Measurement of CP-violating asymmetries in B0 decays to CP eigenstates

We present measurements of time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurement uses a data sample of 23x10(6) Upsilon(4S)-->BbarB decays collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we find events in which one neutral B meson is fully reconstructed in a CP eigenstate containing charmonium and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the standard model is proportional to sin2beta, is derived from the decay time distributions in such events. The result is sin2beta = 0.34+/-0.20 (stat)+/-0.05 (syst).     

Hydroxyl-directed hydrogenation of homoallylic alcohols. Effects of achiral and chiral rhodium catalysts on 1,3 stereocontrol.

The hydroxyl-directed hydrogenation of homoallylic alcohols is examined with cationic rhodium-(I) and iridium-(I) catalysts. These reactions proceed with high levels of diastereoselection when either Rh(Diphos)⁺ or Ir(pry)Pcy₃⁺ are employed as catalysts.     

Muon spin rotation in GdSr2Cu2RuO8: Implications

Muon spin rotation measurements are reported for GdSr₂Cu₂RuO₈, a material with an onset temperature for superconductivity of about 45 K (which is virtually the same for its superconducting sister compounds Sr₂YRu_{1? u} Cu _u O₆ and Gd_{2? z} Ce _z Sr₂Cu₂RuO₁₀). The data indicate two magnetic ordering transitions, at about 15 K and about 130 K, in addition to the Gd ordering transition known to occur at about 2.6 K. We tentatively attribute the 130 K transition to Ru and the 15 K transition to Cu ordering, effectively ruling out any superconducting mechanism based on fluctuating magnetic moments, which are frozen below about 15 K. If there is only one mechanism of high-temperature superconductivity, then the three facts that (i) all three sister compounds have essentially the same onset T _c for superconductivity and (ii) all three of these compounds contain SrO layers but (iii) only two of the three compounds, GdSr₂Cu₂RuO₈ and Gd_{2? z} Ce _z Sr₂Cu₂RuO₁₀ (and not Sr₂YRu_{1? u} Cu _u O₆) contain cuprate planes imply that the superconducting layers of all three compounds must be the common SrO layers, and not the cuprate planes (which do not occur in Cu-doped Sr₂YRuO₆). Otherwise the coincidence of onset temperatures must be an accident, and there must be at least two mechanisms of high-T _c superconductivity: one for doped Sr₂YRuO₆ and another for cuprate-plane superconductivity.     

Measurements of the generalized electric and magnetic polarizabilities of the proton at low Q2 using the virtual-compton-scattering reaction

The mean square polarizability radii of the proton have been measured for the first time in a virtual-Compton-scattering experiment performed at the MIT-Bates out-of-plane scattering facility. Response functions and polarizabilities obtained from a dispersion analysis of the data at Q2 = 0.057 GeV2/c2 are in agreement with O(p3) heavy baryon chiral perturbation theory. The data support the dominance of mesonic effects in the polarizabilities.     

Evidence for superconductivity in the Bi-O layers and not in the cuprate planes of Bi2Sr2CaCu2O8

The superconductivity in Bi₂Sr₂CaCu₂O₈occurs in Bi-O slabs, with the CuO₂planes being insulating.     

Structure-dependent modulation of a pathogen response in plants by synthetic O-antigen polysaccharides

Many phytopathogenic bacteria display lipopolysaccharides (LPS) with the O-chain repeating unit [alpha-l-Rha-(1-->3)-alpha-l-Rha-(1-->3)-alpha-l-Rha-(1-->2)](n)(). This trisaccharide unit was synthesized and oligomerized to obtain hexa- and nonasaccharides. The deprotected rhamnans were effective in suppressing the hypersensitive response (HR) and in inducing PR-1 gene expression in Arabidopsis thaliana. Conformational analysis of the oligorhamnans by NMR spectroscopy and molecular dynamics calculations revealed that a coiled structure develops with increasing chain length of the oligosaccharide. This is associated with increasing efficacy in HR suppression and PR-1 gene expression. We therefore infer that the coiled structure of phytopathogenic bacteria is a plant-recognizable pathogen-associated molecular pattern (PAMP).     

Effects of mini-Umklapp processes on heat transport in superlattices

Superlattice Umklapp processes contribute to phonon-phonon scattering and limit the thermal conductivity of insulating superlattices. The temperature dependence of the thermal conductivity is predicted using Callaway's phenomenological relaxation time approximation.     

Products without remote points

It is shown that ω × Y^ω does not have remote points if Y is a compact space with cellularity larger than ω₁. It is also shown that it is consistent that ω × Y^ω does not have remote points if Y is compact with uncountable cellularity. As an application we construct a compact space with weight ω₂ · c which can be covered by nowhere dense P-sets and a compact space with weight c for which it is independent that it can be covered by nowhere dense P-sets.     

Remote points under the continuum hypothesis

We show that, under CH, (i) every ccc, non-pseudocompact space of weight at most ω₂ has remote points, and (ii) if X_i, for i ∈ I, is a completely regular ccc topological space of weight ω₁ and if X := Π_{i ∈ I} X_i is ccc and non-pseudocompact, then X has remote points. Received July 21, 2006; accepted in final form October 16, 2008.     

Precise measurement of deuteron tensor analyzing powers with BLAST

We report a precision measurement of the deuteron tensor analyzing powers T(20) and T(21) at the MIT-Bates Linear Accelerator Center. Data were collected simultaneously over a momentum transfer range Q=2.15-4.50 fm(-1) with the Bates Large Acceptance Spectrometer Toroid using a highly polarized deuterium internal gas target. The data are in excellent agreement with calculations in a framework of effective field theory. The deuteron charge monopole and quadrupole form factors G(C) and G(Q) were separated with improved precision, and the location of the first node of G(C) was confirmed at Q=4.19±0.05 fm(-1). The new data provide a strong constraint on theoretical models in a momentum transfer range covering the minimum of T(20) and the first node of G(C).