8,210 research outputs found

    Comment on "Exact results for survival probability in the multistate Landau-Zener model"

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    We correct the proof of Brundobler-Elser formula (BEF) provided in [2004 \textit{J. Phys. B: At. Mol. Opt. Phys.} \textbf{37} 4069] and continued in Appendix of [2005 \textit{J. Phys. B: At. Mol. Opt. Phys.} \textbf{38} 907]. After showing that some changes of variables employed in these articles are used erroneously, we propose an alternative change of variables which solves the problem. In our proof, we reveal the connection between the BEF for a general NN-level Landau-Zener system and the exactly solvable bow-tie model. The special importance of the diabatic levels with maximum/minimum slope is emphasized throughout.Comment: 10 page

    NJL interaction derived from QCD: vector and axial-vector mesons

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    In previous works effective non-local SU(2)×SU(2)SU(2)\times SU(2) NJL model was derived in the framework of the fundamental QCD. All the parameters of the model are expressed through QCD parameters: current light quark mass m0m_0 and average non-perturbative αs\alpha_s. The results for scalar and pseudo-scalar mesons are in satisfactory agreement to existing data. In the present work the same model without introduction of any additional parameters is applied for a description of masses and strong decay widths of ρ\rho- and a1a_1-mesons. The results for both scalar and vector sectors agree with data with only one adjusted parameter m0m_0, with account of average αs0.415\alpha_s \simeq 0.415, which is obtained in a previous work as well.Comment: 19 pages, 2 figures, 1 tabl

    Even and odd symplectic and K\"ahlerian structures on projective superspaces

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    Supergeneralization of \DC P(N) provided by even and odd K\"ahlerian structures from Hamiltonian reduction are construct.Operator Δ \Delta which used in Batalin-- Vilkovisky quantization formalism and mechanics which are bi-Hamiltonian under corresponding even and odd Poisson brackets are considered.Comment: 19 page

    Dynamics of Fluxon Lattice in Two Coupled Josephson Junctions

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    We study theoretically the dynamics of a fluxon Lattice (FL) in two coupled Josephson junctions. We show that when the velocity of the moving FL exceeds certain values (Va,b)(V_{a,b}), sharp resonances arise in the system which are related to the excitation of the optical and acoustic collective modes. In the interval (Va,Vb)(V_a, V_b) a reconstruction of the FL occurs. We also establish that one can excite localized nonlinear distortions (dislocations) which may propagate through the FL and carry an arbitrary magnetic flux.Comment: 4 pages, 3 figures, corected typo

    Pion Polarizability in the NJL model and Possibilities of its Experimental Studies in Coulomb Nuclear Scattering

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    The charge pion polarizability is calculated in the Nambu-Jona-Lasinio model, where the quark loops (in the mean field approximation) and the meson loops (in the 1/Nc1/N_c approximation) are taken into account. We show that quark loop contribution dominates, because the meson loops strongly conceal each other. The sigma-pole contribution (mσ2t)1(m^2_\sigma-t)^{-1} plays the main role and contains strong t-dependence of the effective pion polarizability at the region t4Mπ2|t|\geq 4M_\pi^2. Possibilities of experimental test of this sigma-pole effect in the reaction of Coulomb Nuclear Scattering are estimated for the COMPASS experiment.Comment: 11 pages, 8 figure

    The Finite Basis Problem for Kiselman Monoids

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    In an earlier paper, the second-named author has described the identities holding in the so-called Catalan monoids. Here we extend this description to a certain family of Hecke--Kiselman monoids including the Kiselman monoids Kn\mathcal{K}_n. As a consequence, we conclude that the identities of Kn\mathcal{K}_n are nonfinitely based for every n4n\ge 4 and exhibit a finite identity basis for the identities of each of the monoids K2\mathcal{K}_2 and K3\mathcal{K}_3. In the third version a question left open in the initial submission has beed answered.Comment: 16 pages, 1 table, 1 figur

    Gravitational-Recoil Effects on Fermion Propagation in Space-Time Foam

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    Motivated by the possible experimental opportunities to test quantum gravity via its effects on high-energy neutrinos propagating through space-time foam, we discuss how to incorporate spin structures in our D-brane description of gravitational recoil effects in vacuo. We also point to an interesting analogous condensed-matter system. We use a suitable supersymmetrization of the Born-Infeld action for excited D-brane gravitational backgrounds to argue that energetic fermions may travel slower than the low-energy velocity of light: \delta c / c \sim -E/M. It has been suggested that Gamma-Ray Bursters may emit pulses of neutrinos at energies approaching 10^{19} eV: these would be observable only if M \gsim 10^{27} GeV.Comment: 18 pages LaTe
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