Search

We present measurements of Collins asymmetries in the inclusive process $e^+e^- \rightarrow h_1 h_2 X$, $h_1h_2=KK,\, K\pi,\, \pi\pi$, at the center-of-mass energy of 10.6 GeV, using a data sample of 468 fb$^{-1}$ collected by the BaBar experiment at the PEP-II $B$ factory at SLAC National Accelerator Center. Considering hadrons in opposite thrust hemispheres of hadronic events, we observe clear azimuthal asymmetries in the ratio of unlike- to like-sign, and unlike- to all charged $h_1 h_2$ pairs, which increase with hadron energies. The $K\pi$ asymmetries are similar to those measured for the $\pi\pi$ pairs, whereas those measured for high-energy $KK$ pairs are, in general, larger., Comment: 7 pages, 4 postscript figures, 5 pages of Supplemental Material

This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C. Please note that version 3 on the archive is the auxiliary version of the Physics of the B Factories book. This uses the notation alpha, beta, gamma for the angles of the Unitarity Triangle. The nominal version uses the notation phi_1, phi_2 and phi_3. Please cite this work as Eur. Phys. J. C74 (2014) 3026., Comment: 928 pages, version 3 (arXiv:1406.6311v3) corresponds to the alpha, beta, gamma version of the book, the other versions use the phi1, phi2, phi3 notation

We present a study of 649 \pm 35 e+e- --> ccbar events produced at sqrt{s}~10.6 GeV containing both a Lambda_c baryon and a Lambda_c antibaryon. The number observed is roughly four times that expected if the leading charmed hadron types are uncorrelated, confirming an observation by the CLEO Collaboration. We find a 2-jet topology in these events but very few additional baryons, demonstrating that the primary c and cbar are predominantly contained in a correlated baryon-antibaryon system. In addition to the charmed baryons we observe on average 2.6 \pm 0.2 charged intermediate mesons, predominantly pions, carrying 65% of the remaining energy., Comment: 8 pages, 3 postscript figures, submitted to Phys.Rev D-RC

A search for the Z(3930) resonance in gamma gamma production of the DDbar system has been performed using a data sample corresponding to an integrated luminosity of 384 fb^-1 recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The DDbar invariant mass distribution shows clear evidence of the Z(3930) state with a significance of 5.8 sigma. We determine mass and width values of (3926.7 +- 2.7 +- 1.1) MeV/c^2 and (21.3 +- 6.8 +- 3.6) MeV, respectively. A decay angular analysis provides evidence that the Z(3930) is a tensor state with positive parity and C-parity (J^PC = 2^++); therefore we identify the Z(3930) state as the chi_c2(2P) meson. The value of the partial width Gamma_(gamma gamma)xB(Z(3930)-> DDbar) is found to be (0.24 +- 0.05 +- 0.04) keV., Comment: 16 pages, 4 tables, 26 postscript figures, submitted to Phys. Rev. D: Changes V2: description of DDbar reconstruction improved (Section IV), corrected typos

Charged lepton flavor violating processes are unobservable in the standard model, but they are predicted to be enhanced in several extensions to the standard model, including supersymmetry and models with leptoquarks or compositeness. We present a search for such processes in a sample of 99M Y(2S) decays and 117M Y(3S) decays collected with the BABAR detector. We place upper limits on the branching fractions BF(Y(nS) -> e tau) and BF(Y(nS) -> mu tau) (n = 2, 3) at the 10^(-6) level and use these results to place lower limits of order 1 TeV on the mass scale of charged lepton flavor violating effective operators., Comment: 8 pages, 3 figures, submitted to PRL

We present a search for the decay $B^+ \to \ell^+ \nu_{\ell}$ ($\ell = e,\mu\tau$) in $(458.9 \pm 5.1) \times 10^6$ $B\bar{B}$ pairs recorded with the BABAR detector at the PEP-II B-Factory. We search for these B decays in a sample of $B^+B^-$ events where one $B$-meson is reconstructed as $B^- \to D^0 \ell^- \nu X$. Using the method of Feldman and Cousins, we obtain $\mathcal{B}(B^+ \to \tau^+ \nu) = (1.7 \pm 0.8 \pm 0.2) \times 10^{-4}$, which excludes zero at $2.3\sigma$. We interpret the central value in the context of the Standard Model and find the B meson decay constant to be $f^2_B = (62 \pm 31) \times 10^3 \mathrm{MeV}^2$. We find no evidence for $B^+ \to e^+ \nu_{e}$ and $B^+ \to \mu^+ \nu_{\mu}$ and set upper limits at the 90% C.L. $\mathcal{B}(B^+ \to e^+ \nu_{e}) < 0.8 \times 10^{-5}$ and $\mathcal{B}(B^+ \to \mu^+ \nu_{\mu}) < 1.1 \times 10^{-5}$., Comment: 8 pages, 8 postscript figures, submitted to Physical Review D (Rapid Communications)

Using 467 $fb^{-1}$ of $e^+e^-$ annihilation data collected with the BaBar detector, we measure $\frac{{\cal{B}}(\tau^- \to \mu^- \bar{\nu}_\mu \nu_\tau)}{{\cal{B}}(\tau^- \to e^- \bar{\nu}_e \nu_\tau)} = (0.9796 \pm 0.0016 \pm 0.0036)$, $\frac{{\cal{B}}(\tau^- \to \pi^- \nu_\tau)}{{\cal{B}}(\tau^- \to e^- \bar{\nu}_e \nu_\tau)} = (0.5945 \pm 0.0014 \pm 0.0061)$, and $\frac{{\cal{B}}(\tau^- \to \K^- \nu_\tau)}{{\cal{B}}(\tau^- \to e^- \bar{\nu}_e \nu_\tau)} = (0.03882 \pm 0.00032 \pm 0.00057)$, where the uncertainties are statistical and systematic, respectively. From these precision $\tau$ measurements, we test the Standard Model assumption of $\mu$-$e$ and $\tau$-$\mu$ charge current lepton universality and provide determinations of $|V_{us}|$ experimentally independent of the decay of a kaon and which we compare with the value predicted from the unitarity of the Cabibbo-Kobayashi-Maskawa matrix., Comment: 7 pages, 1 encapsulated postscript figures, Phys. Rev. Lett 105, 051602 (2010)

