5,054 research outputs found

    Magnetothermoelectric DC conductivities from holography models with hyperscaling factor in Lifshitz spacetime

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    We investigate an Einstein-Maxwell-Dilaton-Axion holographic model and obtain two branches of a charged black hole solution with a dynamic exponent and a hyperscaling violation factor when a magnetic field presents. The magnetothermoelectric DC conductivities are then calculated in terms of horizon data by means of holographic principle. We find that linear temperature dependence resistivity and quadratic temperature dependence inverse Hall angle can be achieved in our model. The well-known anomalous temperature scaling of the Nernst signal and the Seebeck coefficient of cuprate strange metals are also discussed.Comment: 1+23 pages, 4 figures, references adde

    Electromagnetic radiation of baryons containing two heavy quarks

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    The two heavy quarks in a baryon which contains two heavy quarks and a light one, can constitute a scalar or axial vector diquark. We study electromagnetic radiations of such baryons, (i) \Xi_{(bc)_1} -> \Xi_{(bc)_0}+\gamma, (ii) \Xi_{(bc)_1}^* -> \Xi_{(bc)_0}+\gamma, (iii) \Xi_{(bc)_0}^{**}(1/2, l=1) -> \Xi_{(bc)_0}+\gamma, (iv) \Xi_{(bc)_0}^{**}(3/2, l=1) -> \Xi_{(bc)_0}+\gamma and (v) \Xi_{(bc)_0}^{**}(3/2, l=2) -> \Xi_{(bc)_0}+\gamma, where \Xi_{(bc)_{0(1)}}, \Xi^*_{(bc)_1} are S-wave bound states of a heavy scalar or axial vector diquark and a light quark, and \Xi_{(bc)_0}^{**}(l is bigger than 1) are P- or D-wave bound states of a heavy scalar diquark and a light quark. Analysis indicates that these processes can be attributed into two categories and the physical mechanisms which are responsible for them are completely distinct. Measurements can provide a good judgment for the diquark structure and better understanding of the physical picture.Comment: 15 pages, Late

    Renormalization group improved pQCD prediction for Υ(1S)\Upsilon(1S) leptonic decay

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    The complete next-to-next-to-next-to-leading order short-distance and bound-state QCD corrections to Υ(1S)\Upsilon(1S) leptonic decay rate Γ(Υ(1S)+)\Gamma(\Upsilon(1S)\to \ell^+\ell^-) has been finished by Beneke {\it et al.} \cite{Beneke:2014qea}. Based on those improvements, we present a renormalization group (RG) improved pQCD prediction for Γ(Υ(1S)+)\Gamma(\Upsilon(1S)\to \ell^+\ell^-) by applying the principle of maximum conformality (PMC). The PMC is based on RG-invariance and is designed to solve the pQCD renormalization scheme and scale ambiguities. After applying the PMC, all known-type of β\beta-terms at all orders, which are controlled by the RG-equation, are resummed to determine optimal renormalization scale for its strong running coupling at each order. We then achieve a more convergent pQCD series, a scheme- independent and more accurate pQCD prediction for Υ(1S)\Upsilon(1S) leptonic decay, i.e. ΓΥ(1S)e+ePMC=1.2700.187+0.137\Gamma_{\Upsilon(1S) \to e^+ e^-}|_{\rm PMC} = 1.270^{+0.137}_{-0.187} keV, where the uncertainty is the squared average of the mentioned pQCD errors. This RG-improved pQCD prediction agrees with the experimental measurement within errors.Comment: 11 pages, 4 figures. Numerical results and discussions improved, references updated, to be published in JHE

    Ethyl 1-[(4-acetyl-2-methoxy­phen­oxy)meth­yl]cyclo­propane-1-carboxyl­ate

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    In the title compound, C16H20O5, the dihedral angle between the planar rings, viz. benzene and cyclo­propane, is 52.1 (2)°. Mol­ecules are connected in the crystal via weak inter­molecular C—H⋯O hydrogen bonds, forming chains in the [001] direction

    A 140 GHz High Efficiency Slotted Waveguide Antenna using a Low Loss Feeding Network

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