0000000000048447
AUTHOR
C. Yeche
Measurement of theB0→K2*(1430)0γandB+→K2*(1430)+γbranching fractions
We have investigated the exclusive, radiative B meson decays to K2*(1430) in 89* 10^6 BBbar events with the BaBar detector at the PEP-II storage ring. We measure the branching fractions BR(B0 -> K2*(1430)0 gamma) = (1.22 +-0.25 +-0.10)*10^(-5) and BR(B+ -> K2*(1430)+ gamma) = (1.45 +-0.40 +-0.15) * 10^(-5), where the first error is statistical and the second systematic. In addition, we measure the CP-violating asymmetry ACP(B0 -> K2*(1430)0 gamma) = -0.08 +- 0.15 +- 0.01.
Observation of an Excited Charm BaryonΩc*Decaying toΩc0γ
We report the first observation of an excited singly-charm baryon OmegaC* (css) in the radiative decay OmegaC0 Gamma, where the OmegaC0 baryon is reconstructed in the decays to the final states Omega-pi+, Omega-pi+pi0, Omega-pi+pi-pi+, and Cascade-K-pi+pi+. This analysis is performed using a dataset of 230.7 fb$-1} collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The mass difference between the OmegaC* and the OmegaC0 baryons is measured to be 70.8 +/- 1.0 (stat) +/- 1.1 (syst) MeV/c2. We also measure the ratio of inclusive production cross sections of OmegaC* and OmegaC0 in e+e- annihilation.
Limit on theB0→ρ0ρ0Branching Fraction and Implications for the Cabibbo-Kobayashi-Maskawa Angleα
The authors search for the decay B{sup 0} {yields} {rho}{sup 0}{rho}{sup 0} in a data sample of about 227 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC. They find no significant signal and set an upper limit of 1.1 x 10{sup -6} at 90% CL on the branching fraction. As a result, the uncertainty due to penguin contributions on the CKM unitarity angle {alpha} measured in B {yields} {rho}{rho} decays is 11{sup o} at 68% CL.
Measurement of the Inclusive Charmless Semileptonic Branching Ratio ofBMesons and Determination of|Vub|
We report a measurement of the inclusive charmless semileptonic branching fraction of B mesons in a sample of 89 x 10(6) (-)BB events recorded with the BABAR detector at the Upsilon(4S) resonance. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson. The number of signal events is extracted from the mass distribution of the hadronic system accompanying the lepton and is used to determine the ratio of branching fractions B((-)B-->X(u)lnu;)/B((-)B-->Xlnu;)=[2.06+/-0.25(stat)+/-0.23(syst)+/-0.36(theo)]x10(-2). Using the measured branching fraction for inclusive semileptonic B decays, we find B((-)B-->X(u)lnu;)…
Search for flavor-changing neutral current and lepton-flavor violating decays of D-0 -> l(+)l(-)
We report on a search for the flavor-changing neutral current decays $\Dz\to e^+e^-$ and $\Dz\to\mu^+\mu^-$, and the lepton-flavor violating decay $\Dz\to e^\pm\mu^\mp$. The measurement is based on $122 {fb}^{-1}$ of data collected by the \babar detector at the PEP-II asymmetric $e^+e^-$ collider. No evidence is found for any of the decays. The upper limits on the branching fractions, at the 90 % confidence level, are $1.2\times 10^{-6}$ for $\Dz\to e^+e^-$, $1.3\times 10^{-6}$ for $\Dz\to\mu^+\mu^-$, and $8.1\times 10^{-7}$ for $\Dz\to e^\pm\mu^\mp$.
Measurement of the Spin of the Ω− Hyperon
A measurement of the spin of the Omega(-) hyperon produced through the exclusive process Xi(c)(0)--Omega(-)K(+) is presented using a total integrated luminosity of 116 fb(-1) recorded with the BABAR detector at the e(+)e(-) asymmetric-energy B factory at SLAC. Under the assumption that the Xi(c)(0) has spin 1/2, the angular distribution of the Lambda from Omega(-)--LambdaK(-) decay is inconsistent with all half-integer Omega(-) spin values other than 3/2. Lower statistics data for the process Omega(c)(0)--Omega(-)pi(+) from a 230 fb(-1) sample are also found to be consistent with Omega(-) spin 3/2. If the Xi(c)(0) spin were 3/2, an Omega(-) spin of 5/2 could not be excluded.
