6,238 research outputs found

    Hyperon weak radiative decays in chiral perturbation theory

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    We investigate the leading-order amplitudes for weak radiative decays of hyperons in chiral perturbation theory. We consistently include contributions from the next-to-leading order weak-interaction Lagrangian. It is shown that due to these terms Hara's theorem is violated. The data for the decays of charged hyperons can be easily accounted for. However, at this order in the chiral expansion, the four amplitudes for the decays of neutral hyperons satisfy relations which are in disagreement with the data. The asymmetry parameters for all the decays can not be accounted for without higher-order terms. We shortly comment on the effect of the 27-plet part of the weak interaction.Comment: 8 pages of REVTeX and using macro-package "feynman.tex" (available at http://xxx.lanl.gov/ftp/hep-ph/papers/macros) for the 2 figure

    АСПЕКТЫ ПРИМЕНЕНИЯ ИНДОМЕТАЦИНА В МЕДИЦИНЕ И ФАРМАЦИИ

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    Indomethacin, a non-steroid anti-inflammatory drug (NSAID), has been used in different spheres of medicine since the 1960s. It is successfully administered as an anti-inflammatory and pain-relieving medication in rheumatoid and other diseases. According to recent research, indomethacin may become a promising drug enhancing endogenous remyelination in patients with multiple sclerosis. Also, indomethacin affects cell proliferation and invasion, thus it is used to manage pancreatic cancer in patients with hyperglycemia. In addition, indomethacin can inhibit protein synthesis in colorectal carcinoma and other types of cancer cells. The article reviews modern indomethacin medications and the different dosage forms on the Russian pharmaceutical market. Indomethacin poor water solubility is one of the reasons for decreasing its biopharmaceutical characteristics. According to the conducted research, a prospective way to improve indomethacin solubility and bioavailability is the Solid Dispersion (SD) method. SDs are bi- or multicomponent systems consisting of the drug and the carrier. They are a highly dispersed solid phase of the drug or molecular-dispersed solid solutions with a partial formation of a variable composition complex and a carrier. The article provides a brief overview on different aspects of obtaining, investigating, and applying indomethacin SDs with various polymers.Синтезированный в шестидесятых годах прошлого столетия типичный представитель класса нестероидных противовоспалительных средств индометацин нашел широкое применение в различных областях медицины. Сочетание противовоспалительного и обезболивающего действия обусловило успешное применение индометацина при ревматических заболеваниях. Новейшие исследования выявили, что препарат может стать перспективным средством и в терапии ряда иных патологий. В статье приведен краткий обзор ассортимента современных препаратов и различных лекарственных форм индометацина на отечественном фармацевтическом рынке. Одним из факторов, снижающих биофармацевтические характеристики препаратов индометацина, является его малая растворимость в воде. Согласно результатам анализа литературных данных, одной из перспективных технологий, способных успешно увеличить растворимость и биодоступность индометацина, является метод получения его твердых дисперсий. Твердые дисперсии ― это би- или многокомпонентные системы из лекарственного вещества и носителя, представляющие собой высокодиспергированную твердую фазу лекарственного вещества или молекулярно-дисперсные твердые или жидкие растворы с частичным образованием комплексов переменного состава с материалом носителя. Представлен краткий обзор работ, посвященных различным аспектам получения, исследования и применения твердых дисперсий индометацина с разными полимерами-носителями

    Semileptonic Branching Fraction of Charged and Neutral B Mesons

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    An examination of leptons in Υ(4S){\Upsilon (4S)} events tagged by reconstructed BB decays yields semileptonic branching fractions of b=(10.1±1.8±1.4)%b_-=(10.1 \pm 1.8\pm 1.4)\% for charged and b0=(10.9±0.7±1.1)%b_0=(10.9 \pm 0.7\pm 1.1)\% for neutral BB mesons. This is the first measurement for charged BB. Assuming equality of the charged and neutral semileptonic widths, the ratio b/b0=0.93±0.18±0.12b_-/b_0=0.93 \pm 0.18 \pm 0.12 is equivalent to the ratio of lifetimes. A postscript version is available through World-Wide-Web in http://w4.lns.cornell.edu/public/CLNS/1994Comment: 9 pages (in REVTEX format) Preprint CLNS94-1286, CLEO 94-1

