306 research outputs found
UvA-DARE (Digital Academic Repository) Link to publication Citation for published version (APA): Inclusive search for the charmless radiative decay of the b-quark (b L3 Collaboration
No full textGeneral rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 29 Jun 2019 Physics Letters B 317 ( 1993 ) We report on the search for the electromagnetic penguin decay b --* s7 at v~ ~ mz. We find no evidence for a signal and place an upper limit on the decay rate Br(b ~ s~,) < 1.2 × 10 -3 at 90% C.L
Measurement of energetic single-photon production at LEP
No full textGeneral rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. PHYSICS LETTERS 6 Physics Letters B 346 ( 1995) 190-198 Measurement of energetic single-photon production at LEP Abstract We describe the sample of energetic single-photon events (E, > 15 GeV) collected by L3 in the 1991-1993 LEP runs. The event distributions agree with expectations from the Standard Model. The data are used to constrain the ZZy coupling and to set an upper limit of 4.1 x 10-6p~ (90% CL.) on the the magnetic moment of the T neutrino
Measurement of inclusive eta production in hadronic decays of the Z0
No full textGeneral rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 29 Jun 2019 Physics Letters B 286 (1992) We present a study of the inclusive ~/ production based on 300000 hadronic Z ° decays. The measured inclusive momentum distribution can be reproduced by parton shower Monte Carlo programs and also by an analytical QCD calculation. Comparing our results with low energy e+e -data, we find that QCD describes both the shape and the energy evolution of the r/ spectrum. The comparison of q production rates in quark-and gluon-enriched jet samples does not show statistically significant evidence for more abundant production of q mesons in gluon fragmentation. l Deceased. 2 Supported by the German Forschung und Technologie. Bundesministerium f'ti
UvA-DARE (Digital Academic Repository) Determination of the effective electroweak mixing angle from Z decays L3 Collaboration
No full textGeneral rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. The effective electroweak mixing angle sin 20w is measured from the production and decay of the Z boson in e+e -interactions. The data sample corresponds to an integrated luminosity of 18 pb-l with about 420 000 hadronic and 40 000 leptonic Z decays. The mixing angle sin 20w is determined from several independent measurements: the leptonic and hadronic cross sections, the forward-backward asymmetries of charged leptons and b-quarks, and the z-polarization. The results are found to be in good agreement with each other. The value of sin 20w from a fit to the asymmetries in a model independent method is 0.2321-4-0.0021 and from a global fit to the data in the Standard Model framework is 0.2328+0.0013
UvA-DARE (Digital Academic Repository) A test of QCD based on 3-jet events from Z ° decays L3 Collaboration
No full textA test of QCD based on three jet events from Z0 decays Adeva, B.; Adriani, O.; Aguilar-Benitez, M.; Ahlen, S.P.; Akbari, H.; Alcaraz, J.; Aloisio, A.; Alverson, G.; Linde, F.L. General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. We present a study of 43 000 3-jet events from Z ° boson decays. Both the measured jet energy distributions and the event orientation are reproduced by second order QCD. An alternative model with scalar gluons fails to describe the data
Cosmic-ray positron fraction measurement from 1 to 30 GeV with AMS-01
No full textA measurement of the cosmic ray positron fraction e+/(e+ + e-) in the energy range of 1-30 GeV is presented. The measurement is based on data taken by the AMS-01 experiment during its 10 day Space Shuttle flight in June 1998. A proton background suppression on the order of 10^6 is reached by identifying converted bremsstrahlung photons emitted from positrons.A measurement of the cosmic ray positron fraction e+/(e++e−) in the energy range of 1–30 GeV is presented. The measurement is based on data taken by the AMS-01 experiment during its 10 day Space Shuttle flight in June 1998. A proton background suppression on the order of 10 6 is reached by identifying converted bremsstrahlung photons emitted from positrons.A measurement of the cosmic ray positron fraction e+/(e+ + e-) in the energy range of 1-30 GeV is presented. The measurement is based on data taken by the AMS-01 experiment during its 10 day Space Shuttle flight in June 1998. A proton background suppression on the order of 10^6 is reached by identifying converted bremsstrahlung photons emitted from positrons
Relative Composition and Energy Spectra of Light Nuclei in Cosmic Rays: Results from AMS-01
No full textMeasurement of the chemical and isotopic composition of cosmic rays is essential for the precise understanding of their propagation in the galaxy. While the model parameters are mainly determined using the B/C ratio, the study of extended sets of ratios can provide stronger constraints on the propagation models. In this paper, the relative abundances of light-nuclei lithium, beryllium, boron, and carbon are presented. The secondary-to-primary ratios Li/C, Be/C, and B/C have been measured in the kinetic energy range 0.35-45 GeV nucleon[superscript –1]. The isotopic ratio [superscript 7]Li/[superscript 6]Li is also determined in the magnetic rigidity interval 2.5-6.3 GV. The secondary-to-secondary ratios Li/Be, Li/B, and Be/B are also reported. These measurements are based on the data collected by the Alpha Magnetic Spectrometer AMS-01 during the STS-91 space shuttle flight in 1998 June. Our experimental results are in substantial agreement with other measurements, where they exist. We describe our light-nuclei data with a diffusive-reacceleration model. A 10%-15% overproduction of Be is found in the model predictions and can be attributed to uncertainties in the production cross-section data
A Study of Cosmic Ray Secondaries Induced by the Mir Space Station Using AMS-01
No full textThe Alpha Magnetic Spectrometer (AMS-02) is a high energy particle physics experiment that will study cosmic rays in the to range and will be installed on the International Space Station (ISS) for at least 3 years. A first version of AMS-02, AMS-01, flew aboard the space shuttle \emph{Discovery} from June 2 to June 12, 1998, and collected cosmic ray triggers. Part of the \emph{Mir} space station was within the AMS-01 field of view during the four day \emph{Mir} docking phase of this flight. We have reconstructed an image of this part of the \emph{Mir} space station using secondary and emissions from primary cosmic rays interacting with \emph{Mir}. This is the first time this reconstruction was performed in AMS-01, and it is important for understanding potential backgrounds during the 3 year AMS-02 mission
ISOTOPIC COMPOSITION OF LIGHT NUCLEI IN COSMIC RAYS: RESULTS FROM AMS-01
No full textThe variety of isotopes in cosmic rays allows us to study different aspects of the processes that cosmic rays undergo between the time they are produced and the time of their arrival in the heliosphere. In this paper, we present measurements of the isotopic ratios (2)H/(4)He, (3)He/(4)He, (6)Li/(7)Li, (7)Be/((9)Be+(10)Be), and (10)B/(11)B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The measurements are based on the data collected by the Alpha Magnetic Spectrometer, AMS-01, during the STS-91 flight in 1998 June
Precision Measurement of the Proton Flux in Primary Cosmic Rays from Rigidity 1 GV to 1.8 TV with the Alpha Magnetic Spectrometer on the International Space Station
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