Biomedical subjects

C Buchanan

Publications and source records attributed to C Buchanan.

At least 37 records · Page 2Linked to original sources

PubMed2005

Production and decay of xi(c)(0) at BABAR.

Using 116.1 fb(-1) of data collected by the BABAR detector, we present an analysis of xi(c)(0) production in B decays and from the cc continuum, with the xi(c)(0) decaying into omega- K+ and xi- pi+ final states. We measure the ratio of branching fractions B(xi(c)(0) --> omega- K+)/B(xi(c)(0) --> xi- pi+) spectrum is measured on and 40 MeV below the upsilon(4S) resonance. From these spectra the branching fraction product B(B --> xi(c)(0)X) x B(xi(c)(0) --> xi- pi+) is measured to be (2.11 +/- 0.19 +/- 0.25) x 10(-4), and the cross-section product sigma(e+ e- --> xi(c)(0)X) x B(xi(c)(0) --> xi- pi+) from the continuum is measured to be (388 +/- 39 +/- 41) fb at a center-of-mass energy of 10.58 GeV.

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PubMed2005

Measurement of time-dependent CP asymmetries in B0-->D(*)+/-D+/- decays.

We present a first measurement of CP asymmetries in neutral B decays to D+D-, and updated CP asymmetry measurements in decays to D(*+)D- and D(*-)D+. We use fully reconstructed decays collected in a data sample of (232+/-3) x 10(6) gamma(4S)-->BB events in the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We determine the time-dependent asymmetry parameters to be SD(*+)(D-)=-0.54+/-0.35+/-0.07, CD(*+)(D-)=0.09+/-0.25+/-0.06, SD(*-)(D+)=-0.29+/-0.33+/-0.07, CD(*-)(D+)=0.17+/-0.24+/-0.04, SD+(D-)=-0.29+/-0.63+/-0.06, and CD+(D-)=0.11+/-0.35+/-0.06, where in each case the first error is statistical and the second error is systematic.

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PubMed2005

Measurement of branching fractions and charge asymmetries in B+ decays to eta pi+, eta K+, eta rho+, and eta' pi+, and search for B0 decays to eta K0 and eta omega.

We present measurements of branching fractions and charge asymmetries for six B-meson decay modes with an eta or eta(') meson in the final state. The data sample corresponds to 232 x 10(6) BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) B Factory at SLAC. We measure the branching fractions (in units of 10(-6)): B(B+ -->eta pi(+))=5.1+/-0.6+/-0.3, B(B+ etaK+)=3.3+/-0.6+/-0.3, B(B0-->etaK0)=1.5+/-0.7+/-0.1 (<2.5 at 90% C.L.), B(B+-->eta rho(+))=8.4+/-1.9+/-1.1, B(B0-->eta omiga)=1.0+/-0.5+/-0.2 (<1.9 at 90% C.L.), and B(B+-->eta(')pi(+))=4.0+/-0.8+/-0.4, where the first uncertainty is statistical and second systematic. For the charged modes we also determine the charge asymmetries, all found to be compatible with zero.

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PubMed2005

Measurement of the Cabibbo-Kobayashi-Maskawa angle gamma in B+/--->D*K+/- decays with a Dalitz analysis of D-->K0(S)pi-pi+.

We report on a measurement of the Cabibbo-Kobayashi-Maskawa CP-violating phase gamma through a Dalitz analysis of neutral D decays to K0(S)pi-pi+ in the processes B+/- -->D*K+/-, D*-->Dpi0, Dgamma. Using a sample of 227 x 10(6) BB pairs collected by the BABAR detector, we measure the amplitude ratios r(B)=0.12+/-0.03+/-0.04 and r*(B)=0.17+/-0.10+/-0.03+/-0.03, the relative strong phases delta(B)=(104+/-45(+17+16)(-21-24))degrees and delta*(B)=(-64+/-41(+14)(-12)+/-15) degrees between the amplitudes A(B- -->D*0K-) and A(B- -->D*0)K-), and gamma=(70+/-31(+12+14)(-10-11))degrees. The first error is statistical, the second is the experimental systematic uncertainty, and the third reflects the Dalitz model uncertainty. The results for the strong and weak phases have a twofold ambiguity.

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PubMed2005

Determination of |Vub| from measurements of the electron and neutrino momenta in inclusive semileptonic B decays.