Search for the Radiative DecaysB→ργandB0→ωγ
A search for the exclusive radiative decays B {yields} {rho}(770){gamma} and B{sup 0} {yields} {omega}(782){gamma} is performed on a sample of about 84 million B{bar B} events collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} storage ring. No significant signal is seen in any of the channels. We set upper limits on the branching fractions {Beta} of {Beta}(B{sup 0} {yields} {rho}{sup 0}{gamma}) < 1.2 x 10{sup -6}, {Beta}(B{sup +} {yields} {rho}{sup +}{gamma}) < 2.1 x 10{sup -6}, and {Beta}(B{sup 0} {yields} {omega}{gamma}) < 1.0 x 10{sup -6} at 90% confidence level (C.L.). Using the assumption that {Lambda}(B {yields} {rho}{gamma}) = {Lambda}(B{sup +} {yields} …
Branching fraction measurements ofB→ηcKdecays
We study the decays B{sup +} {yields} {eta}{sub c}K{sup +} and B{sup 0} {yields} {eta}{sub c}K{sup 0}, where the {eta}{sub c} is reconstructed in the K{sub S}{sup 0} K{sup {+-}} {pi}{sup {-+}} and K{sup +}K{sup -} {pi}{sup 0} decay modes. Results are based on a sample of 86 million B{bar B} pairs collected with the BABAR detector at the SLAC e{sup +}e{sup -} B Factory. We measure the branching fractions {Beta}(B{sup +} {yields} {eta}{sub c}K{sup +}) = (1.34 {+-} 0.09 {+-} 0.13 {+-} 0.41) x 10{sup -3} and {Beta}(B{sup 0} {yields} {eta}{sub c}K{sup 0}) = (1.18 {+-} 0.16 {+-} 0.13 {+-} 0.37) x 10{sup -3}, where the first error is statistical, the second is systematic, and the third reflects th…
Measurement of theB→Xsℓ+ℓ−Branching Fraction with a Sum over Exclusive Modes
We present a preliminary measurement of time-dependent We measure the branching fraction for the flavor-changing neutral-current process B -> Xs l+ l- with a sample of 89 x 10^6 Upsilon(4S) -> BBbar events recorded with the BaBar detector at the PEP-II e+e- storage ring. The final state is reconstructed from e+e- or mu+mu- pairs and a hadronic system consisting of one K or K0s and up to two pions, with at most one pi0. We observe a signal of 40 +/- 10(stat) +/- 2(syst) events and extract the inclusive branching fraction B(B -> Xs l+ l-) = (5.6 +/- 1.5(stat) +/- 0.6(exp syst) +/- 1.1(model syst)) x 10^-6 for mll > 0.2 GeV/c^2.
Observation ofΥ(4S)Decays toπ+π−Υ(1S)andπ+π−Υ(2S)
We present the first measurement of Υ(4S) decays to π+π-Υ(1S) and π+π-Υ(2S) based on a sample of 230×106Υ(4S) mesons collected with the BABAR detector. We measure the product branching fractions B(Υ(4S)→π+π-Υ(1S))×B(Υ(1S)→μ+μ-)=(2.23±0.25stat±0.27syst)×10-6 and B(Υ(4S)→π+π-Υ(2S))×B(Υ(2S)→μ+μ-)=(1.69±0.26stat±0.20syst)×10-6, from which we derive the partial widths Γ(Υ(4S)→π+π-Υ(1S))=(1.8±0.4) keV and Γ(Υ(4S)→π+π-Υ(2S))=(2.7±0.8) keV.
