Download or read book Hadron Fragmentation Functions and Leading Particle Effects in Hadronic Z sup 0 Decays New Results from SLD written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors have measured the differential cross sections for the production of[pi][sup[+-]], K[sup[+-]], K[sup 0], K*(892), [phi](1,020), p and[Lambda] in hadronic Z[sup 0] decays and in subsets of flavor-tagged Z[sup 0][yields] light quark (u[anti u], d[anti d], or s[anti s]), Z[sup 0][yields] c[anti c] and Z[sup 0][yields] b[anti b] events. Charged hadrons were identified with the SLD Cherenkov ring imaging detector. The vertex detector was employed to select flavor enriched samples and the polarized electron beam from SLC was used to tag quark and anti-quark jets. The authors observe a flavor dependence in the hadron fragmentation functions. The authors present evidence for leading particle production in hadronic decays of the Z[sup 0] boson to light-flavor jets and a direct measurement of the strangeness suppression factor[gamma][sub s].
Download or read book Hadron Fragmentation Functions and Leading Particle Effects in Hadronic Z Decays written by and published by . This book was released on 1997 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors have measured the differential cross sections for the production of [pi]{sup {+-}}, K{sup {+-}}, K°, K*(892), [phi](1,020), p and [Lambda] in hadronic Z° decays and in subsets of flavor-tagged Z° → light quark (u{anti u}, d{anti d}, or s{anti s}), Z° → c{anti c} and Z° → b{anti b} events. Charged hadrons were identified with the SLD Cherenkov ring imaging detector. The vertex detector was employed to select flavor enriched samples and the polarized electron beam from SLC was used to tag quark and anti-quark jets. The authors observe a flavor dependence in the hadron fragmentation functions. The authors present evidence for leading particle production in hadronic decays of the Z° boson to light-flavor jets and a direct measurement of the strangeness suppression factor [gamma]{sub s}.
Download or read book Graduel de Lyon written by and published by . This book was released on 1780 with total page 739 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Preliminary Measurement of Leading Particle Effects in Hadronic Z sup 0 Decays written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present preliminary evidence for leading particle production in hadronic decays of the Z[sup 0] to light quark pairs using 150,000 events recorded in the SLD experiment at SLAC. The highly polarized electron beam produced by the SLC is used to tag quark and antiquark jets, and a signed impact parameter technique is employed to reject heavy flavor events. Charged hadrons are identified in the SLD Cherenkov Ring Imaging Detector (CRID) and[Lambda]/[bar[Lambda]] are reconstructed using their charged decay modes. In a high purity sample of quark jets, the baryon momentum spectrum is harder that that of the antibaryon, and conversely for a sample of antiquark jets, supporting the hypothesis that the faster particles in jets are more likely to carry the primary quark or antiquark from the Z[sup 0] decay. Similarly, more high momentum K[sup -] that K[sup+] are observed in quark jets and conversely for antiquark jets, consistent with the hypothesis that leading K[sup[+-]] are produced predominantly in s[bar s] events rather than[ital u][bar[ital u]] events.
Download or read book Production of Charged pi sup Kappa sup and P p in Hadronic Z Decays written by and published by . This book was released on 1999 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have updated our results on identified charged hadron production using the full SLD data sample of 550,000 hadronic Z° decays taken between 1993 and 1998. The SLD Cherenkov Ring Imaging Detector allows the identification of clean samples of charged pions, kaons and protons over a wide momentum range, providing precise tests of perturbative QCD calculations and of fragmentation models. We have studied flavor-inclusive Z° decays, as well as decays into light, c and b flavors, selected using the SLD vertex detector. In addition we have updated our comparison of hadron and antihadron production in light quark (rather than antiquark) jets, selected using the high SLC electron beam polarization. Differences between hadron and antihadron production at high momentum fraction provide precise measurements of leading particle production and new, stringent tests of fragmentation models.
