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C Buchanan

Publications and source records attributed to C Buchanan.

At least 73 records · Page 4Linked to original sources

Measurement of the direct CP asymmetry in b-->s gamma Decays.

We describe a measurement of the direct CP asymmetry between inclusive b-->s gamma and b-->s gamma decays. This asymmetry is expected to be less than 0.01 in the standard model, but could be enhanced up to about 0.10 by new physics contributions. We use a sample of 89 x 10(6) BB pairs recorded with the BABAR detector at SLAC PEP-II, from which we reconstruct a set of 12 exclusive b-->s gamma final states containing one charged or neutral kaon and one to three pions. We measure an asymmetry of A(CP)(b-->s gamma)=0.025+/-0.050(stat)+/-0.015(syst), corresponding to an allowed range of -0.06 s gamma)<+0.11 at 90% confidence level.

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Study of B+/ --> J/psi pi+/- and B+/ -->J/psi K+/- decays: measurement of the ratio of branching fractions and search for direct CP violation.

We study B+/ --> J/psi pi(+/-) and B+/ --> J/psi K+/- decays in a sample of about 89 x 10(6) BB pairs collected with the BABAR detector at the PEP-II asymmetric B factory at SLAC. We observe a signal of 244+/-20 B+/ --> J/psi pi(+/-) events and determine the ratio B(B+/ --> J/psi pi(+/-))/B(B+/ --> J/psi K+/-) to be [5.37+/-0.45(stat)+/-0.11(syst)]%. The charge asymmetries for the B+/ --> J/psi pi(+/-) and B+/ --> J/psi K+/- decays are determined to be A(pi)=0.123+/-0.085(stat)+/-0.004(syst) and A(K)=0.030+/-0.015(stat)+/-0.006(syst), respectively.

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Search for lepton-flavor violation in the decay tau- --> l- l+ l-.

A search for the lepton-flavor-violating decay of the tau into three charged leptons has been performed using 91.5 fb(-1) of data collected at an e(+)e(-)center-of-mass energy around 10.58 GeV with the BABAR detector at the SLAC storage ring PEP-II. In all six decay modes considered, the numbers of events found in data are compatible with the background expectations. Upper limits on the branching fractions are set in the range (1-3)x10(-7) at 90% confidence level.

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Search for the radiative decays B-->rhogamma and B0-->omegagamma.

A search of the exclusive radiative decays B-->rho(770)gamma and B0-->omega(782)gamma is performed on a sample of about 84x10(6) BBmacr; events collected by the BABAR detector at the SLAC PEP-II asymmetric-energy e+e- storage ring. No significant signal is seen in any of the channels. We set upper limits on the branching fractions B of B(B0-->rho(0)gamma)<1.2 x 10(-6), B(B+-->rho+gamma)<2.1 x 10(-6), and B(B0-->omegagamma)<1.0 x 10(-6) at 90% confidence level (C.L.). Using the assumption that Gamma(B-->rhogamma)=Gamma(B+-->rho(+)gamma)=2 x Gamma(B0-->rho(0)gamma), we find the combined limit B(B-->rhogamma)<1.9 x 10(-6), corresponding to B(B-->rhogamma)/B(B-->K*gamma)<0.047 at 90% C.L.

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Presentation of vitamin D deficiency.

AIMS: To describe the various ways in which vitamin D deficiency presents in children in selected districts of London and to identify which factors, if any, determine the mode of presentation. METHODS: Retrospective review of patients presenting to Newham General, Royal London, Great Ormond Street, and King's College Hospitals between 1996 and 2001 with either hypocalcaemia or rickets caused by vitamin D deficiency. Children with plasma 25-hydroxyvitamin D levels <25 nmol/l (10 ng/ml) were considered to have vitamin D deficiency. RESULTS: Sixty five children, mostly from Black or Asian ethnic minority groups, were identified, 29 of whom had hypocalcaemic symptoms. Seventeen of these had no radiological evidence of rickets. The remainder (48 children) had radiological evidence of rickets with or without clinical signs. Symptoms and signs reverted to normal in all cases with vitamin D supplementation. All children who presented with symptomatic hypocalcaemia were aged either <3 or >10 years. There was a strong correlation between age at presentation and population growth velocity reference data. CONCLUSIONS: Rickets remains a problem in the UK especially in "at risk" ethnic minority groups. Symptomatic hypocalcaemia is an important, but under-recognised presenting feature. Growth rate is likely to be an important factor in determining the mode of presentation. Unexplained hypocalcaemia should be attributed to vitamin D deficiency in "at risk" ethnic minority groups until proved otherwise.

Adolescent↗

Galactocele in a male infant with congenital hypopituitarism.

Galactocele is an uncommon benign breast lesion usually occurring in young lactating women. It is a rare cause of breast enlargement in children. We report a galactocele in a male child with congenital hypopituitarism and propose an association between the two conditions.

Breast Cyst↗

Search for D0-D(-)0 mixing and a measurement of the doubly Cabibbo-suppressed decay rate in D0-->Kpi decays.