We present a study of the inclusive $D^{*\pm}$ production in the decay of $\Upsilon(1S)$ using $(98.6 \pm 0.9)\times 10^6$ $\Upsilon(2S)$ mesons collected with the BaBar detector at the $\Upsilon(2S)$ resonance. Using the decay chain $\Upsilon(2S)\to \pi^+ \pi^- \Upsilon(1S), \Upsilon(1S) \to D^{*\pm} X$, where X is unobserved, we measure the branching fraction $\BR[\Upsilon(1S)\to D^{*\pm} X] = (2.52 \pm 0.13({\rm stat}) \pm 0.15({\rm syst}))%$ and the $D^{*\pm}$ momentum distribution in the rest frame of the $\Upsilon(1S)$. We find evidence for an excess of $D^{*\pm}$ production over the expected rate from the virtual photon annihilation process $\Upsilon(1S)\to\gamma^*\to c\bar c\to D^{*\pm} X$., Comment: 8 pages, 4 postscript figures, published in PRD-RC

We present an update of the search for the flavor-changing neutral current B+ -> K+vv decay using 351 x 10^6 BB pairs collected at the Y(4S) resonance with the BABAR detector at the SLAC PEP-II B factory. Due to the presence of two neutrinos in the final state, we require the reconstruction of the companion B in the event through the decay channel B- -> D0l-v. We find 38 candidates in the data with an expected background of 31 +/- 12. This allows us to set an upper limit on the branching fraction for B+ -> K+vv of 4.5 x 10^-5 at 90% confidence level., Comment: 11 pages, 6 figures, submitted to Phys. Rev. D

We study the decay $B^-\to DK^{*-}$ using a sample of 379$\times 10^6$ $\Upsilon(4S)\to B\bar{B}$ events collected with the BABAR detector at the PEP-II $B$-factory. We perform a "GLW" analysis where the $D$ meson decays into either a CP-even ($CP+$) eigenstate ($K^+K^-$, $\pi^+\pi^-$), CP-odd ($CP-$) eigenstate ($K^0_S\pi^0$, $K^0_S\phi$, $K^0_S\omega$) or a non-CP state ($K^-\pi^+$). We also analyze $D$ meson decays into $K^+\pi^-$ from a Cabibbo-favored $\bar{D}^0$ decay or doubly suppressed $D^0$ decay ("ADS" analysis). We measure observables that are sensitive to the CKM angle $\gamma$: the partial-rate charge asymmetries ${\cal A}_{CP\pm}$, the ratios ${\cal R}_{CP\pm}$ of the B-decay branching fractions in $CP\pm$ and non-CP decay, the ratio ${\cal R}_{ADS}$ of the charge-averaged branching fractions, and the charge asymmetry ${\cal A}_{ADS}$ of the ADS decays: ${\cal A}_{CP+}= 0.09\pm0.13 \pm 0.06$, ${\cal A}_{CP-}=-0.23\pm 0.21\pm 0.07$, ${\cal R}_{CP+} =2.17 \pm 0.35 \pm 0.09$,${\cal R}_{CP-} =1.03\pm 0.27\pm 0.13$, ${\cal R}_{ADS}=0.066\pm0.031\pm0.010$, and ${\cal A}_{ADS}=-0.34\pm0.43\pm 0.16$, where the first uncertainty is statistical and the second is systematic. Combining all the measurements and using a frequentist approach yields the magnitude of the ratio between the Cabibbo-suppressed and favored amplitudes, $r_B$ = 0.31 with a one (two) sigma confidence level interval of [0.24, 0.38] ([0.17, 0.43]). The value $r_B=0$ is excluded at the 3.3 sigma level. A similar analysis excludes values of $\gamma$ in the intervals $[0, 7]^{\circ}, [55, 111]^{\circ}$, and $[175, 180]^{\circ}$ ([85, 99]$^{\circ}$) at the one (two) sigma confidence level., Comment: 15 pages, 13 figures (.eps), to be submitted to PRD

We present the result from a precision measurement of the mass of the $\tau$ lepton, $M_\tau$, based on $423 fb^{-1}$ of data recorded at the $\Upsilon(4S)$ resonance with the BaBar detector. Using a pseudomass endpoint method, we determine the mass to be $1776.68 \pm 0.12 (stat) \pm 0.41 (syst) MeV$. We also measure the mass difference between the $\tau^+$ and $\tau^-$, and obtain $(M_{\tau^{+}}-M_{\tau^{-}})/M^\tau_{AVG} = (-3.4 \pm 1.3 (stat) \pm 0.3 (syst)) \times 10^{-4}$, where $M^\tau_{AVG}$ is the average value of $M_{\tau^+}$ and $M_{\tau^-}$., Comment: 15 pages, 10 figures, submitted to Phys. Rev. D