Download or read book A Study of Correlations Between Identified Charged Hadrons in Hadronic Z sup 0 Decays written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present a preliminary study of correlations in rapidity between pairs of identified pions, kaons and protons in hadronic Z[sup 0] decays into light flavors. Short range charge correlations are observed between all combinations of these hadron species, confirming that charge, strangeness and baryon number are conserved locally in the jet fragmentation process. The range of this effect is found to be independent of momentum. A strong long-range correlation is observed for high-momentum charged kaon pairs, and weaker long-range[pi][sup+]-[pi][sup -], [pi][sup+]-K[sup -] and p-K[sup -] correlations are observed. The SLC electron beam polarization is used to tag the quark hemisphere in each event, allowing the first study of rapidities signed such that positive rapidity is along the quark rather than antiquark direction. Distributions of signed rapidities and of ordered differences between signed rapidities provide new insights into leading particle production and several new tests of fragmentation models.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Preliminary Measurement of Leading Particle Effects in Hadronic Z Decays written by and published by . This book was released on 1996 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present preliminary evidence for leading particle production in hadronic decays of the Z° to light quark pairs using 150,000 events recorded in the SLD experiment at SLAC. The highly polarized electron beam produced by the SLC is used to tag quark and antiquark jets, and a signed impact parameter technique is employed to reject heavy flavor events. Charged hadrons are identified in the SLD Cherenkov Ring Imaging Detector (CRID) and [Lambda]/{bar {Lambda}} are reconstructed using their charged decay modes. In a high purity sample of quark jets, the baryon momentum spectrum is harder that that of the antibaryon, and conversely for a sample of antiquark jets, supporting the hypothesis that the faster particles in jets are more likely to carry the primary quark or antiquark from the Z° decay. Similarly, more high momentum K− that K are observed in quark jets and conversely for antiquark jets, consistent with the hypothesis that leading K{sup {+-}} are produced predominantly in s{bar s} events rather than {ital u}{bar {ital u}} events.
Download or read book Strange Particle Production in Hadronic Z sup 0 Decays written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A study has been made of neutral strange baryons and pseudoscalar mesons produced in hadronic decays of the weak gauge boson V. The experiment was performed at the Stanford Linear Accelerator Center, which has the unique capability of colliding highly polarized electrons with unpolarized positrons. Overall production rates and spectra of the K[sup 0] and the[Lambda][sup 0] (+[Lambda][sup 0]) were measured and compared with other experiments as well as with Quantum Chromodynamics calculations. The combination of the small, stable beam spots produced by the SLAC Linear Collider (SLC) and the precision vertexing capabilities of the SLC Large Detector (SLD) permitted the separation of the hadronic events into three quark flavor-enriched samples. An unfolding was performed to obtain flavor-pure samples, and for the first time measurements were made of K[sup 0] and[Lambda][sup 0] (+[Lambda][sup 0]) production rates and spectra in uds, c, and b quark events at the Z[sup 0] pole. This measurement revealed significant production differences. Utilizing the large quark production asymmetry due to the polarized electron beam, high-purity quark and antiquark jet samples were obtained. The first measurement of production differences of the[Lambda][sup 0] baryon in quark and antiquark jets was performed, which provided clear evidence for a leading particle effect at high momenta.
Download or read book Properties of Leading Particles in Hadronic Z Decays written by and published by . This book was released on 1996 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present studies of leading particle production in Z° decays into light, c, and b quarks performed with the SLD experiment at SLAC. The SLD precision vertex detector was exploited to tag light-flavor events, to tag charmed meson vertices and separate the prompt and B-decay components, and to reconstruct B-hadrons partially. The relative production of prompt pseudoscalar and vector D-mesons was measured to be P{sub V} = 0.53 " 0.06(stat.) " 0.02(syst.) (preliminary). The shape of the B-hadron energy spectrum was found to be consistent with the predictions of a number of models, and the average energy fraction was measured to be x{sub E} = 0.697 " 0.012(stat.) " 0.028(syst.) (preliminary). Separation of light quark and antiquark jets was achieved using the highly polarized SLC electron beam, and hadrons were identified using the SLD Cherenkov Ring Imaging Detector. Production of particles and antiparticles in quark jets was compared, allowing the first direct observation of leading particles in ee− --> u{anti u}, d{anti d}, s{anti s} events. More high momentum baryons and K−'s than antibaryons and K's were observed, providing evidence for leading baryon and kaon production, as well as for strangeness suppression at high momentum.
Download or read book A Preliminary Measurement of the B Quark Fragmentation Function in Hadronic Z sup 0 Decays written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the[ital b] quark fragmentation function from a sample of semi-leptonic[bold B] decays collected between 1993 and 1995 in the SLD experiment at SLAC. The energy of each tagged[bold B] hadron was reconstructed using information from the lepton and a partially reconstructed charm decay vertex. A comparison of the scaled energy distribution with several phenomenological models of heavy quark fragmentation was made, using the same model in each case to correct the data. The average scaled energy was found to be[l-angle][chi][sub E][r-angle]= 0.697[+-]0.012([ital stat])[sup+0. 028][sub -0.024] ([ital syst])(preliminary).
