Dr Farrukh Azfar: Publications

Search for new physics in the μμ+e/μ+E T channel with a low-pT lepton threshold at the Collider Detector at Fermilab

Physical Review D - Particles, Fields, Gravitation and Cosmology 79:5 (2009)

Authors:

T Aaltonen, J Adelman, T Akimoto, MG Albrow, BA González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, A Apresyan, T Arisawa, A Artikov, W Ashmanskas, A Attal, A Aurisano, F Azfar, P Azzurri, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, V Bartsch, G Bauer, PH Beauchemin, F Bedeschi, D Beecher, S Behari, G Bellettini, J Bellinger, D Benjamin, A Beretvas, J Beringer, A Bhatti, M Binkley, D Bisello, I Bizjak, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, D Bortoletto, J Boudreau, A Boveia, B Brau, A Bridgeman, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, S Burke, K Burkett, G Busetto, P Bussey, A Buzatu, KL Byrum, S Cabrera, C Calancha, M Campanelli, M Campbell, F Canelli, A Canepa, B Carls, D Carlsmith, R Carosi, S Carrillo, S Carron, B Casal, M Casarsa, A Castro, P Catastini, D Cauz, V Cavaliere, 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, T Chwalek, CI Ciobanu, MA Ciocci, A Clark

Abstract:

A search for new physics using three-lepton (trilepton) data collected with the CDF II detector and corresponding to an integrated luminosity of 976 pb-1 is presented. The standard model predicts a low rate of trilepton events, which makes some supersymmetric processes, such as chargino-neutralino production, measurable in this channel. The μμ+ signature is investigated, where ℓ is an electron or a muon, with the additional requirement of large missing transverse energy. In this analysis, the lepton transverse momenta with respect to the beam direction (pT) are as low as 5GeV/c, a selection that improves the sensitivity to particles that are light as well as to ones that result in leptonically decaying tau leptons. At the same time, this low-pT selection presents additional challenges due to the non-negligible heavy-quark background at low lepton momenta. This background is measured with an innovative technique using experimental data. Several dimuon and trilepton control regions are investigated, and good agreement between experimental results and standard-model predictions is observed. In the signal region, we observe one three-muon event and expect 0.4±0.1μμ+ events from standard-model processes. © 2009 The American Physical Society.

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Measurement of the fraction of tt̄ production via gluon-gluon fusion in pp̄ collisions at s=1.96TeV

Physical Review D - Particles, Fields, Gravitation and Cosmology 79:3 (2009)

Authors:

Abstract:

We present a measurement of the ratio of the tt̄ production cross section via gluon-gluon fusion to the total tt̄ production cross section in pp̄ collisions at s=1.96TeV at the Tevatron. Using a data sample with an integrated luminosity of 955pb-1 recorded by the CDF II detector at Fermilab, we select events based on the tt̄ decay to lepton+jets. Using an artificial neural network technique we discriminate between tt̄ events produced via qq̄ annihilation and gg fusion, and find Gf=σ(gg→tt̄)/ σ(pp̄→tt̄)<0.33 at the 68% confidence level. This result is combined with a previous measurement to obtain the most stringent measurement of this quantity by CDF to date, Gf=0.07-0.07+0.15. © 2009 The American Physical Society.

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First measurement of the ratio of branching fractions B(Λb 0→Λc+μ-ν̄μ)/B(Λb 0→Λc+π-)

Physical Review D - Particles, Fields, Gravitation and Cosmology 79:3 (2009)

Authors:

Abstract:

