First observation of the beauty baryon Λb in the decay channel Λb→J/ψΛ at the CERN proton-antiproton collider

C. Albajar; M. G. Albrow; O. C. Allkofer; K. Ankoviak; R. Apsimon; B. Aubert; C. Bacci; S. Bartha; G. Bauer; A. Bettini; A. Bezaguet; P. Biddulph; H. Bohn; A. Böhrer; R. Bonino; K. Bos; M. Botlo; D. Brockhausen; C. Buchanan; A. Bushbeck; G. Busetto; A. Caner; P. Casoli; H. Castilla-Valdez; F. Cavanna; P. Cennini; S. Centro; F. Ceradini; G. Ciapetti; S. Cittolin; E. Clayton; D. Cline; J. Colas; R. Conte; J. A. Coughlan; D. Dau; C. Daum; M. Della Negra; C. Demoulin; D. Denegri; H. Dibon; A. DiCiaccio; F. J. Diez Hedo; L. Dobrzynski; J. Dorenbosch; J. D. Dowell; D. Drijard; K. Eggert; E. Eisenhandler; N. Ellis

doi:10.1016/0370-2693(91)90311-D

First observation of the beauty baryon Λ_b in the decay channel Λ_b→J/ψΛ at the CERN proton-antiproton collider

C. Albajar, M. G. Albrow, O. C. Allkofer, K. Ankoviak, R. Apsimon, B. Aubert, C. Bacci, S. Bartha, G. Bauer, A. Bettini, A. Bezaguet, P. Biddulph, H. Bohn, A. Böhrer, R. Bonino, K. Bos, M. Botlo, D. Brockhausen, C. Buchanan, A. BushbeckG. Busetto, A. Caner, P. Casoli, H. Castilla-Valdez, F. Cavanna, P. Cennini, S. Centro, F. Ceradini, G. Ciapetti, S. Cittolin, E. Clayton, D. Cline, J. Colas, R. Conte, J. A. Coughlan, D. Dau, C. Daum, M. Della Negra, C. Demoulin, D. Denegri, H. Dibon, A. DiCiaccio, F. J. Diez Hedo, L. Dobrzynski, J. Dorenbosch, J. D. Dowell, D. Drijard, K. Eggert, E. Eisenhandler, N. Ellis

Physics and Astronomy (Twin Cities)

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Abstract

We report on the first observation of the beauty baryon Λ_b in an exclusive decay channel at the CERN pp collider. Using 4.7 pb^-1 of muon data collected in the 1988/89 collider runs we reconstruct 16±5 Λ_b's in the decay mode Λ_b→ J ψΛ above a background of 9±1 events, corresponding to a significance of about five standard deviations. We measure the Λ_b mass to be m_Λb=5640±50±30 MeV/c². Using the beauty cross-section measured by UA1 we deduce for the product of the production fraction and branching ratio f^Λb Br (Λ_b→ J ψΛ)=(1.8±1.0)×10^-10. Our sample contains three-muon event in which the beauty particle opposite to the Λ_b is tagged by the third muon. We also observe an indication of a signal in the decay channel B⁰→ J ψK^0* with a significance of three standard deviations.

Original language	English (US)
Pages (from-to)	540-548
Number of pages	9
Journal	Physics Letters B
Volume	273
Issue number	4
DOIs	https://doi.org/10.1016/0370-2693(91)90311-D
State	Published - Dec 26 1991

Bibliographical note

Funding Information:
We are thankful to the management and staff of CERN and of all participating institutes for their vigorous support of the experiment. The following funding agencies have contributed to this programme: Fonds zur F6rderung der Wissenschaftlichen For-schung, Austria; Valtion luonnontieteellinen toimikunta, Suomen Akatemia, Finland; Institut National de Physique Nucl6aire et de Physique des Particules and Institut de Recherche Fon-damentale (CEA), France; Bundesministerium fiir Forschung und Technologic, FRG; Istituto Nazionale di Fisica Nucleare, Italy; Science and Engineering Research Council, UK; Stichting Voor Fundamenteel Onderzoek der Ma-terie, The Netherlands; Centro de Investigaciones Energetica, Medioam-bientales y Tecnologicas (CIEMAT), Spain; Department of Energy, USA. Thanks are also due to the following people who have worked with the collaboration in the preparations for and data collection on the runs described here: L. Baumard, F. Bernasconi, D. Brozzi, V. Cec-coni, L. Dumps, G. Fetchenhauer, G. Gallay, S. La-zic, J.C. Michelon, S. Pavlon and L. Pollet.

