Biomedical subjects

V Aulchenko

Publications and source records attributed to V Aulchenko.

At least 37 records · Page 2Linked to original sources

PubMed2004

Evidence for direct CP violation in B0-->K+pi- decays.

We report evidence for direct CP violation in the decay B0-->K+pi(-) with 253 fb(-1) of data collected with the Belle detector at the KEKB e(+)e(-) collider. Using 275x10(6) BB pairs we observe a B-->K+/-pi(-/+) signal with 2140+/-53 events. The measured CP violating asymmetry is A(CP)(K+pi(-))=-0.101+/-0.025(stat)+/-0.005(syst), corresponding to a significance of 3.9sigma including systematics. We also search for CP violation in the decays B+-->K+pi(0) and B+-->pi(+)pi(0). The measured CP violating asymmetries are A(CP)(K+pi(0))=0.04+/-0.05(stat)+/-0.02(syst) and A(CP)(pi(+)pi(0))=-0.02+/-0.10(stat)+/-0.01(syst), corresponding to the intervals -0.05<A(CP)(K+pi(0))<0.13 and -0.18<A(CP)(pi(+)pi(0))<0.14 at 90% confidence level.

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PubMed2004

Evidence for B0-->rho0pi0.

We present the first evidence of the decay B0-->rho(0)pi(0), using 140 fb(-1) of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) collider. We detect 15.1+/-4.8 signal events with a significance of 3.5 standard deviations and measure the branching fraction to be B(B0-->rho(0)pi(0))=(5.1+/-1.6(stat)+/-0.9(syst))x10(-6).

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PubMed2004

Search for the lepton-flavor-violating decay tau- -->micro-eta at Belle.

We have searched for the lepton flavor violating decay tau(-)-->micro(-)eta using a data sample of 84.3 fb(-1) accumulated with the Belle detector at KEK. The eta meson was detected through the decay modes: eta-->gammagamma and pi(+)pi(-)pi(0). No signal candidates are found, and we obtain an upper limit for the branching fraction B(tau(-)-->micro(-)eta)<3.4 x 10(-7) at the 90% confidence level.

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PubMed2004

Inclusive measurement of the photon energy spectrum in b --> sgamma decays.

We report a fully inclusive measurement of the flavor changing neutral current decay b --> sgamma in the energy range 1.8 GeV < or = E*gamma < or = 2.8 GeV, covering 95% of the total spectrum. Using 140 fb(-1), we obtain B(b --> sgamma) = (3.55+/-0.32(+0.30+0.11)(-0.31-0.07)) x 10(-4), where the errors are statistical, systematic, and from theory corrections. We also measure the first and second moments of the photon energy spectrum above 1.8 GeV and obtain (Egamma) = 2.292+/-0.026+/-0.034 GeV and (E2gamma) - (Egamma)2 = 0.0305+/-0.0074+/-0.0063 GeV2, where the errors are statistical and systematic.

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PubMed2004

Study of CP violating effects in time dependent B0(B0)-->D(*)-/+pi+/- decays.

We report measurements of time dependent decay rates for B0(B(0))-->D((*)-/+)pi(+/-) decays and extraction of CP violation parameters containing phi(3). Using fully reconstructed D((*))pi events from a 140 fb(-1) data sample collected at the Upsilon(4S) resonance, we obtain the CP violation parameters for D(*)pi and Dpi decays, 2R(D((*))pi)sin((2phi(1)+phi(3)+/-delta(D((*))pi)), where R(D((*))pi) is the ratio of the magnitudes of the doubly Cabibbo-suppressed and Cabibbo-favored amplitudes, and delta(D((*))pi) is the strong phase difference between them. Under the assumption of delta(D((*))pi) being close to either 0 degrees or 180 degrees, we obtain |2R(D(*)pi)sin((2phi(1)+phi(3))|=0.060+/-0.040(stat)+/-0.019(syst) and |2R(Dpi)sin((2phi(1)+phi(3))|=0.061+/-0.037(stat)+/-0.018(syst).

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PubMed2004

Observation of large CP violation and evidence for direct CP violation in B0-->pi(+)pi(-) decays.