Search for Radiative Penguin DecaysB+→ρ+γ,B0→ρ0γ, andB0→ωγ
A search for the decays B {yields} {rho}(770){gamma} and B{sup 0} {yields} {omega}(782) is performed on a sample of 211 million {Upsilon}(4S) {yields} B{bar B} events collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} storage ring. No evidence for the decays is seen. We set the following limits on the individual branching fractions {Beta}(B{sup +} {yields} {rho}{sup +}{gamma}) < 1.8 x 10{sup -6}, {Beta}(B{sup 0} {yields} {rho}{sup 0}{gamma}) < 0.4 x 10{sup -6}, and {Beta}(B{sup 0} {yields} {omega}{gamma}) < 1.0 x 10{sup -6} at the 90% confidence level (C.L.). We use the quark model to limit the combined branching fraction {bar {Beta}}[B {yields} ({rho}/{omega})…
Improved Measurement ofCPAsymmetries inB0→(cc¯)K0(*)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 million $\Upsilon$(4S) $\rightarrow B\overline{B}$ decays collected by the BABAR detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. The amplitude of the CP asymmetry, sin2$\Beta$ 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 $B^0$ or $\overline{B}^0$ from its decay products. We measure sin2$\Beta$ = 0.722 $\pm$ 0.040 (stat.) $\pm$ 0.23 (syst.) in ag…
Limits on the decay-rate difference of neutralBmesons and onCP,T, andCPTviolation inB0B0oscillations
Using events in which one of two neutral-B mesons from the decay of an {Upsilon}(4S) resonance is fully reconstructed, we set limits on the difference between the decay rates of the two neutral-B mass eigenstates and on CP, T, and CPT violation in B{sup 0}{bar B}{sup 0} mixing. The reconstructed decays, comprising both CP and flavor eigenstates, are obtained from 88 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We determine six independent parameters governing oscillations ({Delta}m, {Delta}{Lambda}/{Lambda}), CPT and CP violation (Re z, Im z), and CP and T violation (Im {lambda}{sub CP}, |q/p|), where {la…
Measurement of Branching Fractions and Charge Asymmetries inBDecays to anηMeson and aK*Meson
We present measurements of branching fractions and charge asymmetries for the decays B-->etaK*, where K* indicates a spin 0, 1, or 2 Kpi system. The data sample corresponds to 344x10(6) BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+ e- collider at SLAC. We measure the branching fractions (in units of 10(-6): B(B0-->etaK*0(892))=16.5+/-1.1+/-0.8, B(B+-->etaK*+(892))=18.9+/-1.8+/-1.3, B(B0-->eta(Kpi)0*0)=11.0+/-1.6+/-1.5, B(B+-->eta(Kpi)0*+)=18.2+/-2.6+/-2.6, B(B0-->etaK2*0(1430))=9.6+/-1.8+/-1.1, and B(B+-->etaK2*+(1430))=9.1+/-2.7+/-1.4. We also determine the charge asymmetries for all decay modes.