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Albajar, C., Albrow, M. G., Allkofer, O. C., Ankoviak, K., Apsimon, R., Aubert, B., Bacci, C., Bartha, S., Bauer, G., Bettini, A., Bezaguet, A., Biddulph, P., Bohn, H., Böhrer, A., Bonino, R., Bos, K., Botlo, M., Brockhausen, D., Buchanan, C., ... Ellis, N. (1991). First observation of the beauty baryon Λ_b in the decay channel Λ_b→J/ψΛ at the CERN proton-antiproton collider. Physics Letters B, 273(4), 540-548. https://doi.org/10.1016/0370-2693(91)90311-D

Albajar, C, Albrow, MG, Allkofer, OC, Ankoviak, K, Apsimon, R, Aubert, B, Bacci, C, Bartha, S, Bauer, G, Bettini, A, Bezaguet, A, Biddulph, P, Bohn, H, Böhrer, A, Bonino, R, Bos, K, Botlo, M, Brockhausen, D, Buchanan, C, Bushbeck, A, Busetto, G, Caner, A, Casoli, P, Castilla-Valdez, H, Cavanna, F, Cennini, P, Centro, S, Ceradini, F, Ciapetti, G, Cittolin, S, Clayton, E, Cline, D, Colas, J, Conte, R, Coughlan, JA, Dau, D, Daum, C, Della Negra, M, Demoulin, C, Denegri, D, Dibon, H, DiCiaccio, A, Diez Hedo, FJ, Dobrzynski, L, Dorenbosch, J, Dowell, JD, Drijard, D, Eggert, K, Eisenhandler, E & Ellis, N 1991, 'First observation of the beauty baryon Λ_b in the decay channel Λ_b→J/ψΛ at the CERN proton-antiproton collider', Physics Letters B, vol. 273, no. 4, pp. 540-548. https://doi.org/10.1016/0370-2693(91)90311-D

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title = "First observation of the beauty baryon Λb in the decay channel Λb→J/ψΛ at the CERN proton-antiproton collider",

abstract = "We report on the first observation of the beauty baryon Λb in an exclusive decay channel at the CERN pp collider. Using 4.7 pb-1 of muon data collected in the 1988/89 collider runs we reconstruct 16±5 Λb's in the decay mode Λb→ J ψΛ above a background of 9±1 events, corresponding to a significance of about five standard deviations. We measure the Λb mass to be mΛb=5640±50±30 MeV/c2. Using the beauty cross-section measured by UA1 we deduce for the product of the production fraction and branching ratio fΛb Br (Λb→ J ψΛ)=(1.8±1.0)×10-10. Our sample contains three-muon event in which the beauty particle opposite to the Λb is tagged by the third muon. We also observe an indication of a signal in the decay channel B0→ J ψK0* with a significance of three standard deviations.",

author = "C. Albajar and Albrow, {M. G.} and Allkofer, {O. C.} and K. Ankoviak and R. Apsimon and B. Aubert and C. Bacci and S. Bartha and G. Bauer and A. Bettini and A. Bezaguet and P. Biddulph and H. Bohn and A. B{\"o}hrer and R. Bonino and K. Bos and M. Botlo and D. Brockhausen and C. Buchanan and A. Bushbeck and G. Busetto and A. Caner and P. Casoli and H. Castilla-Valdez and F. Cavanna and P. Cennini and S. Centro and F. Ceradini and G. Ciapetti and S. Cittolin and E. Clayton and D. Cline and J. Colas and R. Conte and Coughlan, {J. A.} and D. Dau and C. Daum and {Della Negra}, M. and C. Demoulin and D. Denegri and H. Dibon and A. DiCiaccio and {Diez Hedo}, {F. J.} and L. Dobrzynski and J. Dorenbosch and Dowell, {J. D.} and D. Drijard and K. Eggert and E. Eisenhandler and N. Ellis",

note = "Funding Information: We are thankful to the management and staff of CERN and of all participating institutes for their vigorous support of the experiment. The following funding agencies have contributed to this programme: Fonds zur F6rderung der Wissenschaftlichen For-schung, Austria; Valtion luonnontieteellinen toimikunta, Suomen Akatemia, Finland; Institut National de Physique Nucl6aire et de Physique des Particules and Institut de Recherche Fon-damentale (CEA), France; Bundesministerium fiir Forschung und Technologic, FRG; Istituto Nazionale di Fisica Nucleare, Italy; Science and Engineering Research Council, UK; Stichting Voor Fundamenteel Onderzoek der Ma-terie, The Netherlands; Centro de Investigaciones Energetica, Medioam-bientales y Tecnologicas (CIEMAT), Spain; Department of Energy, USA. Thanks are also due to the following people who have worked with the collaboration in the preparations for and data collection on the runs described here: L. Baumard, F. Bernasconi, D. Brozzi, V. Cec-coni, L. Dumps, G. Fetchenhauer, G. Gallay, S. La-zic, J.C. Michelon, S. Pavlon and L. Pollet.",

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doi = "10.1016/0370-2693(91)90311-D",

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volume = "273",

pages = "540--548",

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TY - JOUR

T1 - First observation of the beauty baryon Λb in the decay channel Λb→J/ψΛ at the CERN proton-antiproton collider

AU - Albajar, C.