We report measurements of the branching fractions of neutral and charged B meson decays to final states containing a K_1(1270) or K_1(1400) meson and a charged pion. The data, collected with the BaBar detector at the SLAC National Accelerator Laboratory, correspond to 454 million B Bbar pairs produced in e^+ e^- annihilation. We measure the branching fractions BF(B^0 --> K_1(1270)^+ \pi^- + K_1(1400)^+ \pi^-) = 3.1^{+0.8}_{-0.7} x10^{-5} and BF(B^+ --> K_1(1270)^0 \pi^+ + K_1(1400)^0 \pi^+) = 2.9^{+2.9}_{-1.7} x10^{-5} (<8.2 x10^{-5} at 90% confidence level), where the errors are statistical and systematic combined. The B^0 decay mode is observed with a significance of 7.5\sigma, while a significance of 3.2\sigma is obtained for the B^+ decay mode. Based on these results, we estimate the weak phase \alpha = (79 +/- 7 +/- 11)^{\circ} from the time dependent CP asymmetries in B^0 --> a_1(1260)^{+/-} \pi^{-/+} decays., Comment: 18 pages, 8 postscript figures, submitted to Phys. Rev. D

A precise measurement of the cross section of the process e+ e- to pi+ pi- (gamma) from threshold to an energy of 3 GeV is obtained with the initial state radiation (ISR) method using 232 fb^-1 of data collected with the BABAR detector at e+ e- center-of-mass energies near 10.6 GeV. The ISR luminosity is determined from a study of the leptonic process e+ e- to mu+ mu- gamma (gamma). The leading-order hadronic contribution to the muon magnetic anomaly calculated using the pi pi cross section measured from threshold to 1.8 GeV is (514.1 +-2.2(stat} +-3.1(syst}) x 10^{-10}., Comment: 7 pages, 1 figure, 1 table, submitted to Physical Review Letters

We search for invisible decays of the Upsilon(1S) meson using a sample of 91.4 x 10^{6} Upsilon(3S) mesons collected at the BaBar/PEP-II B-factory. We select events containing the decay Upsilon(3S) -> pi+ pi- Upsilon(1S) and search for evidence of an undetectable Upsilon(1S) decay recoiling against the dipion system. We set an upper limit on the branching fraction BR(Upsilon(1S) -> invisible) < 3.0 x 10^{-4} at the 90% confidence level., Comment: 7 pages, 3 postscript figures, submitted to Physical Review Letters

Motivated by recent models proposing a hidden sector with $\sim$GeV scale force carriers, we present a search for a narrow dilepton resonance in 4 lepton final states using $536fb^{-1}$ collected by the BaBar detector. We search for the reaction, $e^+e^-\to W^\prime W^\prime\to(l^+l^-)(l^{\prime+}l^{\prime-})$, where the leptons carry the full 4-momentum and the two dilepton pair invariant masses are equal. We do not observe a significant signal and we set 90% upper limits of $\sigma(e^+e^-\to W^\prime W^\prime\to(e^+e^-)(e^+e^-))<(15-70) ab$, $\sigma(e^+e^-\to W^\prime W^\prime\to(e^+e^-)(\mu^+\mu^-))<(15-40) ab$, and $\sigma(e^+e^-\to W^\prime W^\prime\to(\mu^+\mu^-)(\mu^+\mu^-))<(11-17) ab$ in the $W^\prime$ mass range between 0.24 and 5.3GeV. Under the assumption that the $W^\prime$ coupling to electrons and muons is the same, we obtain a combined upper limit of $\sigma(e^+e^-\to W^\prime W^\prime\to(l^+l^-)(l^{\prime+}l^{\prime-}))<(25-60) ab$. Using these limits, we constrain the product of the SM-dark sector mixing and the dark coupling constant in the case of a non-Abelian Higgsed dark sector., Comment: submitted to Lepton-Photon 2009

Searches for lepton-flavor-violating decay of a tau lepton to a lighter mass lepton and a photon have been performed with the entire dataset of (963 +- 7) x 10^6 tau decays collected by the BaBar detector near the Upsilon(4S), Upsilon(3S) and Upsilon(2S) resonances. The searches yield no evidence of signals and we set upper limits on the branching fractions of BR(tau -> e gamma) < 3.3 x 10^-8 and BR(tau -> mu gamma) < 4.4 x 10^-8 at 90% confidence level., Comment: 7 pages, 2 encapsulated postscript figures, Physical Review Letters 104 (2010) 021802

We present a study of ten B-meson decays to a D(*), a proton-antiproton pair, and a system of up to two pions using BaBar's data set of 455x10^6 BBbar pairs. Four of the modes (B0bar -> D0 p anti-p, B0bar -> D*0 p anti-p, B0bar -> D+ p anti-p pi-, B0bar -> D*+ p anti-p pi-) are studied with improved statistics compared to previous measurements; six of the modes (B- -> D0 p anti-p pi-, B- -> D*0 p anti-p pi-, B0bar -> D0 p anti-p pi- pi+, B0bar -> D*0 p anti-p pi- pi+, B- -> D+ p anti-p pi- pi-, B- -> D*+ p anti-p pi- pi-) are first observations. The branching fractions for 3- and 5-body decays are suppressed compared to 4-body decays. Kinematic distributions for 3-body decays show non-overlapping threshold enhancements in m(p anti-p) and m(D(*)0 p) in the Dalitz plots. For 4-body decays, m(p pi-) mass projections show a narrow peak with mass and full width of (1497.4 +- 3.0 +- 0.9) MeV/c2, and (47 +- 12 +- 4) MeV/c2, respectively, where the first (second) errors are statistical (systematic). For 5-body decays, mass projections are similar to phase space expectations. All results are preliminary., Comment: 28 pages, 90 postscript figures, submitted to LP09