We present results of a search for D0-D(-)0 mixing and a measurement of R(D), the ratio of doubly Cabibbo-suppressed decays to Cabibbo-favored decays, using D0-->K+pi- decays from 57.1 fb(-1) of data collected near sqrt[s]=10.6 GeV with the BABAR detector at the PEP-II collider. At the 95% confidence level, allowing for CP violation, we find the mixing parameters x('2)<0.0022 and -0.056<y(')<0.039, and the mixing rate R(M)<0.16%. In the limit of no mixing, R(D)=[0.357+/-0.022(stat)+/-0.027(syst)]% and the CP-violating asymmetry A(D)=0.095+/-0.061(stat)+/-0.083(syst).

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Measurements of CP-violating asymmetries and branching fractions in B meson decays to eta'K.

We present measurements of the branching fractions of the decays B+-->eta'K+ and B0-->eta'K0. For B0-->eta(')K(0)(S) we also measure the time-dependent CP-violation parameters S eta'(K(0)(S)) and C eta'(K(0)(S)), and for B+-->eta'K+ the time-integrated charge asymmetry A(ch). The data sample corresponds to 88.9 x 10(6) BB pairs produced by e(+)e(-) annihilation at the Upsilon(4S). The results are B(B+-->eta'K+)=(76.9+/-3.5+/-4.4) x 10(-6), B(B0-->eta'K0)=(60.6+/-5.6+/-4.6) x 10(-6), S eta'(K(0)(S))=0.02+/-0.34+/-0.03, C eta'(K(0)(S))=0.10+/-0.22+/-0.04, and A(ch)=0.037+/-0.045+/-0.011.

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Rare B decays into states containing a J/psi meson and a meson with s(-)s quark content.

We report a study of the B meson decays, B+ --> J/psiphiK+, B0 --> J/psiphiK(0)(S), B0 --> J/psiphi, B0 --> J/psieta, and B0 --> J/psieta' using 56 x 10(6) B(-)B events collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II e(+)e(-) asymmetric-energy storage ring. We measure the branching fractions B(B+ --> J/psiphiK+)=(4.4+/-1.4(stat)+/-0.5(syst))x 10(-5) and B(B0 --> J/psiphiK(0)(S))=(5.1+/-1.9(stat)+/-0.5(syst))x 10(-5), and set upper limits at 90% confidence level for the branching fractions B(B0 --> J/psiphi)<9.2 x 10(-6), B(B0 --> J/psieta)<2.7 x 10(-5), and B(B0 --> J/psieta')<6.3 x 10(-5).

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Study of time-dependent CP asymmetry in neutral B decays to J/psi pi0.

We present the first study of the time-dependent CP-violating asymmetry in B0-->J/psi pi(0) decays using e(+)e(-) annihilation data collected with the BABAR detector at the Upsilon(4S) resonance during the years 1999-2002 at the PEP-II asymmetric-energy B Factory at SLAC. Using approximately 88 x 10(6) BB; pairs, our results for the coefficients of the cosine and sine terms of the CP asymmetry are C(J/psi pi(0))=0.38+/-0.41(stat)+/-0.09(syst) and S(J/psi pi(0))=0.05+/-0.49(stat)+/-0.16(syst).

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Measurements of the branching fractions and bounds on the charge asymmetries of charmless three-body charged B decays.

We present measurements of branching fractions and charge asymmetries for charmless B-meson decays to three-body final states of charged pions and kaons. The analysis uses 81.8 fb(-1) of data collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC PEP-II asymmetric B Factory. We measure the branching fractions B(B+-->pi(+)pi(-)pi(+))=(10.9+/-3.3+/-1.6)x10(-6), B(B+-->K+pi(-)pi(+))=(59.1+/-3.8+/-3.2)x10(-6), and B(B+-->K+K-K+)=(29.6+/-2.1+/-1.6)x10(-6) and provide 90% C.L. upper limits for other decays. We observe no charge asymmetries for these modes.

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Observation of the decay B+/--->pi+/-pi0, study of B+/--->K+/-pi0, and search for B0-->pi0pi0.

We present results for the branching fractions and charge asymmetries in B+/--->h(+/-)pi(0) (where h(+/-)=pi(+/-),K+/-) and a search for the decay B0-->pi(0)pi(0) using a sample of approximately 88 x 10(6) BBmacr; pairs collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We measure B(B+/--->pi(+/-)pi(0))=(5.5(+1.0)(-0.9)+/-0.6)x10(-6), where the first error is statistical and the second is systematic. The B+/--->pi(+/-)pi(0) signal has a significance of 7.7sigma including systematic uncertainties. We simultaneously measure the K+/-pi(0) branching fraction to be B(B+/--->K+/-pi(0))=(12.8(+1.2)(-1.1)+/-1.0)x10(-6). The charge asymmetries are Api(+/-)(pi(0))=-0.03(+0.18)(-0.17)+/-0.02 and AK+/-(pi(0))=-0.09+/-0.09+/-0.01. We place a 90% confidence-level upper limit on the branching fraction B(B0-->pi(0)pi(0)) of 3.6 x 10(-6).

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Evidence for B+-->J/psip(-)Lambda; and search for B0-->J/psip(-)p.