We report the first observation of CP violation in B0-->pi(+)pi(-) decays based on 152x10(6) gamma (4S)-->BB decays collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We reconstruct a B0-->pi(+)pi(-) CP eigenstate and identify the flavor of the accompanying B meson from its decay products. From the distribution of the time intervals between the two B meson decay points, we obtain A(pipi)=+0.58+/-0.15(stat)+/-0.07(syst) and S(pipi)=-1.00+/-0.21(stat)+/-0.07(syst). We rule out the CP-conserving case, A(pipi)=S(pipi)=0, at a level of 5.2 standard deviations. We also find evidence for direct CP violation with a significance at or greater than 3.2 standard deviations for any S(pipi) value.

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PubMed2004

Upper bound on the decay tau-->microgamma from the Belle detector.

We have performed a search for the lepton-flavor-violating decay tau-->microgamma using a data sample of 86.3 fb(-1) accumulated by the Belle detector at KEK. No evidence for a signal is seen, and we set an upper limit for the branching fraction of B(tau-->microgamma)<3.1 x 10(-7) at the 90% confidence level.

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PubMed2004

Observation of B(+)-->pppi+, B0-->ppK0, and B(+)-->ppK(*+).

We report the first observation of a b-->u type charmless baryonic B decay, B+-->pppi(+), as well as b-->s type B0-->ppK0 and B+-->ppK(*+) decays. The analysis is based on a 78 fb(-1) data sample recorded on the Upsilon(4S) resonance with the Belle detector at KEKB. We find B(B+-->pppi(+))=(3.06(+0.73)(-0.62)+/-0.37)x10(-6), B(B0-->ppK0)=(1.88(+0.77)(-0.60)+/-0.23)x10(-6), and B(B+-->ppK(*+))=(10.3(+3.6+1.3)(-2.8-1.7))x10(-6). We also update B(B+-->ppK+)=(5.66(+0.67)(-0.57)+/-0.62)x10(-6) and present an upper limit on B(B0-->ppK(*0)) at the 90% confidence level. A common feature of the observed decay modes is threshold peaking in baryon pair invariant mass.

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PubMed2004

Observation of the radiative decay D0-->phigamma.

We report the observation of the decay D0-->phigamma with a statistical significance of 5.4sigma in 78.1 fb(-1) of data collected by the Belle experiment at the KEKB e+e- collider. This is the first observation of a flavor-changing radiative decay of a charmed meson. The Cabibbo- and color-suppressed decays D0-->phipi(0), phieta are also observed for the first time. We measure branching fractions B(D0-->phigamma)=[2.60(+0.70)(-0.61)(stat)+0.15-0.17(syst)] x 10(-5), B(D0-->phipi(0))=[8.01+/-0.26(stat)+/-0.47(syst)] x 10(-4), and B(D0-->phieta)=[1.48+/-0.47(stat)+/-0.09(syst)] x 10(-4).

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PubMed2004

Measurement of /V(ub)/ using inclusive B-->X(u)lnu decays with a novel X(u)-reconstruction method.

We report the measurement of an inclusive partial branching fraction for charmless semileptonic B decay and the extraction of /V(ub)/. Candidates for B-->X(u)lnu are identified with a novel X(u) reconstruction method based on neutrino reconstruction via missing 4-momentum and a technique called "simulated annealing." Based on 86.9 fb(-1) of data taken with the Belle detector, we obtain DeltaB(B-->X(u)lnu;M(X)<1.7 GeV/c2,q2>8.0 GeV2/c2)=[7.37+/-0.89(stat)+/-1.12(syst)+/-0.55(b-->c)+/-0.24(b-->u)]x10(-4) and determine |V(ub)|=[4.66+/-0.28(stat)+/-0.35(syst)+/-0.17(b-->c)+/-0.08(b-->u)+/-0.58(theory)]x10(-3).

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PubMed2004

Observation of radiative B-->phi K gamma decays.