Search for the DecayB+→K+νν¯
We search for the rare flavor-changing neutral-current decay ${B}^{+}\ensuremath{\rightarrow}{K}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ in a data sample of $82\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected with the BABAR detector at the PEP-II $B$-factory. Signal events are selected by examining the properties of the system recoiling against either a reconstructed hadronic or semileptonic charged-$B$ decay. Using these two independent samples we obtain a combined limit of $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{K}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}})l5.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ at the 90% confidence level. In addition, by…
Measurement of theB→πlνBranching Fraction and Determination of|Vub|with TaggedBMesons
We report a measurement of the B ->pi center dot nu branching fraction based on 211 fb(-1) of data collected with the BABAR detector. We use samples of B-0 and B+ mesons tagged by a second B meson reconstructed in a semileptonic or hadronic decay and combine the results assuming isospin symmetry to obtain B(B-0 ->pi(-)center dot(+)nu)=(1.33 +/- 0.17(stat)+/- 0.11(syst))x10(-4). We determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element vertical bar V-ub vertical bar by combining the partial branching fractions measured in ranges of the momentum transfer squared and theoretical calculations of the form factor. Using a recent lattice QCD calculation, we find vertical bar V-ub …
Observation ofe+e−Annihilation into theC=+1Hadronic Final Statesρ0ρ0andϕρ0
The authors report the first observation of e{sup +}e{sup -} annihilations into states of positive C-parity, namely {rho}{sup 0}{rho}{sup 0} and {phi}{rho}{sup 0}. The two states are observed in the {pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} and K{sup +}K{sup -} {pi}{sup +}{pi}{sup -} final states, respectively, in a data sample of 225 fb{sup -1} collected by the BABAR experiment at the PEP-II e{sup +}e{sup -} storage rings at energies near {radical}s = 10.58 GeV. The distributions of cos {theta}*, where {theta}* is the center-of-mass polar angle of the {phi} meson or the forward {rho}{sup 0} meson, suggest production by two-virtual-photon annihilation. They measure cross sections within …
Search forD0−D¯0mixing using semileptonic decay modes
Based on an 87-fb{sup -1} data set collected by the BABAR detector at the PEP-II asymmetric-energy B Factory, a search for D{sup 0}-D-bar{sup 0} mixing has been made using the semileptonic decay modes D*{sup +}{yields}{pi}{sup +}D{sup 0}, D{sup 0}{yields}K{sup (}*{sup )}e{nu} (+c.c.). The use of these modes allows unambiguous flavor tagging and a combined fit of the D{sup 0} decay time and D*{sup +}-D{sup 0} mass difference ({delta}M) distributions. The high-statistics sample of unmixed semileptonic D{sup 0} decays is used to model the {delta}M distribution and time dependence of mixed events directly from the data. Neural networks are used to select events and reconstruct the D{sup 0}. A r…
Measurement of branching fractions and rate asymmetries in the rare decays B -> K((*))l(+)l(-)
In a sample of 471 million BB events collected with the BABAR detector at the PEP-II e+e- collider we study the rare decays B -> K(*) l+ l-, where l+ l- is either e+e- or mu+mu-. We report results on partial branching fractions and isospin asymmetries in seven bins of di-lepton mass-squared. We further present CP and lepton-flavor asymmetries for di-lepton masses below and above the J/psi resonance. We find no evidence for CP or lepton-flavor violation. The partial branching fractions and isospin asymmetries are consistent with the Standard Model predictions and with results from other experiments.
Study of thee+e−→π+π−π0process using initial state radiation withBABAR
The process e+e- --> pi+ pi- pi0 gamma has been studied at a center-of-mass energy near the Y(4S) resonance using a 89.3 fb-1 data sample collected with the BaBar detector at the PEP-II collider. From the measured 3pi mass spectrum we have obtained the products of branching fractions for the omega and phi mesons, B(omega --> e+e-)B(omega --> 3pi)=(6.70 +/- 0.06 +/- 0.27)10-5 and B(phi --> e+e-)B(phi --> 3pi)=(4.30 +/- 0.08 +/- 0.21)10-5, and evaluated the e+e- --> pi+ pi- pi0 cross section for the e+e- center-of-mass energy range 1.05 to 3.00 GeV. About 900 e+e- --> J/psi gamma --> pi+ pi- pi0 gamma events have been selected and the branching fraction B(J/psi --> pi+ pi- pi0)=(2.18 +/- 0.19…
Search forB±→[K∓π±]DK±and Upper Limit on theb→uAmplitude inB±→DK±
We search for B±→[K∓π±]DK± decays, where [K∓π±]D indicates that the K∓π± pair originates from the decay of a D0 or D 0. Results are based on 120×106 Υ(4S)→BB decays collected with the BABAR detector at SLAC. We set an upper limit on the ratio RKπ≡ [Γ(B+→[K-π+]DK+)+Γ(B-→[K+π-]DK-)]/[Γ(B+→[K+π-]DK+)+Γ(B-→[K-π+]DK-)]<0.026 (90% C.L.). This constrains the amplitude ratio rB≡ |A(B-→D 0K-)/A(B-→D0K-)|<0.22 (90% C.L.), consistent with expectations. The small value of rB favored by our analysis suggests that the determination of the Cabibbo-Kobayashi-Maskawa phase γ from B→DK will be difficult.
