47 research outputs found
First Observation of a narrow Charm-Strange Meson D+(SJ)(2632)-->D+(S) eta and D0 K+
No full textWe report the first observation of a charm-strange meson D-sJ(+)(2632) at a mass of 2632.5+/-1.7 MeV/c(2) in data from SELEX, the charm hadro-production experiment E781 at Fermilab. This state is seen in two decay modes, D(s)(+)eta and (DK+)-K-0. In the D(s)(+)eta decay mode we observe a peak with 101 events over a combinatoric background of 54.9 events at a mass of 2635.4+/-3.3 MeV/c(2). There is a corresponding peak of 21 events over a background of 6.9 at 2631.5+/-2.0 MeV/c(2) in the decay mode (DK+)-K-0. The decay width of this state is <17 MeV/c(2) at 90% confidence level. The relative branching ratio Gamma((DK+)-K-0)/Gamma(D(s)(+)eta) is 0.14+/-0.06. The mechanism that keeps this state narrow is unclear. Its decay pattern is also unusual, being dominated by the D(s)(+)eta decay mode
Polarization of Σ+ hyperons produced by 800 GeV/c protons on Cu and Be
No full textWe show that Σ+ hyperons produced by 800 GeV/c protons on targets of Be and Cu have significant polarizations (15-20%). These polarizations persist at values of pt = 2 GeV/c and a wide range of xF. The polarizations from the Cu target are consistently less than from Be. The average ratio of the Σ+ polarization from Cu to that from Be is 0.68 ± 0.08.Ball State University, Muncie, IN 47306Bogazici Univerity, Bebek 34342 IstanbulCarnegie-Mellon University, Pittsburgh, PA 15213Centro Brasileiro de Pesquisas Físicas, Rio de JaneiroFermi National Acceleratory Laboratory, Batavia, IL 60510Institute for High Energy Physics, ProtvinoInstitute for High Energy Physics, BeijingInstitute of Theoretical and Experimental Physics, MoscowMax-Planck-Institut für Kernphysik 69117, HeidelbergMoscow State University, MoscowPetersburg Nuclear Physics Institute, St. PetersburgTel Aviv University, 69978 Ramat AvivUniversidad Autónoma de San Luis Potosí, San Luis PotosíUniversidade Ferderal da Paraíba, ParaíbaUniversity of Bristol, Bristol BS8 1TLUniversity of Iowa, Iowa City, IA 52242University of Michigan-Flint, Flint, MI 48502University of Rome 'La Sapienza' INFN, RomeUniversity of Sao Paulo, Sao PauloUniversity of Trieste INFN, TriesteLegal Department Oracle Corporation, Redwood Shores, CAInfinion, MünchenImperial College, London SW7 2BZInstituto de Física Universidade Estadual de Campinas UNICAMP, Sao PauloPhysik-Department Technische Universität München, 85748 GarchingThe Boston Consulting Group, MünchenInstituto de Física Teórica Universidade Estadual Paulista, Sao PauloLucent Technologies, Naperville, ILSPSS Inc, Chicago, ILDOE, Germantown, MDSiemens Medizintechnik, ElangenDeutsche Bank AG, EschbornInstituto de Física Teórica Universidade Estadual Paulista, Sao Paul
Confirmation of the doubly charmed baryon Epsilon(+)(cc)(3520) via its decay to pD(+)K(-)
No full textWe observe a signal for the doubly charmed baryon Xi(cc)(+) in the decay mode Xi(cc)(+) -> pD(+)K(-) to complement the previous cc reported decay Xi(cc)(+) -> Lambda(c)(+)K(-)pi(+) in data from SELEX, the charm hadroproduction experiment at Fermilab. In this new decay mode we observe an excess of 5.62 events over a combinatoric background estimated by event mixing to be 1.38 +/- 0.13 events. The mixed background has Gaussian statistics, giving a signal significance of 4.8 sigma. The Poisson probability that a background fluctuation can produce the apparent signal is less than 6.4 x 10(-4). The observed mass of this state is 3518 +/- 3 MeV/c(2), consistent with the published result. Averaging the two results gives a mass of 3518.7 +/- 1.7 MeV/c(2). The observation of this new weak decay mode confirms the previous SELEX suggestion that this state is a double charm baryon. The relative branching ratio for these two modes is 0.36 +/- 0.21. (c) 2005 Elsevier B.V. All rights reserved
