2,236 research outputs found

    Triple-Product Correlations in B -> V1 V2$ Decays and New Physics

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    In this paper we examine T-violating triple-product correlations (TP's) in B -> V1 V2 decays. TP's are excellent probes of physics beyond the standard model (SM) for two reasons: (i) within the SM, most TP's are expected to be tiny, and (ii) unlike direct CP asymmetries, TP's are not suppressed by the small strong phases which are expected in B decays. TP's are obtained via the angular analysis of B -> V1 V2. In a general analysis based on factorization, we demonstrate that the most promising decays for measuring TP's in the SM involve excited final-state vector mesons, and we provide estimates of such TP's. We find that there are only a handful of decays in which large TP's are possible, and the size of these TP's depends strongly on the size of nonfactorizable effects. We show that TP's which vanish in the SM can be very large in models with new physics. The measurement of a nonzero TP asymmetry in a decay where none is expected would specifically point to new physics involving large couplings to the right-handed b-quark.Comment: 42 pages, LaTeX, no figures. Title changed, several explanatory paragraphs added, references added, analysis and conclusions unchange

    Antimicrobial Activity and Quantum Chemical Calculations of Pyrazol-2,3-Dihydrothiazole Sugar Derivatives

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    A number of new [(pyrazol-4-yl) methylene] hydrazono-2,3-dihydrothiazoles, sugar hydrazones, and their N-glycoside derivatives were synthesized. The chemical structures of the synthesized compounds were confirmed by 1H NMR technique. The newly synthesized compounds were tested for their antimicrobial activities and showed moderate to high inhibition activities. Quantum chemistry calculations were used to study the molecular geometry and electronic structure of the selected derivatives. The energy gap between the highest occupied molecular orbital (HOMO)and lowest unoccupied molecular orbital (LUMO) has been calculated using the theoretical computations to reflect the chemical reactivity and kinetic stability of compounds. Keywords: 1H-pyrazole, aminothiazole, ethylchloroacetate, quantum chemical calculations, antimicrobial activity

    Hyperon Nonleptonic Decays in Chiral Perturbation Theory Reexamined

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    We recalculate the leading nonanalytic contributions to the amplitudes for hyperon nonleptonic decays in chiral perturbation theory. Our results partially disagree with those calculated before, and include new terms previously omitted in the P-wave amplitudes. Although these modifications are numerically significant, they do not change the well-known fact that good agreement with experiment cannot be simultaneously achieved using one-loop S- and P-wave amplitudes.Comment: 14 pages, latex, 3 figures, uses axodraw.sty, minor additions, to appear in Phys. Rev.

    Caracterización estructural y actividad biológica de sulfolípidos de algas marinas seleccionadas

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    The sulfolipid classes (SLs) in the total lipids of five species of marine algae, two species of Rhodophyta (Laurencia popillose, Galaxoura cylindriea), one species of Chlorophyta (Ulva fasciata), and two species of Phaeophyta (Dilophys fasciola, Taonia atomaria) were separated and purified on DEAE-cellulose column chromatography. The SLs component was identified by IR, gas chromatography MS/MS and liquid chromatography MS/MS. The level of SLs contents va ried from 1.25% (in L. papillose) to 11.82% (in D. fasciola) of the total lipid contents. However, no significant differences in sulfate content (0.13 – 0.21%) were observed among all these algae species. All SLs were characterized by high contents of palmitic acid (C 16:0), which ranged from 30.91% in G. cylindriea to 63.11% in T. atomatia. The main constitutes of algal sulfolipids were identified as sulfoquinovosyl-di-acylglycerol and sulfoquinovosyl acylglycerol. The sulfolipids of different algal species exhibited remarkable antiviral activity against herps simplex virus type 1 (HSV-1) with an IC50 ranging from 18.75 to 70. 2 μg mL–1. Moreover, algal sulfolipid inhibited the growth of the tumor cells of breast and liver human cancer cells with IC50 values ranging from 0.40 to 0.67 μg mL–1 for human breast adenocarcinoma cells (MCF7).Se separaron diferentes clases sulfolípidos (SL) a partir de los lípidos totales de cinco especies de algas marinas: una especie de Chlorophyta (Ulva fasciata), dos especies de Phaeophyta (Dilophys fasciola, Taonia atomaria) y dos especies de Rhodophyta (Laurencia popillose, Galaxoura cylindriea) que se purificaron mediante cromatografía en columna de DEAE-celulosa. Los components de SLs fueron identificados por IR, cromatografía de gases MS/MS y cromatografía líquida MS/ MS. Los contenidos de SL en relación al total de lípidos varió de 1,25% (en L. papilosa) al 11,82% (en D. fasciola). Sin embargo, no hay diferencias significativas en el contenido de sulfato observado entre todas estas especies de algas (desde 0,13 hasta 0,21%). Todos los SL se caracterizaron por un alto contenido de ácido palmítico (C16:0), que osciló entre 30,91% en G. cylindriea a 63,11% en T. atomatia. Sulfoquinovosyl-di-acilglicerol y acilglicerol sulfoquinovosyl fueron identificados como los principales constituyentes de los sulfolípidos de estas algas. Los sulfolípidos de las diferentes especies de algas estudiadas mostraron una notable actividad antiviral contra el virus del herpes simple tipo 1 (VHS-1) con una IC50 que osciló entre 18,75 y 70. 2 g mL–1. Por otra parte, los sulfolípidos de estas algas inhibieron el crecimiento de células tumorales de mama y células de cáncer de hígado humano con valores de IC50 que van desde 0,40 hasta 0,67 g mL–1 para las células de adenocarcinoma de mama humano (MCF7)

    On the Production of π+π+\pi^+\pi^+ Pairs in pp Collisions at 0.8 GeV

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    Data accumulated recently for the exclusive measurement of the ppppπ+πpp\to pp\pi^+\pi^- reaction at a beam energy of 0.793 GeV using the COSY-TOF spectrometer have been analyzed with respect to possible events from the ppnnπ+π+pp \to nn\pi^+\pi^+ reaction channel. The latter is expected to be the only ππ\pi\pi production channel, which contains no major contributions from resonance excitation close to threshold and hence should be a good testing ground for chiral dynamics in the ππ\pi\pi production process. No single event has been found, which meets all conditions for being a candidate for the ppnnπ+π+pp \to nn \pi^+\pi^+ reaction. This gives an upper limit for the cross section of 0.16 μ\mub (90% C.L.), which is more than an order of magnitude smaller than the cross sections of the other two-pion production channels at the same incident energy

    SYNTHESIS AND CHARACTERIZATION OF AMINO-BASED CARBOXYMETHYL CHITOSAN AND ITS ADSORPTION FEATURES TOWARDS CU (II) AND ZN (II) IONS

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    This work was supported by the Program 211 of the Government of the Russian Federation, RFBR grants 17-03-00641 and 18-29-12129mk, the State Task from the Ministry of the Education and Science of the Russian Federation
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