We observe the decays $ $D^*_{s1}(2710)^+ \to D^*K$ and $D^*_{sJ}(2860)^+ \to D^*K$ and measure their branching fractions relative to the $D K$ final state. We also observe, in the $D^*K$ mass spectrum, a new broad structure at a mass of $(3044 \pm 8_{stat} (^{+30}_{-5})_{syst})$ $MeV/c^2$ having a width $\Gamma=(239 \pm 35_{stat} (^{+46}_{-42})_{syst})$ $MeV$. To obtain this result we use 470 ${\rm fb}^{-1}$ of data recorded by the BaBar detector at the PEPII asymmetric-energy $e^+e^-$ storage rings at the Stanford Linear Accelerator Center running at center-of-mass energies near 10.6 GeV., Comment: 15 pages, 9 postscript figures, submitted to Phys. Rev. D

We measure the rate of D0-D0bar mixing with the observable yCP=(tauKpi/tauKK)-1, where tauKK and tauKpi are respectively the mean lifetimes of CP-even D0->K+K- and CP-mixed D0->K-pi+ decays, using a data sample of 384/fb collected by the Babar detector at the SLAC PEP-II asymmetric-energy B Factory. From a sample of D0 and D0bar decays where the inital flavor of the decaying meson is not determined, we obtain yCP = [1.12 +/- 0.26 (stat) +/- 0.22 (sys)]%, which excludes the no-mixing hypothesis at 3.3 sigma, including both statistical and systematic uncertainties. This result is in good agreement with a previous Babar measurement of yCP obtained from a sample of D*+->D0pi+ events, where the D0 decays to K-pi+, K+K-, and pi+pi-, which is disjoint with the untagged D0 events used here. Combining the two results taking into account statistical and systematic uncertainties, where the systematic uncertainties are assumed to be 100% correlated, we find yCP = [1.16 +/- 0.22 (stat) +/- 0.18 (sys)]%, which excludes the no-mixing hypothesis at 4.1 sigma., Comment: 8 pages, 4 postscript figures, submitted to PRD-RC

We present results for the moments of observed spectra in inclusive semileptonic B-meson decays to charm hadrons Bbar --> X_c l- nubar. Moments of the hadronic-mass and the combined mass-and-energy spectra for different minimum electron or muon momenta between 0.8 and 1.9 GeV/c are obtained from a sample of 232x10^{6} Y(4S) --> B Bbar events, collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We also present a re-evaluation of the moments of electron-energy spectra and partial decay fractions BR(Bbar --> X_c e- nubar for minimum electron momenta between 0.6 and 1.5 GeV/c based on a sample of 51x10^{6} Y(4S) --> B Bbar events. The measurements are used for the extraction of the total decay fraction, the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V_cb|, the quark masses m_b and m_c, and four heavy-quark QCD parameters in the framework of a Heavy Quark Expansion (HQE). We find BR(Bbar --> X_c l- nubar) = (10.64 +/- 0.17 +/- 0.06)% and |V_cb| = (42.05 +/- 0.45 +/- 0.70) x 10^{-3}., Comment: submitted to Phys. Rev. D

We report the observation of the baryonic B-decay B0bar -> Lambda_c^+ antiproton K^- pi^+, excluding contributions from the decay B0bar -> Lambda_c^+ anti-Lambda K^-. Using a data sample of 467*10^6 BBbar pairs collected with the BABAR detector at the PEP-II storage ring at SLAC, the measured branching fraction is (4.33 +/- 0.82_stat +/- 0.33_syst +/- 1.13_Lambda_c^+)*10^-5. In addition we find evidence for the resonant decay B0bar -> Sigma_c(2455)^++ antiproton K^- and determine its branching fraction to be (1.11 +/- 0.30_stat +/- 0.09_syst +/- 0.29_Lambda_c^+)*10^-5. The errors are statistical, systematic, and due to the uncertainty in the Lambda_c^+ branching fraction. For the resonant decay B0bar -> Lambda_c^+ antiproton K^*0 we obtain an upper limit of 2.42*10^-5 at 90% confidence level., Comment: 7 pages, 3 postscript figures, submitted to PRD RC; BABAR-PUB-09/014, SLAC-PUB-13675

We present a search for decays of $B$ mesons to final states with a $b\_1$ meson and a $\rho$ or $K^*(892)$ meson. The search is based on a data sample consisting of 465 million $B\kern 0.18em{\kern -0.18em B}{}$ pairs collected by the {\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} detector at the SLAC National Accelerator Laboratory. We do not observe any statistically significant signal. The upper limits we set on the branching fractions range from 1.4 to $8.0 \times 10^{-6}$ at the 90% confidence level (C.L.), including systematic uncertainties., Comment: 7 pages, 1 postscript figure, submitted to Phys. Rev. D (Rapid Communications)

We present measurements of the branching fraction B and the longitudinal polarization fraction fL for B0 -> a1(1260)+ a1(1260)- decays, with a1(1260)+/- -> \pi- \pi+ \pi+/-. The data sample, collected with the detector BaBar at the SLAC National Accelerator Laboratory, represents 465 10^6 produced BBbar pairs. We measure B(B0 -> a1(1260)+ a1(1260)-) x [B(a1(1260)+ -> \pi- \pi+ \pi+)]^2 = (11.8 \pm 2.6 \pm 1.6) 10^{-6} and fL = 0.31 \pm 0.22 \pm 0.10, where the first uncertainty is statistical and the second systematic. The decay mode is measured with a significance of 5.0 standard deviations including systematic uncertainties., Comment: 7 pages, 5 postscript figures, submitted to Phys. Rev. Lett