We present a determination of the Cabibbo-Kobayashi-Maskawa matrix element |Vub| based on the analysis of semileptonic B decays from a sample of 88 x 10(6) Gamma(4S) decays collected with the BABAR detector at the SLAC PEP-II e+e- storage ring. Charmless semileptonic B decays are selected using measurements of the electron energy and the invariant mass squared of the electron-neutrino pair. We obtain |Vub| =(3.95 +/- 0.26(+0.58)(-0.42) +/- 0.25) x 10(-3), where the errors represent experimental uncertainties, heavy quark parameter uncertainties, and theoretical uncertainties, respectively.

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PubMed2005

Improved Measurement of the Cabibbo-Kobayashi-Maskawa angle alpha using B0(B) --> rho+rho- decays.

We present results from an analysis of B(0)B(0)--> rho(+)rho(-) using 232 x 10(6) Gamma (4S) --> BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. We measure the longitudinal polarization fraction f(L) = 0.978 +/- 0.014(stat) + 0.021 / -0.029(syst) and the CP-violating parameters S(L)= -0.33 +/- 0.24(stat) + 0.08 / -0.14(syst) and C(L)= -0.03 +/- 0.18(stat) +/- 0.09(syst). Using an isospin analysis of B --> rhorho decays, we determine the unitarity triangle parameter alpha. The solution compatible with the standard model is alpha = (100 +/- 13) degrees.

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PubMed2005

Search for strange-pentaquark production in e+e- annihilation at sqrt[s] = 10.58 GeV.

We search for strange-pentaquark states that have been previously reported by other experiments--the Theta (1540)(+), Xi(5)(1860)(--), and Xi(5)(1860)(0)--in 123 fb(-1) of data recorded with the BABAR detector at the PEP-II e(+)e(-) storage ring. We find no evidence for these states and set 95% confidence level upper limits on the number of Theta(1540)(+) and Xi(5)(1860)(--) pentaquarks produced per e(+)e(-) annihilation into qq and Gamma(4S) decay. For qq events the Theta(1540)(+) [Xi(5)(1860)(--)] limit is about 8 [4] times lower than the rates measured for ordinary baryons of similar mass.

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PubMed2005

Search for the rare leptonic decay B--->tau-nutau.

We present a search for the decay B(-)--> tau(-)nu(tau) in a sample of 88.9 x 10(6) BB pairs recorded with the BABAR detector at the Stanford Linear Accelerator Center B factory. One of the two B mesons from the Gamma(4S) is reconstructed in a hadronic or a semileptonic final state, and the decay products of the other B in the event are analyzed for consistency with a B(-) --> tau(-)nu(tau) decay. We find no evidence of a signal and set an upper limit on the branching fraction of B(B(-) --> tau(-) nu(tau)) < 4.2 x 10(-4) at the 90% confidence level.

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PubMed2005

Measurement of the branching fraction of Gamma(4S) --> B0B0.

We report the first measurement of the branching fraction f(00) for Gamma(4S) --> B(0)B(0). The data sample consists of 81.7 fb(-1) collected at the Gamma(4S) resonance with the BABAR detector at the SLAC PEP-II asymmetric-energy e(+)e(-) storage ring. Using partial reconstruction of the decay B(0) --> D(*+) l(-)nu(l) in which only the charged lepton and the soft pion from the decay D(*+) --> D(0)pi(+) are reconstructed, we obtain f(00) = 0.487 +/- 0.010(stat) +/- 0.008(syst). Our result does not depend on the branching fractions of B(0) --> D(*+)l(-)nu(l) and D(*+) --> D(0)pi(+) decays, on the ratio of the charged and neutral B meson lifetimes, nor on the assumption of isospin symmetry.

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PubMed2005

Search for lepton flavor violation in the decay tau+/- --> mu+ gamma.

A search for the nonconservation of lepton flavor number in the decay tau(+/-) --> mu(+/-) has been performed using 2.07 x 10(8) e(+ )e(-) tau(+) tau(-) events produced at a center-of-mass energy near 10.58 GeV with the BABAR detector at the PEP-II storage ring. We find no evidence for a signal and set an upper limit on the branching ratio of Beta(tau(+/-) --> mu(+/-) gamma) < 6.8 x 10(-8) at 90% confidence level.

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PubMed2005

Branching fraction and CP asymmetries of B0-->K0(S)K0(S)K0(S).

We present measurements of the branching fraction and time-dependent CP-violating asymmetries in B0-->K0(S)K0(S)K0(S) decays based on 227 x 10(6) Upsilon4S-->BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. We obtain a branching fraction of (6.9(+0.9)(-0.8)+/-0.6) x 10(-6), and CP asymmetries C=-0.34(+0.28)(-0.25)+/-0.05 and S=-0.71(+0.38)(-0.32)+/-0.04, where the first uncertainties are statistical and the second systematic.

