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Direct observation of the strange b Baryon Ξb

Physical Review Letters 99:5 (2007)

Authors:

VM Abazov, B Abbott, M Abolins, BS Acharya, M Adams, T Adams, E Aguilo, SH Ahn, M Ahsan, GD Alexeev, G Alkhazov, A Alton, G Alverson, GA Alves, M Anastasoaie, LS Ancu, T Andeen, S Anderson, B Andrieu, MS Anzelc, Y Arnoud, M Arov, M Arthaud, A Askew, B Åsman, ACS Assis Jesus, O Atramentov, C Autermann, C Avila, C Ay, F Badaud, A Baden, L Bagby, B Baldin, DV Bandurin, S Banerjee, P Banerjee, E Barberis, AF Barfuss, P Bargassa, P Baringer, J Barreto, JF Bartlett, U Bassler, D Bauer, S Beale, A Bean, M Begalli, M Begel, C Belanger-Champagne, L Bellantoni, A Bellavance, JA Benitez, SB Beri, G Bernardi, R Bernhard, L Berntzon, I Bertram, M Besançon, R Beuselinck, VA Bezzubov, PC Bhat, V Bhatnagar, C Biscarat, G Blazey, F Blekman, S Blessing, D Bloch, K Bloom, A Boehnlein, D Boline, TA Bolton, G Borissov, K Bos, T Bose, A Brandt, R Brock, G Brooijmans, A Bross, D Brown, NJ Buchanan, D Buchholz, M Buehler, V Buescher, S Burdin, S Burke, TH Burnett, CP Buszello, JM Butler, P Calfayan, S Calvet, J Cammin, S Caron, W Carvalho, BCK Casey, NM Cason, H Castilla-Valdez, S Chakrabarti, D Chakraborty, KM Chan

Abstract:

We report the first direct observation of the strange b baryon Ξb-(Ξ̄b+). We reconstruct the decay Ξb-→J/ψΞ-, with J/ψ→μ+μ-, and Ξ-→Λπ-→pπ-π- in pp̄ collisions at s=1.96TeV. Using 1.3fb-1 of data collected by the D0 detector, we observe 15.2±4.4(stat)-0.4+1.9(syst) Ξb- candidates at a mass of 5.774±0.011(stat)±0.015(syst)GeV. The significance of the observed signal is 5.5σ, equivalent to a probability of 3.3×10-8 of it arising from a background fluctuation. Normalizing to the decay Λb→J/ψΛ, we measure the relative rate σ(Ξb-)×B(Ξb-→J/ψΞ-)σ(Λb) ×B(Λb→J/ψΛ)=0.28±0.09(stat)-0.08+0.09(syst). © 2007 The American Physical Society.
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Direct observation of the strange b baryon Xib-.

Phys Rev Lett 99:5 (2007) 052001

Authors:

VM Abazov, B Abbott, M Abolins, BS Acharya, M Adams, T Adams, E Aguilo, SH Ahn, M Ahsan, GD Alexeev, G Alkhazov, A Alton, G Alverson, GA Alves, M Anastasoaie, LS Ancu, T Andeen, S Anderson, B Andrieu, MS Anzelc, Y Arnoud, M Arov, M Arthaud, A Askew, B Asman, ACS Assis Jesus, O Atramentov, C Autermann, C Avila, C Ay, F Badaud, A Baden, L Bagby, B Baldin, DV Bandurin, S Banerjee, P Banerjee, E Barberis, A-F Barfuss, P Bargassa, P Baringer, J Barreto, JF Bartlett, U Bassler, D Bauer, S Beale, A Bean, M Begalli, M Begel, C Belanger-Champagne, L Bellantoni, A Bellavance, JA Benitez, SB Beri, G Bernardi, R Bernhard, L Berntzon, I Bertram, M Besançon, R Beuselinck, VA Bezzubov, PC Bhat, V Bhatnagar, C Biscarat, G Blazey, F Blekman, S Blessing, D Bloch, K Bloom, A Boehnlein, D Boline, TA Bolton, G Borissov, K Bos, T Bose, A Brandt, R Brock, G Brooijmans, A Bross, D Brown, NJ Buchanan, D Buchholz, M Buehler, V Buescher, S Burdin, S Burke, TH Burnett, CP Buszello, JM Butler, P Calfayan, S Calvet, J Cammin, S Caron, W Carvalho, BCK Casey, NM Cason, H Castilla-Valdez, S Chakrabarti, D Chakraborty, KM Chan, K Chan, A Chandra, F Charles, E Cheu, F Chevallier, DK Cho, S Choi, B Choudhary, L Christofek, T Christoudias, S Cihangir, D Claes, C Clément, B Clément, Y Coadou, M Cooke, WE Cooper, M Corcoran, F Couderc, M-C Cousinou, S Crépé-Renaudin, D Cutts, M Cwiok, H da Motta, A Das, G Davies, K De, SJ de Jong, P de Jong, E De La Cruz-Burelo, C De Oliveira Martins, JD Degenhardt, F Déliot, M Demarteau, R Demina, D Denisov, SP Denisov, S Desai, HT Diehl, M Diesburg, A Dominguez, H Dong, LV Dudko, L Duflot, SR Dugad, D Duggan, A Duperrin, J Dyer, A Dyshkant, M Eads, D Edmunds, J Ellison, VD Elvira, Y Enari, S Eno, P Ermolov, H Evans, A Evdokimov, VN Evdokimov, AV Ferapontov, T Ferbel, F Fiedler, F Filthaut, W Fisher, HE Fisk, M Ford, M Fortner, H Fox, S Fu, S Fuess, T Gadfort, CF Galea, E Gallas, E Galyaev, C Garcia, A Garcia-Bellido, V Gavrilov, P Gay, W Geist, D Gelé, CE Gerber, Y Gershtein, D Gillberg, G Ginther, N Gollub, B Gómez, A Goussiou, PD Grannis, H Greenlee, ZD Greenwood, EM Gregores, G Grenier, Ph Gris, J-F Grivaz, A Grohsjean, S Grünendahl, MW Grünewald, J Guo, F Guo, P Gutierrez, G Gutierrez, A Haas, NJ Hadley, P Haefner, S Hagopian, J Haley, I Hall, RE Hall, L Han, K Hanagaki, P Hansson, K Harder, A Harel, R Harrington, JM Hauptman, R Hauser, J Hays, T Hebbeker, D Hedin, JG Hegeman, JM Heinmiller, AP Heinson, U Heintz, C Hensel, K Herner, G Hesketh, MD Hildreth, R Hirosky, JD Hobbs, B Hoeneisen, H Hoeth, M Hohlfeld, SJ Hong, R Hooper, S Hossain, P Houben, Y Hu, Z Hubacek, V Hynek, I Iashvili, R Illingworth, AS Ito, S Jabeen, M Jaffré, S Jain, K Jakobs, C Jarvis, R Jesik, K Johns, C Johnson, M Johnson, A Jonckheere, P Jonsson, A Juste, D Käfer, S Kahn, E Kajfasz, AM Kalinin, JR Kalk, JM Kalk, S Kappler, D Karmanov, J Kasper, P Kasper, I Katsanos, D Kau, R Kaur, V Kaushik, R Kehoe, S Kermiche, N Khalatyan, A Khanov, A Kharchilava, YM Kharzheev, D Khatidze, H Kim, TJ Kim, MH Kirby, M Kirsch, B Klima, JM Kohli, J-P Konrath, M Kopal, VM Korablev, B Kothari, AV Kozelov, D Krop, A Kryemadhi, T Kuhl, A Kumar, S Kunori, A Kupco, T Kurca, J Kvita, F Lacroix, D Lam, S Lammers, G