Study of High Momentumη′Production inB→η′Xs
We measure the branching fraction for the charmless semi-inclusive process B --> eta'Xs, where the eta' meson has a momentum in the range 2.0 to 2.7 GeV/c in the upsilon4S center-of-mass frame and Xs represents a system comprising a kaon and zero to four pions. We find B(B --> eta'Xs) = [3.9 +/- 0.8(stat) +/- 0.5(syst) +/- 0.8(model)] x 10(-4). We also obtain the Xs mass spectrum and find that it fits models predicting high masses.
Measurements ofCP-Violating Asymmetries inB0→Ks0π0Decays
The authors present measurements of CP-violating asymmetries in the decay B{sup 0} {yields} a{sub 1}{sup {+-}}(1260){pi}{sup {-+}} with a{sub 1}{sup {+-}}(1260) {yields} {pi}{sup {-+}}{pi}{sup {+-}}{pi}{sup {+-}}. The data sample corresponds to 384 x 10{sup 6} B{bar B} pairs collected with the BABAR detector at the PEP-II asymmetric B-factory at SLAC. They measure the CP-violating asymmetry {Alpha}{sub CP}{sup a{sub 1}{pi}} = -0.07 {+-} 0.07 {+-} 0.02, the mixing-induced CP violation parameter S{sub a{sub 1}{pi}} = 0.37 {+-} 0.21 {+-} 0.07, the direct Cp violation parameter C{sub a{sub 1}{pi}} = -0.10 {+-} 0.15 {+-} 0.09, and the parameters {Delta}C{sub a{sub 1}{pi}} = 0.26 {+-} 0.15 {+-} 0…
Measurement of Time-DependentCP-Violating Asymmetries inB0→ϕKS0,K+K−KS0, andη′KS0Decays
We present an improved measurement of $CP$-violation parameters in ${B}^{0}\ensuremath{\rightarrow}\ensuremath{\phi}{K}_{S}^{0}$, ${K}^{+}{K}^{\ensuremath{-}}{K}_{S}^{0}$, and ${\ensuremath{\eta}}^{\ensuremath{'}}{K}_{S}^{0}$ decays based on a $140\text{ }{\mathrm{f}\mathrm{b}}^{\ensuremath{-}1}$ data sample collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB energy-asymmetric ${e}^{+}{e}^{\ensuremath{-}}$ collider. One neutral $B$ meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying $B$ meson is identified from its decay products. $CP$-violation parameters for each of the three modes are obtained from…
DirectCPViolating Asymmetry inB0→K+π−Decays
We present an updated search for direct CP violation in the decay B0 -> K+pi-. Using 227 million Y(4S) -> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we observe a total signal yield of n(K-pi+) + n(K+pi-) = 1606 +- 51 decays and measure the asymmetry [n(K-pi+)-n(K+pi-)]/[n(K-p+-)+n(K+pi-)] = -0.133+-0.030 (stat) +- 0.009 (syst). This measurement establishes direct CP violation in the B0 meson system at the level of 4.2 standard deviations.
Measurements of the Absolute Branching Fractions of B± →k±Xc c
A study of the two-body decays B±→XccK±, where Xcc refers to one charmonium state, is reported by the BABAR Collaboration using a data sample of 424 fb-1. The absolute determination of branching fractions for these decays are significantly improved compared to previous BABAR measurements. Evidence is found for the decay B+→X(3872)K+ at the 3σ level. The absolute branching fraction B[B+→X(3872)K+]=[2.1±0.6(stat)±0.3(syst)]×10-4 is measured for the first time. It follows that B[X(3872)→J/ψπ+π-]=(4.1±1.3)%, supporting the hypothesis of a molecular component for this resonance.
