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Scalar and tensor couplings in kaon decays

Description: In the past few years charged kaon experiments have indicated possible scalar and tensor couplings in semileptonic kaon decays (K{yields}{pi}e{nu}). These couplings, if correct, are not predicted by the Standard Model and may indicate the onset of new physics. We present a summary of the existing data and a new, precision measurement of these couplings in the neutral kaon system based on a 3% subset of the data taken by the KTeV (E799) experiment at Fermilab.
Date: May 10, 1999
Creator: Tesarek, Richard J.
Partner: UNT Libraries Government Documents Department

1/m<sub>c</sub> Terms in lambda<sup>+</sup><sub>c</sub> Semileptonic Decays

Description: We use the heavy quark effective theory to investigate the form factors that describe the semileptonic decays lambda<sup>+</sup><sub>c</sub> -> lambda e<sup>+</sup> nu, to order 1/m<sub>c</sub>. We find that a total of four form factors are needed to this order, in contrast with two form factors to leading order, and six form factors in the most general case. We point out some relationships that arise among the general form factors.
Date: February 1, 1992
Creator: Roberts, Winston
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

b {r_arrow} sl{sup +}l{sup {minus}} in the left-right symmetric model

Description: We begin to analyze and contrast the predictions for the decay b {r_arrow} sl{sup +}l{sup {minus}} in the Left-Right Symmetric Model (LMR) with those of the Standard Model (SM). In particular, we show that the forward-backward asymmetry of the lepton spectrum can be used to distinguish the SM from the simplest manifestation of the LRM.
Date: May 1, 1997
Creator: Rizzo, T.G.
Partner: UNT Libraries Government Documents Department

Estimated Errors in |Vcd|/|Vcs| from semileptonic D decays

Description: We estimate statistical and systematic errors in the extraction of the CKM ratio {vert_bar}V{sub cd}{vert_bar}/{vert_bar}v{sub cs}{vert_bar} from exclusive D-meson semileptonic decays using lattice QCD and anticipated new experimental results.
Date: November 1, 1998
Creator: J.N.Simone, A.X.El-Khadra, S.Hashimoto, A.S.Kronfeld, P.B.Mackenzie, and S.M.Ryan
Partner: UNT Libraries Government Documents Department

Observation of the Decay K{sup +} yields P{sup +} v...

Description: We have observed 1 event consistent with the signature expected of the rare decay of a positive kaon to a positive pion and a neutrino anti-neutrino pair. In the examined momentum region of 211 to 230 MeV/c in the center of mass of the kaon we estimated the backgrounds to be about 0.08 &plusmn; 0.03 events. From this observation we estimate the branching ratio to be 4.2<SUP>+9.7</SUP><SUB>-3.5</SUB> x 10<SUP>-10</SUP>. In this presentation I will explain the experiment, and the analysis techniques. I will also discuss the expected improvements in the near future from the analysis of new data sets.
Date: May 21, 1999
Creator: Diwan, M.V.
Partner: UNT Libraries Government Documents Department

Observation of the Semileptonic Decays B to D*taunu and Evidence for B to D tau nu

Description: We present measurements of the semileptonic decays B{sup -} {yields} D{sup 0}{tau}{sup -}{bar {nu}}{sub {tau}}, B{sup -} {yields} D{sup *0}{tau}{sup -}{bar {nu}}{sub {tau}}, B{sup -} {yields} D{sup +}{tau}{sup -}{bar {nu}}{sub {tau}}, and B{sup -} {yields} D{sup *+}{tau}{sup -}{bar {nu}}{sub {tau}}, which are potentially sensitive to non-Standard Model amplitudes, The data sample comprises 232 x 10{sup 6} {Upsilon}(4s) {yields} B{bar B} decays collected with the BABAR detector. From a combined fit to B{sup -} and {bar B}{sup 0} channels, we obtain the branching fractions {beta}(B {yields} D{sub {tau}}{sup -}{bar {nu}}{sub {tau}}) = (0:86 {+-} 0:24 {+-} 0:11 {+-} 0:06)% and {beta}(B {yields} D*{tau}{sup -}{bar {nu}}{sub {tau}}) = (1:62 {+-} 0:31 {+-} 0:10 {+-} 0:05)% (normalized for the {bar B}{sup 0}), , where the uncertainties are statistical, systematic, and normalization-mode-related.
Date: September 14, 2007
Creator: B., Aubert
Partner: UNT Libraries Government Documents Department

Measurement of the charge asymmetry in semileptonic Bs decays

Description: The authors have performed the first direct measurement of the time integrated flavor untagged charge asymmetry in semileptonic B{sub s}{sup 0} decays, A{sub SL}{sup a,unt}, by comparing the decay rate of B{sub s}{sup 0} {yields} {mu}{sup +} D{sub s}{sup -}{nu}X, where D{sub s}{sup -} {yields} {phi}{pi}{sup -} and {phi} {yields} K{sup +}K{sup -}, with the charge-conjugate {bar B}{sub s}{sup 0} decay rate. This sample was selected from 1.3 fb{sup -1} of data collected by the D0 experiment in Run II of the Fermilab Tevatron collider. They obtain A{sub SL}{sup a,unt} = [1.23 {+-} 0.97(stat) {+-} 0.17(syst)] x 10{sup -2}. Assuming that {Delta}m{sub s}/{bar {Lambda}}{sub s} &gt;&gt; 1 and {Delta}{Lambda}{sub a}/(2{bar {Lambda}}{sub s}) &lt; 1, this result can be translated into a measurement on the CP-violating phase in B{sub s}{sup 0} mixing: {Delta}{Lambda}{sub s}/{Delta}m{sub s} {center_dot} tan {phi}{sub s} = [2.45 {+-} 1.93(stat) {+-} 0.35(syst)] x 10{sup -2}.
Date: January 1, 2007
Creator: Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Study of High pT Muons in IceCube

Description: Muons with a high transverse momentum (p{sub T}) are produced in cosmic ray air showers via semileptonic decay of heavy quarks and the decay of high p{sub T} kaons and pions. These high p{sub T} muons have a large lateral separation from the shower core muon bundle. IceCube is well suited for the detection of high p{sub T} muons. The surface shower array can determine the energy, core location and direction of the cosmic ray air shower while the in-ice array can reconstruct the energy and direction of the high p{sub T} muon. This makes it possible to measure the decoherence function (lateral separation spectrum) at distances greater than 150 meters. The muon p{sub T} can be determined from the muon energy (measured by dE/dx) and the lateral separation. The high p{sub T} muon spectrum may also be calculated in a perturbative QCD framework; this spectrum is sensitive to the cosmic-ray composition.
Date: June 1, 2009
Creator: Collaboration, IceCube; Gerhardt, Lisa & Klein, Spencer
Partner: UNT Libraries Government Documents Department

Averages of B-Hadron Properties at the End of 2005

Description: This article reports world averages for measurements on b-hadron properties obtained by the Heavy Flavor Averaging Group (HFAG) using the available results as of at the end of 2005. In the averaging, the input parameters used in the various analyses are adjusted (rescaled) to common values, and all known correlations are taken into account. The averages include lifetimes, neutral meson mixing parameters, parameters of semileptonic decays, branching fractions of B decays to final states with open charm, charmonium and no charm, and measurements related to CP asymmetries.
Date: September 27, 2006
Creator: Barberio, E.; U., /Melbourne; Bizjak, I.; /Novosibirsk, IYF; Blyth, S.; /CERN et al.
Partner: UNT Libraries Government Documents Department

Search for CP violation in semileptonic B(s)0 decays

Description: We have performed a search for CP violation in a sample of semileptonic B{sub s}{sup 0} decays corresponding to approximately 5 fb{sup -1} of data collected by the D0 detector in Run II at the Fermilab Tevatron Collider. A time-dependent fit to the distributions of the B{sub s}{sup 0} candidates yields the flavor-specific asymmetry a{sub fs}{sup s} = [-1.7 {+-} 9.1(stat){sub -2.3}{sup +1.2}(syst)] x 10{sup -3}. This is the most precise measurement to date of this CP violation parameter.
Date: April 1, 2009
Creator: Abazov, : V.
Partner: UNT Libraries Government Documents Department

Semileptonic Decays of B Mesons Into Excited Charm Mesons:LeadingOrder and 1/m(sub)c Contributions(sub)c Con

Description: We use the heavy quark effective theory to investigate the form factors that describe the semileptonic decays of a B meson into excited daughter mesons.For an excited daughter meson with charm, a single form factor is needed at leading order, while five form factors and two dimensionful constants are needed to order 1/m(sub)c in the heavy quark expansion.For non-charmed final states, a total of four form factors are needed at leading order.For the process B ->D^(*)Xlv, four form factors are also needed at leading order.
Date: October 1, 1992
Creator: Mannel, Thomas & Roberts, Winston
Partner: UNT Libraries Government Documents Department

Measurement of the B+ ->eta l+ nu and B+ -> eta' l+ nu Branching Fractions using Upsilon(4S) -> B Bbar Events Tagged by a Fully Reconstructed B Meson

Description: We report preliminary measurements of the exclusive charmless semileptonic branching fractions of the B{sup +} {yields} {eta}{ell}{sup +}{nu} and B{sup +} {yields} {eta}'{ell}{sup +}{nu} decays. These measurements are based on 316 fb{sup -1} of data collected at the {Upsilon}(4S) resonance by the BABAR detector. In events in which the decay of one B meson to a hadronic final state is fully reconstructed, the semileptonic decay of the recoiling B meson is identified by the detection of a charged lepton and an {eta} or {eta}'. We measure the branching fraction {Beta}(B{sup +} {yields} {eta}{ell}{sup +}{nu}) = (0.84 {+-} 0.27 {+-} 0.21) x 10{sup -4}, where the first error is statistical and the second one systematic. We also set an upper limit on the branching fraction of {Beta}(B{sup +} {yields} {eta}{ell}{sup +}{nu}) &lt; 1.4 x 10{sup -4} and {Beta}(B{sup +} {yields} {eta}'{ell}{sup +}{nu}) &lt; 1.3 x 10{sup -4} at the 90% confidence level.
Date: August 18, 2006
Creator: D'Orazio, A
Partner: UNT Libraries Government Documents Department

First measurement of the b^0_s semileptonic branching ratio to an orbitally excited d _s** state

Description: In a data sample of approximately 1.3 fb{sup -1} collected with the D0 detector between 2002 and 2006, the orbitally excited charm state D{sub s1}{sup {+-}}(2536)has been observed with a measured mass of 2535.7 {+-} 0.6(stat) {+-} 0.5(syst) MeV/c{sup 2} via the decay mode B{sub s}{sup 0} {yields} D{sub s1}{sup -}(2536){mu}{sup +}{nu}X followed by D{sub s1}{sup {+-}}(2536) {yields} D*{sup {+-}}K{sub S}{sup 0}. By normalizing to the known branching ratio Br({bar b} {yields} D*{sup -} {mu}{sup +}{nu}X) and to the number of reconstructed D* mesons with an associated identified muon, a first-ever measurement is made of the product branching ratio ({bar b} {yields} D{sub s1}{sup -}(2536){mu}{sup +}{nu}X) {center_dot} Br(D{sub s1}{sup -} {yields} D*{sup -}K{sub S}{sup 0}). Assuming that D{sub s1}{sup -}(2536) production in semileptonic decay is entirely from B{sub s}{sup 0}, an extraction of the semileptonic branching ratio Br(B{sub s}{sup 0} {yields} D{sub s1}{sup -}(2536){mu}{sup +}{nu}X) is made. Comparisons are made with theoretical expectations.
Date: December 1, 2007
Creator: Rieger, Jason & U., /Indiana
Partner: UNT Libraries Government Documents Department

Measurement of the B0(s) semileptonic branching ratio to an orbitally excited D**(s) state, Br(B0(s) ---> D-(s1)(2536) mu+ nu X)

Description: In a data sample of approximately 1.3 fb{sup -1} collected with the D0 detector between 2002 and 2006, the orbitally excited charm state D{sub s1}{sup {+-}}(2536) has been observed with a measured mass of 2535.7 {+-} 0.6(stat) {+-} 0.5(syst) MeV/c{sup 2} via the decay mode B{sub s}{sup 0} {yields} D{sub s1}{sup -}(2536){mu}{sup +} {nu}X. A first measurement is made of the branching ratio product Br({bar B} {yields} D{sub s1}{sup -}(2536){mu}{sup +}{nu}X) {center_dot} Br(D{sub s1}{sup -} {yields} D*{sup -} K{sub S}{sup 0}). Assuming that D{sub s1}{sup -}(2536) production in semileptonic decay is entirely from B{sub s}{sup 0}, an extraction of the semileptonic branching ratio Br(B{sub s}{sup 0} {yields} D{sub s1}{sup -}(2536){mu}{sup +}{nu}X) is made.
Date: December 1, 2007
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

A Precise measurement of the B0(s) lifetime

Description: The authors report a measurement of the B{sub s}{sup 0} lifetime in the semileptonic decay channel B{sub s}{sup 0} {yields} D{sub s}{sup -}{mu}{sup +}{nu}X (and its charge conjugate), using approximately 0.4 fb{sup -1} of data collected with the D0 detector during 2002-2004. They have reconstructed 5176 D{sub s}{sup -} {mu}{sup +} signal events, where the D{sub s}{sup -} is identified via the decay D{sub s}{sup 0} {yields} {phi}{pi}{sup -}, followed by {phi} {yields} K{sup +}K{sup -}. Using these events, they have measured the B{sub s}{sup 0} lifetime to be {tau}(B{sub s}{sup 0}) = 1.398 {+-} 0.044 (stat){sub -0.025}{sup +0.028}(syst) ps. This is the most precise measurement of the B{sub s}{sup 0} lifetime to date.
Date: April 1, 2006
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Rare kaon decays

Description: The phenomenology of rare kaon decays is reviewed, with emphasis on tests of standard model flavordynamics.
Date: January 1, 1997
Creator: Buchalla, G.
Partner: UNT Libraries Government Documents Department

Evidence for {Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}}

Description: The first observation of the decay {Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} has been reported. The E787 experiment presented evidence for the {Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} decay, based on the observation of a single clean event from data collected during the 1995 run of the AGS (Alternating Gradient Synchrotron at Brookhaven National Laboratory). The branching ratio indicated by this observation, {Beta}({Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}}) = 4.2{sub {minus}3.5}{sup +9.7} {times} 10{sup {minus}10}, is consistent with the Standard Model expectation although the central experimental value is four times larger. The final E787 data sample, from the 1995--98 runs, should reach a sensitivity of about five times that of the 1995 run alone. A new experiment, E949, has been given scientific approval and should start data collection in 2001. It is expected to achieve a sensitivity of more than an order of magnitude below the prediction of the Standard Model.
Date: December 31, 1998
Creator: Kettell, S.
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