Landsberg, J Lazoflores, P Lebrun, WM Lee, A Leflat, F Lehner, J Lellouch, V Lesne, J Leveque, P Lewis, J Li, QZ Li, L Li, SM Lietti, JGR Lima, D Lincoln, J Linnemann, VV Lipaev, R Lipton, Y Liu, Z Liu, L Lobo, A Lobodenko, M Lokajicek, A Lounis, P Love, HJ Lubatti, AL Lyon, AKA Maciel, D Mackin, RJ Madaras, P Mättig, C Magass, A Magerkurth, N Makovec, PK Mal, HB Malbouisson, S Malik, VL Malyshev, HS Mao, Y Maravin, B Martin, R McCarthy, A Melnitchouk, A Mendes, L Mendoza, PG Mercadante, YP Merekov, M Merkin, KW Merritt, J Meyer, A Meyer, M Michaut, T Millet, J Mitrevski, J Molina, RK Mommsen, NK Mondal, RW Moore, T Moulik, GS Muanza, M Mulders, M Mulhearn, O Mundal, L Mundim, E Nagy, M Naimuddin, M Narain, NA Naumann, HA Neal, JP Negret, P Neustroev, H Nilsen, A Nomerotski, SF Novaes, T Nunnemann, V O'Dell, DC O'Neil, G Obrant, C Ochando, D Onoprienko, N Oshima, J Osta, R Otec, GJ Otero y Garzón, M Owen, P Padley, M Pangilinan, G Panov, N Parashar, S-J Park, SK Park, J Parsons, R Partridge, N Parua, A Patwa, G Pawloski, B Penning, PM Perea, K Peters, Y Peters, P Pétroff, M Petteni, R Piegaia, J Piper, M-A Pleier, PLM Podesta-Lerma, VM Podstavkov, Y Pogorelov, M-E Pol, P Polozov, A Pompos, BG Pope, AV Popov, C Potter, WL Prado da Silva, HB Prosper, S Protopopescu, J Qian, A Quadt, B Quinn, A Rakitine, MS Rangel, KJ Rani, K Ranjan, PN Ratoff, P Renkel, S Reucroft, P Rich, M Rijssenbeek, I Ripp-Baudot, F Rizatdinova, S Robinson, RF Rodrigues, C Royon, A Rozhdestvenski, P Rubinov, R Ruchti, G Safronov, G Sajot, A Sánchez-Hernández, MP Sanders, A Santoro, G Savage, L Sawyer, T Scanlon, D Schaile, RD Schamberger, Y Scheglov, H Schellman, P Schieferdecker, T Schliephake, C Schmitt, C Schwanenberger, A Schwartzman, R Schwienhorst, J Sekaric, S Sengupta, H Severini, E Shabalina, M Shamim, V Shary, AA Shchukin, RK Shivpuri, D Shpakov, V Siccardi, V Simak, V Sirotenko, P Skubic, P Slattery, D Smirnov, RP Smith, J Snow, GR Snow, S Snyder, S Söldner-Rembold, L Sonnenschein, A Sopczak, M Sosebee, K Soustruznik, M Souza, B Spurlock, J Stark, J Steele, V Stolin, A Stone, DA Stoyanova, J Strandberg, S Strandberg, MA Strang, M Strauss, E Strauss, R Ströhmer, D Strom, M Strovink, L Stutte, S Sumowidagdo, P Svoisky, A Sznajder, M Talby, P Tamburello, A Tanasijczuk, W Taylor, P Telford, J Temple, B Tiller, F Tissandier, M Titov, VV Tokmenin, M Tomoto, T Toole, I Torchiani, T Trefzger, D Tsybychev, B Tuchming, C Tully, PM Tuts, R Unalan, S Uvarov, L Uvarov, S Uzunyan, B Vachon, PJ van den Berg, B van Eijk, R Van Kooten, WM van Leeuwen, N Varelas, EW Varnes, A Vartapetian, IA Vasilyev, M Vaupel, P Verdier, LS Vertogradov, Y Vertogradova, M Verzocchi, F Villeneuve-Seguier, P Vint, P Vokac, E Von Toerne, M Voutilainen, M Vreeswijk, R Wagner, HD Wahl, L Wang, MHLS Wang, J Warchol, G Watts, M Wayne, M Weber, G Weber, H Weerts, A Wenger, N Wermes, M Wetstein, A White, D Wicke, GW Wilson, SJ Wimpenny, M Wobisch, DR Wood, TR Wyatt, Y Xie, S Yacoob, R Yamada, M Yan, T Yasuda, YA Yatsunenko, K Yip, HD Yoo, SW Youn, J Yu, C Yu, A Yurkewicz, A Zatserklyaniy, C Zeitnitz, D Zhang, T Zhao, B Zhou, J Zhu, M Zielinski, D Zieminska, A Zieminski, L Zivkovic, V Zutshi, EG Zverev, D0 Collaboration

