η, π0, and γγ through χc0,1,2. These measurements use 27M ψ(2S) decays produced in e+e- collision data collected with the CLEO detector. The resulting branching fractions and ratios thereof improve upon previously achieved precision in all cases, and in combination with other measurements permit determination of B(χcJ→γJ/ψ) and B(ψ(2S)→light hadrons). © 2008 The American Physical Society.
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