Hadronic production of Lambda c from 600 GeV/c pi(-), Sigma(-) and p beams
No full textWe present data from Fermilab experiment E781 (SELEX) on the hadroproduction asymmetry for (&ULambda;) over bar((c)) over bar compared to Lambda(c)(+) as a function of x(F), and on p(t)(2) distributions for Lambda(c)(+). These data were measured in the same apparatus using incident pi(-),Sigma(-) beams at 600 GeV/c and proton beam at 540 GeV/c. The asymmetry is studied as a function of x(F). In the forward hemisphere with x(F) greater than or equal to 0.2 both baryon beams exhibit very strong preference for producing charm baryons rather than charm antibaryons, while the pion beam asymmetry is much smaller. In this energy regime the results show that beam fragments play a major role in the kinematics of Lambda(c) formation, as suggested by the leading quark picture. (C) 2002 Published by Elsevier Science B.V
Hadronic production of Lambda c from 600 GeV/c pi(-), Sigma(-) and p beams
No full textWe present data from Fermilab experiment E781 (SELEX) on the hadroproduction asymmetry for (&ULambda;) over bar((c)) over bar compared to Lambda(c)(+) as a function of x(F), and on p(t)(2) distributions for Lambda(c)(+). These data were measured in the same apparatus using incident pi(-),Sigma(-) beams at 600 GeV/c and proton beam at 540 GeV/c. The asymmetry is studied as a function of x(F). In the forward hemisphere with x(F) greater than or equal to 0.2 both baryon beams exhibit very strong preference for producing charm baryons rather than charm antibaryons, while the pion beam asymmetry is much smaller. In this energy regime the results show that beam fragments play a major role in the kinematics of Lambda(c) formation, as suggested by the leading quark picture. (C) 2002 Published by Elsevier Science B.V
Upper limit on the decay Sigma(1385)(-) -> Sigma(-)gamma and cross section for gamma Sigma(-) -> Lambda pi(-)
No full textFirst Observation Of The Doubly Charmed Baryon Ξcc+
No full textThe first experimental evidence for one of the six predicted baryon states which contain two valence charmed quarks-the doubly charmed baryons. As such, there were many predictions of the masses and other properties of these states. The properties of doubly charmed baryons provide a new window into the structure of baryonic matter.8911112001/1112001/5Groom, D.E., (2000) Eur. Phys. J. C, 15, p. 1. , Particle Data GroupDerujula, A., Georgi, H., Glashow, S., (1975) Phys. Rev. D, 12, p. 147Savage, M., Wise, M., (1990) Phys. Lett. B, 248, p. 177Körner, J.G., Krämer, M., Pirjol, D., (1994) Prog. Part. Nucl. Phys., 33, p. 787hep-ph/0201071, see Refs. [111-124]Mattson, M., (2002), Ph.D. thesis, Carnegie Mellon UniversityRuss, J.S., (1998) Proceedings of the 29th International Conference on High Energy Physics, 1998, 2, p. 1259. , SELEX Collaborationedited by A. Astbury (World Scientific, Singapore,)hep-ex/9812031Engelfried, J., (1999) Nucl. Instrum. Methods Phys. Res., Sect. A, 431, p. 53Kushnirenko, A., (2001) Phys. Rev. Lett., 86, p. 5243Garcia, F., (2002) Phys. Lett. B, 