57 research outputs found
A search for the decay
We search for the rare flavor-changing neutral-current decay in a data sample of 82 fb collected with the {\sl 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
at the 90% confidence level. In addition, by selecting for pions rather than
kaons, we obtain a limit of using only the hadronic B reconstruction method.Comment: 7 pages, 8 postscript figures, submitted to Phys. Rev. Let
High-reflectivity broadband distributed Bragg reflector lattice matched to ZnTe
We report on the realization of a high quality distributed Bragg reflector
with both high and low refractive index layers lattice matched to ZnTe. Our
structure is grown by molecular beam epitaxy and is based on binary compounds
only. The high refractive index layer is made of ZnTe, while the low index
material is made of a short period triple superlattice containing MgSe, MgTe,
and ZnTe. The high refractive index step of Delta_n=0.5 in the structure
results in a broad stopband and the reflectivity coefficient exceeding 99% for
only 15 Bragg pairs.Comment: 4 pages, 3 figure
EuFeAs under high pressure: an antiferromagnetic bulk superconductor
We report the ac magnetic susceptibility and resistivity
measurements of EuFeAs under high pressure . By observing nearly
100% superconducting shielding and zero resistivity at = 28 kbar, we
establish that -induced superconductivity occurs at ~30 K in
EuFeAs. shows an anomalous nearly linear temperature dependence
from room temperature down to at the same . indicates that
an antiferromagnetic order of Eu moments with ~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.
Improved measurement of CP asymmetries in B-0 ->(c(c)over-bar)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 227x10(6) Upsilon(4S)-> B (B) over bar decays collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The amplitude of the CPasymmetry, 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 (0) from its decay products. We measure sin2 beta=0.722 +/- 0.040(stat)+/- 0.023(syst) in agreement with the standard model expectation
The BaBar detector: Upgrades, operation and performance
Contains fulltext :
121729.pdf (preprint version ) (Open Access
Study of e(+)e(-)->Lambda(Lambda)over-bar, Lambda(Sigma)over-bar(0), Sigma(0)(Sigma)over-bar(0) using initial state radiation with BABAR
We study the e(+)e(-)->Lambda(Lambda) over bar gamma, Lambda(Sigma) over bar (0)gamma, Sigma(0)(Sigma) over bar (0)gamma processes using 230 fb(-1) of integrated luminosity collected by the BABAR detector at e(+)e(-) center-of-mass energy of 10.58 GeV. From the analysis of the baryon-antibaryon mass spectra the cross sections for e(+)e(-)->Lambda(Lambda) over bar, Lambda(Sigma) over bar (0), Sigma(0)(Sigma) over bar>(0) are measured in the dibaryon mass range from threshold up to 3 GeV/c(2). The ratio of electric and magnetic form factors, |G(E)/G(M)|, is measured for e(+)e(-)->Lambda(Lambda) over bar, and limits on the relative phase between Lambda form factors are obtained. We also measure the J/psi ->Lambda(Lambda) over bar, Sigma(0)(Sigma) over bar (0), and psi(2S)->Lambda(Lambda) over bar branching fractions
Observation of the decay B+-> K+K-pi(+)
We report the observation of charmless hadronic decays of charged B mesons to the final state K+K-pi(+). Using a data sample of 347.5 fb(-1) collected at the Upsilon(4S) resonance with the BABAR detector, we observe 429 +/- 43 signal events with a significance of 9.6 sigma. We measure the inclusive branching fraction B(B+-> K+K-pi(+))=[5.0 +/- 0.5(stat)+/- 0.5(syst)]x10(-6). Inspection of the Dalitz plot of signal candidates shows a broad structure peaking near 1.5 GeV/c(2) in the K+K- invariant mass distribution. We find the direct CP asymmetry to be consistent with zero
Observation of B meson decays to b(1)pi and b(1)K
We present the results of searches for decays of B mesons to final states with a b(1) meson and a charged pion or kaon. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 382x10(6) B(B)over bar pairs produced in e(+)e(-) annihilation. The results for the branching fractions are, in units of 10(-6), B(B+ -> b(1)(0)pi(+)) = 6.7 +/- 1.7 +/- 1.0, B(B+ -> b(1)(0)K(+)) = 9.1 +/- 1.7 +/- 1.0, B(B-0 -> b(1)(-/+)pi +/- ) = 10.9 +/- 1.2 +/- 0.9, and B(B-0 -> b(1)(-)K(+)) = 7.4 +/- 1.0 +/- 1.0, with the assumption that B(b(1) -> omega pi) = 1. We also measure charge and flavor asymmetries A(ch)(B+ -> b(1)(0)pi(+)) = 0.05 +/- 0.16 +/- 0.02, A(ch)(B+ -> b(1)(0)K(+)) = -0.46 +/- 0.20 +/- 0.02, A(ch)(B-0 -> b(1)(-/+)pi +/- ) = -0.05 +/- 0.10 +/- 0.02, C(B-0 -> b(1)(-/+)pi +/- ) = -0.22 +/- 0.23 +/- 0.05, Delta C(B-0 -> b(1)(-/+)pi +/- ) = -1.04 +/- 0.23 +/- 0.08, and A(ch)(B-0 -> b(1)(-)K(+)) = -0.07 +/- 0.12 +/- 0.02. The first error quoted is statistical, and the second systematic
Branching fraction and CP-violation charge asymmetry measurements for B-meson decays to ηK±, ηπ±, η′K, η′π±, ωK, and ωπ±
We present measurements of the branching fractions for B-0-meson decays to eta'K-0 and omega K-0, and of the branching fractions and CP-violation charge asymmetries for B+-meson decays to eta pi(+), eta K+, eta'pi(+), eta'K+, omega pi(+), and omega K+. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 383x10(6) B (B) over bar pairs produced in e(+)e(-) annihilation. The measurements agree with previous results; we find no evidence for direct CP violation
- …