We present updated measurements of the branching fractions for B0 meson decays to etaK0, etaeta, etaphi, etaomega, eta'K0, eta'eta', eta'phi, and eta'omega, and branching fractions and CP-violating charge asymmetries for B+ decays to etapi+, etaK+, eta'pi+ and eta'K+. The data represent the full dataset of 467 10^{6} BB pairs collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory. Besides large signals for the four charged B decay modes and for B0\to eta'K0, we find evidence for three B0 decay modes at greater than 3.0sigma significance. We find B(B0\to etaK0) = (1.15^{+0.43}_{-0.38} \pm0.09)x10^{-6}, B(B0\to etaomega) = (0.94^{+0.35}_{-0.30}\pm0.09)x10^{-6}, and B(B0\to eta'omega) = (1.01^{+0.46}_{-0.38}\pm0.09)x10^{-6}, where the first (second) uncertainty is statistical (systematic). For the B+\to etaK+ decay mode, we measure the charge asymmetry A_{ch}(B+\to etaK+) = -0.36 \pm 0.11 \pm 0.03., Comment: 12 pages, 6 figures. Text improvement with respect to version 1

We present a search for the radiative leptonic decay B+ -> l+ nu gamma, where l=e,mu, using a data sample of 465 million B-meson pairs collected by the BABAR experiment. In this analysis, we fully reconstruct the hadronic decay of one of the B mesons in Upsilon(4S) -> B+B- decays, then search for evidence of B+ -> l+ nu gamma in the rest of the event. We observe no significant evidence of signal decays and report model-independent branching fraction upper limits of BR(B+ -> e+ nu gamma)<17e-6, BR(B+ -> mu+ nu gamma)< 24e-6, and BR(B+ -> l+ nu gamma)<15.6e-6 (l= e or mu), all at the 90% confidence level., Comment: 7 pages, 5 figures, submitted to Phys. Rev. D (Rapid Communications)

We search for a light Higgs boson, $A^0$, in the radiative decay $\Upsilon(3S)\to\gamma A^0$, $A^0\to\tau^+\tau^-$, $\tau^+\to e^+\nu_e \bar{\nu}_{\tau}$ or $\tau^+\to \mu^+ \nu_{\mu} \bar{\nu}_{\tau}$. The data sample contains 122 million $\Upsilon(3S)$ events recorded with the \babar detector. We find no evidence for a narrow structure in the studied $\tau^+\tau^-$ invariant mass region of $4.03(1.5-16)\times 10^{-5}$ across the $m_{\tau^+\tau^-}$ range. We also set a 90% C.L. upper limit on the $\tau^+\tau^-$-decay of the $\eta_b$ at ${\mathcal{B}}(\eta_b\to \tau^+\tau^-)<8%$.

We present an analysis of the decays B0 -> K*0 gamma and B+ -> K*+ gamma using a sample of 383 million BBbar events collected with the BaBar detector at the PEP2 asymmetric energy B factory. We measure the branching fractions BF[B0 -> K*0 Gamma] = 4.47 +/- 0.10 +/- 0.16 x 10^-5 and BF[B+ -> K*+ Gamma] = 4.22 +/- 0.14 +/- 0.16 x 10^-5. We constrain the direct CP asymmetry to be -0.033 < Acp < 0.028 and the isopin asymmetry to be 0.017 < \Delta0- < 0.116, where the limits are determined at the 90% confidence interval and include both statistical systematic uncertainties., Comment: 7 pages, 11 postscript figures, submitted to Phys. Rev. Lett

We study the reaction e+e- --> e+e-pi0 and measure the gamma gamma* --> pi0 transition form factor in the momentum transfer range from 4 to 40 GeV^2. The analysis is based on 442 fb^-1 of integrated luminosity collected at PEP-II with the BABAR detector at e+e- center-of-mass energies near 10.6 GeV., Comment: 19 pages, 23 postscript figures, submitted to Phys. Rev. D

We search for evidence of a light scalar boson in the radiative decays of the Upsilon(2S) and Upsilon(3S) resonances: Upsilon(2S,3S)-> gamma A0, A0 -> mu^+ mu^-. Such a particle appears in extensions of the Standard Model, where a light CP-odd Higgs boson naturally couples strongly to b-quarks. We find no evidence for such processes in the mass range 0.212<= m(A0)<= 9.3 GeV in the samples of 99*10^6 Upsilon(2S) and 122*10^6 Upsilon(3S) decays collected by the BABAR detector at the PEP-II B-factory and set stringent upper limits on the effective coupling of the b quark to the A0. We also limit the dimuon branching fraction of the eta_b meson: BR(eta_b->mu^+mu^-)<0.9% at 90% confidence level., Comment: 10 pages, 11 postscript figures, submitted to Physical Review Letters