We have performed a search for the decays B+-->J/psip(-)Lambda; and search for B0-->J/psip(-)p. in a data set of (88.9+/-1.0) x 10(6) Upsilon(4S) decays collected by the BABAR experiment at the PEP-II e(+)e(-) storage ring at the Stanford Linear Accelerator Center. Four charged B candidates have been observed with an expected background of 0.21+/-0.14 events. The corresponding branching fraction is (12(+9)(-6)) x 10(-6), where statistical and systematic uncertainties have been combined. The result can be interpreted as a 90% confidence level (C.L.) upper limit of 26 x 10(-6). We also find one B0 candidate, with an expected background of 0.64+/-0.17 events, implying a 90% C.L. upper limit of 1.9 x 10(-6).

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Measurement of the branching fraction, and bounds on the CP-violating asymmetries, of neutral B decays to D*+/- D-/+.

We present measurements of the branching fraction and CP-violating asymmetries for neutral B decays to D(*+/-)D-/+. The measurement uses a data sample of approximately 88x10(6) Upsilon(4S)-->BBmacr; decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy e(+)-e(-) collider. By fully reconstructing the D(*+/-)D-/+ decay products, we measure the branching fraction to be (8.8+/-1.0+/-1.3)x10(-4) and the time-integrated CP-violating asymmetry between the rates to D(*-)D+ and D(*+)D- to be A=-0.03+/-0.11+/-0.05. We also measure the time-dependent CP-violating asymmetry parameters to be S(-+)=-0.24+/-0.69+/-0.12, C(-+)=-0.22+/-0.37+/-0.10 for B-->D(*-)D+ and S(+-)=-0.82+/-0.75+/-0.14, C(+-)=-0.47+/-0.40+/-0.12 for B-->D(*+)D-. In each case, the first error is statistical and the second error is systematic.

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Study of the rare decays B0-->D((*)+)(s)pi(-) and B0-->D((*)-)(s)K+.

We report evidence for the decays B0-->D(+)(s)pi(-) and B0-->D(-)(s)K+ and the results of a search for B0-->D(*+)(s)pi(-) and B0-->D(*-)(s)K+ in a sample of 84 x 10(6) upsilon(4S) decays into BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) storage ring. We measure the branching fractions B(B0-->D(+)(s)pi(-))=[3.2+/-0.9(stat)+/-1.0(syst)] x 10(-5) and B(B0-->D(-)(s)K+)=[3.2+/-1.0(stat)+/-1.0(syst)] x 10(-5). We also set 90% C.L. limits B(B0-->D(*+)(s)pi(-))<4.1 x 10(-5) and B(B0-->D(*-)(s)K+)<2.5 x 10(-5).

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Measurement of the Cabibbo-Kobayashi-Maskawa matrix element V(ub) with B-->rhoenu decays.

We present a measurement of the branching fraction for the rare decays B-->rhoenu and extract a value for the magnitude of V(ub), one of the smallest elements of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix. The results are given for five different calculations of form factors used to para-metrize the hadronic current in semileptonic decays. Using a sample of 55 x 10(6) BB meson pairs recorded with the BABAR detector at the PEP-II e(+)e(-) storage ring, we obtain B(B0-->rho(-)e(+)nu)=(3.29+/-0.42+/-0.47+/-0.55) x 10(-4) and |V(ub)|=(3.64+/-0.22+/-0.25(+0.39)(-0.56)) x 10(-3), where the uncertainties are statistical, systematic, and theoretical, respectively.

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Measurement of the B0-->J/psipi+pi- branching fraction.

We present a measurement of the branching fraction for the decay of the neutral B meson into the final state J/psipi(+)pi(-). The data set contains approximately 56 x 10(6) BB pairs produced at the Upsilon(4S) resonance and recorded with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) storage ring. The result of this analysis is B(B0-->J/psipi(+)pi(-))=(4.6+/-0.7+/-0.6) x 10(-5), where the first error is statistical and the second is systematic. In addition, we measure B(B0-->J/psirho(0))=(1.6+/-0.6+/-0.4) x 10(-5).

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Measurements of branching fractions and CP-violating asymmetries in B0-->pi+pi-, K+pi-, K+K- decays.

We present measurements of branching fractions and CP-violating asymmetries for two-body neutral B meson decays to charged pions and kaons based on a sample of about 88x10(6) Upsilon(4S)-->BB decays. From a time-independent fit we measure the charge-averaged branching fractions B(B0-->pi+pi-)=(4.7+/-0.6+/-0.2)x10(-6), B(B0-->K+pi-)=(17.9+/-0.9+/-0.7)x10(-6), and the direct CP-violating charge asymmetry A(Kpi)=-0.102+/-0.050+/-0.016 [-0.188,-0.016], where the ranges in square brackets indicate the 90% confidence intervals. From a time-dependent fit we measure the B0-->pi+pi- CP-violating parameters S(pipi)=0.02+/-0.34+/-0.05 [-0.54,+0.58] and C(pipi)=-0.30+/-0.25+/-0.04 [-0.72,+0.12].

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