64,639 research outputs found

    Ferromagnetic one dimensional Ti atomic chain

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    Using the full potential linearized augmented plane wave (FLAPW) method, we have explored the magnetic properties of one dimensional (1D) Ti atomic chain. Astonishingly, we for the first time observed that the 1D Ti atomic chain has ferromagnetic ground state even on NiAl(110) surface although the Ti has no magnetic moment in bulk or macroscopic state. It was found that the physical property of direct exchange interaction among Ti atoms occurred in free standing state is well preserved on NiAl(110) surface and this feature has an essential role in ferromagnetism of 1D Ti atomic chain. It was shown that the m=2|2| state has the largest contribution to the magnetic moment of Ti atom grown on NiAl(110) surface. In addition, we found that the magnetic dipole interaction is a key factor in the study of magnetic anisotropy, not the magnetocrystalline anisotropy arising from spin-orbit interaction

    Pseudoscalar or vector meson production in non-leptonic decays of heavy hadrons

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    We have addressed the study of non-leptonic weak decays of heavy hadrons (Λb,Λc,B\Lambda_b, \Lambda_c, B and DD), with external and internal emission to give two final hadrons, taking into account the spin-angular momentum structure of the mesons and baryons produced. A detailed angular momentum formulation is developed which leads to easy final formulas. By means of them we have made predictions for a large amount of reactions, up to a global factor, common to many of them, that we take from some particular data. Comparing the theoretical predictions with the experimental data, the agreement found is quite good in general and the discrepancies should give valuable information on intrinsic form factors, independent of the spin structure studied here. The formulas obtained are also useful in order to evaluate meson-meson or meson-baryon loops, for instance of BB decays, in which one has PP, PV, VP or VV intermediate states, with P for pseudoscalar mesons and V for vector meson and lay the grounds for studies of decays into three final particles.Comment: 54 pages, 7 figures, 13 tables; v2: 60 pages, 9 figures, 14 tables, discussion added, references added, version to appear in Eur.Phys.J.

    Irregular and multi--channel sampling of operators

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    The classical sampling theorem for bandlimited functions has recently been generalized to apply to so-called bandlimited operators, that is, to operators with band-limited Kohn-Nirenberg symbols. Here, we discuss operator sampling versions of two of the most central extensions to the classical sampling theorem. In irregular operator sampling, the sampling set is not periodic with uniform distance. In multi-channel operator sampling, we obtain complete information on an operator by multiple operator sampling outputs

    Baryon states with hidden charm in the extended local hidden gauge approach

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    The s-wave interaction of DˉΛc,DˉΣc,DˉΛc,DˉΣc\bar{D} \Lambda_c, \bar{D} \Sigma_c, \bar{D} \Lambda_c, \bar{D}{}^* \Sigma_c and DˉΣc,DˉΣc\bar{D}\Sigma^*_c, \bar{D}{}^*\Sigma^*_c, is studied within a unitary coupled channels scheme with the extended local hidden gauge approach. In addition to the Weinberg-Tomozawa term, several additional diagrams via the pion-exchange are also taken into account as box potentials. Furthermore, in order to implement the full coupled channels calculation, some of the box potentials which mix the vector-baryon and pseudoscalar-baryon sectors are extended to construct the effective transition potentials. As a result, we have observed six possible states in several angular momenta. Four of them correspond to two pairs of admixture states, two of DˉΣc\bar{D}\Sigma_c - DˉΣc\bar{D}{}^*\Sigma_c with JP=1/2J^P = 1/2^-, and two of DˉΣc\bar{D}\Sigma^*_c - DˉΣc\bar{D}{}^*\Sigma^*_c with JP=3/2J^P = 3/2^-. Moreover, we find a DˉΣc\bar{D}{}^* \Sigma_c resonance which couples to the DˉΛc\bar{D}\Lambda_c channel and one spin degenerated bound state of DˉΣc\bar{D}{}^*\Sigma^*_c with JP=1/2,5/2J^P = 1/2^-, 5/2^-.Comment: 24 pages, 6 figure

    Theoretical description of the J/ψη(η)h1(1380)\boldsymbol{J/\psi \to \eta (\eta') h_1(1380)}, J/ψη(η)h1(1170)\boldsymbol{J/\psi \to \eta (\eta') h_1(1170)} and J/ψπ0b1(1235)0\boldsymbol{J/\psi \to \pi^0 b_1(1235)^0} reactions