We perform a time-dependent amplitude analysis of $B^0 \to K^0_S\pi^+\pi^-$ decays to extract the CP violation parameters of $f_0(980) K^0_S$ and $\rho^0(770) K^0_S$ and the direct CP asymmetry of $K^{*+}(892) \pi^-$. The results are obtained from a data sample of $(383 \pm 3) \times 10^6$ $B\bar{B}$ decays, collected with the BABAR detector at the PEP-II asymmetric-energy $B$ factory at SLAC. We find two solutions, with an equivalent goodness-of-fit. Including systematic and Dalitz plot model uncertainties, the combined confidence interval for values of the CP parameter $\beta_{eff}$ in $B^0$ decays to $f_0(980) K^0_S$ is $18^o < \beta_{eff} < 76^o$ at 95% confidence level (C.L). CP conservation in $B^0$ decays to $f_0(980) K^0_S$ is excluded at $3.5\sigma$ including systematic uncertainties. For $B^0$ decays to $\rho^0(770) K^0_S$, the combined confidence interval is $-9^o < \beta_{eff} < 57^o$ at 95% C.L. In decays to $K^{*+}(892) \pi^-$ we measure the direct CP asymmetry to be $A_{CP}=-0.20 \pm 0.10 \pm 0.01 \pm 0.02$. The measured phase difference (including $B^0\bar{B}^0$ mixing) between decay amplitudes of $B^0 \to K^{*+}(892) \pi^-$ and $\bar{B}^0 \to K^{*-}(892) \pi^+$, excludes the interval $-137^o < \Delta\Phi(K^{*+}(892) \pi^-) < -5^o$ at 95% C.L., Comment: 30 pages, 42 postscript figures, submitted to Phys. Rev. D

We describe searches for $B^0$ meson decays to the charmless final states $\pi^0 K^0_SK^0_S$, $\eta K^0_S K^0_S$, and $\eta^{\prime}K^0_SK^0_S$. The data sample corresponds to $467 \times 10^{6}$ $B\bar{B}$ pairs produced in $e^+e^-$ annihilation and collected with the BABAR detector at the SLAC National Accelerator Laboratory. We find no significant signals and determine the 90% confidence level upper limits on the branching fractions, in units of $10^{-7}$, $\cal{B}(B^0 \ra \pi^0K^0_SK^0_S) <9 $, $\cal{B}(B^0 \ra \eta K^0_SK^0_S) <10$, and $\cal{B}(B^0 \ra \eta^{\prime}K^0_SK^0_S) <20$., Comment: 7 pages, 1 postscript figure. Submitted to Phys. Rev. D (Rapid Communications), changed content

We present a measurement of the B0 --> Lambda-bar p pi- branching fraction performed using the BaBar detector at the PEP-II asymmetric e+e- collider. Based on a sample of 467 million BB-bar pairs we measure B(B0 --> Lambda-bar p pi-) = [3.07 pm 0.31 (stat.) pm 0.23 (syst.)] x 10^{-6}. The measured differential spectrum as a function of the dibaryon invariant mass m(Lambda p) shows a near-threshold enhancement similar to that observed in other baryonic B decays. We study the Lambda-bar polarization as a function of Lambda-bar energy in the B0 rest frame (E*_Lambda) and compare it with theoretical expectations of fully longitudinally right-polarized Lambda-bar at large E*_Lambda., Comment: 12 pages, 6 figures, submitted to PRD

We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element |V_cb| and the form-factor slope rho^2 in Bbar -> Dl- nubar decays based on 460 million BBar events recorded at the Upsilon(4S) resonance with the BaBar detector. BBar -> Dl- nubar decays are selected in events in which a hadronic decay of the second B meson is fully reconstructed. We measure the differential decay rate and determine G(1) |V_cb|= (43.0 \pm 1.9 \pm 1.4)\times 10^{-3} and rho^2 = 1.20 \pm 0.09 \pm 0.04, where G(1) is the the hadronic form factor at the point of zero recoil. We also determine the exclusive branching fractions and find BF(B^- -> D0l- nubar) = (2.31 \pm 0.08 \pm 0.09)% and BF (B0bar -> D+ l^- nubar)=(2.23 \pm 0.11 \pm 0.11)%., Comment: 8 pages, 2 postscript figures, submitted to Physical Review Letters

We report an analysis of tau- decaying into omega.pi-.nu_tau with omega -> pi+pi-pi0 using a data sample containing nearly 320 million tau pairs collected with the BABAR detector at the PEP-II B-Factory. We find no evidence for second-class currents and we set an upper limit of 0.69% at 90% confidence level for the fraction of second-class currents in this decay mode., Comment: Submitted to Phys. Rev. Lett

We present a study of the decays B0 -> D0 K*0 and B0 -> barD0 K*0 with K*0 -> K+pi-. The D0 and the barD0 mesons are reconstructed in the final states f=K+pi-, K+pi-pi0, K+pi-pi+pi- and their charge conjugates. Using a sample of 465 million BBbar pairs collected with the Babar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we measure the ratio R_{ADS}=[Gamma(barB0 -> [f]_D barK*0)+Gamma(B0 -> [bar{f}]_D K*0)]/ [Gamma(barB0 -> [bar{f}]_D barK*0)+Gamma(B0 -> [f]_D K*0)] for the three final states. We do not find significant evidence for a signal and set the following limits at 95% probability: R_{ADS}(Kpi)<0.244, R_{ADS}(Kpipi0)<0.181 and R_{ADS}(Kpipipi)<0.391. From the combination of these three results, we find that the ratio rS between the b -> u and the b -> c amplitudes lies in the range [0.07,0.41] at 95% probability., Comment: 11 pages, 12 postscript figures, submitted to Phys. Rev. D (Rapid Communications)

We search for the neutrinoless, lepton-flavor-violating tau decays tau -> l V^0, where l is an electron or muon and V^0 is a vector meson reconstructed as phi -> K^+K^-, rho -> pi^+pi^-, K^* -> K^+pi^-, or K^*bar -> K^-pi^+. The analysis has been performed using 451 fb^{-1} of data collected at an e^+e^- center-of-mass energy near 10.58 GeV with the BaBar detector at the PEP-II storage rings. The number of events found in the data is compatible with the background expectation, and upper limits on the branching fractions are set in the range (2.6-19) x 10^{-8} at the 90% confidence level., Comment: 7 pages, 1 postscript figure, published in Physical Review Letters

