Biomedical subjects

R-S Lu

Publications and source records attributed to R-S Lu.

15 recordsLinked to original sources

PubMed2003

Studies of the decay B+/- -->D(CP)K+/-.

We report studies of the Cabibbo-suppressed decay B+/--->D(CP)K+/-, where D(CP) denotes CP eigenstates of the D0-D0; system. The analysis is based on a 29.1 fb(-1) sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) storage ring. We measure ratios of branching fractions, relative to Cabibbo-favored B+/--->D(CP)pi(+/-), of B(B--->D1K-)/B(B--->D1pi(-))=0.125+/-0.036+/-0.010 and B(B--->D2K-)/B(B--->D2pi(-))=0.119+/-0.028+/-0.006; the index 1 (2) denotes the CP=+1 (-1) eigenstate. We also extract the partial rate asymmetries for B+/--->D(CP)K+/-, finding A(1)=0.29+/-0.26+/-0.05 and A(2)=-0.22+/-0.24+/-0.04.

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PubMed2003

Observation of the decay B0-->lambda+cp.

We report the measurement of the charmed baryonic decay B(0)-->Lambda(+)(c)p with a branching fraction of (2.19(+0.56)(-0.49)+/-0.32+/-0.57)x10(-5) and a statistical significance of 5.8 sigma. The errors are statistical, systematic, and the error of the Lambda(+)(c)-->pK(-)pi(+) decay branching fraction. This is the first observation of a two-body baryonic B decay. The analysis is based on 78.2 fb(-1) of data accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) collider.

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PubMed2003

Measurement of branching fractions for B-->eta(c)K(*) decays.

We report measurements of branching fractions for charged and neutral B-->eta(c)K decays where the eta(c) meson is reconstructed in the K(0)(S)K+/-pi(-/+), K+K-pi(0), K(*0)K-pi(+), and pp; decay channels. The neutral B0 channel is a CP eigenstate and can be used to measure the CP violation parameter sin(2phi(1). We also report the first observation of the B0-->eta(c)K(*0) mode. The results are based on an analysis of 29.1 fb(-1) of data collected by the Belle detector at KEKB.

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PubMed2003

Measurement of the electroweak penguin process B-->X(s)l+l-.

We report the first measurement of the branching fraction for the inclusive decay B-->X(s)l(+)l(-), where l is either an electron or a muon, and X(s) is a hadronic recoil system that contains an s quark. We analyzed a data sample of 65.4 x 10(6) B meson pairs collected with the Belle detector at the KEKB e(+)e(-) asymmetric-energy collider. We find B(B-->X(s)l(+)l(-))=[6.1 +/-1.4(stat) +1.4-1.1(syst)] x 10(-6) for dilepton masses greater than 0.2 GeV/c(2).

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PubMed2002

Measurement of the B(0)-B(0) mixing parameter Deltam(d) using semileptonic B0 decays.

We present a measurement of the B0-Bmacr;(0) mixing parameter Deltam(d) using neutral B meson pairs in a 29.1 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We exclusively reconstruct one neutral B meson in the semileptonic B0-->D(*-)l(+)nu decay mode and identify the flavor of the accompanying B meson from its decay products. From the distribution of the time intervals between the two flavor-tagged B meson decay points, we obtain Deltam(d)=(0.494+/-0.012+/-0.015) ps(-1), where the first error is statistical and the second error is systematic.

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PubMed2002

Observation of D+(s)K- and evidence for D+(s)pi- final states in neutral B decays.

We report the first observation of a B meson decay that is not accessible by a direct spectator process. The channel B(0)-->D(+)(s)K- is found in a sample of 85 x 10(6) BB; events, collected with the Belle detector at KEKB, with a branching fraction B(B(0)-->D(+)(s)K-)=(4.6(+1.2)(-1.1)+/-1.3) x 10(-5). We also obtain evidence for the B0-->D(+)(s)pi(-) decay with branching fraction B(B0-->D(+)(s)pi(-))=(2.4(+1.0)(-0.8)+/-0.7) x 10(-5). This value may be used to extract a model-dependent value of |V(ub)|.

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PubMed2002

Radiative B meson decays into kpigamma and kpipigamma final states.

We report observations of radiative B meson decays into the K+pi(-)gamma and K+pi(-)pi(+)gamma final states. In the B0-->K+pi(-)gamma channel, we present evidence for decays via an intermediate tensor meson state with a branching fraction of B(B0-->K(*)(2)(1430)(0)gamma)=[1.3+/-0.5(stat)+/-0.1(syst)]x10(-5). We measure the branching fraction B(B+-->K+pi(-)pi(+)gamma)=[2.4+/-0.5(stat) +0.4-0.2(syst)]x10(-5), in which the B+-->K(*0)pi(+)gamma and B+-->K+rho(0)gamma channels dominate. The analysis is based on a data set of 29.4 fb(-1) recorded by the Belle experiment at the KEKB collider.

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PubMed2002

Observation of B+/- -->omegaK+/- decay.

We report the first observation of the charmless two-body mode B+/--->omegaK+/- decay, and a new measurement of the branching fraction for the B+/--->omegapi(+/-) decay. The measured branching fractions are B(B+/--->omegaK+/-)=(9.2(+2.6)(-2.3)+/-1.0)x10(-6) and B(B+/--->omegapi(+/-))=(4.2(+2.0)(-1.8)+/-0.5)x10(-6). We also measure the partial rate asymmetry of B+/--->omegaK+/- decays and obtain A(CP)=-0.21+/-0.28+/-0.03. The results are based on a data sample of 29.4 fb(-1) collected on the Upsilon(4S) resonance by the Belle detector at the KEKB e(+)e(-) collider.

