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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

Rare b decays from the CDF experiment

Description: The high cross-section for the production of b quarks at the Tevatron hadron collider make it an ideal place to search for rare B meson species and very low branching fraction decay modes of the more common B mesons. This paper reports the recent discovery of the Bc meson by the CDF collaboration. It also discusses the observation of rare B meson final states involving {psi}(2S) mesons and searches for ultra-rare decays such as B {yields} {mu}{sup +}{mu}{sup -}
Date: October 1, 1998
Creator: Trischuk, W.
Partner: UNT Libraries Government Documents Department

B {right arrow}Dl{nu}form factors and the Determination of |V{sub cb}|

Description: The zero recoil limit of the B{yields}Dl{nu} form factors is calculated on the lattice, which provides a model-independent determination of {vert_bar}V{sub cb}{vert_bar}. Considering a ratio of form factors, in which the bulk of statistical and systematic errors cancel, we obtain a precise result both for h{sub +}(1) and for h{sub -}(1).
Date: November 1, 1998
Creator: al., S.Hashimoto et
Partner: UNT Libraries Government Documents Department

Prospects for mixing and CP violation at the Tevatron

Description: The Fermilab p{bar p} Tevatron collider, operating at {radical}s = 1. 8 TeV, is a proficient source of B hadrons. The first collider run, Run I, has clearly proven that B states can be observed cleanly and can be studied in great detail in a hadron collider environment. In this presentation the future of the study of B{bar B} mixing and of CP violation at the Tevatron, with an upgraded machine and detectors, is discussed.
Date: December 1, 1996
Creator: Rijssenbeek, M. & collaborations, The CDF and DO
Partner: UNT Libraries Government Documents Department

CP violation, mixing and rare decays at the Tevatron now and in Run II

Description: We review the status of current B mixing and CP violation measurements from the Fermilab Tevatron. With the existing data sample, the CDF collaboration has made competitive measurements of B{sub d}{sup 0} mixing; set limits on B{sub s}{sup 0} mixing and has begun a direct search of CP violation in the B system through the decay B{sup 0}/{anti B}{sup 0}{yields}J/{psi}K{sub S}{sup 0}. The prospects for future b measurements at the Tevatron, including CP violation, B{sub s}{sup 0} mixing and rare decay searches are discussed.
Date: December 1, 1998
Creator: Pitts, Kevin T.
Partner: UNT Libraries Government Documents Department

Theoretical developments in inclusive B decays

Description: Some recent theoretical work on inclusive B decays relevant for the model independent determination of {vert_bar}V{sub ub}{vert_bar} and {vert_bar}V{sub cb}{vert_bar} is summarized. The theoretical predictions and their reliability for several differential decay distributions in {anti B}{yields}X{sub c,u}e{anti {nu}} and {anti B}{yields}X{sub s}{gamma} are reviewed. These can be used to determine certain important HQET matrix elements. The upsilon expansion and ways of testing it are discussed.
Date: May 17, 1999
Creator: Ligeti, Zoltan
Partner: UNT Libraries Government Documents Department

B Decays as a probe of spontaneous cp-violation in SUSY models

Description: We consider phenomenological implications of susy models with spontaneously broken CP-symmetry. In particular, we analyze CP-asymmetries in B decays and find that the predictions of these models are vastly different from those of the SM. These features are common to NMSSM-like models with an arbitrary number of sterile superfields and the MSSM with broken R-parity.
Date: July 8, 1999
Creator: Lebedev, Oleg
Partner: UNT Libraries Government Documents Department

Towards a next-to-leading logarithmic result in B {r_arrow} X{sub s}{gamma}

Description: The calculation of the O ({alpha}{sub s}) virtual corrections to the matrix element of the inclusive decay b {r_arrow} s{gamma} is reported. These contributions drastically reduce the large renormalization scale dependence of the leading logarithmic calculation. Combining these results with the preliminary result for the Wilson coefficient C{sub {gamma}} (m{sub b}) calculated recently by Chetyrkin, Misiak, and Muenz, we estimate the branching ratio to be BR(B {r_arrow} X{sub s} {gamma}) = (3.25 {plus_minus} 0.50) x 10{sup {minus}4}.
Date: August 1, 1996
Creator: Greub, C. & Hurth, T.
Partner: UNT Libraries Government Documents Department

Low level RF system design for the PEP-II B factory

Description: Heavy beam loading in PEP-II has driven the design of the low level RF system to contain feedback loops similar to those used in proton rings. The RF feedback loops control longitudinal coupled-bunch instabilities caused by the beam interaction with the accelerating mode of the RF cavities by reducing the cavity impedance observed by the beam. The RF system employs a modular design housed in a VXI environment and uses the EPICS control system. Modem control system design and signal processing is used throughout the system. This paper describes the RF system topology and the signal processing used to fulfill the system requirements.
Date: October 1, 1995
Creator: Corredoura, P.; Claus, R. & Sapozhnikov, L.
Partner: UNT Libraries Government Documents Department

B physics in Run II with upgraded CDF II

Description: At the beginning of next millennium B-factories at KEK or PEP collider will be operating and will provide precise measurements of CP violation parameters in the B{sup 0} systems. In order to test the Standardd Model predictions, measurements of parameters which involve B{sub s}, B{sub u} and {Lambda}{sub b} decays will be necessary. We present here how the upgraded CDF detector will be suited for these studies.
Date: October 1, 1998
Creator: Lucchesi, Donatella
Partner: UNT Libraries Government Documents Department

Probing supersymmetry in rare B decays

Description: We determine the ability of future experiments to observe supersymmetric contributions to the rare decays B {r_arrow} X{sub s}{gamma} and B {r_arrow} X{sub s}l{sup +}l{sup -}. A global fit to the Wilson coefficients which contribute to these decays is performed from Monte Carlo generated data. This fit is then compared to supersymmetric predictions for several different patterns of the superpartner spectrum.
Date: October 1, 1996
Creator: Hewett, J.L.
Partner: UNT Libraries Government Documents Department

A measurement of the b quark fragmentation function at {radical}Q{sup 2} = 45.6 GeV

Description: Presented here is a measurement of the b quark fragmentation function D{sub b}(X), taken from a sample of 504 semi-leptonic B decays which were selected from the 150,000 Z{sup 0} decays collected between 1993 and 1995 at the SLD at SLAC. The energy of each tagged B hadron is reconstructed using missing jet energy, based on the information from the lepton and a partially-reconstructed charm-decay vertex. Account is taken of the effect of primary orbitally excited mesons (B**s). An iterative unfolding procedure is used which serves to effectively extract the true fragmentation function from the reconstructed B energy spectrum. The final result is shown to be compatible with many theoretical models. A comparison is made with other b fragmentation function measurements at 45.6 GeV, and this measurement is shown to be consistent with those results. The average scaled energy is found to be (x{sub E}) = 0.697{+-} 0.017(stat) {+-} 0.034(sys).
Date: June 1, 1996
Creator: Church, E.D.
Partner: UNT Libraries Government Documents Department

Search for new mechanism of CP violation through tau decay and semileptonic decay at hadrons

Description: If CP is violated in any decay process involving leptons it will signify the existence of a new force (called the X boson) responsible for CP violation that may be the key to understanding matter-antimatter asymmetry in the universe. The author discusses the signatures of CP violation in (1) the decay of tau lepton, and (2) the semileptonic decay of {pi}, K, D, B and t particles by measuring the polarization of the charged lepton in the decay. The author discusses how the coupling constants and their phases of the coupling of the X boson to 9 quark vertices and 3 lepton vertices can be obtained through 12 decay processes.
Date: November 1, 1996
Creator: Tsai, Yung Su
Partner: UNT Libraries Government Documents Department

Status of BTeV: A dedicated b physics experiment at the Fermilab Tevatron Collider

Description: BTeV is a program whose long term goal is to carry out precision studies of CP violation, mixing, and raare decays of bottom and charmed quarks in the forward direction at the Fermilab Tevatron Collider. It is planned for the new interaction region, C0, currently being constructed. We describe the technique, physics reach, and status of BTeV.
Date: October 1, 1998
Creator: Butler, Joel N.
Partner: UNT Libraries Government Documents Department

Triggering BTeV

Description: BTeV is a collider experiment at Fermilab designed for precision studies of CP violation and mixing. Unlike most collider experiments, the BTeV detector has a forward geometry that is optimized for the measurement of B and charm decays in a high-rate environment. While the rate of B production gives BTeV an advantage of almost four orders of magnitude over e{sup +} e{sup {minus}} B factories, the BTeV Level 1 trigger must be able to accept data at a rate of 100 Gigabytes per second, reconstruct tracks and vertices, trigger on B events with high efficiency, and reject minimum bias events by a factor of 100:1. An overview of the Level 1 trigger will be presented.
Date: April 16, 1999
Creator: Gottschalk, Erik
Partner: UNT Libraries Government Documents Department

New puzzles in nonleptonic B and D decays

Description: Exclusive charged B decays show an unexplained enhancement in low-lying channels which must be reversed in other channels to equalise charged and neutral lifetimes. One suggested explanation involves decay modes with excited mesons like the a{sub 1}. The anomalous behavior of decay modes of D and B mesons into final states containing the {eta} and {eta}{prime} mesons is discussed.
Date: September 1, 1997
Creator: Lipkin, H.J.
Partner: UNT Libraries Government Documents Department

The PEP II injection kicker system

Description: PEP II or the B Factory consists of two asymmetric storage rings. The injection energy for electrons is 9 GeV, while that for positrons is 3.1 GeV. The bend angle into the high energy ring (HER) is 0.35 m-rad, and the angle into the low energy ring (LER) is 0.575 m-rad. The magnetic length for the HER kicker is 0.85 m, and 0.55 m for the LER kicker. The field produced by the magnet is therefore 123.5 G for the HER, and 132 G for the LER. Each ring has a kicker magnet upstream of the injection line which is used to distort the orbit of the stored beam. An identical magnet downstream of the injection line is used to restore the orbit of the stored beam and inject the incoming beam. The two magnets are driven in parallel by the modulator. The apeture of the magnets is 3.86x3.46 cm (HxV). Therefore the current required to drive the HER is 863 A, while for the LER it is 756 A. The inductance of the magnet is approximately 1.4 uH/m. The current pulse is a critically damped sinusoid with a rise time of less than 300 ns. A kicker system has been designed which can be used for injection of both beams by varying the charge of voltage. The modulator uses a conjugate circuit to match the impedance of the magnet, and coupling to the beam chamber.
Date: July 1, 1997
Creator: Pappas, G.C.; Donaldson, A.R. & Williams, D.
Partner: UNT Libraries Government Documents Department

Development of a movable plunger tuner for the high-power RF cavity for the PEP-II B-factory

Description: A 10 cm diameter by 5 cm travel plunger tuner was developed for the PEP-II RF copper cavity system. The single cell cavity including the tuner is designed to operate up to 150 kW of dissipated RF power are specially placed 8.5 cm away from the inside wall of the cavity to avoid fundamental and higher order mode resonances. The spring fingers are made of dispersion-strengthened copper to accommodate relatively high heating. The design, alignment, testing and performance of the tuner is described.
Date: May 1, 1997
Creator: Schwarz, H.D.; Fant, K. & Judkins, J.G.
Partner: UNT Libraries Government Documents Department

Results from a prototype permanent magnet dipole-quadrupole hybrid for the PEP-II B-factory

Description: We describe the construction of a prototype hybrid permanent magnet dipole and quadrupole. The magnet consists of two concentric rings of Sm{sub 2}Co{sub 17} magnetic material 5 cm in length. The outer ring is made of 16 uniformly magnetized blocks assembled as a Halbach dipole and the inner ring has 32 blocks oriented in a similar fashion so as to generate a quadrupole field. The resultant superimposed field is an offset quadrupole field which allows us to center the field on the high-energy beam in the interaction region of the PEP-II B-factory. The dipole blocks are glued to the inside surface of an outer support collar and the quadrupole blocks are held in a fixture that allows radial adjustment of the blocks prior to potting the entire assembly with epoxy. An extensive computer model of the magnet has been made and from this model we developed a tuning algorithm that allowed us to greatly reduce the n=3 17 harmonics of the magnet.
Date: June 1, 1997
Creator: Sullivan, M.; Bowden, G. & Ecklund, S.
Partner: UNT Libraries Government Documents Department