Download or read book A Study of Correlations Between Identified Charged Hadrons in Hadronic Z Decays written by and published by . This book was released on 1999 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a preliminary study of correlations in rapidity between pairs of identified charged pions, kaons and protons using the entire SLD data sample of 550,000 hadronic Z° decays. Short range charge correlations are observed between all combinations of these hadron species, indicating local conservation of quantum numbers and charge ordering in the jet fragmentation process. The rapidity range of this effect is found to be independent of particle momentum. A strong long-range K-K− correlation is observed at high-momentum and weaker long-range [pi]-[pi]−, [pi]+-K− and p-K− and p{bar p} correlations are observed in light flavor events, providing new information on leading particle production in u, d and s jets. The long-range correlations observed in c{bar c} and b{bar b} events are markedly different and consistent with expectations based on known decay properties of the leading heavy hadrons. In addition, the SLC electron beam polarization is used to tag the quark hemisphere in each event, allowing the first study of rapidities signed such that positive rapidity is along the quark rather than antiquark direction. Distributions of ordered differences in signed rapidity between pairs of particles provide a direct probe of quantum number ordering along the quark-antiquark axis and other new insights into the fragmentation process.
Download or read book Catalogage mati res synth ses written by and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Improved Measurement of the B Quark Fragmentation Function in Z Decays at SLD written by and published by . This book was released on 1999 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present preliminary results of a new measurement of the b quark fragmentation function in Z° decays using a novel kinematic B hadron energy reconstruction technique. The measurement is performed using 150,000 hadronic Z° events recorded in the SLD experiment at SLAC between 1996 and 1997. The small and stable SLC beam spot and the CCD-based vertex detector are used to reconstruct topological B-decay vertices with high efficiency and purity, and to provide precise measurements of the kinematic quantities used in this technique. We measure the B energy with good efficiency and resolution over the full kinematic range. We compare the scale B hadron energy distribution with several functional forms of the B hadron energy distribution and predictions of several models of b quark fragmentation. Several functions including JETSET + Peterson are excluded by the data. The average scaled energy of the weakly decaying B hadron is measured to be x{sub B} = 0.719 " 0.005 (stat) " 0.007 (syst) " 0.001 (model) (preliminary).
Download or read book Measurements of Hadronic Decays of Z sup 0 Bosons written by and published by . This book was released on 1992 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Z[degrees] bosons have been produced by collisions of longitudinally polarized electrons with unpolarized positrons at the SLAC Linear Collider and their decays have been recorded by the SLD experiment. We present preliminary measurements of the properties of the resulting Z[degrees] decays into multi-hadronic final states. We find good agreement with the predictions of perturbative QCD and fragmentation models.
Download or read book Heavy Flavor Decays of the Z0 and a Search for Flavor Changing Neutral Currents written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented here are the results of a direct search for flavor changing neutral currents via the rare process Z[sup 0] [yields] bs and a measurement of R[sub bs] = [Lambda](Z[sup 0] [yields] bs)/[Lambda](Z[sup 0] [yields] hadrons). Because the decays Z[sup 0] [yields] b[bar b] and Z[sup 0] [yields] c[bar c] contribute significant backgrounds to Z[sup 0] [yields] bs, simultaneous measurements of R[sub b] = [Lambda](Z[sup 0] [yields] b[bar b])/[Lambda](Z[sup 0] [yields] hadrons) and R[sub c] = [Lambda](Z[sup 0] [yields] c[bar c])/[Lambda](Z[sup 0] [yields] hadrons) were also made. The standard double tag technique was extended and self calibrating tags were used for s, c, and b quarks. These measurements were made possible by the unique capabilities of the SLAC Large Detector (SLD) at the Stanford Linear Accelerator Center (SLAC): The b and c tags relied upon the SLD's VXD3 307 megapixel CCD vertex detector for topological and kinematic reconstruction of the B and D decay vertices; the s tag identified K[sup [+-]] mesons using the particle identification capabilities of SLD's Cherenkov Ring Imaging Detector (CRID), and K[sub S][sup 0] mesons and [Lambda] hadrons by kinematic reconstruction of their decay vertices in SLD's 5120 channel central drift chamber (CDC) particle tracking system.
Download or read book Charged particle Inclusive Distributions from Hadronic Z Sup 0 Decays written by and published by . This book was released on 1990 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured inclusive distributions for charged particles in hadronic decays of the Z boson. The variables chosen for study were the mean charged-particle multiplicity ({l angle} n{sub ch} {r angle}), scaled momentum (x), and momenta transverse to the sphericity axes (p(up tack){sub in} and p(up tack){sub out}). The distributions have been corrected for detector effects and are compared with data from ee− annihilation at lower energies and with the predictions of several QCD-based models. The data are in reasonable agreement with expectations. 12 refs., 2 figs.
