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D Riley

Publications and source records attributed to D Riley.

At least 55 records · Page 3Linked to original sources
PubMed2002

Observation of B-->K(0)(S)pi(+)pi(-) and Evidence for B-->K(*+/-)pi(-/+).

We report on a search for charmless hadronic B decays to the three-body final states K(0)(S)h(+)pi(-), K(+)h(-)pi(0), K(0)(S)h(+)pi(0) (h(+/-) denotes a charged pion or kaon), and their charge conjugates, using 13.5 fb(-1) of integrated luminosity produced near sqrt[s]=10.6 GeV, and collected with the CLEO detector. We observe the decay B-->K0pi(+)pi(-) with a branching fraction (50(+10)(-9)(stat.)+/-7(syst.))x10(-6) and the decay B-->K(*+)(892)pi(-) with a branching fraction (16(+6)(-5)(stat.)+/-2(syst.))x10(-6).

Journal Article↗
PubMed2002

Direct observation of strong coupling in a dense plasma.

We present differential x-ray scattering cross sections for a radiatively heated plasma showing overall consistency, in both form and absolute value, with theoretical simulations. In particular, the evolution of the plasma from a strongly coupled high density phase to a lower density weakly coupled phase is quite clearly shown in both experiment and simulation. The success of this experiment shows that x-ray scattering has the potential to become an extremely useful diagnostic technique for dense plasma physics.

Journal Article↗
PubMed2002

Improved measurement of /V(cb)/ using B-->D*l nu decays.

We determine the weak coupling /V(cb)/ between the b and c quarks using a sample of 3 x 10(6) BB; events in the CLEO detector at the Cornell Electron Storage Ring. We determine the yield of reconstructed B-->D*l nu; decays as a function of w, the boost of the D* in the B rest frame, and from this we obtain the differential decay rate d Gamma/dw. By extrapolating d Gamma/dw to w=1, the kinematic end point at which the D* is at rest relative to the B, we extract the product /V(cb)/F(1), where F(1) is the form factor at w=1. Combined with theoretical results for F(1) we determine /V(cb)/=0.0469+/-0.0014(stat)+/-0.0020(syst)+/-0.0018(theor).

Journal Article↗
PubMed2002

Improved measurement of Vub with inclusive semileptonic B decays.

We report a new measurement of the Cabibbo-Kobayashi-Maskawa parameter Vub made with a sample of 9.7 x 10(6) BB- events collected with the CLEO II detector. Using heavy quark theory, we combine the observed yield of leptons from semileptonic B decay in the end-point momentum interval 2.2-2.6 GeV/c with recent CLEO II data on B-->X(s)gamma to find Vub = (4.08+/-0.34+/-0.44+/-0.16+/-0.24)x10(-3), where the first two uncertainties are experimental and the last two are from theory.

Journal Article↗
PubMed2002

Search for CP violation in tau--> K(pi)nu(tau) decays.

We search and find no evidence for CP violation in tau decays into the K(pi)nu(tau) final state. We provide limits on the imaginary part of the coupling constant Lambda describing a relative contribution of the CP violating processes with respect to the standard model to be -0.172<Im(Lambda)<0.067 at 90% C.L.

Journal Article↗
PubMed2002

Observation of exclusive B --> D(*)K(*-) decays.

We report the first observation of the exclusive decays B-->D((*))K(*-), using 9.66 x 10(6) BB pairs collected at the Upsilon(4S) with the CLEO detector. We measure the following branching fractions: B(B--->D(0)K(*-)) = (6.1+/-1.6+/-1.7)x10(-4), B(B(0)-->D(+)K(*-)) = (3.7+/-1.5+/-1.0)x10(-4), B(B(0)-->D(*+)K(*-)) = (3.8+/-1.3+/-0.8)x10(-4), and B(B--->D(*0)K(*-)) = (7.7+/-2.2+/-2.6)x10(-4). The B-->D(*)K(*-) branching ratios are the averages of those corresponding to the 00 and 11 helicity states. The errors shown are statistical and systematic, respectively.

Journal Article↗
PubMed2002

Observation of B(0) --> D0pi(0) and B(0) -->D(*0)pi(0).

