Angular distributions in the decay B -> K*l(+)l(-)

We use a sample of 384 million BBbar events collected with the Babar detector at the PEP-II e+e- collider to study angular distributions in the rare decays B -> K* l+l-, where l+l- is either e+e- or mu+mu-. For low dilepton invariant masses, m(l+l-)3.2$ GeV/c^2, we measure AFB=0.76 (+0.52,-0.32) +/- 0.07 FL=0.71 (+0.20,-0.22) +/- 0.04.We are grateful for the excellent luminosity and machine conditions provided by our PEP-II colleagues, and for the substantial dedicated effort from the computing organizations that support BABAR. The collaborating institutions wish to thank SLAC for its support and kind hospitality. This work is supported by DOE and NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3 (France), BMBF and DFG (Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MES (Russia), MEC (Spain), and STFC (United Kingdom). Individuals have received support from the Marie Curie EIF (European Union) and the A. P. Sloan Foundation.Peer reviewe

EuFe2_2As2_2 under high pressure: an antiferromagnetic bulk superconductor

We report the ac magnetic susceptibility $\chi_{ac}$ and resistivity $\rho$ measurements of EuFe$_2$As$_2$ under high pressure $P$. By observing nearly 100% superconducting shielding and zero resistivity at $P$ = 28 kbar, we establish that $P$-induced superconductivity occurs at $T_c \sim$~30 K in EuFe$_2$As$_2$. $\rho$ shows an anomalous nearly linear temperature dependence from room temperature down to $T_c$ at the same $P$. $\chi_{ac}$ indicates that an antiferromagnetic order of Eu$^{2+}$ moments with $T_N \sim$~20 K persists in the superconducting phase. The temperature dependence of the upper critical field is also determined.Comment: To appear in J. Phys. Soc. Jpn., Vol. 78 No.

Search for Lepton Flavor Violation in the Decay τ^{±}→μ^{±}γ

A search for the nonconservation of lepton flavor number in the decay τ±→μ±γ has been performed using 2.07×108 e+e-→τ+τ- events produced at a center-of-mass energy near 10.58 GeV with the BABAR detector at the PEP-II storage ring. We find no evidence for a signal and set an upper limit on the branching ratio of B(τ±→μ±γ)<6.8×10-8 at 90% confidence level

Study of the B-→J/ψK-π+π- decay and measurement of the B-→X(3872)K- branching fraction

We study the decay B-→J/ψK-π+π- using 117×106 BB̅ events collected at the Y(4S) resonance with the BABAR detector at the PEP-II e+e- asymmetric-energy storage ring. We measure the branching fractions B (B-→J/ψK-π+π-)=(116±7(stat.)±9(syst.))×10-5 and B (B-→X(3872)K-)× B (X(3872)→J/ψπ+π-)=(1.28±0.41)×10-5 and find the mass of the X(3872) to be 3873.4±1.4  MeV/c2. We search for the hc narrow state in the decay B-→hcK-, hc→J/ψπ+π- and for the decay B-→J/ψD0π-, with D0→K-π+. We set the 90% C.L. limits B(B-→hcK-)×B(hc→J/ψπ+π-)<3.4×10-6 and B(B-→J/ψD0π-)<5.2×10-5

Observation of B0B^0 Meson Decay to a1±(1260)π∓a^\pm_1(1260) \pi^\mp

7 pages, 2 postscript figures. Submitted to Phys. Rev. Lett - P. Grenier aussi au LPCWe present a measurement of the branching fraction of the decay B0 --> a1(1260)^{+-} pi^{-+} with a1(1260)^{+-} --> pi^{-+} pi^{+-} pi^{+-}. The data sample consists of 218 million B B-bar pairs collected at the Y(4S) resonance and recorded by the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC. The analysis is based on unbinned multivariate maximum likelihood fit. The measured branching fraction is: (16.6 +/- 1.9 +/- 1.5) 10^{-6}. The decay mode, observed for the first time, is seen with a significance of 9.2 sigma (systematic uncertainties included)

Observation of B0 Meson Decay to a1±(1260)π∓

We present a measurement of the branching fraction of the decay B0→a1±(1260)π∓ with a1±(1260)→π∓π±π±. The data sample corresponds to 218×106 BB̅ pairs produced in e+e- annihilation through the Υ(4S) resonance. We measure the branching fraction B(B0→a1±(1260)π∓)B(a1±(1260)→π∓π±π±)=(16.6±1.9±1.5)×10-6, where the first error quoted is statistical and the second is systematic

Observation of Tree-Level B Decays with ss̅ Production from Gluon Radiation

We report on our search for decays proceeding via a tree-level b→c quark transition in which a gluon radiates into an ss̅ pair. We present observations of the decays B-→Ds(*)+K-π- and B̅ 0→Ds+KS0π- and evidence for B-→Ds+K-K- and set upper limits on the branching fractions for B̅ 0→Ds*+KS0π- and B-→Ds*+K-K- using 383×10^6 Υ(4S)→BB̅ events collected by the BABAR detector at SLAC. We present evidence that the invariant mass distributions of Ds(*)+K- pairs from B-→Ds(*)+K-π- decays are inconsistent with the phase-space model, suggesting the presence of charm resonances lying below the Ds(*)+K- threshold

Measurement of CP violation parameters with a Dalitz plot analysis of B-+/- -> D pi+pi(-)pi K-0(+/-)

We report the results of a CP violation analysis of the decay B-+/- -> D pi+pi(-)pi K-0(+/-), where D-pi(+)pi(-)pi(0) indicates a neutral D meson detected in the final state pi(+)pi(-)pi(0), excluding K-S(0)pi(0). The analysis makes use of 324x10(6) e(+)e -> B (B) over bar events recorded by the BABAR experiment at the PEP-II e(+)e(-) storage ring. Analyzing the pi(+)pi(-)pi(0) Dalitz plot distribution and the B-+/- -> D-pi(+)pi(-)pi K-0(+/-) branching fraction and decay rate asymmetry, we find the following one-standard-deviation constraints on the amplitude ratio and on the weak and strong phases: 0.06 pi(+)pi(-)pi(0) decay amplitude

Measurements of the Branching Fractions of B0→K∗0K+K−,B0→K∗0π+K−,B0→K∗0K+π−B^0 \to K^{*0}K^+K^-, B^0 \to K^{*0}\pi^+K^-, B^0 \to K^{*0}K^+\pi^-, and B0→K∗0π+π−B^0 \to K^{*0}\pi^+\pi^-

8 pages, 2 postscript figures, submitted to Lepton Photon 2007A search for the neutrinoless, lepton-flavor violating decay of the tau lepton into three charged leptons has been performed using 376 fb^{-1} of data collected at an e^+e^- center-of-mass energy around 10.58 GeV with the BaBar detector at the PEP-II storage rings. 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 (4-8) x 10^{-8} at 90% confidence level

Measurement of the B→Xsγ branching fraction and photon energy spectrum using the recoil method

We present a measurement of the branching fraction and photon-energy spectrum for the decay B→Xsγ using data from the BABAR experiment. The data sample corresponds to an integrated luminosity of 210 fb-1, from which approximately 680 000 BB̅ events are tagged by a fully reconstructed hadronic decay of one of the B mesons. In the decay of the second B meson, an isolated high-energy photon is identified. We measure B(B→Xsγ)=(3.66±0.85stat±0.60syst)×10-4 for photon energies Eγ above 1.9 GeV in the B rest frame. From the measured spectrum we calculate the first and second moments for different minimum photon energies, which are used to extract the heavy-quark parameters mb and μπ2. In addition, measurements of the direct CP asymmetry and isospin asymmetry are presented