18,245 research outputs found
Composite components under impact load and effects of defects on the loading capacity
Investigations were carried out on a horizontal tail assembly made of carbon fiber reinforced plastic for the Alpha Jet. The possibility of obtaining a leading edge nose design lighter but not more expensive than a metal version was studied. An important consideration was sufficient resistance of the leading edge against impact of stones and hailstones combined with high degree of stiffness. The improvement of energy reception characteristics of the materials through suitable laminate design was considered. Since certain defects occur in structural components, the effects of such defects on the characteristics of the parts were also studied
Two-dimensional Lattice Gross-Neveu Model with Wilson Fermion Action at Finite Temperature and Chemical Potential
We investigate the phase structure of the two-dimensional lattice Gross-Neveu
model formulated with the Wilson fermion action to leading order of 1/N
expansion. Structural change of the parity-broken phase under the influence of
finite temperature and chemical potential is studied. The connection between
the lattice phase structure and the chiral phase transition of the continuum
theory is clarified.Comment: 42 pages, 20 EPS figures, using REVTe
One loop renormalization for the axial Ward-Takahashi identity in Domain-wall QCD
We calculate one-loop correction to the axial Ward-Takahashi identity given
by Furman and Shamir in domain-wall QCD. It is shown perturbatively that the
renormalized axial Ward-Takahashi identity is satisfied without fine tuning and
the ``conserved'' axial current receives no renormalization, giving .
This fact will simplify the calculation of the pion decay constant in numerical
simulations since the decay constant defined by this current needs no lattice
renormalization factor.Comment: 16 pages, 3 axodraw.sty figure
Spontaneous Parity Violation in QCD At Finite Temperature: On the Inapplicability of the Vafa-Witten Theorem
The generalization of the Vafa-Witten theorem ruling out parity violation to
QCD at finite temperature is considered. It is shown that this generalization
of the theorem rules out Lorentz-invariant parity violating operators from
spontaneously acquiring vacuum expectation values. However, it does not rule
out Lorentz-noninvariant parity-violating operators from acquiring expectation
values. Other situations where the theorem is inapplicable are also discussed.Comment: Minor typos correcte
A fully-integrated 1.8-V, 2.8-W, 1.9-GHz, CMOS power amplifier
This paper demonstrated the first 2-stage, 2.8W, 1.8V, 1.9GHz fully-integrated DAT power amplifier with 50Ω input and output matching using 0.18Όm CMOS transistors. It has a small-signal gain of 27dB. The amplifier provides 2.8W of power into a 50Ω load with a PAE of 50%
Diquarks, Pentaquarks and Dibaryons
We explore the connection between pentaquarks and dibaryons composed of three
diquarks in the framework of the diquark model. With the available experimental
data on H dibaryon, we estimate the Pauli blocking and annihilation effects and
constrain the pentaquark singlet mass. Using the
pentaquark mass, we estimate dibaryon mass
Domain Wall Fermions in Quenched Lattice QCD
We study the chiral properties and the validity of perturbation theory for
domain wall fermions in quenched lattice QCD at beta=6.0. The explicit chiral
symmetry breaking term in the axial Ward-Takahashi identity is found to be very
small already at Ns=10, where Ns is the size of the fifth dimension, and its
behavior seems consistent with an exponential decay in Ns within the limited
range of Ns we explore. From the fact that the critical quark mass, at which
the pion mass vanishes as in the case of the ordinary Wilson-type fermion,
exists at finite Ns, we point out that this may be a signal of the parity
broken phase and investigate the possible existence of such a phase in this
model at finite Ns. The rho and pi meson decay constants obtained from the
four-dimensional local currents with the one-loop renormalization factor show a
good agreement with those obtained from the conserved currents
Chiral perturbation theory in a theta vacuum
We consider chiral perturbation theory (ChPT) with a non-zero theta term. Due
to the CP violating term, the vacuum of chiral fields is shifted to a
non-trivial element on the SU(N_f) group manifold. The CP violation also
provides mixing of different CP eigenstates, between scalar and pseudoscalar,
or vector and axialvector operators. We investigate upto O(theta^2) effects on
the mesonic two point correlators of ChPT to the one-loop order. We also
address the effects of fixing topology, by using saddle point integration in
the Fourier transform with respect to theta.Comment: 31 pages, references added, minor corrections, version published in
PR
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