A. E. Blinov

Measurement of the branching fraction of Υ(4S)→B0B̄0

We report the first measurement of the branching fraction f00 for Υ(4S)→B0B 0. The data sample consists of 81.7  fb-1 collected at the Υ(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-ν l in which only the charged lepton and the soft pion from the decay D*+→D0π+ are reconstructed, we obtain f00=0.487±0.010(stat)±0.008(syst). Our result does not depend on the branching fractions of B 0→D*+l-ν l and D*+→D0π+ decays, on the ratio of the charged and neutral B meson lifetimes, nor on the assumption of isospin symmetry.

Search for factorization-suppressed B→χcK(*) decays

We search for the factorization-suppressed decays B→χc0K(*) and B→χc2K(*), with χc0 and χc2 decaying into J/ψγ, using a sample of 124×106 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.

Improved measurement of the Cabibbo-Kobayashi-Maskawa angle α using B0(B̄)→ρ+ρ- 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.

Search for decays of B0→e+e-, B0→μ+μ-, B0→e± μ

We present a search for the decays B0->e+e-, B0->mu+mu-, and B0->e+- mu-+ in data collected at the Y(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-) mu+mu-) e+-mu-+) < 18 x 10^-8.

Study of B→π ν and B→ρ ν decays and determination of

We present an analysis of exclusive charmless semileptonic B-meson decays based on 83×106 BB pairs recorded with the BABAR detector at the Υ(4S) resonance. Using isospin symmetry, we measure branching fractions B(B0→π- +ν)=(1.38±0.10±0.16±0.08)×10-4 and B(B0→ρ- +ν)=(2.14±0.21±0.48±0.28)×10-4, where the errors are statistical, experimental systematic, and due to form-factor shape uncertainties. We compare the measured distribution in q2, the momentum-transfer squared, with theoretical predictions for the form factors from lattice QCD and light-cone sum rules, and extract the Cabibbo-Kobayashi- Maskawa (CKM) matrix element |Vub|=(3.82±0.14±0.22±0.11-0. 52+0.88)×10-3 from B→π ν, where the fourth error reflects the uncertainty of the form-factor normalization.

Amplitude analysis of the decay B±→π±π±π - eScholarship

The authors present a Dalitz-plot analysis of charmless B{sup {+-}} decays to the final state {pi}{sup {+-}}{pi}{sup {+-}}{pi}{sup {-+}} using 210 fb{sup -1} of data recorded by the BABAR experiment at {radical}s = 10.58 GeV. We measure the branching fractions {Beta}(B{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup {+-}}{pi}{sup {-+}}) = (16.2 {+-} 1.2 {+-} 0.9) x 10{sup -6} and {Beta}(B{sup {+-}} {yields} {rho}{sup 0}(770){pi}{sup {+-}}) = (8.8 {+-} 1.0 {+-} 0.6{sub -0.7}{sup +0.1}) x 10{sup -6}. Measurements of branching fractions for the quasi-two-body decays B{sup {+-}} {yields} {rho}{sup 0}(1450){pi}{sup {+-}}, B{sup {+-}} {yields} f{sub 0}(980){pi}{sup {+-}} and B{sup {+-}} f{sub 2}(1270){pi}{sup {+-}} are also presented. They observe no charge asymmetries for the above modes, and there is no evidence for the decays B{sup {+-}} {yields} {chi}{sub c0}{pi}{sup {+-}}, B{sup {+-}} {yields} f{sub 0}(1370){pi}{sup {+-}} and B{sup {+-}} {yields} {sigma}{pi}{sup {+-}}.We present a Dalitz-plot analysis of charmless B+- decays to the final state pi+- pi+- pi-+ using 210 fb^-1 of data recorded by the BABAR experiment at sqrt(s) = 10.58 GeV. We measure the branching fractions B(B+- -> pi+- pi+- pi-+) = (16.2 +- 1.2 +- 0.9) x 10^-6 and B(B+- -> rho^0(770) pi+-) = (8.8 +- 1.0 +- 0.6 +0.1-0.7) x 10^-6. Measurements of branching fractions for the quasi-two-body decays B+- -> rho^0(1450) pi+-, B+- -> f_0(980) pi+- and B+- -> f_2(1270) pi+- are also presented. We observe no charge asymmetries for the above modes, and there is no evidence for the decays B+- -> chic0 pi+-, B+- -> f_0(1370) pi+- and B+- -> sigma pi+-.

Measurement of the B0 → φ K*0 decay amplitudes

With a sample of about 227x10(6) BB pairs recorded with the BABAR detector we perform a full angular analysis of the decay B0-->phiK(*0)(892). We make novel measurements of five parameters sensitive to CP violation. We also measure the branching fraction to be (9.2+/-0.9+/-0.5)x10(-6) and determine the fractions of longitudinal and parity-odd transverse contributions as f(L)=0.52+/-0.05+/-0.02 and f( perpendicular)=0.22+/-0.05+/-0.02. The phases of the parity-even and parity-odd transverse amplitudes relative to the longitudinal amplitude are found to be phi( parallel)=2.34(+0.23)(-0.20)+/-0.05 rad and phi( perpendicular)=2.47+/-0.25+/-0.05 rad. We also observe the decay B0-->phiK(*0)(1430).

Direct CP violating asymmetry in B0→ K+π-decays - eScholarship

We present a measurement of the direct CP violating asymmetry in the decay B0-->K+pi(-) using a data sample of 227x10(6) Upsilon(4S)-->BB decays collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC. We observe a total signal yield of nK-(pi(+))+nK+(pi(-))=1606+/-51 decays and measure the asymmetry (nK-(pi(+))-nK+(pi(-)))/(nK-(pi(+))+nK+(pi(-)))=-0.133+/-0.030(stat)+/-0.009(syst). The probability of observing such an asymmetry in the absence of direct CP violation is 1.3x10(-5), corresponding to 4.2 standard deviations.