We have studied the color-suppressed hadronic decays of neutral B mesons into the final states D*0pi(0). Using 9.67 x 10(6) BB pairs collected with the CLEO detector, we observe the decays B( 0) --> D0pi(0) and B( 0) -->D(*0)pi(0) with the branching fractions BB( 0) -->D0pi(0)) = (2.74(+0.36)(-0.32) +/- 0.55)x10(-4) and BB( 0) -->D(*0)pi(0)) = (2.20(+0.59)(-0.52) +/- 0.79)x10(-4). The first error is statistical and the second systematic. The statistical significance of the D0pi(0) signal is 12.1sigma ( 5.9sigma for D(*0)pi(0)). Utilizing the B( 0) -->D*0)pi(0) branching fractions we determine the strong phases delta(I,D(*)) between isospin 1/2 and 3/2 amplitudes in the Dpi and D*pi final states to be cosdelta(I,D) = 0.89 +/-0.08 and cosdelta(I,D*) = 0.89 +/- 0.08, respectively.

Journal Article↗
PubMed2002

v-Src-induced modulation of the calpain-calpastatin proteolytic system regulates transformation.

v-Src-induced oncogenic transformation is characterized by alterations in cell morphology, adhesion, motility, survival, and proliferation. To further elucidate some of the signaling pathways downstream of v-Src that are responsible for the transformed cell phenotype, we have investigated the role that the calpain-calpastatin proteolytic system plays during oncogenic transformation induced by v-Src. We recently reported that v-Src-induced transformation of chicken embryo fibroblasts is accompanied by calpain-mediated proteolytic cleavage of the focal adhesion kinase (FAK) and disassembly of the focal adhesion complex. In this study we have characterized a positive feedback loop whereby activation of v-Src increases protein synthesis of calpain II, resulting in degradation of its endogenous inhibitor calpastatin. Reconstitution of calpastatin levels by overexpression of exogenous calpastatin suppresses proteolytic cleavage of FAK, morphological transformation, and anchorage-independent growth. Furthermore, calpastatin overexpression represses progression of v-Src-transformed cells through the G(1) stage of the cell cycle, which correlates with decreased pRb phosphorylation and decreased levels of cyclins A and D and cyclin-dependent kinase 2. Calpain 4 knockout fibroblasts also exhibit impaired v-Src-induced morphological transformation and anchorage-independent growth. Thus, modulation of the calpain-calpastatin proteolytic system plays an important role in focal adhesion disassembly, morphological transformation, and cell cycle progression during v-Src-induced cell transformation.

Actins↗
PubMed2001

Search for charmless B --> VV decays.

We have studied two-body charmless decays of the B meson into the final states rho(0)rho(0), K(*0)rho(0), K(*0)K(*0), K(*0)K(*0), K(*+)rho(0), K(*+)K(*0), and K(*+)K(*-) using only decay modes with charged daughter particles. Using 9.7x10(6) BB pairs collected with the CLEO detector, we place 90% confidence level upper limits on the branching fractions (1.4-14.1)x10(-5), depending on final state and polarization.

Journal Article↗
PubMed2001

Branching fraction and photon energy spectrum for b --> s gamma.

We have measured the branching fraction and photon energy spectrum for the radiative penguin process b-->s gamma. We find Beta(b-->s gamma) = (3.21+/-0.43+/-0.27(+0.18)(-0.10))x10(-4), where the errors are statistical, systematic, and from theory corrections. We obtain first and second moments of the photon energy spectrum above 2.0 GeV, = 2.346+/-0.032+/-0.011 GeV, and - (2) = 0.0226+/-0.0066+/-0.0020 GeV(2), where the errors are statistical and systematic. From the first moment, we obtain (in the modified minimal subtraction renormalization scheme, to order 1/M(3)(B) and beta(0)alpha(2)(s)) the heavy quark effective theory parameter Lambda = 0.35+/-0.08+/-0.10 GeV.

Journal Article↗
PubMed2001

Hadronic mass moments in inclusive semileptonic B meson decays.

We have measured the first and second moments of the hadronic mass-squared distribution in B-->X(c)l nu, for P(lepton)>1.5 GeV/c. We find = 0.251+/-0.066 GeV(2), <(M(2)(X)- )(2)> = 0.576+/-0.170 GeV(4), where M macro(D) is the spin-averaged D meson mass. From that first moment and the first moment of the photon energy spectrum in b-->s gamma, we find the heavy quark effective theory parameter lambda(1) (in the modified minimal subtraction renormalization scheme, to order 1/M(3)(B) and beta(0)alpha(2)(s)) to be -0.24+/-0.11 GeV(2). Using these first moments and the B semileptonic width, and assuming parton-hadron duality, we obtain absolute value of V(cb) = 0.0404+/-0.0013.

Journal Article↗
PubMed2001

The mechanism of cell cycle regulation by v-Src.

