24,272 research outputs found

    Two photon decay and photoproduction of radial excitation of pion π0\pi_0'

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    Within the framework of non-local quark model of Nambu--Jona-Lasinio type the two-photon decay of radial excited state of π0\pi_0-meson -- π0\pi_0' -- is found to be 3.6\KeV. The radial excitation of pion is described with the use of polynomial formfactor of second order over q2\vec q^2 where q\vec q is the transverse momentum, which corresponds to relative motion of quark-antiquark pair within the energy range from 0 up to 1\GeV. The probabilities of production of π0\pi_0' and (π0+γ)(\pi_0'+\gamma) states in the electron-positron colliders are estimated. The production of π0\pi_0'-meson in the interaction of photon with electron or muon is as well considered (Primakoff effect). The relevant total cross sections are 0.14 or 0.06\nb.Comment: 10 page

    The decays ρηπ\rho^{-}\to\eta\pi^{-} and τη(η)πν\tau^{-}\to\eta(\eta')\pi^{-}\nu in the NJL model

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    The widths of the decays ρηπ\rho^{-}\to\eta\pi^{-} and τη(η)πν\tau^{-}\to\eta(\eta')\pi^{-}\nu are calculated in the framework of the NJL model. It is shown that these decays are defined by the uu and dd quark mass difference. It leads to the suppression of these decays in comparison with the main decay modes. In the process ρηπ\rho^{-}\to\eta\pi^{-} the intermediate scalar a0a_0^{-} state is taken into account. For the τ\tau decays the intermediate states with a0a_0^{-}, ρ(770)\rho^{-}(770) and ρ(1450)\rho^{-}(1450) mesons are used. Our estimates are compared with the results obtained in other works.Comment: 6 pages, 5 figures, 1 tabl

    The processes e+eππ(π)e^{+}e^{-} \to \pi\pi(\pi') in the extended NJL model

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    The process e+eπ+πe^{+}e^{-} \to \pi^{+}\pi^{-} is described in the framework of the extended NJL model. Intermediate vector mesons ρ0(770)\rho^0(770), ω(782)\omega(782) and \rho'(1450)aretakenintoaccount.Ourresultsareinsatisfactoryagreementwithexperimentaldata.Thepredictionfortheprocess are taken into account. Our results are in satisfactory agreement with experimental data. The prediction for the process e^{+}e^{-} \to \pi\pi'(1300)isgiven.Herethemaincontributionisgivenbythediagramwithintermediate is given. Here the main contribution is given by the diagram with intermediate \rho'(1450)$ meson.Comment: 7 pages, 5 figure

    Supersymmetry and the Odd Poisson Bracket

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    Some applications of the odd Poisson bracket developed by Kharkov's theorists are represented, including the reformulation of classical Hamiltonian dynamics, the description of hydrodynamics as a Hamilton system by means of the odd bracket and the dynamics formulation with the Grassmann-odd Lagrangian. Quantum representations of the odd bracket are also constructed and applied for the quantization of classical systems based on the odd bracket and for the realization of the idea of a composite spinor structure of space-time. At last, the linear odd bracket, corresponding to a semi-simple Lie group, is introduced on the Grassmann algebra.Comment: 17 pages, LATEX 2e. Invited talk given at the International Symposium "30 Years of Supersymmetry" (Theoretical Physics Institute, University of Minnesota, Minneapolis, MN, USA, 13-27 October, 2000) due to the support kindly offered by the Organizing Committee of this meeting and, especially, by Keith Olive and Mikhail Shifma

    Dmitrij Volkov, super-Poincare group and Grassmann variables

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    A fundamental role of the Hermann Grassmann anticommuting variables both in physics and mathematics is discussed on the example of supersymmetry. The talk describes how the D. Volkov question about possibility of the existence of Nambu-Goldstone fermions, realized by the Grassmannian variables, resulted in the discovery of the super-Poincare group, its spontaneous breaking and gauging.Comment: 9 pages, corrected version published in Annalen der Physik, invited talk at the Grassmannian Conference in Fundamental Cosmology, Szczecin, 14-19 September 200

    THE NUMBER OF SPHALERON INSTABILITIES OF THE BARTNIK-McKINNON SOLITONS AND NON-ABELIAN BLACK HOLES

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    It is proven that there are precisely nn odd-parity sphaleron-like unstable modes of the nn-th Bartnik-McKinnon soliton and the nn-th non-abelian black hole solution of the Einstein-Yang-Mills theory for the gauge group SU(2)SU(2).Comment: one reference is adde

    On the cancellation of 4-derivative terms in the Volkov-Akulov action

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    Recently Kuzenko and McCarty observed the cancellation of 4-derivative terms in the D=4N=1D=4 {\cal N}=1 Volkov-Akulov supersymmetric action for the fermionic Nambu-Goldstone field. Here is presented a simple algebraic proof of the cancellation based on using the Majorana bispinors and Fiertz identities. The cancellation shows a difference between the Volkov-Akulov action and the effective superfield action recently studied by Komargodski and Seiberg and containing one 4-derivative term. We find out that the cancellation effect takes place in coupling of the Nambu-Goldstone fermion with the Dirac field. Equivalence between the KS and the VA Lagrangians is proved up to the first order in the interaction constant of the NG fermions.Comment: 18 pages; the version accepted for publication in Phys. Rev. D; new section regarding the proof of the equivalence between the Komargodski-Seiberg and the Volkov-Akulov actions is added: some comments and new references are include

    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

    Abelian Current Algebra and the Virasoro Algebra on the Lattice

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    We describe how a natural lattice analogue of the abelian current algebra combined with free discrete time dynamics gives rise to the lattice Virasoro algebra and corresponding hierarchy of conservation laws.Comment: 11 pages, LATEX, HU-TFT-93-2

    Supersymmetric Model with Grassmann-odd Lagrangian

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    A supersymmetric D=1,N=1D = 1, N =1 model with a Grassmann-odd Lagrangian is proposed which, in contrast to the model with an even Lagrangian, contains not only a kinetic term but also an interaction term for the coordinates entering into one real scalar Grassmann-even (bosonic) superfield.Comment: 6 pages, LATEX 2e. The talk given at the International Conference "Supersymmetries and Quantum Field Theory" (SSQFT'2000, NSC KIPT, Kharkov, Ukraine, 25-29 July, 2000). To be published in the Proceedings of this Conference. Corrections of misprint
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