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PubMed2005

Search for decays of B0-->e+ e-, B0-->mu+ mu-, B0-->e +/- mu-/+.

We present a search for the decays B0-->e+ e-, B0-->mu+ mu-, and B0-->e (+/-) mu (-/+) in data collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC B Factory. Using a data set of 111 fb(-1), we find no evidence for a signal in any of the three channels investigated and set the following branching fraction upper limits at the 90% confidence level: B(B0-->e+ e-) < 6.1 x 10(-8), B(B0-->mu+ mu-) < 8.3 x 10(-8), and B(B0-->e (+/-) mu (-/+) )<18 x 10(-8).

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PubMed2005

Measurements of branching fractions and time-dependent CP-violating asymmetries in B --> eta'K decays.

We present measurements of the B --> eta(')K branching fractions; for B(+) --> eta(')K(+) we measure also the time-integrated charge asymmetry Alpha(ch), and for B(0) --> eta(')K(0)(S) the time-dependent CP-violation parameters S and C. The data sample corresponds to 232 x 10(6) BB pairs produced by e(+)e(-) annihilation at the Upsilon (4S). The results are Beta(B --> eta(')K(+)) = (68.9 +/- 2.0 +/- 3.2) x 10(-6), Beta(B(0) --> eta(')K(0)) = (67.4 +/- 3.2) x 10(-6), Alpha(ch) = 0.033 +/- 0.028 +/- 0.005, S = 0.30 +/- 0.140 +/- 0.02, and C = -0.21 +/- 0.10 +/- 0.02, where the first error quoted is statistical and the second is systematic.

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PubMed2005

Branching fractions and CP asymmetries in B0-->pi0pi0, B+-->pi+pi0, and B+-->K+pi0 decays and isospin analysis of the B-->pipi system.

Based on a sample of 227 x 10(6) BB pairs collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC, we measure the branching fraction B(B0-->pi(0)pi(0))=(1.17+/-0.32+/-0.10)x10(-6), and the asymmetry Cpi(0)(pi(0))=-0.12+/-0.56+/-0.06. The B0-->pi(0)pi(0) signal has a significance of 5.0 sigma. We also measure B(B+-->pi(+)pi(0))=(5.8+/-0.6+/-0.4)x10(-6), B(B+-->K+pi(0))=(12.0+/-0.7+/-0.6)x10(-6), and the charge asymmetries Api(+)(pi(0))=-0.01+/-0.10+/-0.02 and AK+(pi(0))=0.06+/-0.06+/-0.01. Using isospin relations, we find an upper bound on the angle difference |alpha-alpha(eff)| of 35 degrees at the 90% C.L.

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PubMed2005

Search for factorization-suppressed B-->chi(c)K(*) decays.

We search for the factorization-suppressed decays B-->chi(c0)K(*) and B-->chi(c2)K(*), with chi(c0) and chi(c2) decaying into J/psi gamma, using a sample of 124 x 10(6) BB events collected with the BABAR detector at the PEP-II storage ring of the Stanford Linear Accelerator Center. We find no significant signal and set upper bounds for the branching fractions.

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PubMed2005

Improved measurement of CP asymmetries in B0 --> (cc)K(0(*)) decays.

We present results on time-dependent CP asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 227 x 10(6) upsilon(4S) --> BB decays collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The amplitude of the CPasymmetry, sin2beta in the standard model, is derived from decay-time distributions from events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B0 or B0 from its decay products. We measure sin2beta = 0.722 +/- 0.040(stat) +/- 0.023(syst) in agreement with the standard model expectation.

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PubMed2005

Measurement of branching fractions and charge asymmetries for exclusive B decays to charmonium.

We report measurements of branching fractions and charge asymmetries of exclusive decays of neutral and charged B mesons into two-body final states containing a charmonium state and a light strange meson. The charmonium mesons considered are J/psi, psi(2S) and chi(c1), and the light meson is either K or K(*). We use a sample of about 124x10(6) BB pairs collected with the BABAR detector at the PEP-II storage ring at the Stanford Linear Accelerator Center.

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PubMed2005

Limit on the B0-->rho0rho0 branching fraction and implications for the Cabibbo-Kobayashi-Maskawa angle alpha.

We search for the decay B0-->rho(0)rho(0) in a data sample of about 227x10(6) Upsilon(4S)-->BB decays collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC. We find no significant signal and set an upper limit of 1.1x10(-6) at 90% C.L. on the branching fraction. As a result, the uncertainty due to penguin contributions on the Cabibbo-Kobayashi-Maskawa unitarity angle alpha measured in B-->rhorho decays is decreased to 11 degrees at 68% C.L.

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