We perform a study of the exclusive production of $D \bar D$, $D \bar D^*$, and $D^* \bar D^*$ in initial-state-radiation events, from $e^+ e^-$ annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium and possible new resonances. The data sample corresponds to an integrated luminosity of 384 $fb^{-1}$ and was recorded by the BaBar experiment at the PEP-II storage rings. The $D \bar D$, $D \bar D^*$, and $D^* \bar D^*$ mass spectra show clear evidence of several $\psi$ resonances. However, there is no evidence for $Y(4260) \to D \bar D^*$ or $Y(4260)\to D^* \bar D^*$., Comment: 16 pages, 8 tables, 13 postscript figures, submitted to Phys. Rev. D

We have performed a search for the rare leptonic decays \Bp \to \ellp \nul ($l=e,\mu$), using data collected at the \FourS resonance by the \babar\ detector at the \pep2 storage ring. In a sample of 468 million \BB pairs we find no evidence for a signal and set an upper limit on the branching fractions $\BR(\bmunu) < 1.0\times10^{-6}$ and $\BR(\benu) < 1.9\times10^{-6}$ at the 90% confidence level, using a Bayesian approach., Comment: 8 pages, 4 figures

We have performed a search for the eta_b(1S) meson in the radiative decay of the Upsilon(2S) resonance using a sample of 91.6 million Upsilon(2S) events recorded with the BABAR detector at the PEP-II B factory at the SLAC National Accelerator Laboratory. We observe a peak in the photon energy spectrum at E_gamma = 609.3 {+4.6} {-4.5} (stat) +/- 1.9 (syst) MeV, corresponding to an eta_b(1S) mass of 9394.2 {+4.8} {-4.9} (stat) +/- 2.0 (syst) MeV/c^2. The branching fraction for the decay Upsilon(2S) --> gamma eta_b(1S) is determined to be [3.9 +/-1.1 (stat) {+1.1} {-0.9} (syst)] x 10^(-4). We find the ratio of branching fractions B[Upsilon(2S) --> gamma eta_b(1S)]/B[Upsilon(3S) --> gamma eta_b(1S)] = 0.82 +/- 0.24 (stat) {+0.20}{-0.19} (syst)., Comment: 7 pages, 2 figures; published version

We present measurements of the semileptonic decays B- --> D0 tau- nubar_tau, B- --> D*0 tau- nubar_tau, B0bar --> D+ tau- nubar_tau, and B0bar --> D*+ tau- nubar_tau, which are sensitive to non--Standard Model amplitudes in certain scenarios. The data sample consists of 232x10^6 Upsilon(4S) --> BBbar decays collected with the BaBar detector at the PEP-II e+e- collider. We select events with a D or D* meson and a light lepton (ell=e or mu) recoiling against a fully reconstructed B meson. We perform a fit to the joint distribution of lepton momentum and missing mass squared to distinguish signal B --> D(*) tau- nubar_tau (tau- --> ell- nubar_ell nu_tau) events from the backgrounds, predominantly B --> D(*) ell- nubar_ell. We measure the branching-fraction ratios R(D) == BR(B --> D tau- nubar_tau) / BR(B --> D ell- nubar_ell) and R(D*) == BR(B --> D* tau- nubar_tau) / BR(B --> D* ell- nubar_ell) and, from a combined fit to B- and B0bar channels, obtain the results R(D)=(41.6 +/- 11.7 +/- 5.2)% and R(D*)=(29.7 +/- 5.6 +/- 1.8)%, where the uncertainties are statistical and systematic. Normalizing to measured B- --> D(*)0 ell- nubar_ell branching fractions, we obtain BR(B --> D tau- nubar_tau)=(0.86 +/- 0.24 +/- 0.11 +/- 0.06)% and BR(B --> D* tau- nubar_tau)=(1.62 +/- 0.31 +/- 0.10 +/- 0.05)%, where the additional third uncertainty is from the normalization mode. We also present, for the first time, distributions of the lepton momentum, p*_ell, and the squared momentum transfer, q^2., Comment: 29 pages, 19 postscript figures, submitted to Phys. Rev. D

The fundamental nature of mass is one of the greatest mysteries in physics. The Higgs mechanism is a theoretically appealing way to account for the different masses of elementary particles and implies the existence of a new, yet unseen particle, the Higgs boson. We search for evidence of a light scalar (e.g. a Higgs boson) in the radiative decays of the narrow Y(3S) resonance: Y(3S)->gamma A0, A0->mu+mu-. Such an object appears in extensions of the Standard Model, where a light CP-odd Higgs boson naturally couples strongly to b-quarks. We find no evidence for such processes in a sample of 122*10^6 Y(3S) decays collected by the BABAR collaboration at the PEP-II B-factory, and set 90% C.L. upper limits on the branching fraction product B(Y(3S)-> gamma A0)*B(A0->mu+mu-) at (0.25-5.2)*10^{-6} in the mass range 0.212<= m(A0)<=9.3 GeV. We also set a limit on the dimuon branching fraction of the eta_b meson B(eta_b->mu+mu-)<0.8% at 90% C.L. The results are preliminary., Comment: 17 pages, 11 postscript figures, submitted to Aspen-2009