AU - Albrow, M. G.

AU - Allkofer, O. C.

AU - Ankoviak, K.

AU - Apsimon, R.

AU - Aubert, B.

AU - Bacci, C.

AU - Bartha, S.

AU - Bauer, G.

AU - Bettini, A.

AU - Bezaguet, A.

AU - Biddulph, P.

AU - Bohn, H.

AU - Böhrer, A.

AU - Bonino, R.

AU - Bos, K.

AU - Botlo, M.

AU - Brockhausen, D.

AU - Buchanan, C.

AU - Bushbeck, A.

AU - Busetto, G.

AU - Caner, A.

AU - Casoli, P.

AU - Castilla-Valdez, H.

AU - Cavanna, F.

AU - Cennini, P.

AU - Centro, S.

AU - Ceradini, F.

AU - Ciapetti, G.

AU - Cittolin, S.

AU - Clayton, E.

AU - Cline, D.

AU - Colas, J.

AU - Conte, R.

AU - Coughlan, J. A.

AU - Dau, D.

AU - Daum, C.

AU - Della Negra, M.

AU - Demoulin, C.

AU - Denegri, D.

AU - Dibon, H.

AU - DiCiaccio, A.

AU - Diez Hedo, F. J.

AU - Dobrzynski, L.

AU - Dorenbosch, J.

AU - Dowell, J. D.

AU - Drijard, D.

AU - Eggert, K.

AU - Eisenhandler, E.

AU - Ellis, N.

N1 - Funding Information: We are thankful to the management and staff of CERN and of all participating institutes for their vigorous support of the experiment. The following funding agencies have contributed to this programme: Fonds zur F6rderung der Wissenschaftlichen For-schung, Austria; Valtion luonnontieteellinen toimikunta, Suomen Akatemia, Finland; Institut National de Physique Nucl6aire et de Physique des Particules and Institut de Recherche Fon-damentale (CEA), France; Bundesministerium fiir Forschung und Technologic, FRG; Istituto Nazionale di Fisica Nucleare, Italy; Science and Engineering Research Council, UK; Stichting Voor Fundamenteel Onderzoek der Ma-terie, The Netherlands; Centro de Investigaciones Energetica, Medioam-bientales y Tecnologicas (CIEMAT), Spain; Department of Energy, USA. Thanks are also due to the following people who have worked with the collaboration in the preparations for and data collection on the runs described here: L. Baumard, F. Bernasconi, D. Brozzi, V. Cec-coni, L. Dumps, G. Fetchenhauer, G. Gallay, S. La-zic, J.C. Michelon, S. Pavlon and L. Pollet.

PY - 1991/12/26

Y1 - 1991/12/26

N2 - We report on the first observation of the beauty baryon Λb in an exclusive decay channel at the CERN pp collider. Using 4.7 pb-1 of muon data collected in the 1988/89 collider runs we reconstruct 16±5 Λb's in the decay mode Λb→ J ψΛ above a background of 9±1 events, corresponding to a significance of about five standard deviations. We measure the Λb mass to be mΛb=5640±50±30 MeV/c2. Using the beauty cross-section measured by UA1 we deduce for the product of the production fraction and branching ratio fΛb Br (Λb→ J ψΛ)=(1.8±1.0)×10-10. Our sample contains three-muon event in which the beauty particle opposite to the Λb is tagged by the third muon. We also observe an indication of a signal in the decay channel B0→ J ψK0* with a significance of three standard deviations.

AB - We report on the first observation of the beauty baryon Λb in an exclusive decay channel at the CERN pp collider. Using 4.7 pb-1 of muon data collected in the 1988/89 collider runs we reconstruct 16±5 Λb's in the decay mode Λb→ J ψΛ above a background of 9±1 events, corresponding to a significance of about five standard deviations. We measure the Λb mass to be mΛb=5640±50±30 MeV/c2. Using the beauty cross-section measured by UA1 we deduce for the product of the production fraction and branching ratio fΛb Br (Λb→ J ψΛ)=(1.8±1.0)×10-10. Our sample contains three-muon event in which the beauty particle opposite to the Λb is tagged by the third muon. We also observe an indication of a signal in the decay channel B0→ J ψK0* with a significance of three standard deviations.

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U2 - 10.1016/0370-2693(91)90311-D

DO - 10.1016/0370-2693(91)90311-D

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EP - 548

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