18,455 research outputs found
Diffusive versus displacive contact plasticity of nanoscale asperities: Temperature- and velocity-dependent strongest size
We predict a strongest size for the contact strength when asperity radii of
curvature decrease below ten nanometers. The reason for such strongest size is
found to be correlated with the competition between the dislocation plasticity
and surface diffusional plasticity. The essential role of temperature is
calculated and illustrated in a comprehensive asperity size-strengthtemperature
map taking into account the effect of contact velocity. Such a map should be
essential for various phenomena related to nanoscale contacts such as nanowire
cold welding, self-assembly of nanoparticles and adhesive nano-pillar arrays,
as well as the electrical, thermal and mechanical properties of macroscopic
interfaces
Two-Body Strong Decay of Z(3930) as the State
The new particle Z(3930) found by the Belle and BaBar Collaborations through
the process is identified to be the
state. Since the mass of this particle is above the threshold, the OZI-allowed two-body strong decays are the main
decay modes. In this paper, these strong decay modes are studied with two
methods. One is the instantaneous Bethe-Salpeter method within Mandelstam
formalism. The other is the combination of the model and the former
formalism. The total decay widths are 26.3 and 27.3 MeV for the methods with or
without the vertex, respectively. The ratio of over
which changes along with the mass of the initial meson
is also presented.Comment: 11 pages, 3 figure
The Electromagnetic Decays of
We calculate the electromagnetic (EM) decay widths of the
meson, which is observed recently by the ATLAS Collaboration. The main EM decay
channels of this particle are and , which, in
literature, are estimated to have the branching ratio of about . In this
work, we get the partial decay widths: keV,
keV and keV. In the
calculation, the instantaneous approximated Bethe-Salpeter method is used. For
the -wave mesons, the wave functions are given by mixing the
and states. Within the Mandelstam formalism, the decay amplitude is
given, which includes the relativistic corrections.Comment: 9 pages, 3 figures, 3 table
The rare semi-leptonic decays involving orbitally excited final mesons
The rare processes , where
stands for the final meson ,
,~, ,
or~, are studied within the Standard Model. The hadronic matrix
elements are evaluated in the Bethe-Salpeter approach and furthermore a
discussion on the gauge-invariant condition of the annihilation hadronic
currents is presented. Considering the penguin, box, annihilation,
color-favored cascade and color-suppressed cascade contributions, the
observables , , and are
calculated
- β¦