799 Matching Results

Search Results

Advanced search parameters have been applied.

Highlights of B physics at CDF

Description: The CDF experiment at the Fermilab Tevatron collider has produced many B physics results. Recent measurements on B meson masses, B lifetimes, B branching ratios, limits on rare B decays, and B flavour tagging studies are reviewed.
Date: August 1, 1995
Creator: Paulini, M.
Partner: UNT Libraries Government Documents Department

Weak matrix elements on the lattice - Circa 1995

Description: Status of weak matrix elements is reviewed. In particular, e{prime}/e, B {yields} K*{gamma}, B{sub B} and B{sub B}, are discussed and the overall situation with respect to the lattice effort and some of its phenomenological implications are summarised. For e{prime}/e the need for the relevant matrix elements is stressed in view of the forthcoming improved experiments. For some of the operators, (e.g. O{sub 6}), even bound on their matrix elements would be very helpful. On B {yields} K{degrees}{gamma}, a constant behavior of T{sub 2} appears disfavored although dependence of T{sub 2} could, of course, be milder than a simple pole. Improved data is badly needed to settle this important issue firmly, especially in view of its ramification for extractions of V{sub td} from B {yields} {rho}{gamma}. On B{sub {kappa}}, the preliminary result from JLQCD appears to contradict Sharpe et al. JLQCD data seems to fit very well to linear {alpha} dependence and leads to an appreciably lower value of B{sub {kappa}}. Four studies of B{sub {kappa}} in the {open_quotes}full{close_quotes} (n{sub f} = 2) theory indicate very little quenching effects on B{sub {kappa}}; the full theory value seems to be just a little less than the quenched result. Based on expectations from HQET, analysis of B-parameter (B{sub h}{ell}) for the heavy-light mesons via B{sub h}{ell}) = constant + constants{prime}/m{sub h}{ell} is suggested. A summary of an illustrative sample of hadron matrix elements is given and constraints on CKM parameters (e.g. V{sub td}/V{sub ts}, on the unitarity triangle and on x{sub s}/x{sub d}, emerging from the lattice calculations along with experimental results are briefly discussed. In quite a few cases, for the first time, some indication of quenching errors on weak matrix elements are now becoming available.
Date: October 3, 1995
Creator: Soni, A.
Partner: UNT Libraries Government Documents Department

Hadronic Charmless B Decays at the SLD

Description: Rare decays of beauty particles were studied in several two-body exclusive hadronic charmless modes using the 19.4 pb<sup>-1</sup> Z-pole data collected with the SLD detector at SLAC from 1993 to 1998. These decays are mediated by both tree level b {yields} u and one-loop penguin b {yields} s, d transitions. Upper limits for the branching ratios are set for the investigated modes B<sub>s</sub>, B<sub>0</sub> {yields} P<sup>+</sup>P<sup>-</sup>, B<sup>+</sup> {yields} V P<sup>+</sup> and B<sub>s</sub>, B<sup>0</sup> {yields} V V , where the pseudoscalar particle P<sup>+</sup> is either {pi}<sup>+</sup> or K<sup>+</sup> and the vector particle V is either {rho}<sup>0</sup>, K<sup>* 0</sup> or {phi}. Using an event selection algorithm consisting of a set of hard cuts combined with a set of discriminator functions, the efficiencies range between 24% and 37% with near zero background.
Date: September 2, 1999
Creator: Reinertsen, Per L
Partner: UNT Libraries Government Documents Department

Impedance study for the PEP-II B-factory

Description: The paper summarizes results of the impedance studies of the components of the B-factory. The prime goal of this activity was to support the design of the vacuum chamber and, at the same time, to get a reasonable model of the machine impedance, which can be used later for detail studies of collective effects.
Date: June 1, 1995
Creator: Heifets, S.; Daly, C.E. & Ko, K.
Partner: UNT Libraries Government Documents Department

Trojan Penguins and Isospin Violation in Hadronic B Decays

Description: Some rare hadronic decays of B mesons, such as B {yields} {pi}K, are sensitive to isospin-violating contributions from physics beyond the Standard Model. Although commonly referred to as electroweak penguins, such contributions can often arise through tree-level exchanges of heavy particles, or through strong-interaction loop diagrams. The Wilson coefficients of the corresponding electroweak penguin operators are calculated in a large class of New Physics models, and in many cases are found not to be suppressed with respect to the QCD penguin coefficients. Several tests for these effects using observables in B{sup {+-}} {yields} {pi}K decays are discussed, and nontrivial bounds on the couplings of the various New Physics models are derived.
Date: September 10, 1999
Creator: Grossman, yuval
Partner: UNT Libraries Government Documents Department

Production of J/{Psi} from {chi}{sub c} decays at CDF

Description: We have measured the fraction of J/{psi} originating from {chi}{sub c} states in p{bar p} collisions at {radical}s = 1.8 TeV in four bins of J/{psi} P{sub T}. The fraction in the inclusive CDF J/{psi} sample with P{sub T}{sup J/{psi}} > 4.0 GeV/c and {vert_bar}{eta}{sup J/{psi}}{vert_bar} < 0.6 is f{sub x}{sup J/{psi}} = 28.3{+-}1.6(stat){+-}6.8(syst)%. The fraction of J/{psi} from {chi}{sub c} not including contributions from B{yields}J/{psi}. X and B {yields} {chi}{sub c} X is f(Nob){chi}{sup J/{psi}} = 32.3{+-}2.0(stat){+-}8.5(syst)%. We have also found that directly produced {chi}{sub c}`s are produced in the ratio = {sigma}({chi}{sub c2}) over {sigma}({chi}{sub cl}) + {sigma}({chi}{sub c2})= 0.47{+-}0.08(stat){+-}0.02(syst.)
Date: July 1, 1995
Creator: Abe, F.
Partner: UNT Libraries Government Documents Department

The PEP-II design

Description: The Stanford Linear Accelerator Center (SLAC), Lawrence Berkeley Laboratory (LBL), Lawrence Livermore National Laboratory (LLNL) Positron Electron Project-II (PEP-II) is a design for a high-luminosity, asymmetric energy, electron-positron colliding beam accelerator that will operate at the center-of-mass energy of the {Upsilon}4S (10.58 GeV). The goal of the design is to achieve a large enough integrated luminosity with a moving center-of-mass reference frame to he able to observe the predicted rare decay modes of the {Upsilon}4S that do not conserve charge parity (CP).
Date: May 1, 1995
Creator: Sullivan, M.K.
Partner: UNT Libraries Government Documents Department

Test of CPT Invariance in B Factories

Description: Feasibility of setting limits on CPT violating parameters for the case of both CP conjugate and semileptonic decays of neutral Bd mesons were examined. For the case of semileptonic final states of neutral Bd meson decays, bounds on CPT violating parameters at the level of few percent can be easily obtained. This sensitivity is better than the similar analysis using the CP conjugate final states of neutral Bd meson decays mainly due to the substantial increase on the statistics.
Date: February 2, 1999
Creator: Yang, Songhoon
Partner: UNT Libraries Government Documents Department

Measurement of the B{sup +} and B{sup 0} lifetimes at CDF

Description: Two measurements of the lifetime of neutral and charged B mesons in p{bar p} collisions at {radical}s = 1.8 TeV by the CDF experiment are presented. The first relies on the study of exclusive decays of the type B {yields} {psi} K, the second on semileptonic decays of a B meson into a D{degrees} or a D. The combined results are {tau}(B{sup +}) = 1.62 {+-} 0.09 ps, {tau}(B{sub 0}) = 1.60 {+-} 0.09 ps and {tau}(B{sup +})/{tau}(B{sup 0}) = 1.00 {+-} 0.07.
Date: October 1, 1995
Creator: Bortoletto, D.
Partner: UNT Libraries Government Documents Department

CDF B spectroscopy results: B** and Bc{sup +}

Description: The authors report on two spectroscopy results from CDF. First, they observe the orbitally excited B** mesons in B {r_arrow} {ell}D(*) X events. They find 28 {+-} 6 {+-} 3% of light B mesons produced are B** states. A collective mass fit results in a B{sub 1} mass of 5.71 {+-} 0.02 GeV/c{sup 2}. Secondly, they observe 20.4{sub {minus}5.5}{sup +0.18} {+-} 0.03 ps lifetime. The production rate is in reasonable accordance with expectations.
Date: September 8, 1999
Creator: Bauer, G.
Partner: UNT Libraries Government Documents Department

Beauty and charm production from Fermilab experiment 789

Description: Experiment 789 is a fixed-target experiment at Fermilab designed to study low-multiplicity decays of charm and beauty. During the 1991 run. E789 collected {approx} 10{sup 9} events using an 800 GeV proton beam incident upon gold and beryllium targets. Analyses of these data include searches for b {yields} J/{psi}+{Chi} decays and {Alpha}- dependence measurements of neutral D meson production. Preliminary results from the 1991 run are presented in this paper.
Date: June 1, 1993
Creator: Jansen, D.M.; Boissevain, J.; Carey, T.A.; Jeppesen, R.G.; Kapustinsky, J.S.; Lane, D.W. et al.
Partner: UNT Libraries Government Documents Department

Properties of b {anti b} Production at the Tevatron

Description: The authors present a number of recent results obtained at the Fermilab Tevatron for b{bar b} production in p{bar p} interactions. The preliminary CDF and D0 measurements of the inclusive b-quark production cross section at {radical}s = 630 GeV are compared with the UA1 results and the next-to-leading order QCD predictions. These results are used to compute the ratio of the cross sections at 630 GeV to 1800 GeV. The CDF results on the B meson differential cross section and {Lambda}{sub b}{sup 0} baryon production and decay properties at {radical}s = 1800 GeV are also presented.
Date: May 1, 1997
Creator: Stichelbaut, Frederic
Partner: UNT Libraries Government Documents Department

B production at CDF

Description: Preliminary measurements of B meson cross sections, b quark cross sections, and b-{bar b} correlated cross sections are presented from the 1992---1993 data obtained at CDF. A search for new states in the 75 pb{sup {minus}1} sample obtained through early 1995 yields no evidence for B{sub c} {yields} J/{psi} {minus} {pi} or {Lambda}{sub b} {yields} J/{psi} {minus} {Lambda}(1520).
Date: July 1, 1995
Creator: Lukens, P.T. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

CP Violation and mixing of B mesons at CDF

Description: We report recent studies of CP-violation and mixing in neutral B mesons from the CDF experiment at the Fermilab Tevatron Collider. Results of a direct measurement of the CP-violation parameter sin 2{beta} using B{sup 0} {yields} J/{psi}K{sub S}{sup 0} with multi flavor tagging algorithms, a search for B{sub s}{sup 0} - {bar B}{sub s}{sup 0} mixing using semileptonic decays, and the updated precision measurements of the B{sup 0} - {bar B}{sup 0} mixing parameter will be presented. The prospects for B physics with the upgraded CDF detector in the next Tevatron Collider run will also be discussed.
Date: December 13, 1999
Creator: Miao, Ting
Partner: UNT Libraries Government Documents Department

Heavy meson observables and Dyson Schwinger equations.

Description: Dyson-Schwinger equation (DSE) studies show that the b-quark mass-function is approximately constant, and that this is true to a lesser extent for the c-quark. This observation provides the basis for a study of the leptonic and semileptonic decays of heavy pseudoscalar mesons using a ''heavy-quark'' limit of the DSES, which, when exact, reduces the number of independent form factors. Semileptonic decays with light mesons in the final state are also accessible because the DSES provide a description of light-quark propagation characteristics and light-meson structure. A description of B-meson decays is straightforward, however, the study of decays involving the D-meson indicates that c-quark mass-corrections are quantitatively important.
Date: October 20, 1998
Creator: Ivanov, M. A.
Partner: UNT Libraries Government Documents Department

Measurement of the Probability for Gluon Splitting into b{bar b} in Z{sup 0} Decays

Description: We present a preliminary measurement of the rate of gluon splitting into bottom quarks, g {r_arrow} b{bar b}, in hadronic Z{sup 0} decays collected by SLD between 1996 and 1998. The analysis was performed by looking for secondary bottom production in 4-jet events of any primary flavor. 4-jet events were identified, and a topological vertex-mass technique was applied to each jet in order to identify b or {bar b} jets. The upgraded CCD based vertex detector gives very high B-tagging efficiency, especially for B hadrons of the low energies typical of this process. The two most nearly collinear b/{bar b} jets were tagged as originating from g {r_arrow} b{bar b}. We measured the rate of secondary b/{bar b} production per hadronic event, g{sub b{bar b}}, to be (3.07 {+-} 0.71(stat.) {+-} 0.66(syst.)) x 10{sup {minus}3} (preliminary).
Date: July 9, 1999
Creator: Muller, David
Partner: UNT Libraries Government Documents Department

B physics results from CDF

Description: B-physics results from the CDF Collaboration based on data collected during the Tevatron run 1A and 1B are presented. In particular we discuss the measurements of B meson masses and lifetimes, the limits set on rare B decay branching ratios and B{sub o}{bar B}{sub o} mixing results obtained with both time-integrated and time-evolution analysis. We use the current results to extrapolate CDF B-physics prospects to the end of run 1 and to the future high luminosity run II.
Date: July 1, 1995
Creator: Bedeschi, F.
Partner: UNT Libraries Government Documents Department

J/{psi} production in p{anti p} collisions at {radical}s = 1.8 TeV

Description: The authors have studied J/{psi} production in p{anti p} collisions at {radical}s = 1.8 TeV with the D0 detector at Fermilab, using a {mu}{sup +}{mu}{sup {minus}} data sample corresponding to an integrated luminosity of 13 pb{sup {minus}1}. They have measured the inclusive J/{psi} production cross section as a function of J/{psi} transverse momentum p{sub T}. For the kinematic range p{sub T} > 8 GeV/c and {vert_bar}{eta}{vert_bar} < 0.6 they obtain Br(J/{psi} {yields} {mu}{sup +}{mu}{sup {minus}}) {center_dot} {sigma}(p{anti p} {yields} J/{psi} + X) = 1.93 {+-} 0.16(stat) {+-} 0.43(syst) nb. Using the muon impact parameter they have estimated the fraction of J/{psi} mesons coming from B meson decays to be f{sub b} = 0.35 {+-} 0.09 (stat) {+-} 0.10 (syst) and inferred the inclusive b production cross section. From the information on the event topology a fraction of non-isolated J/{psi} events has been measured to be f{sub non-isol} = 0.64 {+-} 0.09(stat) {+-} 0.06(syst). They have also obtained the fraction of events resulting from radiative decays of {chi}{sub c} states as f{sub {chi}} = 0.30 {+-} 0.07(stat) {+-} 0.07(syst). They discuss the implications of the measurements for charmonium production processes.
Date: July 1, 1995
Creator: Abachi, S.
Partner: UNT Libraries Government Documents Department

PEP-II B-Factory prototype higher order mode load design

Description: To reduce the impedance of the cavity higher order modes, (HOM`s), a compact broad-band, low-reflection, waveguide load is required with a VSWR less than 2:1 in the frequency range 714 MHz to 2500 MHz. The load must also work in the high vacuum of the cavity, and be capable of dissipating up to 10 kW of power which is generated by the interaction of the beam with the cavity HOM`s and which is directed to each load assembly. A prototype load assembly is being fabricated which uses the lossy ceramic Al-N with 7% by weight glassy carbon to absorb the microwave power.
Date: October 1, 1995
Creator: Pendleton, R.; Ko, K. & Ng, N.
Partner: UNT Libraries Government Documents Department

Limits on rare B decays B {yields} {mu}{sup +}{mu}{sup {minus}}K{sup {+-}} and B {yields} {mu}{sup +}{mu}{sup {minus}}K*{sup 0}

Description: The authors report on a search for flavor-changing neutral current decays of B mesons B {yields} {mu}{sup +}{mu}{sup {minus}}K{sup {+-}} and B {yields} {mu}{sup +}{mu}{sup {minus}}K*{sup 0} using data obtained in the Collider Detector at Fermilab (CDF) 1992--1993 data taking run. To reduce the amount of background in the data the authors use precise tracking information from the CDF silicon vertex detector to pinpoint the location of the decay vertex of the B candidate, and accept only events which have a large decay time. They compare this data to a B meson signal obtained in a similar fashion, but where the muon pairs originate from {psi} decays, and calculate the relative branching ratios. In absence of any indication of flavor-changing neutral current decays they set an upper limits of BR(B {yields} {mu}{sup +}{mu}{sup {minus}}K{sup {+-}}) < 1.1 {times} 10{sup {minus}5}, and BR(B {yields} {mu}{sup +}{mu}{sup {minus}}K*{sup 0}) < 2.1 {times} 10{sup {minus}5} at 90% confidence level, which are consistent with Standard Model expectations but leave little room for non-standard physics.
Date: July 1, 1995
Creator: Anway-Wiese, C.
Partner: UNT Libraries Government Documents Department

B{sup o} - {bar B}{sup o} mixing, lifetimes and rare decays at CDF and D0

Description: CDF and D0 have collected a huge number of B meson during 1992-1993 collider run. The major results on B lifetimes, rare decays and B{sup o} - {bar B}{sup o} mixing will be here reviewed. The first measurement of time dependent mixing at hadron collider is also presented.
Date: June 1, 1995
Creator: Lucchesi, D.
Partner: UNT Libraries Government Documents Department

Production of heavy quark states at CDF

Description: In this paper the author presents results on quarkonia production, B-meson production and b{bar b} correlations in p{bar p} collisions at {radical}s = 1.8 TeV. These results were obtained from data taken with the CDF detector at Fermilab. The author covers recently completed analyses of the 1992-95 collider run. Prospects for the near and more distant future are also discussed.
Date: July 1, 1995
Creator: Papadimitriou, V.
Partner: UNT Libraries Government Documents Department

All hadronic B decay trigger with the CDF silicon vertex tracker

Description: Silicon Vertex tracks are of fundamental importance for reconstructing B meson decays at a hadron collider. The upgraded CDF detector will deploy an online Silicon Vertex Tracker in the level 2 trigger. We have studied how this new device exploits the Tevatron large B meson production to select hadronic B decays fundamental for measuring CP violation and B{sub s} mixing.
Date: October 19, 1999
Creator: Donati, Simone
Partner: UNT Libraries Government Documents Department

Photo- and hadro-production of charm and beauty at Fermilab

Description: This report concentrates on results from three Fermilab experiments: the photoproduction of charm in the fixed target mode from experiment E687, and the collider hadroproduction of b-quarks and B-mesons as measured respectively by the D0 and CDF detectors. Only the production of open flavors is considered. For heavy quarkonia results see the contribution from B. Naroska to these proceedings.
Date: September 1, 1995
Creator: Maciel, A.K.A.
Partner: UNT Libraries Government Documents Department