LHCb

Research group

Sub department

About

Determination of the average lifetime of b-baryons

European Physical Journal C 71:1 (2011) 199-210

Authors:

P Abreu, W Adam, T Adye, E Agasi, I Ajinenko, R Aleksan, GD Alekseev, R Alemany, PP Allport, S Almehed, U Amaldi, S Amato, A Andreazza, ML Andrieux, P Antilogus, WD Apel, Y Arnoud, B 脜sman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barate, M Barbi, G Barbiellini, DY Bardin, A Baroncelli, O Barring, JA Barrio, W Bartl, MJ Bates, M Battaglia, M Baubillier, J Baudot, KH Becks, M Begalli, P Beilliere, Y Belokopytov, AC Benvenuti, M Berggren, D Bertrand, F Bianchi, M Bigi, MS Bilenky, P Billoir, D Bloch, M Blume, S Blyth, T Bolognese, M Bonesini, W Bonivento, PSL Booth, G Borisov, C Bosio, S Bosworth, O Botner, E Boudinov, B Bouquet, C Bourdarios, TJV Bowcock, M Bozzo, P Branchini, KD Brand, T Brenke, RA Brenner, C Bricman, L Brillault, RCA Brown, P Bruckman, JM Brunet, L Bugge, T Buran, T Burgsmueller, P Buschmann, A Buys, S Cabrera, M Caccia, M Calvi, AJ Camacho Rozas, T Camporesi, V Canale, M Canepa, K Cankocak, F Cao, F Carena, L Carroll, C Caso, CMV Gimenez, A Cattai, FR Cavallo, L Cerrito, V Chabaud, M Chapkin, P Charpentier, L Chaussard, J Chauveau, P Checchia, GA Chelkov, M Chen

Abstract:

The average lifetime of b-baryons has been studied using 3 脳 106 hadronic Z0 decays collected by the DEL-PHI detector at LEP. Three methods have been used, based on the measurement of different observables: the proper decay time distribution of 206 vertices reconstructed with a A, a lepton and an oppositely charged pion; the impact parameter distribution of 441 muons with high transverse momentum accompanied by a A in the same jet; and the proper decay time distribution of 125 A0-lepton decay vertices with the A, exclusively reconstructed through its pK蟺, pK0 and A3蟺 decay modes. The combined result is:, where the first systematic error is due to experimental uncertainties and the second to the uncertainties in the modelling of the b-baryon production and semi-leptonic decay. Including the measurement recently published by DELPHI based on a sample of proton-muon vertices, the average b-baryon lifetime is T (b-baryon) = (1.255+0.115-0.102(stat)0102 卤 0.05) ps. 漏 Springer-Verlag 1996.

Lifetime and mixing parameters of neutral D mesons and neutral B hadrons in experimental particle physics

Proceedings of the 6th International Workshop on the CKM Unitarity Triangle, CKM 2010 (2011)

Abstract:

A review of recent experimental measurements of the lifetime and mixing parameters of neutral D and B hadrons is presented. In particular, focus is given to measurements of D mixing and the 螞B lifetime.

First observation of the decay B虅s 0鈫扗0K脳0 and a measurement of the ratio of branching fractions B(B虅s 0鈫扗0K脳0) B(B虅0鈫扗0蟻0)

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 706:1 (2011) 32-39

Authors:

R Aaij, C Abellan Beteta, B Adeva, M Adinolfi, C Adrover, A Affolder, Z Ajaltouni, J Albrecht, F Alessio, M Alexander, G Alkhazov, P Alvarez Cartelle, AA Alves, S Amato, Y Amhis, J Anderson, RB Appleby, O Aquines Gutierrez, F Archilli, F Archilli, L Arrabito, A Artamonov, M Artuso, M Artuso, E Aslanides, G Auriemma, S Bachmann, JJ Back, DS Bailey, V Balagura, V Balagura, W Baldini, RJ Barlow, C Barschel, S Barsuk, W Barter, A Bates, C Bauer, T Bauer, A Bay, I Bediaga, K Belous, I Belyaev, I Belyaev, E Ben-Haim, M Benayoun, G Bencivenni, S Benson, J Benton, R Bernet, MO Bettler, M van Beuzekom, A Bien, S Bifani, A Bizzeti, PM Bj酶rnstad, T Blake, F Blanc, C Blanks, J Blouw, S Blusk, A Bobrov, V Bocci, A Bondar, N Bondar, W Bonivento, S Borghi, A Borgia, TJV Bowcock, C Bozzi, T Brambach, J van den Brand, J Bressieux, D Brett, S Brisbane, M Britsch, T Britton, NH Brook, H Brown, A B眉chler-Germann, I Burducea, A Bursche, J Buytaert, S Cadeddu, JM Caicedo Carvajal, O Callot, M Calvi, M Calvo Gomez, A Camboni, P Campana, P Campana, A Carbone, G Carboni, R Cardinale, R Cardinale, A Cardini, L Carson, K Carvalho Akiba, G Casse, M Cattaneo

Abstract:

The first observation of the decay B虅s 0鈫扗0K脳0 using pp data collected by the LHCb detector at a centre-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 36 pb-1, is reported. A signal of 34.4卤6.8 events is obtained and the absence of signal is rejected with a statistical significance of more than nine standard deviations. The B虅s 0鈫扗0K脳0 branching fraction is measured relative to that of B虅0鈫扗0 蟻0: B(B虅s 0鈫扗0K脳0) B(B虅0鈫扗0蟻0)=1.48卤0 .34卤0.15卤0.12, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the B0 and Bs0 hadronisation fractions. 漏 2011 CERN.