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PubMed2002

Observation of B(0)-->D((*)0)pp.

The B meson decay modes B-->Dpp; and B-->D(*)pp; have been studied using 29.4 fb(-1) of data collected with the Belle detector at KEKB. The B;(0)-->D(0)pp; and B;(0)-->D(*0)pp; decays have been observed for the first time with branching fractions B(B;(0)-->D(0)pp;)=(1.18+/-0.15+/-0.16)x10(-4) and B(B;(0)-->D(*0)pp;)=(1.20(+0.33)(-0.29)+/-0.21)x10(-4). No signal has been found for the B+-->D(+)pp; and B+-->D(*+)pp; decay modes, and the corresponding upper limits at 90% C.L. are presented.

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PubMed2002

Observation of double cć production in e+e- annihilation at squareroot[s] approximately 10.6 GeV.

We report the observation of prompt J/psi via double cc; production from the e+e- continuum. In this process one cc; pair fragments into a J/psi meson while the remaining pair either produces a charmonium state or fragments into open charm. Both cases have been experimentally observed. We find cross sections of sigma[e+e- -->J/psieta(c)(gamma)]xB(eta(c)-->>or=4 charged)=(0.033(+0.007)(-0.006)+/-0.009) pb and sigma(e+e- -->J/psiD(*+)X)=(0.53(+0.19)(-0.15)+/-0.14) pb and infer sigma(e+e- -->J/psicc;)/sigma(e+e- -->J/psiX)=0.59(+0.15)(-0.13)+/-0.12. These results are obtained from a 46.2 fb(-1) data sample collected near the Upsilon(4S) resonance, with the Belle detector at the KEKB collider.

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PubMed2002

Observation of the eta(c)(2S) in Exclusive B-->KK(S)K-pi(+) Decays.

We report the observation of a narrow peak in the K(S)K-pi(+) invariant mass distribution in a sample of exclusive B-->KK(S)K-pi(+) decays collected with the Belle detector at the KEKB asymmetric e(+)e(-) collider. The measured mass of the peak is M=3654+/-6(stat)+/-8(syst) MeV/c(2), and we place a 90% confidence level upper limit on the width of Gamma<55 MeV/c(2). The properties agree with heavy-quark potential model expectations for the eta(c)(2S) meson, the n=2 singlet S charmonium state.

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PubMed2002

Observation of the color-suppressed decay B( 0)-->D(0)pi(0).

We report the first observation of color-suppressed B( 0)-->D(0)pi(0), D(*0)pi(0), D0eta, and D0omega decays, and evidence for B( 0)-->D(*0)eta and D(*0)omega. The branching fractions are B(B( 0)-->D0pi(0)) = (3.1 +/- 0.4 +/- 0.5)x10(-4), B(B( 0) -->D(*0)pi(0)) = (2.7(+0.8+0.5)(-0.7-0.6))x10(-4), B(B( 0) --> D0eta) = (1.4(+0.5)(-0.4) +/- 0.3)x10(-4), B(B( 0) --> D0omega) = (1.8 +/- 0.5(+0.4)(-0.3))x10(-4), and we set 90% confidence level upper limits of B(B( 0) --> D(*0)eta)<4.6 x 10(-4) and B(B( 0)-->D(*0)omega)<7.9 x 10(-4). The analysis is based on a data sample of 21.3 fb(-1) collected at the Upsilon(4S) resonance by the Belle detector at the KEKB e(+)e(-) collider.

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PubMed2002

Production of prompt charmonia in e(+)e(-) annihilation at square root of s approximately equals 0.6 GeV.

The production of prompt J/psi, psi(2S), chi(c1), and chi(c2) is studied using a 32.4 fb(-1) data sample collected with the Belle detector at Upsilon(4S) and at 60 MeV below the resonance. The yield of prompt J/psi mesons in the Upsilon(4S) sample is compatible with that of continuum production; we set an upper limit B(Upsilon(4S)-->J/psiX) < 1.9 x 10(-4) at the 95% confidence level, and find sigma(e(+)e(-)-->J/psiX) = 1.47 plus/minus 0.10 plus/minus 0.13 pb. The cross sections for prompt psi(2S) and direct J/psi are measured. The J/psi momentum spectrum, production angle distribution, and polarization are studied.

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PubMed2002

Observation of B+ --> chi(c0)K+.

Using a sample of 31.3x10(6) BB pairs collected with the Belle detector at the Upsilon(4S) resonance, we make the first observation of the charged B meson decay to chi(c0) and a charged kaon. The measured branching fraction is B(B+-->chi(c0)K+) = (6.0(+2.1)(-1.8)+/-1.1)x10(-4), where the first error is statistical, and the second is systematic.

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PubMed2001

Observation of the decay B --> Kl+l-.

We report a search for the flavor-changing neutral current decay B-->K(*)l+l- using a 29.1 fb(-1) data sample accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- storage ring. We observe the decay process B-->Kl+l-(l = e, mu), for the first time, with a branching fraction of B(B-->Kl+l-) = (0.75(+0.25)(-0.21)+/-0.09)x10(-6).

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