Abstract:

We report the first direct observation of the strange b baryon Xi(b)- (Xi(b)+). We reconstruct the decay Xi(b)- -->J/psiXi-, with J/psi-->mu+mu-, and Xi--->Lambdapi--->ppi-pi- in pp collisions at square root of s =1.96 TeV. Using 1.3 fb(-1) of data collected by the D0 detector, we observe 15.2 +/- 4.4(stat)(-0.4)(+1.9)(syst) Xi(b)- candidates at a mass of 5.774 +/- 0.011(stat) +/- 0.015(syst) GeV. The significance of the observed signal is 5.5 sigma, equivalent to a probability of 3.3 x 10(-8) of it arising from a background fluctuation. Normalizing to the decay Lambda(b)-->J/psiLambda, we measure the relative rate sigma(Xi(b-) x B(Xi)b})- -->J/psiXi-)/sigma(Lambda(b)) x B(Lambda(b)-->J/psiLambda) = 0.28+/-0.09(stat)(-0.08)(+0.09)(syst).
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Observation and mass measurement of the baryon Xib-.

Phys Rev Lett 99:5 (2007) 052002

Authors:

T Aaltonen, A Abulencia, J Adelman, T Affolder, T Akimoto, MG Albrow, S Amerio, D Amidei, A Anastassov, K Anikeev, A Annovi, J Antos, M Aoki, G Apollinari, 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, P-H Beauchemin, F Bedeschi, 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, 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, S Carrillo, D Carlsmith, R Carosi, 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, I Cho, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, M Cilijak, 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 Crescioli, C Cuenca Almenar, J Cuevas, R Culbertson, JC Cully, S DaRonco, M Datta, S D'Auria, T Davies, D Dagenhart, P de Barbaro, S De Cecco, A Deisher, G De Lentdecker, G De Lorenzo, M Dell'Orso, F Delli Paoli, L Demortier, J Deng, M Deninno, D De Pedis, PF Derwent, GP Di Giovanni, C Dionisi, B Di Ruzza, JR Dittmann, M D'Onofrio, C Dörr, S Donati, P Dong, J Donini, T Dorigo, S Dube, J Efron, 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, R Forrest, S Forrester, M Franklin, JC Freeman, I Furic, M Gallinaro, J Galyardt, JE Garcia, F Garberson, AF Garfinkel, C Gay, H Gerberich, D Gerdes, S Giagu, P Giannetti, K Gibson, JL Gimmell, C Ginsburg, N Giokaris, M Giordani, P Giromini, M Giunta, G Giurgiu, V Glagolev, D Glenzinski, M Gold, N Goldschmidt, J Goldstein, 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, A Hamilton, B-Y Han, JY Han, R Handler, F Happacher, K Hara, D Hare, M Hare, S Harper, RF Harr, RM Harris, M Hartz, K Hatakeyama, J Hauser, C Hays, M Heck, A Heijboer, B Heinemann, J Heinrich, C Henderson, M Herndon, J Heuser, D Hidas, CS Hill, D Hirschbuehl, A Hocker, A Holloway, S Hou, M Houlden, S-C Hsu, BT Huffman, RE Hughes, U Husemann, J Huston, J Incandela, G Introzzi, M Iori, A Ivanov, B Iyutin, E James, D Jang, B Jayatilaka, D Jeans, EJ Jeon, S Jindariani, W Johnson, M Jones, KK Joo, SY Jun, JE Jung, TR Junk, T Kamon, 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, N Kimura, L Kirsch, S Klimenko, M Klute, B Knuteson, BR Ko, K Kondo, DJ Kong, J Konigsberg, A Korytov, AV Kotwal, AC Kraan, J Kraus, M Kreps, J Kroll, N Krumnack, M Kruse, V