Nicotinamide–2,2,2-trifluoro­ethanol (2/1)

The nicotinamide (NA) mol­ecules of the title compound, 2C6H6N2O·C2H3F3O, form centrosymmetric R 2 2(8) hydrogen-bonded dimers via N—H⋯O contacts. The asymmetric unit contains two mol­ecules of NA and one trifluoroethanol molecule disordered over two sites of equal occupancy. The packing consists of alternating layers of nicotinamide dimers and disordered 2,2,2-trifluoro­ethanol mol­ecules stacking in the c-axis direction. Intra­molecular C—H⋯O and inter­molecular N—H⋯N, O—H⋯N, C—H⋯N, C—H⋯O and C—H⋯F inter­actions are present

Aqueous solubility of organic salts. Investigating trends in a systematic series of 51 crystalline salt forms of methylephedrine

A dataset consisting of structures and aqueous solubility and melting point data for 51 salt forms of the phenylethylamine base methylephedrine is presented. Analysis showed correlation between solubility and melting point and between melting point of the salt and melting point of the parent acid, but no correlation of salt solubility with solubility of the parent acid. Identification of associations was aided by examining chemically sensible subgroups of the dataset, and this approach highlighted significantly different relationships between solubility and melting point for these subgroups. Thus, for example, the expected negative correlation between solubility and melting point was found for 24 anhydrous benzoate salts, but a positive correlation observed for 8 halide salts. Hydrated forms were anomalous. Packing analysis identified groups of structures that were isostructural with respect to cation packing. Correlation between solubility and melting point was found to be greatest within these isostructural groups, implying a role for packing structure in determining solubility

Regioselective reaction of heterocyclic N-oxides, an acyl chloride and cyclic thioethers

Treatment of electron deficient pyridine N-oxides with 4-nitrobenzoyl chloride and a cyclic thioether in the presence of triethylamine leads to the corresponding 2-functionalized product in up to 74% iso-lated yield. The transformation can also be accomplished with alternative nitrogen containing hetero-cycles including quinolines, pyrimidines, and pyrazines. To expand the scope of the transformation diisopropyl ether can be used as the reaction medium to allow for the use of solid thioether substrates

Measurement of the ttˉproductioncrosssectionint\bar{t} production cross section in p\bar{p}collisionsat collisions at \sqrt{s}$ = 1.8 TeV

We update the measurement of the top production cross section using the CDF detector at the Fermilab Tevatron. This measurement uses $t\bar{t}$ decays to the final states $e+\nu$+jets and $\mu+\nu$+jets. We search for $b$ quarks from $t$ decays via secondary-vertex identification or the identification of semileptonic decays of the $b$ and cascade $c$ quarks. The background to the $t\bar{t}$ production is determined primarily through a Monte Carlo simulation. However, we calibrate the simulation and evaluate its uncertainty using several independent data samples. For a top mass of 175 $GeV/c^2$, we measure $\sigma_{t\bar{t}}=5.1 \pm 1.5$ pb and $\sigma_{t\bar{t}}=9.2 \pm 4.3$ pb using the secondary vertex and the lepton tagging algorithms, respectively. Finally, we combine these results with those from other $t\bar{t}$ decay channels and obtain $\sigma_{t\bar{t}} = 6.5^{+1.7}_{-1.4}$ pb.Comment: The manuscript consists of 130 pages, 35 figures and 42 tables in RevTex. The manuscript is submitted to Physical Review D. Fixed typo in author lis

Search for Narrow Diphoton Resonances and for gamma-gamma+W/Z Signatures in p\bar p Collisions at sqrt(s)=1.8 TeV

We present results of searches for diphoton resonances produced both inclusively and also in association with a vector boson (W or Z) using 100 pb^{-1} of p\bar p collisions using the CDF detector. We set upper limits on the product of cross section times branching ratio for both p\bar p\to\gamma\gamma + X and p\bar p\to\gamma\gamma + W/Z. Comparing the inclusive production to the expectations from heavy sgoldstinos we derive limits on the supersymmetry-breaking scale sqrt{F} in the TeV range, depending on the sgoldstino mass and the choice of other parameters. Also, using a NLO prediction for the associated production of a Higgs boson with a W or Z boson, we set an upper limit on the branching ratio for H\to\gamma\gamma. Finally, we set a lower limit on the mass of a `bosophilic' Higgs boson (e.g. one which couples only to \gamma, W, and Z$ bosons with standard model couplings) of 82 GeV/c^2 at 95% confidence level.Comment: 30 pages, 11 figure

