Present Bounds on New Neutral Vector Resonances from Electroweak Gauge Boson Pair Production at the LHC

Several extensions of the Standard Model predict the existence of new neutral spin-1 resonances associated to the electroweak symmetry breaking sector. Using the data from ATLAS (with integrated luminosity of L=1.02 fb^{-1}) and CMS (with integrated luminosity of L=1.55 fb^{-1}) on the production of W+W- pairs through the process pp -> l^+ l^{\prime -} \sla{E}_T, we place model independent bounds on these new vector resonances masses, couplings and widths. Our analyses show that the present data excludes new neutral vector resonances with masses up to 1-2.3 TeV depending on their couplings and widths. We also demonstrate how to extend our analysis framework to different models working a specific example.Comment: 10 pages, 6 figure

Enhanced time response of 1-in. LaBr3(Ce) crystals by leading edge and constant fraction techniques

We have characterized in depth the time response of three detectors equipped with cylindrical LaBr$_{3}$ (Ce) crystals with dimensions of 1-in. in height and 1-in. in diameter, and having nominal Ce doping concentration of 5%, 8% and 10%. Measurements were performed at $^{60}$Co and $^{22}$Na {\gamma}-ray energies against a fast BaF$_{2}$ reference detector. The time resolution was optimized by the choice of the photomultiplier bias voltage and the fine tuning of the parameters of the constant fraction discriminator, namely the zero-crossing and the external delay. We report here on the optimal time resolution of the three crystals. It is observed that timing properties are influenced by the amount of Ce doping and the crystal homogeneity. For the crystal with 8% of Ce doping the use of the ORTEC 935 CFD at very shorts delays in addition to the Hamamatsu R9779 PMT has made it possible to improve the LaBr$_{3}$(Ce) time resolution from the best literature value at 60Co photon energies to below 100 ps.Comment: Article submitted to Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipmen

Constraining anomalous Higgs interactions

The recently announced Higgs discovery marks the dawn of the direct probing of the electroweak symmetry breaking sector. Sorting out the dynamics responsible for electroweak symmetry breaking now requires probing the Higgs interactions and searching for additional states connected to this sector. In this work we analyze the constraints on Higgs couplings to the standard model gauge bosons using the available data from Tevatron and LHC. We work in a model--independent framework expressing the departure of the Higgs couplings to gauge bosons by dimension--six operators. This allows for independent modifications of its couplings to gluons, photons and weak gauge bosons while still preserving the Standard Model (SM) gauge invariance. Our results indicate that best overall agreement with data is obtained if the cross section of Higgs production via gluon fusion is suppressed with respect to its SM value and the Higgs branching ratio into two photons is enhanced, while keeping the production and decays associated to couplings to weak gauge bosons close to their SM prediction.Comment: v3: Added acknowledgment to FP7 ITN INVISIBLES (Marie Curie Actions PITN-GA-2011-289442). Nothing else changed with respect to v

CP violation with a dynamical Higgs

We determine the complete set of independent gauge and gauge-Higgs CP-odd effective operators for the generic case of a dynamical Higgs, up to four derivatives in the chiral expansion. The relation with the linear basis of dimension six CP-odd operators is clarified. Phenomenological applications include bounds inferred from electric dipole moment limits, and from present and future collider data on triple gauge coupling measurements and Higgs signals.Comment: 41 pages, 3 figures; V2: citations added, typos corrected, version published on JHE

Disentangling a dynamical Higgs

The pattern of deviations from Standard Model predictions and couplings is different for theories of new physics based on a non-linear realization of the $SU(2)_L\times U(1)_Y$ gauge symmetry breaking and those assuming a linear realization. We clarify this issue in a model-independent way via its effective Lagrangian formulation in the presence of a light Higgs particle, up to first order in the expansions: dimension-six operators for the linear expansion and four derivatives for the non-linear one. Complete sets of pure gauge and gauge-Higgs operators are considered, implementing the renormalization procedure and deriving the Feynman rules for the non-linear expansion. We establish the theoretical relation and the differences in physics impact between the two expansions. Promising discriminating signals include the decorrelation in the non-linear case of signals correlated in the linear one: some pure gauge versus gauge-Higgs couplings and also between couplings with the same number of Higgs legs. Furthermore, anomalous signals expected at first order in the non-linear realization may appear only at higher orders of the linear one, and vice versa. We analyze in detail the impact of both type of discriminating signals on LHC physics.Comment: Version published in JHE

Simple metal-free oxidative cleavage of 1,2-diols

Cleavage of 1,2-diols is easily carried out under mild conditions with the Oxone/KBr (or Oxone/NaCl) method in either acetonitrile/water or tert-butanol/water medium at room temperature. This procedure is highly efficient for the cleavage of dihydroxyfatty esters and acids. The reaction takes place through a double oxidation of the 1,2-diol, leading to the 1,2-diketone that undergoes a Baeyer-Villiger oxidation, with a final hydrolysis of the generated anhydride. The application to other diols, including simple internal and terminal diols, is also possible, but the nature of the diol substrate conditions the optimal halide/solvent system, given that important differences in reactivity are observed. These differences are ascribed to the change in the rate limiting step depending on the substrate/halide/solvent combinatio

Synthesis of hydroxyfatty esters by sequential epoxidation-hydrogenolysis: Solvent effects

The tandem/sequential combination of epoxidation and hydrogenolysis for unsaturated fatty esters is not straightforward, due to incompatibility problems with the impurities present or generated in the used solvents. The chlorinated impurities in alpha, alpha, alpha-trifluorotoluene leads to the formation of important amounts of chlorohydrins by HCl formation in the hydrogenolysis step. The use of trifluoroethanol (TFE) in the epoxidation step produces trifluoroacetic acid traces by oxidation, responsible for the opening of the epoxide with water and TFE. The solvent of choice was finally isobutyl acetate, which gathers the required physicochemical properties, with 85 % yield of hydroxystearates from methyl oleate in a sequential process