Krutelyov, T Kubo, SE Kuhlmann, T Kuhr, NP Kulkarni, 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, A Lister, DO Litvintsev, T Liu, NS Lockyer, A Loginov, M Loreti, 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, K Makhoul, T Maki, P Maksimovic, S Malde, S Malik, G Manca, A Manousakis, F Margaroli, R Marginean, C Marino, CP Marino, A Martin, M Martin, V Martin, M Martínez, R Martínez-Ballarín, T Maruyama, P Mastrandrea, T Masubuchi, H Matsunaga, ME Mattson, R Mazini, P Mazzanti, KS McFarland, P McIntyre, R McNulty, A Mehta, P Mehtala, S Menzemer, A Menzione, P Merkel, C Mesropian, A Messina, T Miao, N Miladinovic, J Miles, R Miller, C Mills, M Milnik, A Mitra, G Mitselmakher, A Miyamoto, S Moed, N Moggi, B Mohr, CS Moon, R Moore, M Morello, P Movilla Fernandez, J Mülmenstädt, A Mukherjee, Th Muller, R Mumford, P Murat, M Mussini, J Nachtman, A Nagano, J Naganoma, K Nakamura, I Nakano, A Napier, V Necula, C Neu, MS Neubauer, J Nielsen, L Nodulman, O Norniella, E Nurse, SH Oh, YD Oh, I Oksuzian, T Okusawa, R Oldeman, R Orava, K Osterberg, C Pagliarone, E Palencia, V Papadimitriou, A Papaikonomou, 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, V Ramakrishnan, N Ranjan, I Redondo, B Reisert, V Rekovic, P Renton, M Rescigno, S Richter, F Rimondi, L Ristori, A Robson, T Rodrigo, E Rogers, S Rolli, R Roser, M Rossi, R Rossin, P Roy, A Ruiz, J Russ, V Rusu, H Saarikko, A Safonov, WK Sakumoto, G Salamanna, O Saltó, 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, A Sfyrla, SZ Shalhout, MD Shapiro, T Shears, PF Shepard, D Sherman, M Shimojima, M Shochet, Y Shon, I Shreyber, A Sidoti, P Sinervo, A Sisakyan, AJ Slaughter, J Slaunwhite, K Sliwa, JR Smith, FD Snider, R Snihur, M Soderberg, A Soha, S Somalwar, V Sorin, J Spalding, 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, H Sun, I Suslov, T Suzuki, A Taffard, R Takashima, Y Takeuchi, R Tanaka, M Tecchio, PK Teng, K Terashi, J Thom, AS Thompson, E Thomson, P Tipton, V Tiwari, S Tkaczyk, D Toback, S Tokar, K Tollefson, T Tomura, D Tonelli, S Torre, D Torretta, S Tourneur, W Trischuk, S Tsuno, Y Tu, N Turini, F Ukegawa, S Uozumi, S Vallecorsa, N van Remortel, A Varganov, E Vataga, F Vazquez, G Velev, C Vellidis, G Veramendi, V Veszpremi, M Vidal, R Vidal, I Vila, R Vilar, T Vine, M Vogel, I Vollrath, I Volobouev, G Volpi, F Würthwein, P Wagner, RG Wagner, RL Wagner, J Wagner, W Wagner, R Wallny, SM Wang, A Warburton, D Waters, M Weinberger, 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, X Zhang, J Zhou, S Zucchelli, CDF Collaboration

Abstract:

We report the observation and measurement of the mass of the bottom, strange baryon Xi(b)- through the decay chain Xi(b)- -->J/psiXi-, where J/psi-->mu+mu-, Xi- -->Lambdapi-, and Lambda-->ppi-. A signal is observed whose probability of arising from a background fluctuation is 6.6 x 10(-15), or 7.7 Gaussian standard deviations. The Xi(b)- mass is measured to be 5792.9+/-2.5(stat) +/- 1.7(syst) MeV/c2.
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Observation and mass measurement of the baryon Ξb-