Analysis of the decay D0鈫扠S0蟺0蟺0

Physical Review D - Particles, Fields, Gravitation and Cosmology 84:9 (2011)

Authors:

N Lowrey, S Mehrabyan, M Selen, J Wiss, J Libby, M Kornicer, RE Mitchell, MR Shepherd, CM Tarbert, D Besson, TK Pedlar, J Xavier, D Cronin-Hennessy, J Hietala, P Zweber, S Dobbs, Z Metreveli, KK Seth, A Tomaradze, T Xiao, S Brisbane, L Martin, A Powell, P Spradlin, G Wilkinson, H Mendez, JY Ge, DH Miller, IPJ Shipsey, B Xin, GS Adams, D Hu, B Moziak, J Napolitano, KM Ecklund, J Insler, H Muramatsu, CS Park, LJ Pearson, EH Thorndike, F Yang, S Ricciardi, C Thomas, M Artuso, S Blusk, R Mountain, T Skwarnicki, S Stone, JC Wang, LM Zhang, G Bonvicini, D Cinabro, A Lincoln, MJ Smith, P Zhou, J Zhu, P Naik, J Rademacker, DM Asner, KW Edwards, K Randrianarivony, G Tatishvili, RA Briere, H Vogel, PUE Onyisi, JL Rosner, JP Alexander, DG Cassel, S Das, R Ehrlich, L Fields, L Gibbons, SW Gray, DL Hartill, BK Heltsley, DL Kreinick, VE Kuznetsov, JR Patterson, D Peterson, D Riley, A Ryd, AJ Sadoff, X Shi, WM Sun, J Yelton, P Rubin

Abstract:

We present the results of a Dalitz plot analysis of D0鈫扠S0蟺0蟺0 using the CLEO-c data set of 818pb-1 of e+e- collisions accumulated at 鈭歴=3.77GeV. This corresponds to 3脳106 D0D虅0 pairs from which we select 1259 tagged candidates with a background of 7.5卤0.9 percent. Several models have been explored, all of which include the K*(892), K2*(1430), K *(1680), the f0(980), and the 蟽(500). We find that the combined 蟺0蟺0 S-wave contribution to our preferred fit is (28.9卤6.3卤3.1)% of the total decay rate while D0鈫扠 虅*(892)0蟺0 contributes (65.6卤5. 3卤2.5)%. Using three tag modes and correcting for quantum correlations we measure the D0鈫扠S0蟺0蟺0 branching fraction to be (1.058卤0. 038卤0.073)%. 漏 2011 American Physical Society.

Determination of fs/fd for 7 TeV pp collisions and measurement of the B0鈫扗-K+ branching fraction

Physical Review Letters 107:21 (2011)

Authors:

R Aaij, B Adeva, M Adinolfi, C Adrover, A Affolder, Z Ajaltouni, J Albrecht, F Alessio, M Alexander, G Alkhazov, P Alvarez Cartelle, AA Alves, S Amato, Y Amhis, J Amoraal, J Anderson, RB Appleby, O Aquines Gutierrez, L Arrabito, A Artamonov, M Artuso, E Aslanides, G Auriemma, S Bachmann, JJ Back, DS Bailey, V Balagura, W Baldini, RJ Barlow, C Barschel, S Barsuk, W Barter, A Bates, C Bauer, T Bauer, A Bay, I Bediaga, K Belous, I Belyaev, E Ben-Haim, M Benayoun, G Bencivenni, S Benson, J Benton, R Bernet, MO Bettler, M Van Beuzekom, A Bien, S Bifani, A Bizzeti, PM Bj酶rnstad, T Blake, F Blanc, C Blanks, J Blouw, S Blusk, A Bobrov, V Bocci, A Bondar, N Bondar, W Bonivento, S Borghi, A Borgia, TJV Bowcock, C Bozzi, T Brambach, J Van Den Brand, J Bressieux, S Brisbane, M Britsch, T Britton, NH Brook, A B眉chler-Germann, A Bursche, J Buytaert, S Cadeddu, JM Caicedo Carvajal, O Callot, M Calvi, M Calvo Gomez, A Camboni, P Campana, A Carbone, G Carboni, R Cardinale, A Cardini, L Carson, K Carvalho Akiba, G Casse, M Cattaneo, M Charles, P Charpentier, N Chiapolini, X Cid Vidal, PEL Clarke, M Clemencic, HV Cliff, J Closier, C Coca, V Coco

Abstract:

The relative abundance of the three decay modes B0鈫扗-K +, B0鈫扗-蟺+, and Bs0鈫扗s- 蟺+ produced in 7 TeV pp collisions at the LHC is determined from data corresponding to an integrated luminosity of 35pb-1. The branching fraction of B0鈫扗-K+ is found to be B(B0鈫扗-K+)=(2.01卤0.18stat卤0.14syst) 脳10-4. The ratio of fragmentation fractions f s/fd is determined through the relative abundance of Bs0鈫扗s-蟺+ to B0鈫扗-K+ and B0鈫扗-蟺+, leading to fs/f d=0.253卤0.017卤0.017卤0.020, where the uncertainties are statistical, systematic, and theoretical, respectively. 漏 2011 CERN.