676 research outputs found

    Grand unification in the minimal left-right symmetric extension of the standard model

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    The simplest minimal left-right symmetric extension of the standard model is studied in the high energy limit, and some consequences of the grand unification hypothesis are explored assuming that the parity breaking scale is the only relevant energy between the electro-weak scale and the unification point. While the model is shown to be compatible with the observed neutrino phenomenology, the parity breaking scale and the heavy boson masses are predicted to be above 10^7 TeV, quite far from the reach of nowadays experiments. Below that scale only an almost sterile right handed neutrino is allowed with a mass M \approx 100 TeV

    Studies on uracils : a facile one-pot synthesis of oxazino[4,5- d]-, pyrano[2,3-d]-, pyrido[2,3-d]- and pyrimido[4,5-d]pyrimidines using microwave irradiation in the solid state

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    —N,N-Dimethyl-5-formylbarbituric acid 1 reacts with maleimide 2 and phenyl isocyanate/phenyl isothiocyanate 4 under microwave-assisted conditions in the solid phase to afford pyrano[2,3-d]pyrimidines3 and oxazino[4,5-d]pyrimidines5 in excellent yields. Under identical conditions, N,N-dimethyl-6-amino-5-formyluracil 6 reacts with 2 and 4 to give pyrido[2,3-d]pyrimidine derivative 7 and pyrimido[4,5-d]pyrimidines 8 in high yield

    Baker's Yeast-catalysed ring opening of benzofuroxans : an efficient green synthesis of aryl-1,2-diamines

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    A simple and inexpensive method for the reductive cleavage of N–O bond of benzofuroxans with bakers’ yeast under nonfermenting condition in aqueous media was achieved. The procedure gives excellent yields of aryl-1, 2-diamines

    Studies on uracils : synthesis of novel pyrido[2,3-d]- pyrimidine oxides via ring transformation of isoxazolo[3,4-d]pyrimidine

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    The reaction of isoxazolo[3,4-d]pyrimidine 1 and cyanoolefins 2 in the presence of triethylamine (Et3N) as a catalyst afforded an unprecedented one-pot synthesis of biologically important pyrido[2,3-d]pyrimidine oxides 3 in excellent yields

    A facile one pot synthesis of pyrazolo[3,4-D] pyrimidines

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    The reaction of 6-hydrazino uracils 1 with isocyanates 2 gave access to an efficient one-pot synthesis of pyrazolo[3,4- d]pyrimidines 3 in excellent yield

    STEREOSELECTIVE INTRAMOLECULAR HETERO-DIELS-ALDER REACTIONS OF 1-OXA-1,3-BUTADIENES - SYNTHESIS OF NOVEL ANNELATED PYRROLO[1,2-A]INDOLES

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    14Novelclassesofpyrano-1,3-dioxane-,pyranopyrimidine-andpyranopyrazole-fusedpyrrolo[1,2-a]indolesaresynthesised via stereoselective intramolecular 1-oxa-1,3-butadiene hetero Diels 13Alder reaction

    Lowering solar mixing angle in inverted hierarchy without charged lepton corrections

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    In the present work, the inverted hierarchical neutrino mass model which is characterised by opposite CP parity in the first two mass eigenvalues (m1,m2,m3)(m_1,-m_2,m_3), is studied in order to lower the predicted value of solar mixing angle tan2θ12\tan^2\theta_{12}, from the tri-bimaximal mixing (TBM), without sacrificing the conditions of maximal atmospheric mixing angle and zero reactor angle. The present attempt is different from the earlier approach where the correction from the charged lepton mass matrix is included in the leptonic mixing matrix to lower the prediction on solar mixing angle. The lowering of the solar mixing angle without charged lepton correction, can be obtained through the variation of the input value of a flavour twister term present in the texture of neutrino mass matrix having a 2-3 symmetry. The present analysis agrees with the latest experimental bounds on neutrino mass parameters and also represents an important result on the survival of the inverted hierarchical neutrino mass models having opposite CP parity in the first two eigenvalues.Comment: 10 pages, two figures. Accepted for publication in Journal of Physics G:Nuclear and Particle Physic

    Deviation from tri-bimaximal mixings in two types of inverted hierarchical neutrino mass models

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    An attempt is made to explore the possibility for deviations of solar mixing angle (θ12\theta_{12}) from tri-bimaximal mixings, without sacrificing the predictions of maximal atmospheric mixing angle (θ23=π/4\theta_{23}=\pi/4) and zero reactor angle (θ13=0\theta_{13}=0). We find that the above conjecture can be automatically realised in the inverted hierarchical neutrino mass model having 2-3 symmetry, in the basis where charged lepton mass matrix is diagonal. For the observed ranges of m212\bigtriangleup m^2_{21} and \bigtriangleup m^2_{23], we calculate the predictions on tan2θ12=0.5,0.45,0.35\tan^2\theta_{12}=0.5, 0.45, 0.35 for different input values of the parameters in the neutrino mass matrix. We also observe a possible crossing over from one type of inverted hierarchical model having same CP parity (Type-IHA) to other type having opposite CP parity (Type-IHB). Such neutrino mass matrices can be obtained from the canonical seesaw formula using diagonal form of Dirac neutrino mass matrix and non-diagonal texture of right-handed Majorana mass matrix, and may have important implications in model building using discrete as well as non-abelian symmetry groups.Comment: 13 pages, 7 figure
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