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    We have made a study of the J/ψηh1,ηh1J/\psi \to \eta' h_1, \eta h_1 (with h1h_1 being h1(1170)h_1(1170) and h1(1380)h_1(1380)) and J/ψπ0b1(1235)0J/\psi \to \pi^0 b_1(1235)^0 assuming the axial vector mesons to be dynamically generated from the pseudoscalar-vector meson interaction. We have taken the needed input from previous studies of the J/ψϕππ,ωππJ/\psi \to \phi \pi \pi, \omega \pi \pi reactions. We obtain fair agreement with experimental data and provide an explanation on why the recent experiment on J/ψηh1(1380),h1(1380)K+K+c.c.J/\psi \to \eta' h_1(1380), h_1(1380) \to K^{*+} K^- +c.c. observed in the K+Kπ0K^+ K^- \pi^0 mode observes the peak of the h1(1380)h_1(1380) at a higher energy than its nominal mass.Comment: 21 pages, 6 figure

    Small-scale Effects of Thermal Inflation on Halo Abundance at High-zz, Galaxy Substructure Abundance and 21-cm Power Spectrum

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    We study the impact of thermal inflation on the formation of cosmological structures and present astrophysical observables which can be used to constrain and possibly probe the thermal inflation scenario. These are dark matter halo abundance at high redshifts, satellite galaxy abundance in the Milky Way, and fluctuation in the 21-cm radiation background before the epoch of reionization. The thermal inflation scenario leaves a characteristic signature on the matter power spectrum by boosting the amplitude at a specific wavenumber determined by the number of e-foldings during thermal inflation (NbcN_{\rm bc}), and strongly suppressing the amplitude for modes at smaller scales. For a reasonable range of parameter space, one of the consequences is the suppression of minihalo formation at high redshifts and that of satellite galaxies in the Milky Way. While this effect is substantial, it is degenerate with other cosmological or astrophysical effects. The power spectrum of the 21-cm background probes this impact more directly, and its observation may be the best way to constrain the thermal inflation scenario due to the characteristic signature in the power spectrum. The Square Kilometre Array (SKA) in phase 1 (SKA1) has sensitivity large enough to achieve this goal for models with Nbc26N_{\rm bc}\gtrsim 26 if a 10000-hr observation is performed. The final phase SKA, with anticipated sensitivity about an order of magnitude higher, seems more promising and will cover a wider parameter space.Comment: 28 pages, 8 figure

    Finite-size scaling in complex networks

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    A finite-size-scaling (FSS) theory is proposed for various models in complex networks. In particular, we focus on the FSS exponent, which plays a crucial role in analyzing numerical data for finite-size systems. Based on the droplet-excitation (hyperscaling) argument, we conjecture the values of the FSS exponents for the Ising model, the susceptible-infected-susceptible model, and the contact process, all of which are confirmed reasonably well in numerical simulations

    Wilson-t'Hooft Loops in Finite-Temperature Non-commutative Dipole Field Theory from Dual Supergravity

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    We first study the temporal Wilson loop in the finite-temperature non-commutative dipole field theory from the string/gauge correspondence. The associated dual supergravity background is constructed from the near-horizon geometry of near-extremal D-branes, after applying T-duality and smeared twist. We investigate the string configuration therein and find that while the temperature produces a maximum distance LmaxL_{max} in the interquark distance the dipole in there could produce a minimum distance LminL_{min}. The quark boundary pair therefore could be found only if their distance is between LminL_{min} and LmaxL_{max}. We also show that, beyond a critical temperature the quark pair becomes totally free due to screening by thermal bath. We next study the spatial Wilson loop and find the confining nature in the zero temperature 3D and 4D non-supersymmetry dipole gauge theory. The string tension of the linear confinement potential is obtained and found to be a decreasing function of the dipole field. We also investigate the associated t'Hooft loop and determine the corresponding monopole anti-monopole potential. The conventional screening of magnetic charge which indicates the confinement of the electric charge is replaced by a strong repulsive however. Finally, we show that the dual string which is rotating along the dipole deformed S5S^5 will behave as a static one without dipole field, which has no minimum distance and has larger energy than a static one with dipole field. We discuss the phase transition between these string solutions.Comment: Latex, 22 pages, 8 figures, add several comment

    Price Determination in the Bottled Water Industry: A Case Study of Poland Spring

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    This paper analyzes the price of a single brand in the bottled water industry. We find that the brand's price is negatively related to its own share. We also find that price is positively related to the four firm concentration ratio in the carbonated segment, but unrelated in the noncarbonated segment.Demand and Price Analysis,
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