This article presents the first measurement of the ratio of branching fractions B(Λb0→Λc+μ-ν̄μ)/ B(Λb0→Λc+π-). Measurements in two control samples using the same technique B(B̄0→D+μ- ν̄μ)/B(B̄0→D+π-) and B(B̄ 0→D*(2010)+μ-ν̄μ)/ B(B̄0→D*(2010)+π-) are also reported. The analysis uses data from an integrated luminosity of approximately 172pb-1 of pp̄ collisions at s=1.96TeV, collected with the CDF II detector at the Fermilab Tevatron. The relative branching fractions are measured to be B(Λb 0→Λc+μ-ν̄μ)B(Λb 0→Λc+π-)=16.6±3.0(stat) ±1.0(syst)+2.6-3.4(PDG) ±0.3(EBR), B(B̄0→D+μ-ν̄μ) B(B̄0→D+π-)=9.9±1.0(stat) ±0.6(syst)±0.4(PDG)± 0.5(EBR), and B(B̄0→D*( 2010)+μ-ν̄μ)B(B̄0→D*( 2010)+π-)=16.5±2.3(stat) ±0.6(syst)±0.5(PDG)± 0.8(EBR). The uncertainties are from statistics (stat), internal systematics (syst), world averages of measurements published by the Particle Data Group or subsidiary measurements in this analysis (PDG), and unmeasured branching fractions estimated from theory (EBR), respectively. This article also presents measurements of the branching fractions of four new Λb 0 semileptonic decays: Λb0→Λc( 2595)+μ-ν̄μ, Λb0→Λc( 2625)+μ-ν̄μ, Λb0→Σc( 2455)0π+μ-ν̄μ, and Λb 0→Σc(2455)++π-μ-ν̄μ, relative to the branching fraction of the Λb0→Λc+μ- ν̄μ decay. Finally, the transverse-momentum distribution of Λb0 baryons produced in pp̄ collisions is measured and found to be significantly different from that of B̄0 mesons, which results in a modification in the production cross-section ratio σΛb0/σB̄0 with respect to the CDF I measurement. © 2009 The American Physical Society.

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Publisher’s Note: Search for High-Mass e+e- Resonances in pp¯ Collisions at s=1.96 TeV [Phys. Rev. Lett. 102, 031801 (2009)]

Physical Review Letters American Physical Society (APS) 102:5 (2009) 059901

Authors:

T Aaltonen, J Adelman, T Akimoto, MG Albrow, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, A Apresyan, T Arisawa, A Artikov, W Ashmanskas, A Attal, A Aurisano, F Azfar, P Azzurri, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, V Bartsch, G Bauer, P-H Beauchemin, F Bedeschi, D Beecher, S Behari, G Bellettini, J Bellinger, D Benjamin, A Beretvas, J Beringer, A Bhatti, M Binkley, D Bisello, I Bizjak, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, D Bortoletto, J Boudreau, A Boveia, B Brau, A Bridgeman, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, S Burke, K Burkett, G Busetto, P Bussey, A Buzatu, KL Byrum, S Cabrera, C Calancha, M Campanelli, M Campbell, F Canelli, A Canepa, B Carls, D Carlsmith, R Carosi, S Carrillo, S Carron, B Casal, M Casarsa, A Castro, P Catastini, D Cauz, V Cavaliere, 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, T Chwalek, CI Ciobanu, MA Ciocci, A Clark, D Clark, G Compostella, ME Convery, J Conway, M Cordelli, G Cortiana, CA Cox, DJ Cox, F Crescioli, C Cuenca Almenar, J Cuevas, R Culbertson, JC Cully, D Dagenhart, M Datta, T Davies, P de Barbaro, S De Cecco, A Deisher, G De Lorenzo, M Dell’Orso, C Deluca, L Demortier, J Deng, M Deninno, PF Derwent, GP di Giovanni, C Dionisi, B Di Ruzza, JR Dittmann, M D’Onofrio, S Donati, P Dong, J Donini, T Dorigo, S Dube, J Efron, A Elagin, R Erbacher, D Errede, S Errede, R Eusebi, HC Fang, S Farrington, WT Fedorko, RG Feild, M Feindt, JP Fernandez, C Ferrazza, R Field, G Flanagan, R Forrest, MJ Frank, M Franklin, JC Freeman, I Furic, M Gallinaro, J Galyardt, F Garberson, JE Garcia, AF Garfinkel, K Genser, H Gerberich, D Gerdes, A Gessler, S Giagu, V Giakoumopoulou, P Giannetti, K Gibson, JL Gimmell, CM Ginsburg, N Giokaris, M Giordani, P Giromini, M Giunta, G Giurgiu, V Glagolev, D Glenzinski, M Gold, N Goldschmidt, A Golossanov, G Gomez, G Gomez-Ceballos, M Goncharov, O González, I Gorelov, AT Goshaw, K Goulianos, A Gresele, S Grinstein, C Grosso-Pilcher, RC Group, U Grundler, J Guimaraes da Costa, Z Gunay-Unalan, C Haber, K Hahn, SR Hahn, E Halkiadakis, B-Y Han, JY Han, F Happacher, K Hara, D Hare, M Hare, S Harper, RF Harr, RM Harris, M Hartz, K Hatakeyama, C Hays, M Heck, A Heijboer, J Heinrich, C Henderson, M Herndon, J Heuser, S Hewamanage, D Hidas, CS Hill, D Hirschbuehl, A Hocker, S Hou, M Houlden, S-C Hsu, BT Huffman, RE Hughes, U Husemann, J Huston, J Incandela, G Introzzi, M Iori, A Ivanov, E James, B Jayatilaka, EJ Jeon, MK Jha, S Jindariani, W Johnson, M Jones, KK Joo, SY Jun, JE Jung, TR Junk, T Kamon, D Kar, PE Karchin, Y Kato, R Kephart, J Keung, V Khotilovich, B Kilminster, DH Kim, HS Kim, HW Kim, JE Kim, MJ Kim, SB Kim, SH Kim, YK Kim, N Kimura, L Kirsch, S Klimenko, B Knuteson, BR Ko, K Kondo, DJ Kong, J Konigsberg, A Korytov, AV Kotwal, M Kreps, J Kroll, D Krop, N Krumnack, M Kruse, V Krutelyov, T Kubo, T Kuhr, NP Kulkarni, M Kurata, Y Kusakabe, S Kwang, AT Laasanen, S Lami, S Lammel, M Lancaster, RL Lander, K Lannon, A Lath, G Latino, I Lazzizzera, T LeCompte, E Lee, HS Lee, SW Lee, S Leone, JD Lewis, C-S Lin, J Linacre, M Lindgren, E Lipeles, A Lister, DO Litvintsev, C Liu, T Liu, NS Lockyer, A Loginov, M Loreti, L Lovas, D Lucchesi, C Luci, J Lueck, P Lujan, P Lukens, G Lungu, L Lyons, J Lys, R Lysak, D MacQueen, R Madrak, K Maeshima, K Makhoul, T Maki, P Maksimovic, S Malde, S Malik, G Manca, A Manousakis-Katsikakis, F Margaroli, C Marino, CP Marino, A Martin, V Martin, M Martínez, R Martínez-Ballarín, T Maruyama, P Mastrandrea, T Masubuchi, M Mathis, ME Mattson, P Mazzanti, KS McFarland, P McIntyre, R McNulty, A Mehta, P Mehtala, A Menzione, P Merkel, C Mesropian, T Miao, N Miladinovic, R Miller, C Mills, M Milnik, A Mitra, G Mitselmakher, H Miyake, N Moggi, CS Moon, R Moore, MJ Morello, J Morlok, P Movilla Fernandez, J Mülmenstädt, A Mukherjee, Th Muller, R Mumford, P Murat, M Mussini, J Nachtman, Y Nagai, A Nagano, J Naganoma, K Nakamura, I Nakano, A Napier, V Necula, J Nett, C Neu, MS Neubauer, S Neubauer, J Nielsen, L Nodulman, M Norman, O Norniella, E Nurse, L Oakes, SH Oh, YD Oh, I Oksuzian, T Okusawa, R Orava, S Pagan Griso, E Palencia, V Papadimitriou, A Papaikonomou, AA Paramonov, B Parks, S Pashapour, J Patrick, G Pauletta, M Paulini, C Paus, T Peiffer, DE Pellett, A Penzo, TJ Phillips, G Piacentino, E Pianori, L Pinera, K Pitts, C Plager, L Pondrom, O Poukhov, N Pounder, F Prakoshyn, A Pronko, J Proudfoot, F Ptohos, E Pueschel, G Punzi, J Pursley, J Rademacker, A Rahaman, V Ramakrishnan, N Ranjan, I Redondo, V Rekovic, P Renton, M Renz, M Rescigno, S Richter, F Rimondi, L Ristori, A Robson, T Rodrigo, T Rodriguez, E Rogers, S Rolli, R Roser, M Rossi, R Rossin, P Roy, A Ruiz, J Russ, V Rusu, A Safonov, WK Sakumoto, O Saltó, L Santi, S Sarkar, L Sartori, K Sato, A Savoy-Navarro, P Schlabach, A Schmidt, EE Schmidt, MA Schmidt, MP Schmidt, M Schmitt, T Schwarz, L Scodellaro, A Scribano, F Scuri, A Sedov, S Seidel, Y Seiya, A Semenov, L Sexton-Kennedy, F Sforza, A Sfyrla, SZ Shalhout, T Shears, PF Shepard, M Shimojima, S Shiraishi, M Shochet, Y Shon, I Shreyber, A Sidoti, P Sinervo, A Sisakyan, AJ Slaughter, J Slaunwhite, K Sliwa, JR Smith, FD Snider, R Snihur, A Soha, S Somalwar, V Sorin, J Spalding, T Spreitzer, P Squillacioti, M Stanitzki, R St.Denis, B Stelzer, O Stelzer-Chilton, D Stentz, J Strologas, GL Strycker, D Stuart, JS Suh, A Sukhanov, I Suslov, T Suzuki, A Taffard, R Takashima, Y Takeuchi, R Tanaka, M Tecchio, PK Teng, K Terashi, J Thom, AS Thompson, GA Thompson, E Thomson, P Tipton, P Ttito-Guzmán, S Tkaczyk, D Toback, S Tokar, K Tollefson, T Tomura, D Tonelli, S Torre, D Torretta, P Totaro, S Tourneur, M Trovato, S-Y Tsai, Y Tu, N Turini, F Ukegawa, S Vallecorsa, N van Remortel, A Varganov, E Vataga, F Vázquez, G Velev, C Vellidis, V Veszpremi, M Vidal, R Vidal, I Vila, R Vilar, T Vine, M Vogel, I Volobouev, G Volpi, P Wagner, RG Wagner, RL Wagner, W Wagner, J Wagner-Kuhr, T Wakisaka, R Wallny, C Wang, SM Wang, A Warburton, D Waters, M Weinberger, J Weinelt, WC Wester, B Whitehouse, D Whiteson, AB Wicklund, E Wicklund, S Wilbur, G Williams, HH Williams, P Wilson, BL Winer, P Wittich, S Wolbers, C Wolfe, T Wright, X Wu, F Würthwein, SM Wynne, S Xie, A Yagil, K Yamamoto, J Yamaoka, 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, X Zhang, Y Zheng, S Zucchelli

