1,678 research outputs found

    The Riemann-Cartan space in the O-theory

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    Nonrelativistic equation of particle with a spin for the Lagrangian on a nonassociative algebra is obtained. It is shown that in this model arises Riemann-Cartan space. In the case of central symmetry in addition to the pseudo-curvature appears torsion as pseudovector that interacts with the spin of the particle. An estimation of the influence of torsion on the strength of gravitational attraction in the central gravitational field is given.Comment: 12 page

    Spontaneous symmetry breaking for long-wave gravitons in the early Universe

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    It is shown that nonlinear terms in equations of gravitons on the background of curved space-time of the expanding Universe can solve the problem of the negative square of the effective mass formally arising in linear approximation for gravitons. Similar to well known spontaneous breaking of symmetry in Goldstone model one must take another vacuum so that nonzero vacuum expectation value of the quantized graviton field leads to change of spectrum for gravitons. There appears two graviton fields, one with the positive mass, another with the zero mass. Energy density and the density of particles created by gravitation of the expanding Universe are calculated for some special cases of the scale factor. Numerical results are obtained for the dust universe case.Comment: 13 page

    Absolute Calibration of a Large-diameter Light Source

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    A method of absolute calibration for large aperture optical systems is presented, using the example of the Pierre Auger Observatory fluorescence detectors. A 2.5 m diameter light source illuminated by an ultra--violet light emitting diode is calibrated with an overall uncertainty of 2.1 % at a wavelength of 365 nm.Comment: 15 pages, 8 figures. Submitted to JINS

    Conductivity in Two-Dimensional Disordered Model with Anisotropic Long-Range Hopping

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    We consider two-dimensional system of particles localized on randomly distributed sites of squared lattice with anisotropic transfer matrix elements between localized sites. By summing of "diffusion ladder" and "cooperon ladder" type vertices we calculated the conductivity for various sites and particles densities.Comment: Latex, 10 page

    Zero mode effect in the 1+1^{-+} four quark states

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    We calculate the masses of the 1+1^{-+} four quark states which decay dominantly into ρπ\rho\pi and ηπ\eta\pi respectively by QCD sum rules approach. We include the zero mode contribution and find it plays an important role in the sum rules. We predict that the masses of the states ηπ\eta\pi and ρπ\rho\pi both are 1.4-1.5 GeV. This is close to the experimental candidates π1(1370)\pi_1(1370) and π1(1440)\pi_1(1440).Comment: 5 pages, 4 Postscript figure

    Aspects of phi-meson production in proton-proton collisions

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    We analyze near-threshold cross section data for the reaction pp->pp phi published by the DISTO collaboration and recent, still preliminary results presented by the ANKE Collaboration. We formulate a procedure to evaluate the OZI ratio at low energies by taking into account corrections from the kinematics and the final-state interaction. Combining the new data with the few measurements available at higher energies we give a limit for the OZI rule violation and estimate the possible contribution from a five-quark baryonic resonance coupled to the phi-p system.Comment: 6 pages, 4 figure

    Radiative Effects in the Standard Model Extension

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    The possibility of radiative effects induced by the Lorentz and CPT non-invariant interaction term for fermions in the Standard Model Extension is investigated. In particular, electron-positron photo-production and photon emission by electrons and positrons are studied. The rates of these processes are calculated in the Furry picture. It is demonstrated that the rates obtained in the framework of the model adopted strongly depend on the polarization states of the particles involved. As a result, ultra-relativistic particles produced should occupy states with a preferred spin orientation, i.e., photons have the sign of polarization opposite to the sign of the effective potential, while charged particle are preferably in the state with the helicity coinciding with the sign of the effective potential. This leads to evident spatial asymmetries which may have certain consequences observable at high energy accelerators, and in astrophysical and cosmological studies.Comment: 10 pages, 2 figures, Revtex4, to appear in Phys.Rev.D, misprints are correcte

    A search for J^{PC}=1^{-+} exotic mesons in the pi- pi- pi+ and pi- pi0 pi0 systems

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    A partial wave analysis (PWA) of the pi-pi-pi+ and pi-pi0pi0 systems produced in the reaction pi- p -> (3pi)-p at 18 GeV/c was carried out using an isobar model assumption. This analysis is based on 3.0M pi-pi0pi0 events and 2.6M pi-pi-pi+ events and shows production of the a2(1320), pi2(1670) and \pi(1800) mesons. An earlier analysis of 250K pi-pi-pi+ events from the same experiment showed possible evidence for a J^{PC}=1^{-+}$ exotic meson with a mass of 1.6 GeV/c^2 decaying into rho pi. In this analysis of a higher statistics sample of the (3pi)- system in two charged modes we find no evidence of an exotic meson.Comment: 4 pages, 5 figures, added comment about the negative reflectivity exotic wave

    Search for f1(1285)π+ππ0f_1(1285) \to \pi^+\pi^-\pi^0 decay with VES detector

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    The isospin violating decay f1(1285)π+ππ0f_1(1285)\to\pi^+\pi^-\pi^0 has been studied at VES facility. This study is based at the statistics acquired in πBe\pi^- Be interactions at 27, 36.6 and 41 GeV/c in diffractive reaction πN(f1π)N\pi^- N \to (f_1 \pi^-) N. The f1(1285)π+ππ0f_1(1285) \to \pi^+\pi^-\pi^0 decay is observed. The ratio of decay probabilities BR(f1(1285)π+ππ0)BR(f_1(1285) \to \pi^+\pi^-\pi^0) to BR(f1(1285)ηπ+π)BR(ηγγ)BR(f_1(1285) \to \eta \pi^+\pi^-) \cdot BR(\eta \to \gamma\gamma) is 1.4\sim\:1.4%.Comment: 10 pages, 8 figures, presented at XII Conference on Hadron Spectroscop
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