Search for Chargino-Neutralino Associated Production at the Fermilab Tevatron Collider

We have searched in $p \bar{p}$ collisions at $\sqrt{s}$ = 1.8 TeV for events with three charged leptons and missing transverse energy. In the Minimal Supersymmetric Standard Model, we expect trilepton events from chargino-neutralino (\chione \chitwo) pair production, with subsequent decay into leptons. We observe no candidate $e^+e^-e^\pm$, $e^+e^-\mu^\pm$, $e^\pm\mu^+\mu^-$ or $\mu^+\mu^-\mu^\pm$ events in 106 pb$^{-1}$ integrated luminosity. We present limits on the sum of the branching ratios times cross section for the four channels: \sigma_{\chione\chitwo}\cdot BR(\chione\chitwo\to 3\ell+X) 81.5 \mgev\sp and M_\chitwo > 82.2 \mgev\sp for $\tan\beta=2$, $\mu =-600$~\mgev\sp and M_\squark= M_\gluino.Comment: 9 pages and 3 figure

Search for a Fourth-Generation Quark More Massive than the Z0 Boson in ppbar Collisions at sqrt(s) = 1.8 TeV

We present the results of a search for pair production of a fourth-generation charge -1/3 quark (b') in sqrt(s)=1.8 TeV ppbar collisions using 88 pb^(-1) of data obtained with the Collider Detector at Fermilab. We assume that both quarks decay via the flavor-changing neutral current process b' -> bZ and that the b' mass is greater than m_Z + m_b. We studied the decay mode b'b'bar -> ZZ b bbar where one Z0 decays into e^+e^- or mu^+ mu^- and the other decays hadronically, giving a signature of two leptons plus jets. An upper limit on the cross section of ppbar -> b'b'bar times [BR (b' -> bZ)]^2 is established as a function of the b' mass. We exclude at 95% confidence level a b' quark with mass between 100 and 199 GeV/c^2 for BR(b' -> bZ) = 100%.Comment: 12 pages, 2 figures, submitted to Phys. Rev. Letters on 9/12/9

Production of Y(1S) Mesons from chib Decays in pp(bar) Collisions at sqrt(s)=1.8 TeV

We have reconstructed the radiative decays $\chi_{b}(1P) \to \Upsilon(1S) \gamma$ and $\chi_{b}(2P) \to \Upsilon(1S) \gamma$ in $p \bar{p}$ collisions at $\sqrt{s} = 1.8$ TeV, and measured the fraction of $\Upsilon(1S)$ mesons that originate from these decays. For $\Upsilon(1S)$ mesons with $p^{\Upsilon}_{T}>8.0$ GeV/$c$, the fractions that come from $\chi_{b}(1P)$ and $\chi_{b}(2P)$ decays are $(27.1\pm6.9(stat)\pm4.4(sys))$ and $(10.5\pm4.4(stat)\pm1.4(sys))$, respectively. We have derived the fraction of directly produced $\Upsilon(1S)$ mesons to be $(50.9\pm8.2(stat)\pm9.0(sys))$.Comment: 13 Pages, 2 figure

Measurement of the Helicity of W Bosons in Top Quark Decays

We use the transverse momentum spectrum of leptons in the decay chain t-->bW with W-->l nu to measure the helicity of the W bosons in the top quark rest frame. Our measurement uses a ttbar sample isolated in 106 +/- 4 inverse picobarns of data collected in ppbar collisions at sqrt(s)=1.8 TeV with the CDF detector at the Fermilab Tevatron. Assuming a standard V--A weak decay, we find that the fraction of W's with zero helicity in the top rest frame is F_0 = 0.91 +/- 0.37 (stat) +/- 0.13 (syst), consistent with the standard model prediction of F_0=0.70 for a top mass of 175 GeV/c**2.Comment: Submitted to PRL. 8 pages, 2 figure

Limits on Gravitino Production and New Processes with Large Missing Transverse Energy in p-pbar Collisions at sqrt(s)=1.8 TeV

Events collected by the Collider Detector at Fermilab (CDF) with an energetic jet plus large missing transverse energy can be used to search for physics beyond the Standard Model. We see no deviations from the expected background and set upper limits on the production of new processes. We consider in addition the production of light gravitinos within the framework of the Gauge Mediated Supersymmetry Breaking models and set a limit at 95% confidence level on the breaking scale sqrt(F) >= 217 GeV, which excludes gravitino masses smaller than 1.1x10^-5 eV/c^2.Comment: 13 pages, 4 figures. Submitted to Physical Review Letter