1,678 research outputs found
The Riemann-Cartan space in the O-theory
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
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
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
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 four quark states
We calculate the masses of the four quark states which decay
dominantly into and 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 and
both are 1.4-1.5 GeV. This is close to the experimental candidates
and .Comment: 5 pages, 4 Postscript figure
Aspects of phi-meson production in proton-proton collisions
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
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
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 decay with VES detector
The isospin violating decay has been studied at
VES facility. This study is based at the statistics acquired in
interactions at 27, 36.6 and 41 GeV/c in diffractive reaction . The decay is observed. The ratio of
decay probabilities to is .Comment: 10 pages, 8 figures, presented at XII Conference on Hadron
Spectroscop
- …