We present a Dalitz plot analysis of charmless B+- decays to the final state pi+-pi+-pi-+ using a sample of (465+-5)x10^-6 BBbar pairs collected by the BABAR experiment at \sqrt{s} = 10.58 GeV. We measure the branching fractions BF(B+- --> pi+-pi+-pi-+) = (15.2+-0.6+-1.2+-0.4)x10^-6, BF(B+- --> rho0(770)pi+-) = (8.1+-0.7+-1.2^{+0.4}_{-1.1})x10^-6, BF(B+- --> f2(1270)pi+-) = (1.57+-0.42+-0.16^{+0.53}_{-0.19})x10^-6, and BF(B+- --> pi+-pi+-pi-+ nonresonant) = (5.3+-0.7+-0.6^{+1.1}_{-0.5})x10^-6, where the uncertainties are statistical, systematic, and model-dependent, respectively. Measurements of branching fractions for the modes B+- --> rho0(1450)pi+- and B+- --> f0(1370)pi+- are also presented. We observe no significant direct CP asymmetries for the above modes, and there is no evidence for the decays B+- --> chiC0 pi+-, or B+- --> chiC2 pi+-., Comment: 16 pages, 8 postscript figures, published in Phys. Rev. D

We present updated measurements of time-dependent CP asymmetries in fully reconstructed neutral B decays containing a charmonium meson. The measurements reported here use a data sample of (465+/-5) million Upsilon(4S)->BBbar decays collected with the Babar detector at the PEPII asymmetric energy e+e- storage rings operating at the SLAC National Accelerator Laboratory. The time-dependent CP asymmetry parameters measured from JpsiKs, JpsiKL, Psi(2S)Ks, Chi_c1Ks, eta_cKs and JpsiK*0 decays are: C_f = 0.024+/-0.020(stat)+/-0.016(syst) and -\eta_f S_f = 0.687+/-0.028(stat)+/-0.012(syst)., Comment: Minor changes of the text and reference for the publication

We present measurements of B meson decays to the final states omegaK*, omegarho, and omega f_0, where K* indicates a spin 0, 1, or 2 strange meson. The data sample corresponds to 465x10^6 BBbar pairs collected with the BABAR detector at the PEP-II e+e- collider at SLAC. B meson decays involving vector-scalar, vector-vector, and vector-tensor final states are analyzed; the latter two shed new light on the polarization of these final states. We measure the branching fractions for nine of these decays; five are observed for the first time. For most decays we also measure the charge asymmetry and, where relevant, the longitudinal polarization f_L., Comment: 8 pages, 4 postscript figures, submitted to PRD RC

We present improved measurements of the branching fraction ${\cal B}$, the longitudinal polarization fraction $f_L$, and the direct {\ensuremath{CP}\xspace} asymmetry {\ensuremath{{\cal A}_{CP}}\xspace} in the $B$ meson decay channel $B^+\to\rho^+\rho^0$. The data sample was collected with the {{\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}}} detector at SLAC. The results are ${\cal B} (\Bp\ra\rprz)=(23.7\pm1.4\pm1.4)\times10^{-6}$, $f_L=0.950\pm0.015\pm0.006$, and $\Acp=-0.054\pm0.055\pm0.010$, where the uncertainties are statistical and systematic, respectively. Based on these results, we perform an isospin analysis and determine the CKM weak phase angle $\alpha$ to be $(92.4^{+6.0}_{-6.5})^{\circ}$., Comment: 7 pages, 1 figure, short version in Phys. Rev. Lett. (Fig.2 removed), adding color Figure 2 for the earlier versions of arxiv.0901.3522

We report on a Dalitz plot analysis of B- -> D+ pi- pi- decays, based on a sample of about 383 million Upsilon(4S) -> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC. We find the total branching fraction of the three-body decay: BR(B- -> D+ pi- pi-) = (1.08 +/- 0.03 +/- 0.05) x 10^-3. The masses and widths of D^{*0}_2 and D^{*0}_0, the 2+ and 0+ cubar P-wave states decaying to D+ pi-, are measured: mass_{D^{*0}_2} = (2460.4 +/- 1.2 +/- 1.2 +/- 1.9) MeV/c2, width_{D^{*0}_2} = (41.8 +/- 2.5 +/- 2.1 +/- 2.0) MeV, mass_{D^{*0}_0} = (2297 +/- 8 +/- 5 +/- 19) MeV/c2 and width_{D^{*0}_0} = (273 +/- 12 +/- 17 +/-45) MeV. The stated errors reflect the statistical and systematic uncertainties, and the uncertainty related to the assumed composition of signal events and the theoretical model., Comment: 18 pages, 12 postscript figures

We present measurements of the branching fraction and fraction of longitudinal polarization for the decay B+ -> K*0bar K*+ with a sample of 467 +/- 5 million BBbar pairs collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory. We obtain the branching fraction Br(B+ -> K*0bar K*+) = (1.2 +/- 0.5 +/- 0.1) x 10^{-6} with a significance of 3.7 standard deviations including systematic uncertainties. We measure the fraction of longitudinal polarization f_L = 0.75+0.16-0.26 +/- 0.03. The first error quoted is statistical and the second is systematic., Comment: 8 pages, 14 postscript figures, submitted to Phys. Rev. D. RC

A search for the lepton flavour violating decays $\tau^- \to l^- K^0_{\scriptscriptstyle S}$ ($l = e$ or $\mu$) has been performed using a data sample corresponding to an integrated luminosity of 469 ${fb}^{-1}$, collected with the {\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} detector at the SLAC PEP-II $e^+e^-$ asymmetric energy collider. No statistically significant signal has been observed in either channel and the estimated upper limits on branching fractions are ${\cal B}(\tau^- \to e^- K^0_{\scriptscriptstyle S}) < 3.3 \times 10^{-8}$ and ${\cal B}(\tau^- \to \mu^- K^0_{\scriptscriptstyle S}) < 4.0 \times 10^{-8}$ at 90% confidence level., Comment: 9 pages, 8 postscript figures, submitted to Phys. Rev. D