Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

Measurement of the top quark mass using charged particles in pp collisions at root s=8 TeV

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Kinetics of reduction of [Co(NH₃)₅N₃]Cl₂ by iron (II) in CTAB/n-heptane/butanol/water reverse micelles

952-956The kinetic study of reduction of pentaammineazidocobalt(III) chloride complex by Mohr’s salt (ammonium ferrous sulphate) has been carried out in the water pools of cationic reverse micelles of cetyltrimethylammonium bromide (CTAB). The reaction is first order each in Co(III) complex and iron(II) in all water-to-surfactant molar ratios, i.e. at all W values. The observed pseudo first order rate constant (kobs) versus W plot shows highest rate at W = 8.33. The kinetics has been accounted for by a mechanism involving bimolecular azido-bridged inner-sphere intermediate complex formation between Co(III) complex and iron(II). The significant increase of rate in reverse micellar media as compared to that in aqueous medium is due to the lower micropolarity of the water pool and bound state of reactants in this reverse micellar media, both facilitating the intermediate formation. The activation parameters (standard enthalpy of activation, Δ‡Hº and standard entropy of activation, Δ‡Sº) of the reaction at different W values have been calculated which corroborate the kinetics of the reaction

Kinetic and mechanistic studies on the interaction of 2-aminopyrimidine with dichloro[1-alkyl-2-(arylazo )imidazole] palladium (II) complexes

877-881Nucleophilic substitution of Pd (RaaiR/)Cl2 [(RaaiR/= l-alkyl-2 -(arylazo) imid azole, p-R-C6H4-N=N-C3H2NN-1-R/: where R = H(a)/Me(b)/Cl(c) and R/ = Et(1 )/Bz(2)] with 2-aminopyrimidine (2-NH2- Pym) in MeCN at 303 K, to form [Pd2(2-NH2- Pym)2 Cl4], has been studied spectrophotometrically under pseudo-first-order conditions. The results obtained support a nucleophilic association path . The reaction follows the rate law, Rate = {k0 + k [2-NH2-Pym]0} Pd (RaaiR/)Cl2 ], first order each in Pd (RaaiR/)Cl2 and 2-NH2-Pym. The rate increases as follows: Pd (RaaiEt)Cl2< Pd (RaaiBz)Cl2 and Pd (MeaaiR/)Cl2 /)Cl2 /)Cl2 . External addition of Cl- (LiCl) suppresses the rate inversely. The reactions have been studied at different temperatures (298-3 13 K) and activation parameters.Δ#Ho and Δ#So of the reactions have been calculated from the Eyring plot. The data support the proposed mechanism