667 research outputs found
Production of \phi Mesons in Near-Threshold \pi N and N N Reactions
We analyze the production of mesons in and NN reactions in the
near-threshold region, using throughout the conventional ``non-strange''
dynamics based on such processes which are allowed by the non-ideal
mixing. We show that the occurrence of the direct
interaction may show up in different unpolarized and polarization observables
in reactions. We find a strong non-trivial difference between
observables in the reactions and caused by the
different role of the spin singlet and triplet states in the entrance channel.
A series of predictions for the experimental study of this effect is presented.Comment: 35 pages including 18 figure
Topological Wilson-loop area law manifested using a superposition of loops
We introduce a new topological effect involving interference of two meson
loops, manifesting a path-independent topological area dependence. The effect
also draws a connection between quark confinement, Wilson-loops and topological
interference effects. Although this is only a gedanken experiment in the
context of particle physics, such an experiment may be realized and used as a
tool to test confinement effects and phase transitions in quantum simulation of
dynamic gauge theories.Comment: Superceding arXiv:1206.2021v1 [quant-ph
Resonant magnetic excitations at high energy in superconducting
A detailed inelastic neutron scattering study of the high temperature
superconductor provides evidence of new resonant
magnetic features, in addition to the well known resonant mode at 41 meV: (i) a
commensurate magnetic resonance peak at 53 meV with an even symmetry under
exchange of two adjacent layers; and (ii) high energy
incommensurate resonant spin excitations whose spectral weight is around 54
meV. The locus and the spectral weight of these modes can be understood by
considering the momentum shape of the electron-hole spin-flip continuum of
d-wave superconductors. This provides new insight into the interplay between
collective spin excitations and the continuum of electron-hole excitations.Comment: 5 figure
Bremsstrahlung in intermediate-energy nucleon reactions within an effective one-beson exchange model
Within a covariant effective one-boson exchange model for the T matrix of NN interactions we present detailed calculations of bremsstrahlung cross sections for proton - proton and proton - neutron reactions at beam energies in the 1 GeV region. Besides pure bremsstrahlung processes we consider photons from ∆ decays and contributions from the η → γγ process. At beam energies above 700 MeV the ∆ decay channel dominates the spectra at large photon energies, where the interference between non-resonance processes and the ∆ decay channel becomes also important. Low energy photons stem from pure bremsstrahlung processes. The available experimental data at 730 MeV beam energy is well described. We extrapolate the model down to 280 MeV, where more detailed experimental data exist, and find agreement with angular distributions
СТРУКТУРА И МЕХАНИЧЕСКИЕ СВОЙСТВА СЛИТКОВ И ПРОФИЛЕЙ ИЗ АЛЮМИНИЕВОГО СПЛАВА НА ОСНОВЕ СИСТЕМЫ AL-MG-MN
Commercial ingots and hot-pressed rolled sections of Al-Mg-Mn alloy doped with zinc, scandium, zirconium, chromium, and vanadium have been studied using optical microscopy, thermal analysis, electron microscopy, and electron-probe microanalysis. The compositions of the phase constituents and aluminum matrix of the alloy are determined. The sensitivity of the alloy to the formation of complex intermetallic compounds during solidification is revealed. The mechanical properties of ingots and rolled sections are determined. © 2013 Pleiades Publishing, Ltd
An AB effect without closing a loop
We discuss the consequences of the Aharonov-Bohm effect in setups involving
several charged particles, wherein none of the charged particles encloses a
closed loop around the magnetic flux. We show that in such setups, the AB phase
is encoded either in the relative phase of a bi-partite or multi-partite
entangled photons states, or alternatively, gives rise to an overall AB phase
that can be measured relative to another reference system. These setups involve
processes of annihilation or creation of electron/hole pairs. We discuss the
relevance of such effects in "vacuum Birefringence" in QED, and comment on
their connection to other known effects.Comment: 4 pages, 3 figure
Modes of Oscillation in Radiofrequency Paul Traps
We examine the time-dependent dynamics of ion crystals in radiofrequency
traps. The problem of stable trapping of general three-dimensional crystals is
considered and the validity of the pseudopotential approximation is discussed.
We derive analytically the micromotion amplitude of the ions, rigorously
proving well-known experimental observations. We use a method of infinite
determinants to find the modes which diagonalize the linearized time-dependent
dynamical problem. This allows obtaining explicitly the ('Floquet-Lyapunov')
transformation to coordinates of decoupled linear oscillators. We demonstrate
the utility of the method by analyzing the modes of a small `peculiar' crystal
in a linear Paul trap. The calculations can be readily generalized to
multispecies ion crystals in general multipole traps, and time-dependent
quantum wavefunctions of ion oscillations in such traps can be obtained.Comment: 24 pages, 3 figures, v2 adds citations and small correction
The role of secondary Reggeons in central meson production
We estimate the contribution of f_2 trajectory exchange to the central \eta
and \eta^\prime production. It is shown that secondary Reggeons may give a
large contribution to processes of double diffractive meson production at high
energy.Comment: 7 pages, Latex, 5 figure
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