    Production and Decay of D_1(2420)^0 and D_2^*(2460)^0

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    We have investigated D+πD^{+}\pi^{-} and D+πD^{*+}\pi^{-} final states and observed the two established L=1L=1 charmed mesons, the D1(2420)0D_1(2420)^0 with mass 242122+1+22421^{+1+2}_{-2-2} MeV/c2^{2} and width 2053+6+320^{+6+3}_{-5-3} MeV/c2^{2} and the D2(2460)0D_2^*(2460)^0 with mass 2465±3±32465 \pm 3 \pm 3 MeV/c2^{2} and width 2876+8+628^{+8+6}_{-7-6} MeV/c2^{2}. Properties of these final states, including their decay angular distributions and spin-parity assignments, have been studied. We identify these two mesons as the jlight=3/2j_{light}=3/2 doublet predicted by HQET. We also obtain constraints on {\footnotesize ΓS/(ΓS+ΓD)\Gamma_S/(\Gamma_S + \Gamma_D)} as a function of the cosine of the relative phase of the two amplitudes in the D1(2420)0D_1(2420)^0 decay.Comment: 15 pages in REVTEX format. hardcopies with figures can be obtained by sending mail to: [email protected]

    Precision Measurement of the Ds+Ds+D_s^{*+}- D_s^+ Mass Difference

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    We have measured the vector-pseudoscalar mass splitting M(Ds+)M(Ds+)=144.22±0.47±0.37MeVM(D_s^{*+})-M(D_s^+) = 144.22\pm 0.47\pm 0.37 MeV, significantly more precise than the previous world average. We minimize the systematic errors by also measuring the vector-pseudoscalar mass difference M(D0)M(D0)M(D^{*0})-M(D^0) using the radiative decay D0D0γD^{*0}\rightarrow D^0\gamma, obtaining [M(Ds+)M(Ds+)][M(D0)M(D0)]=2.09±0.47±0.37MeV[M(D_s^{*+})-M(D_s^+)]-[M(D^{*0})-M(D^0)] = 2.09\pm 0.47\pm 0.37 MeV. This is then combined with our previous high-precision measurement of M(D0)M(D0)M(D^{*0})-M(D^0), which used the decay D0D0π0D^{*0}\rightarrow D^0\pi^0. We also measure the mass difference M(Ds+)M(D+)=99.5±0.6±0.3M(D_s^+)-M(D^+)=99.5\pm 0.6\pm 0.3 MeV, using the ϕπ+\phi\pi^+ decay modes of the Ds+D_s^+ and D+D^+ mesons.Comment: 18 pages uuencoded compressed postscript (process with uudecode then gunzip). hardcopies with figures can be obtained by sending mail to: [email protected]

    Observation of a New Charmed Strange Meson

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    Using the CLEO-II detector, we have obtained evidence for a new meson decaying to D0K+D^0 K^+. Its mass is 2573.21.6+1.7±0.8±0.52573.2^{+1.7}_{-1.6}\pm 0.8\pm 0.5 {}~MeV/c2c^2 and its width is 164+5±316^{+5}_{-4}\pm 3~MeV/c2c^2. Although we do not establish its spin and parity, the new meson is consistent with predictions for an L=1L=1, S=1S=1, JP=2+J_P=2^+ charmed strange state.Comment: 9 pages uuencoded compressed postscript (process with uudecode then gunzip). hardcopies with figures can be obtained by sending mail to: [email protected]

    First Observation of CP Violation in B0->D(*)CP h0 Decays by a Combined Time-Dependent Analysis of BaBar and Belle Data

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    We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S omega. The measurement is performed combining the final data samples collected at the Y(4S) resonance by the BaBar and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector. We measure the CP asymmetry parameters -eta_f S = +0.66 +/- 0.10 (stat.) +/- 0.06 (syst.) and C = -0.02 +/- 0.07 (stat.) +/- 0.03 (syst.). These results correspond to the first observation of CP violation in B0->D(*)CP h0 decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.Comment: 9 pages, 2 figures, submitted to Physical Review Letter
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