Measurements of the Branching Fraction andCP-Violation Asymmetries inB0→f0(980)KS0
The authors present measurements of the branching fraction and CP-violating asymmetries in the decay B{sup 0} {yields} f{sub 0}(980)K{sub S}{sup 0}. The results are obtained from a data sample of 123 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays. From a time-dependent maximum likelihood fit they measure the branching fraction {Beta}(B{sup 0} {yields} f{sub 0}(980)({yields}{Pi}{sup +}{pi}{sup 0})K{sup 0}) = (6.0 {+-} 0.9 {+-} 0.6 {+-} 1.2) x 10{sup -6}, the mixing-induced CP violation parameter S = 1.62{sub -0.51}{sup +0.56} {+-} 0.09 {+-} 0.04 and the direct CP violation parameter C = 0.27 {+-} 0.36 {+-} 0.10 {+-} 0.07, where the first errors are statistical, the second systematic and …
Search forB0Decays to Invisible Final States and toνν¯γ
We establish upper limits on branching fractions for B0 decays to final states where the decay products are purely invisible (i.e., no observable final state particles) and for B0 decays to nunugamma. Within the standard model, these decays have branching fractions that are below current experimental sensitivity, but various models of physics beyond the standard model predict significant contributions from these channels. Using 88.5 x 10(6) BB pairs collected at the Upsilon(4S) resonance by the BABAR experiment at the PEP-II e(+)e- storage ring at the Stanford Linear Accelerator Center, we establish upper limits at the 90% confidence level of 22 x 10(-5) for the branching fraction of B0-->i…
Measurement of the Time-DependentCPAsymmetry in theB0→ϕK0Decay
The authors present a measurement of the time-dependent CP asymmetry for the neutral B-meson decay B{sup 0} {yields} {phi} K{sup 0}. They use a sample of approximately 114 million B-meson pairs taken at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II B-meson Factory at SLAC. They reconstruct the CP eigenstates {phi}K{sub S}{sup 0} and {phi}K{sub L}{sup 0} where {phi} {yields} K{sup +}K{sup -}, K{sub S}{sup 0} {yields} {pi}{sup +}{pi}{sup -}, and K{sub L}{sup 0} is observed via its hadronic interactions. The other B meson in the event is tagged as either a B{sup 0} or {bar B}{sup 0} from its decay products. The values of the CP-violation parameters are S{sub {phi}K} = 0.47 …
Bound on the Ratio of Decay Amplitudes forB¯0→J/ψK*0andB0→J/ψK*0
We have measured the time-dependent decay rate for the process B→J/ψK*0(892) in a sample of about 88×106 Υ(4S)→BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. In this sample we study flavor-tagged events in which one neutral B meson is reconstructed in the J/ψK*0 or J/ψK *0 final state. We measure the coefficients of the cosine and sine terms in the time-dependent asymmetries for J/ψK*0 and J/ψK *0, find them to be consistent with the standard model expectations, and set upper limits at 90% confidence level (C.L.) on the decay amplitude ratios |A(B 0→J/ψK*0)|/|A(B0→J/ψK*0)|<0.26 and |A(B0→J/ψK *0)|/|A(B 0→J/ψK *0)|<0.32. For a single ratio of w…
Search for Lepton-Flavor Violation in the Decayτ−→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.
Observation ofB0Meson Decay toa1±(1260)π∓
We present a measurement of the branching fraction of the decay B-0 -> a(1)(+/-)(1260)pi(-/+) with a(1)(+/-)(1260)->pi(-/+)pi(+/-)pi(+/-). The data sample corresponds to 218x10(6) B (B) over bar pairs produced in e(+)e(-) annihilation through the Upsilon(4S) resonance. We measure the branching fraction B(B-0 -> a(1)(+/-)(1260)pi(-/+))B(a(1)(+/-)(1260)->pi(-/+)pi(+/-)pi(+/-))=(16.6 +/- 1.9 +/- 1.5)x10(-6), where the first error quoted is statistical and the second is systematic.