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Erratum: Search for high-mass e+e- Resonances in pp̄ collisions at s=1.96TeV (Physical Review Letters (2009) 102 (031801))

Physical Review Letters 102:5 (2009)

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Dr Farrukh Azfar

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Search for new physics in the μμ+e/μ+E T channel with a low-pT lepton threshold at the Collider Detector at Fermilab

Authors:

Abstract:

Measurement of the fraction of tt̄ production via gluon-gluon fusion in pp̄ collisions at s=1.96TeV

Authors:

Abstract:

First measurement of the ratio of branching fractions B(Λb 0→Λc+μ-ν̄μ)/B(Λb 0→Λc+π-)

Authors:

Abstract:

Publisher’s Note: Search for High-Mass e+e- Resonances in pp¯ Collisions at s=1.96 TeV [Phys. Rev. Lett. 102, 031801 (2009)]

Authors:

Erratum: Search for high-mass e+e- Resonances in pp̄ collisions at s=1.96TeV (Physical Review Letters (2009) 102 (031801))

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Dr Farrukh Azfar

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Search for new physics in the μμ+e/μ+E T channel with a low-pT lepton threshold at the Collider Detector at Fermilab

Authors:

Abstract:

Measurement of the fraction of tt̄ production via gluon-gluon fusion in pp̄ collisions at s=1.96TeV

Authors:

Abstract:

First measurement of the ratio of branching fractions B(Λb 0→Λc+μ-ν̄μ)/B(Λb 0→Λc+π-)

Authors:

Abstract:

Publisher’s Note: Search for High-Mass e+e- Resonances in pp¯ Collisions at s=1.96 TeV [Phys. Rev. Lett. 102, 031801 (2009)]

Authors:

Erratum: Search for high-mass e+e- Resonances in pp̄ collisions at s=1.96TeV (Physical Review Letters (2009) 102 (031801))

Authors: