187 Matching Results

Search Results

Advanced search parameters have been applied.

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

Electromagnetic Mass Splittings in Heavy Mesons

Description: The electromagnetic contribution to the isomultiplet mass splittings of heavy mesons is reanalyzed within the framework of the heavy mass expansion. It is shown that the leading term in the expansion is given to a good approximation by the elastic term. 1/mQ-corrections can only be estimated, the main source of uncertainty now being inelastic contributions. The 1/mQ-corrections to the elastic term turn out to be relatively small in both D and B mesons.
Date: November 1, 1992
Creator: Goity, Jose
Partner: UNT Libraries Government Documents Department

Improved Measurement of the CKM Angle gamma in B^-+ to D^(*) K^(*)-+Decays with a Dalitz Plot Analysis of D Decays to K_S^0 pi+ pi- and K_S^0 K+ K-

Description: We report on an improved measurement of the Cabibbo-Kobayashi-Maskawa CP-violating phase {gamma} through a Dalitz plot analysis of neutral D meson decays to K{sub s}{sup 0}{pi}{sup +}{pi}{sup -} and K{sub s}{sup 0}K{sup +}K{sup -} produced in the processes B{sup {-+}} {yields} DK{sup {-+}}, B{sup {-+}} {yields} D* K{sup {-+}} with D* {yields} D{pi}{sup 0}, D{gamma}, and B{sup {-+}} {yields} DK*{sup {-+}} with K8{sup {-+}} {yields} K{sub S}{sup 0}{pi}{sup {-+}}. Using a sample of 383 million B{bar B} pairs collected by the BABAR detector, we measure {gamma} = (76 {+-} 22 {+-} 5{+-} 5){sup o} (mod 180{sup o}), where the first error is statistical, the second is the experimental systematic uncertainty and the third reflects the uncertainty on the description of the Dalitz plot distributions. The corresponding two standard deviation region is 29{sup o} < {gamma} < 122{sup o}. This result has a significance of direct CP violation ({gamma} {ne} 0) of 3.0 standard deviations.
Date: April 22, 2008
Creator: Aubert, : B.
Partner: UNT Libraries Government Documents Department

D0 - Anti-D0 Mixing at BaBar

Description: The BABAR and Belle collaborations have recently found evidence for mixing within the D meson system. We present some of the mixing search techniques used by BABAR and their status as of the beginning of the summer 2007. These have culminated in a measurement in the K{pi} decay final state of the D that is inconsistent with the no-mixing hypothesis with a significance of 3.9 standard deviations.
Date: October 23, 2007
Creator: Seiden, A. & /UC, Santa Cruz
Partner: UNT Libraries Government Documents Department

Rare Decays And Exotic States With BaBar

Description: Results from the BABAR experiment are presented for searches for several rare FCNC B and D meson decays, including the modes B{sup 0} {yields} {ell}{sup +}{ell}{sup -} and D{sup 0} {yields} {ell}{sup +}{ell}{sup -}, B {yields} ({rho},{omega}){gamma} and B{sup +} {yields} (K,{pi}){sup +}{nu}{bar {nu}}. Limits on lepton flavor violation in neutrino-less {tau} decays are also discussed. Finally, results of BABAR searches for the strange pentaquark states {Theta}{sup +}(1540), {Xi}{sup --}(1860) and {Xi}{sup 0}(1860) are summarized.
Date: August 28, 2006
Creator: Robertson, S.H. & U., /McGill
Partner: UNT Libraries Government Documents Department

Search for flavor-changing-neutral-current D meson decays

Description: We study the flavor-changing-neutral-current process c {yields} u{mu}{sup +}{mu}{sup -} using 1.3 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We see clear indications of the D{sup +}{sub s} and D{sup +} {yields} {phi}{pi}{sup +} {yields} {mu}{sup +}{mu}{sup -}{pi}{sup +} final states with significance greater than four standard deviations above background for the D{sup +} state. We search for the continuum decay of D{sup +} {yields} {pi}{sup +}{mu}{sup +}{mu}{sup -} in the dimuon invariant mass spectrum away from the {phi} resonance. We see no evidence of signal above background and set a limit of B(D{sup +} {yields} {pi}{sup +}{mu}{sup +}{mu}{sup -}) < 3.9 x 10{sup -6} at the 90% CL. This limit places the most stringent constraint on new phenomena in the c {yields} u{mu}{sup +}{mu}{sup -} transition.
Date: August 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

Measurement of the Branching Fraction and Decay Rate Asymmetry of B to D_pi+ pi- pi0 K-

Description: The authors report the observation of the decay B{sup -} {yields} D{sub {pi}{sup +}{pi}{sup -}{pi}{sup 0}}K{sup -}, where D{sub {pi}{sup +}{pi}{sup -}{pi}{sup 0}} indicates a neutral D meson detected in the final state {pi}{sup +}{pi}{sup -}{pi}{sup 0}, excluding K{sub S}{sup 0}{pi}{sup 0}. This doubly Cabibbo-suppressed decay chain can be used to measure the CKM phase {gamma}. Using about 229 million e{sup +}e{sup -} {yields} B{bar B} events recorded by the BABAR experiment at the PEP-II e{sup +}e{sup -} storage ring, they measure the branching fraction {Beta}(B{sup -} {yields} D{sub {pi}{sup +}{pi}{sup -}{pi}{sup 0}K{sup -}}) = (5.5 {+-} 1.0 (stat.) {+-} 0.7 (syst.)) x 10{sup -6} and the decay rate asymmetry A = -0.02 {+-} 0.16 (stat.) {+-} 0.03 (syst.) for the full decay chain.
Date: June 10, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Partner: UNT Libraries Government Documents Department

Measurement of CP violation observables and parameters for the decays $B^{\pm}\to DK^{*\pm}$

Description: We study the decay B{sup -} {yields} DK*{sup -} using a sample of 379 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II B-factory. We perform a 'GLW' analysis where the D meson decays into either a CP-even (CP+) eigenstate (K{sup +}K{sup -}, {pi}{sup +}{pi}{sup -}), CP-odd (CP-) eigenstate (K{sub S}{sup 0}{pi}{sup 0}, K{sub S}{sup 0}{phi}, K{sub S}{sup 0}{omega}) or a non-CP state (K{sup -}{pi}{sup +}). We also analyze D meson decays into K{sup +}{pi}{sup -} from a Cabibbo-favored {bar D}{sup 0} decay or doubly suppressed D{sup 0} decay ('ADS' analysis). We measure observables that are sensitive to the CKM angle {gamma}: the partial-rate charge asymmetries A{sub CP{+-}}, the ratios R{sub CP{+-}} of the B-decay branching fractions in CP{+-} and non-CP decay, the ratio R{sub ADS} of the charge-averaged branching fractions, and the charge asymmetry A{sub ADS} of the ADS decays: A{sub CP+} = 0.09 {+-} 0.13 {+-} 0.06, A{sub CP-} = -0.23 {+-} 0.21 {+-} 0.07, R{sub CP+} = 2.17 {+-} 0.35 {+-} 0.09, R{sub CP-} = 1.03 {+-} 0.27 {+-} 0.13, R{sub ADS} = 0.066 {+-} 0.031 {+-} 0.010, and A{sub ADS} = -0.34 {+-} 0.43 {+-} 0.16, where the first uncertainty is statistical and the second is systematic. Combining all the measurements and using a frequentist approach yields the magnitude of the ratio between the Cabibbo-suppressed and favored amplitudes, r{sub B} = 0.31 with a one (two) sigma confidence level interval of [0.24, 0.38] ([0.17, 0.43]). The value r{sub B} = 0 is excluded at the 3.3 sigma level. A similar analysis excludes values of {gamma} in the intervals [0, 7]{sup o}, [55, 111]{sup o}, and [175, 180]{sup o} ([85, 99]{sup o}) at the one (two) sigma confidence level.
Date: August 26, 2010
Creator: Aubert, Bernard; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Partner: UNT Libraries Government Documents Department

D meson hadronic decays at CLEO-c

Description: The recent CLEO-c results on hadronic decays of D and D{sub s} mesons are presented. First the absolute branching fractions for D and D{sub s} mesons using a double tag technique are discussed, then are the Cabibbo suppressed decays and doubly Cabibbo suppressed decays. Finally, I present the inclusive and rare decay modes and other measurements from CLEO-c. These decays illuminate a wide range of physics. A brief theoretical introduction is given before the corresponding discussion on measurement.
Date: January 1, 2011
Creator: Yang, Fan
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

Searching for new physics with charm

Description: The author considers the prospect of using the charm system as a laboratory for probing new physics. The theoretical expectations for rare charm meson decays, D{sup 0} - {bar D}{sup 0}, and charm quark asymmetries in Z decays are examined in the Standard Model. The effects of new physics from several classes of nonstandard dynamical models are summarized for these phenomena.
Date: June 1995
Creator: Hewett, J. L.
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

Production asymmetries in x{sub f} and P{sub t}{sup 2} for D{sup {plus_minus}} mesons

Description: We present differences in leading and non-leading charged D meson production as a doubly-differential function of both P{sup 2}{sub t} and {chi}{integral}. Comparisons to specific models are made. This information is from the analysis of half the data from Fermilab experiment E791, taken during the 1991-2 fixed target run with a 500 GeV/c {pi}{sup {minus}} beam incident on a segmented target.
Date: November 1, 1994
Creator: Carter, T. & Collaboration, E791
Partner: UNT Libraries Government Documents Department

B and D mesons in lattice QCD

Description: Computational and theoretical developments in lattice QCD calculations of B and D mesons are surveyed. Several topical examples are given: new ideas for calculating the HQET parameters {bar {Lambda}} and {lambda}{sub 1}; form factors needed to determine {vert_bar}V{sub cb}{vert_bar} and {vert_bar}V{sub ub}{vert_bar}; bag parameters for the mass differences of the B mesons; and decay constants. Prospects for removing the quenched approximation are discussed.
Date: October 17, 2000
Creator: Kronfeld, Andreas S.
Partner: UNT Libraries Government Documents Department

Phenomenological study of strong decays of heavy hadrons in heavy quark effective theory

Description: The application of the tensor formalism of the heavy quark effective theory (HQET) at leading order to strong decays of heavy hadrons is presented. Comparisons between experimental and theoretical predictions of ratios of decay rated for B mesons, D mesons and kaons are given. The application of HQET to strange mesons presents some encouraging results. The spin-flavor symmetry is used to predict some decay rates that have not yet been measured.
Date: December 1999
Creator: Tregoures, N. & Roberts, W.
Partner: UNT Libraries Government Documents Department

Three electroweak results from lattice QCD

Description: Quantum chromodynamics is needed to understand quarks and, hence, to determine the quarks` Yukawa couplings from experimental measurements. As a short illustration, the results of three lattice calculations are given.
Date: August 1, 1998
Creator: Kronfeld, A.S., FERMI
Partner: UNT Libraries Government Documents Department

On constraints for heavy-meson form factors

Description: We examine the recent work of de Rafael and Taron where model-independent bounds on the Isgur-Wise function are presented. We first argue that the bounds cannot hold in as much generality as implied. We show that the effects of resonances omitted in their discussion (such as heavy-heavy ``onium`` states below threshold) modify the bound. The resulting bound is much weaker but may be useful where the size of the additional contribution may be computed or estimated.
Date: November 1, 1992
Creator: Grinstein, B. & Mende, P.F.
Partner: UNT Libraries Government Documents Department

The B {r{underscore}arrow} D*{ell}{nu} form factor at zero recoil

Description: The authors describe a model independent lattice QCD method for determining the deviation from unity for h{sub A{sub 1}}, the B {r{underscore}arrow} D*{ell}{nu} form factor at zero recoil. They extend the double ratio method previously used to determine the B {r{underscore}arrow} D{ell}{nu} form factor. The bulk of statistical and systematic errors cancel in the double ratios they consider, yielding form factors which promise to reduce present theoretical uncertainties in the determination of {vert{underscore}bar}V{sub cb}{vert{underscore}bar}. They present results from a prototype calculation at a single lattice spacing corresponding to {beta} = 5.7.
Date: January 26, 2000
Creator: Simone, J.N.; Hashimoto, S.; El-Khadra, A.X.; Kronfeld, A.S.; Mackenzie, P.B. & Ryan, S.M.
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

Time Dependent B{sub s}{sup 0}-{bar B}{sub s}{sup 0} Mixing Using Inclusive and Semileptonic B Decays at SLD

Description: We set a preliminary 95% C.L. exclusion on the oscillation frequency of B{sub s}{sup 0}-{bar B}{sub s}{sup 0} mixing using a sample of 350,000 hadronic Z{sup 0} decays collected by the SLD experiment at the SLC during the 1997-98 run. The analyses determine the b-hadron flavor at production by exploiting the large forward-backward asymmetry of polarized Z{sup 0} {yields} b{bar b} decays as well as information from the hemisphere opposite that of the reconstructed B decay. In one analysis, B decay vertices are reconstructed inclusively with a new topological technique, and separation between B{sub s}{sup 0} and {bar B}{sub s}{sup 0} decays exploits the B{sub s}{sup 0} {yields} D{sub s}{sup -} cascade charge structure. In the other analysis, semileptonic decays are selected and the B decay point is reconstructed by intersecting a lepton track with the trajectory of a topologically reconstructed D meson. The two analyses are combined with a third analysis described elsewhere to exclude the following values of the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} mixing oscillation frequency: {Delta}m{sub s} < 5.2 ps{sup -1} and 11.3 < {Delta}m{sub s} < 14.2 ps{sup -1} at the 95% confidence level.
Date: September 14, 1999
Creator: Willocq, Stephane
Partner: UNT Libraries Government Documents Department

D-meson enhancement in pp collisions at the LHC due to nonlinear gluon evolution

Description: When nonlinear effects on the gluon evolution are included with constraints from HERA, the gluon distribution in the free proton is enhanced at low momentum fractions, x {approx}< 0.01, and low scales, Q{sup 2} {approx}< 10 GeV{sup 2}, relative to standard, DGLAP-evolved, gluon distributions. Consequently, such gluon distributions can enhance charm production in pp collisions at center of mass energy 14 TeV by up to a factor of five at midrapidity, y {approx} 0, and transverse momentum p{sub T} {yields} 0 in the most optimistic case. We show that most of this enhancement survives hadronization into D mesons. Assuming the same enhancement at leading and next-to-leading order, we show that the D enhancement may be measured by D{sup 0} reconstruction in the K{sup -}{pi}{sup +} decay channel with the ALICE detector.
Date: August 22, 2004
Creator: Dainese, A.; Vogt, R.; Bondila, M.; Eskola, K.J. & Kolhinen, V.J.
Partner: UNT Libraries Government Documents Department