2,393 research outputs found
g-2 in composite models of leptons
Based on the bound state description of the muon and general relativistic
covariant quantum field theory, we illustrate with a simple composite model
that the observed deviation of (g-2)_\mu can be a demonstration of the
substructure of the muon and give the constraints on the radius of the muon in
different cases of light constituents and heavy constituents.Comment: 14 pages, 4 eps figures, revtex, several arguments and some
references renewe
Twist-3 contribution to the pion electromagnetic form factor
Non-leading contribution to the pion electromagnetic form factor which comes
from the pion twist-3 wave function is analyzed in the modified hard scattering
approach (MHSA) proposed by Li and Sterman. This contribution is enhanced
significantly due to bound state effect (the twist-3 wave function is
independent of the fractional momentum carried by the parton and has a large
factor with being the pion meson mass and
being the mean u- and d-quark masses). Consequently, although it is suppressed
by the factor , the twist-3 contribution is comparable with and even
larger than the leading twist (twist-2) contribution at intermediate energy
region of being .Comment: 10 pages, 2 fgures, latex. More discussions on the Sudakov effect
added, references added. To appear in European Physical Journal C
(Zeitschrift fur Physik C
Simulation of droplet impacting a square solid obstacle in microchannel with different wettability by using high density ratio pseudopotential multiplerelaxation- time (MRT) lattice Boltzmann Method (LBM)
In this paper, a pseudopotential high density ratio (DR) lattice Boltzmann Model was developed by incorporating multi-relaxation-time (MRT) collision matrix, large DR external force term, surface tension adjustment external force term and solid-liquid pseudopotential force. It was found that the improved model can precisely capture the two-phase interface at high DR. Besides, the effects of initial Reynolds number, Weber number, solid wall contact angle (CA), ratio of obstacle size to droplet diameter ( 1 χ ), ratio of channel width to droplet diameter ( 2 χ ) on the deformation and breakup of droplet when impacting on a square obstacle were investigated. The results showed that with the Reynolds number increasing, the droplet will fall along the obstacle and then spread along both sides of the obstacle. Besides, by increasing Weber number, the breakup of the liquid film will be delayed and the liquid film will be stretched to form an elongated ligament. With decreasing of the wettability of solid particle (CA→ 180°), the droplet will surround the obstacle and then detach from the obstacle. When 1 χ is greater than 0.5, the droplet will spread along both sides of the obstacle quickly; otherwise, the droplet will be ruptured earlier. Furthermore, when 2 χ decreases, the droplet will spread earlier and then fall along the wall more quickly; otherwise, the droplet will expand along both sides of the obstacle. Moreover, increasing the hydrophilicity of the microchannel, the droplet will impact the channel more rapidly and infiltrate the wall along the upstream and downstream simultaneously; on the contrary, the droplet will wet downstream only
Decay Widths of Excited Heavy Mesons From QCD Sum Rules at the Leading Order of HQET
The widths for pionic decays of lowest two excited doublets (0^+,1^+) and
(1^+,2^+) of heavy mesons are studied with QCD sum rules in the leading order
of heavy quark effective theory. The ambiguity due to presence of two distinct
1^+ states are solved. The soft pion approximation is not used.Comment: RevTeX, 16 pages including 1 figure; minor changes, final version to
appear in Physical Review
Quasiperiodic Tip Splitting in Directional Solidification
We report experimental results on the tip splitting dynamics of seaweed
growth in directional solidification of succinonitrile alloys with
poly(ethylene oxide) or acetone as solutes. The seaweed or dense branching
morphology was selected by solidifying grains which are oriented close to the
{111} plane. Despite the random appearance of the growth, a quasiperiodic tip
splitting morphology was observed in which the tip alternately splits to the
left and to the right. The tip splitting frequency f was found to be related to
the growth velocity V as a power law f V^{1.5}. This finding
is consistent with the predictions of a tip splitting model that is also
presented. Small anisotropies are shown to lead to different kinds of seaweed
morphologies.Comment: 4 pages, 7 figures, submitted to Physical Review Letter
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