528, p. 49noteMoinester, M., (1996) Z. Phys. A, 355, p. 349Kiselev, V., Likhoded, A., (2001), hep-ph/0103169and references thereinBjorken, J.B., (1985), Report No. Fermilab-Conf-85/69Aoki, S., (1987) Phys. Lett. B, 187, p. 185Barlag, S., (1991) Phys. Lett. B, 257, p. 519. , ACCMOR CollaborationRatti, S., Proceedings of the 5th International Conference on Hyperons, Charm and Beauty Hadrons, Vancouver, B.C., 2002, , www.hep.vanderbilt.edu/-stenson/xicc/xicc_focus.html, (to be published)Abe, K., Belle Collaborationhep-ex/020510
First observation of the Cabibbo-suppressed decays Xi(+)(c)->Sigma(+)pi(-)pi(+) and Xi(+)(c)->Sigma(-)pi(+)pi(+) and measurement of their branching ratios
No full textHadronic production of Lambda c from 600 GeV/c pi(-), Sigma(-) and p beams
No full textWe present data from Fermilab experiment E781 (SELEX) on the hadroproduction asymmetry for (Lambda) over bar((c)) over bar compared to Lambda(c)(+) as a function of x(F), and on p(t)(2) distributions for Lambda(c)(+). These data were measured in the same apparatus using incident pi(-),Sigma(-) beams at 600 GeV/c and proton beam at 540 GeV/c. The asymmetry is studied as a function of x(F). In the forward hemisphere with x(F) greater than or equal to 0.2 both baryon beams exhibit very strong preference for producing charm baryons rather than charm antibaryons, while the pion beam asymmetry is much smaller. In this energy regime the results show that beam fragments play a major role in the kinematics of Lambda(c) formation, as suggested by the leading quark picture. (C) 2002 Published by Elsevier Science B.V
Measurement of the Ds ± lifetime
No full textWe report a precise measurement of the Ds± meson lifetime. The data were taken by the SELEX experiment (E781) spectrometer using 600 GeV/c ∑-, π- and p beams. The measurement has been done using 918 reconstructed Ds±. The lifetime of the Ds± is measured to be 472.5 ± 17.2 ± 6.6 fs, using K*(892)0K± and φπ± decay modes. The lifetime ratio of Ds± to D0 is 1.145 ± 0.049. © 2001 Elsevier Science B.V. All rights reserved.Ball State University, Muncie, IN 47306Bogazici University, Bebek 80815 IstanbulCarnegie-Mellon University, Pittsburgh, PA 15213Centro Brasileiro de Pesquisas F�sicas, Rio de JaneiroFermilab, Batavia, IL 60510Institute for High Energy Physics, ProtvinoInstitute of High Energy Physics, BeijingInstitute of Theoretical and Experimental Physics, MoscowMax-Planck-Institut für Kernphysik, 69117 HeidelbergMoscow State University, MoscowPetersburg Nuclear Physics Institute, St. PetersburgTel Aviv University, 69978 Ramat AvivUniversidad Autónoma de San Luis Potosí, San Luis PotosíUniversidade Federal da Paraíba, ParaíbaUniversity of Bristol, Bristol BS8 1TLUniversity of Iowa, Iowa City, IA 52242University of Michigan-Flint, Flint, MI 48502University of Rome “La Sapienza” and INFN, RomeUniversity of São Paulo, São PauloUniversity of Trieste and INFN, TriesteInfinion, MünchenImperial College, London SW7 2BZInstituto de F�sica da Universidade Estadual de Campinas UNICAMP, SPPhysik-Department Technische Universität München, 85748 GarchingThe Boston Consulting Group, MünchenLucent Technologies, Naperville, ILInstituto de Física Teórica da Universidade Estadual Paulista, São PauloSPSS Inc, Chicago, ILUniversity of Alabama at Birmingham, Birmingham AL 35294DOE, Germantown, MDSiemens Medizintechnik, ErlangenDeutsche Bank AG, EschbornInstituto de Física Teórica da Universidade Estadual Paulista, São Paul