The radiative decay B-->phi K gamma is observed for the first time. The branching fraction for the charged B--->phi K- gamma decay mode is measured to be B(B--->phi K- gamma)=(3.4+/-0.9+/-0.4)x10(-6). The photon energy distribution for the B--->phi K- gamma decay is presented. The signal for the neutral B(0)-->phi K(0)gamma decay mode is not statistically significant and an upper limit, B(B(0)-->phi K(0)gamma)<8.3x10(-6) at 90% C.L., is set. The analysis is based on a data set of 90 fb(-1) collected by the Belle experiment at the e(+)e(-) asymmetric collider KEKB.

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PubMed2003

Observation of B-->K*l+l-.

We report the observation of the flavor-changing neutral current decay B-->K(*)l(+)l(-) and an im-proved measurement of the decay B-->Kl(+)l(-), where l represents an electron or a muon, with a data sample of 140 fb(-1) accumulated at the Upsilon(4S) resonance with the Belle detector at KEKB. The results for the branching fractions are B(B-->K(*)l(+)l(-))=(11.5(+2.6)(-2.4)+/-0.8+/-0.2)x10(-7) and B(B-->Kl(+)l(-))=(4.8(+1.0)(-0.9)+/-0.3+/-0.1)x10(-7), where the first error is statistical, the second is systematic and the third is from model dependence.

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PubMed2003

Evidence for B0-->pi0pi0.

We report evidence for the decay B0-->pi(0)pi(0). The analysis is based on a data sample of 152x10(6) BBmacr; pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) storage ring. We detect a signal for B0-->pi(0)pi(0) with a significance of 3.4 standard deviations, and measure the branching fraction to be [1.7+/-0.6(stat)+/-0.2(syst)]x10(-6).

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PubMed2003

Observation of a narrow charmoniumlike state in exclusive B+/--->K+/-pi+pi-J/psi decays.

We report the observation of a narrow charmoniumlike state produced in the exclusive decay process B+/--->K+/-pi(+)pi(-)J/psi. This state, which decays into pi(+)pi(-)J/psi, has a mass of 3872.0+/-0.6(stat)+/-0.5(syst) MeV, a value that is very near the M(D0)+M(D(*0)) mass threshold. The results are based on an analysis of 152M B-Bmacr; events collected at the Upsilon(4S) resonance in the Belle detector at the KEKB collider. The signal has a statistical significance that is in excess of 10sigma.

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PubMed2003

Evidence for B-->phiphiK.

We report evidence for the decay mode B-->phiphiK based on an analysis of 78 fb(-1) of data collected with the Belle detector at KEKB. This is the first example of a b-->sssss transition. The branching fraction for this decay is measured to be B(B+/--->phiphiK+/-)=(2.6(+1.1)(-0.9)+/-0.3)x10(-6) for a phiphi invariant mass below 2.85 GeV/c(2). Results for other related charmonium decay modes are also reported.

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PubMed2003

Observation of B-/+-->rho-/+rho0 decays.

We report the first observation of the charmless vector-vector decay process B-/+-->rho(-/+)rho(0). The measurement uses a 78 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric e(+)e(-) collider operating at the Upsilon(4S) resonance. We obtain a branching fraction of B(B-/+-->rho(-/+)rho(0))=[31.7+/-7.1(stat)+3.8-6.7(syst)]x10(-6). An analysis of the rho helicity-angle distributions gives a longitudinal polarization fraction of Gamma(L)/Gamma=0.95+/-0.11(stat)+/-0.02(syst). We also measure the direct-CP-violating asymmetry A(CP)(B-/+-->rho(-/+)rho(0))=0.00+/-0.22(stat)+/-0.03(syst).

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PubMed2003

Observation of B0 -->D0K0 and B0 -->D0K*0 decays.

We report on a search for B(0)-->D(*0)K(*0) decays based on 85 x 10(6) BB events collected with the Belle detector at KEKB. The B(0)-->D0K(0) and B(0)-->D0K(*0) decays have been observed for the first time with the branching fractions B(B(0)-->D0K(0))=(5.0(+1.3)(-1.2)+/-0.6)x10(-5) and B(B(0)-->D0K(*0))=(4.8(+1.1)(-1.0)+/-0.5)x10(-5). No significant signal has been found for the B(0)-->D(*0)K*0) and B(0)-->D(*0)K(*0) decay modes, and upper limits at 90% C.L. are presented.

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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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