The tyrosine kinase oncoprotein v-Src can overcome the requirements for serum growth factors and anchorage which restrain normal cell growth. Here we investigated the biochemical mechanisms whereby v-Src induces quiescent cells to enter S phase in the absence of serum mitogens. Activating a temperature sensitive v-Src in quiescent cells sequentially induced cyclins D1, E and A and also down regulated p27. We addressed whether p27 down regulation was required to activate cyclin D1/CDK4/6 or cyclin E/CDK2 by engineering cells with inducible p27. Both S phase entry and activation of cyclin/CDKs were inhibited by over expression of p27. Using cells engineered with inducible p16 we showed that Cyclin D/CDK4/6 activity was required for v-Src to increase expression of cyclin A but not cyclin E. To determine which downstream kinases mediated these effects of v-Src we added pharmacological inhibitors of phosphatidylinositol 3-kinase (PI3-K), LY294002 or mitogen activated protein kinase kinase (MEK), U0126. PI3-K was required for v-Src to activate MEK and MEK was required for v-Src to increase expression of cyclins D1 and E. However, the MEK inhibitor prevented p27 protein down regulation whereas the PI3-K inhibitor did not. This was because reduced PI3-K activity lead to proteolytic degradation of p27.

Animals↗
PubMed2001

Search for the decay upsilon(1S) --> gammaeta(').

We report on a search for the radiative decay Upsilon(1S)-->gammaeta(') in 61.3 pb(-1) of data taken with the CLEO II detector at the Cornell Electron Storage Ring. Three decay chains were investigated, all involving eta(')-->pi(+)pi(-)eta, followed by eta-->gammagamma, eta-->pi(0)pi(0)pi(0), or eta-->pi(+)pi(-)pi(0). We find no candidate events in any of the three cases and set a combined upper limit of 1.6x10(-5) at 90% C.L., significantly smaller than the previous limit. We compare our result to other radiative Upsilon decays, to radiative J/psi decays, and to theoretical predictions.

Journal Article↗
PubMed2001

A 13-year-old boy with cognitive impairment, retinoblastoma, and Wilson disease.

A developmentally delayed child manifested retinoblastoma at age 4 years and Wilson disease at age 11, a previously unreported association. Cytogenetic and molecular analysis showed an interstitial deletion in the long arm of the paternally derived homologue of chromosome 13 (13q14.2-13q22.2), which encompasses the retinoblastoma and Wilson disease loci. The authors postulate that the co-occurrence of retinoblastoma and Wilson disease was the consequence of an acquired somatic mutation at the retinoblastoma locus and an inherited mutation at the Wilson disease locus of the maternally derived chromosome 13, superimposed on the hemizygosity associated with the paternally derived deletion.

Brain↗
PubMed2001

Bounds on the CP asymmetry in b --> sgamma decays.

We have measured the CP asymmetry A(CP) identical with[gamma(b-->sgamma)-gammab-->sgamma)]/[gamma(b-->sgamma)+gamma(b-->sgamma)] to be A(CP) = (-0.079+/-0.108+/-0.022) (1.0+/-0.030), implying that, at 90% confidence level, A(CP) lies between -0.27 and +0.10. These limits rule out some extreme non-standard-model predictions, but are consistent with most, as well as with the standard model.

Journal Article↗
PubMed2001

Bounds on the CP asymmetry in like-sign dileptons from B(0)B*(0) meson decays.

We have measured the charge asymmetry in like-sign dilepton yields from B(0)B*(0) meson decays using the CLEO detector at the Cornell Electron Storage Ring. We find a(0)(ll) identical with[N(l(+)l(+))-N(l(-)l(-))]/[N(l(+)l(+))+N(l(-)l(-))] = +0.013+/-0.050+/-0.005. We combine this result with a previous, independent measurement and obtain Re(epsilon(B))/(1+ the absolute value of epsilon(B)(2)) = +0.0035+/-0.0103+/-0.0015 (uncertainties are statistical and systematic, respectively) for the CP impurity parameter, epsilon(B).

Journal Article↗
PubMed2001

Observation of new states decaying into Lambda+(c)pi(-)pi(+).

Using 13.7 fb(-1) of data recorded by the CLEO detector at the Cornell Electron Storage Ring, we investigate the spectrum of charmed baryons which decay into Lambda+(c)pi(-)pi(+) and are more massive than the Lambda+(c)(2625) baryon. We find evidence for two new states: one is broad and has an invariant mass roughly 480 MeV above that of the Lambda+(c) baryon; the other is narrow with an invariant mass of 596+/-1+/-2 MeV above the Lambda+(c) mass.

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