Physical Review Letters 99:5 (2007)

Authors:

T Aaltonen, A Abulencia, J Adelman, T Affolder, T Akimoto, MG Albrow, S Amerio, D Amidei, A Anastassov, K Anikeev, A Annovi, J Antos, M Aoki, G Apollinari, 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, 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, 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, S Carrillo, D Carlsmith, R Carosi, 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, I Cho, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, M Cilijak

Abstract:

We report the observation and measurement of the mass of the bottom, strange baryon Ξb- through the decay chain Ξb-→J/ψΞ-, where J/ψ→μ+μ-, Ξ-→Λπ-, and Λ→pπ-. A signal is observed whose probability of arising from a background fluctuation is 6.6×10-15, or 7.7 Gaussian standard deviations. The Ξb- mass is measured to be 5792.9±2.5(stat) ±1.7(syst)MeV/c2. © 2007 The American Physical Society.
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Measurement of the production of charged pions by protons on a tantalum target

European Physical Journal C 51:4 (2007) 787-824

Authors:

MG Catanesi, E Radicioni, R Edgecock, M Ellis, S Robbins, FJP Soler, C Gößling, S Bunyatov, A Krasnoperov, B Popov, V Serdiouk, V Tereschenko, E Di Capua, G Vidal-Sitjes, P Arce, A Artamonov, S Giani, S Gilardoni, P Gorbunov, A Grant, A Grossheim, P Gruber, V Ivanchenko, A Kayis-Topaksu, J Panman, I Papadopoulos, J Pasternak, E Tcherniaev, I Tsukerman, R Veenhof, C Wiebusch, P Zucchelli, A Blondel, S Borghi, M Campanelli, MC Morone, G Prior, R Schroeter, R Engel, C Meurer, I Kato, U Gastaldi, GB Mills, JS Graulich, G Grégoire, M Kirsanov, M Bonesini, F Ferri, M Paganoni, F Paleari, A Bagulya, V Grichine, N Polukhina, V Palladino, L Coney, D Schmitz, G Barr, A De Santo, C Pattison, K Zuber, F Bobisut, D Gibin, A Guglielmi, M Mezzetto, J Dumarchez, F Vannucci, U Dore, D Orestano, F Pastore, A Tonazzo, L Tortora, C Booth, C Buttar, P Hodgson, L Howlett, M Bogomilov, M Chizhov, D Kolev, R Tsenov, S Piperov, P Temnikov, M Apollonio, P Chimenti, G Giannini, G Santin, J Burguet-Castell, A Cervera-Villanueva, JJ Gómez-Cadenas, J Martín-Albo, P Novella, M Sorel, A Tornero

Abstract:

A measurement of the double-differential cross-section for the production of charged pions in proton-tantalum collisions emitted at large angles from the incoming beam direction is presented. The data were taken in 2002 with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 GeV/c to 12 GeV/c hitting a tantalum target with a thickness of 5% of a nuclear interaction length. The angular and momentum range covered by the experiment (100 MeV/c ≤ p< 800 MeV/c and 0.35 rad ≤ θ< 2.15 rad) is of particular importance for the design of a neutrino factory. The produced particles were detected using a small-radius cylindrical time projection chamber (TPC) placed in a solenoidal magnet. Track recognition, momentum determination and particle identification were all performed based on the measurements made with the TPC. An elaborate system of detectors in the beam line ensured the identification of the incident particles. Results are shown for the double-differential cross-sections d 2σ/dpdθ at four incident proton beam momenta (3 GeV/c, 5 GeV/c, 8 GeV/c and 12 GeV/c). In addition, the pion yields within the acceptance of typical neutrino factory designs are shown as a function of beam momentum. The measurement of these yields within a single experiment eliminates most systematic errors in the comparison between rates at different beam momenta and between positive and negative pion production. © 2007 Springer-Verlag / Società Italiana di Fisica.
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