2,054 research outputs found
Passivity-Based Control of Human-Robotic Networks with Inter-Robot Communication Delays and Experimental Verification
In this paper, we present experimental studies on a cooperative control
system for human-robotic networks with inter-robot communication delays. We
first design a cooperative controller to be implemented on each robot so that
their motion are synchronized to a reference motion desired by a human
operator, and then point out that each robot motion ensures passivity.
Inter-robot communication channels are then designed via so-called scattering
transformation which is a technique to passify the delayed channel. The
resulting robotic network is then connected with human operator based on
passivity theory. In order to demonstrate the present control architecture, we
build an experimental testbed consisting of multiple robots and a tablet. In
particular, we analyze the effects of the communication delays on the human
operator's behavior
Tensor mesons produced in tau lepton decays
Light tensor mesons (T = a_2, f_2 and K_2^*) can be produced in decays of tau
leptons. In this paper we compute the branching ratios of tau --> T pi nu
decays by assuming the dominance of intermediate virtual states to model the
form factors involved in the relevant hadronic matrix element. The exclusive
f_2(1270) pi^- decay mode turns out to have the largest branching ratio, of
O(10^-4) . Our results indicate that the contributions of tensor meson
intermediate states to the three-pseudoscalar channels of tau decays are rather
small.Comment: 10 pages, 1 figure. Version accepted for publication in PRD, some
typos are corrected and comments are added in section 4. Conclusions remain
unchange
The Gauge Hierarchy Problem and Higher Dimensional Gauge Theories
We report on an attempt to solve the gauge hierarchy problem in the framework
of higher dimensional gauge theories. Both classical Higgs mass and
quadratically divergent quantum correction to the mass are argued to vanish.
Hence the hierarchy problem in its original sense is solved. The remaining
finite mass correction is shown to depend crucially on the choice of boundary
condition for matter fields, and a way to fix it dynamically is presented. We
also point out that on the simply-connected space even the finite mass
correction vanishes.Comment: LaTeX2e. 12 pages, 3 Postscript figures; Added references, some
comment
Finite Higgs mass without Supersymmetry
We identify a class of chiral models where the one-loop effective potential
for Higgs scalar fields is finite without any requirement of supersymmetry. It
corresponds to the case where the Higgs fields are identified with the
components of a gauge field along compactified extra dimensions. We present a
six dimensional model with gauge group U(3)xU(3) and quarks and leptons
accomodated in fundamental and bi-fundamental representations. The model can be
embedded in a D-brane configuration of type I string theory and, upon
compactification on a T^2/Z_2 orbifold, it gives rise to the standard model
with two Higgs doublets.Comment: 28 pages, 4 figures, uses axodraw. Some typos corrected and
references rearrange
Measurement of the mass of the Ï„ lepton
The mass of the τ lepton has been measured at the Beijing Electron-Positron Collider using the Beijing Spectrometer. A search near threshold for e^+e^-→τ^+τ^- was performed. Candidate events were identified by requiring that one τ decay via τ→eνν¯, and the other via τ→μνν¯. The mass value, obtained from a fit to the energy dependence of the τ^+τ^- cross section, is m_τ=1776.9_(-0.5)^(+0.4)±0.2 MeV
Radiative and Semileptonic B Decays Involving the Tensor Meson K_2^*(1430) in the Standard Model and Beyond
We study semileptonic and radiative B decays involving the strange tensor
meson K_2^*(1430) in the final state. Using the large energy effective theory
(LEET) techniques, we formulate the B \to K_2^* transition form factors in
large recoil region. All the form factors can be parametrized in terms of two
independent LEET parameters \zeta_\perp and \zeta_\parallel. The magnitude of
\zeta_\perp is estimated from the data for Br(B \to K_2^*(1430)\gamma).
Assuming a dipole q^2-dependence for the LEET parameters and
\zeta_\parallel/\zeta_\perp = 1.0 \pm 0.2, we investigate the decays B \to
K_2^* \ell^+ \ell^- and B \to K_2^* \nu \bar{\nu}, where the contributions due
to $\zeta_\parallel are suppressed by m_{K_2^*}/m_B. For the B \to K_2^* \ell^+
\ell^- decay, in the large recoil region where the hadronic uncertainties are
considerably reduced, the longitudinal distribution d F_L/ds is reduced by
20-30 % due to the flipped sign of c_7^eff compared with the standard model
result. Moreover, the forward-backward asymmetry zero is about 3.4 GeV^2 in the
standard model, but changing the sign of c_7^eff yields a positive asymmetry
for all values of the invariant mass of the lepton pair. We calculate the
branching fraction for B \to K_2^* \nu \bar{\nu} in the standard model. Our
result exhibits the impressed resemblance between B \to K_2^*(1430)
\ell^+\ell^-, \nu \bar{\nu} and B \to K^*(892) \ell^+ \ell^-, \nu\bar{\nu}.Comment: 21 pages, 4 figures (v2) comments adde
Radiative and Semileptonic B Decays Involving Higher K-Resonances in the Final States
We study the radiative and semileptonic B decays involving a spin-
resonant with parity for and for
in the final state. Using the large energy effective theory (LEET)
techniques, we formulate transition form factors in the large
recoil region in terms of two independent LEET functions
and , the values of
which at zero momentum transfer are estimated in the BSW model. According to
the QCD counting rules, exhibit a dipole
dependence in . We predict the decay rates for ,
and . The
branching fractions for these decays with higher -resonances in the final
state are suppressed due to the smaller phase spaces and the smaller values of
. Furthermore, if the spin of
becomes larger, the branching fractions will be further suppressed due to the
smaller Clebsch-Gordan coefficients defined by the polarization tensors of the
. We also calculate the forward backward asymmetry of the decay, for which the zero is highly insensitive to the
-resonances in the LEET parametrization.Comment: 27 pages, 4 figures, 7 tables;contents and figures corrected, title
and references revise
MUTANTS OF NONPRODUCER CELL LINES TRANSFORMED BY MURINE SARCOMA VIRUSES : I. INDUCTION, ISOLATION, PARTICLE PRODUCTION, AND TUMORIGENICITY
A variety of cell mutants were obtained by a single 5'-bromodeoxyuridine (BrdU) treatment of an nonproducer (NP) cell line transformed by the Kirsten strain of murine sarcoma virus (Ki-MSV). Isolation procedures of these cell See PDF for Structure mutants are described. The cell mutants obtained were classified by tumorigenic potential and shedding of Type C virus particles. The cell mutants were classified into four groups: (A) tumorigenic, without particles; (B) tumorigenic, with Type C particles; (C) nontumorigenic, without particles; and (D) nontumorigenic, with Type C particles. The tumorigenic cell lines showed variability in morphology with both flat and typical transformed appearing cell lines showing equal transplantability
Selectivity of the Nucleon Induced Deuteron Breakup and Relativistic Effects
Theoretical predictions for the nucleon induced deuteron breakup process
based on solutions of the three-nucleon Faddeev equation including such
relativistic features as the relativistic kinematics and boost effects are
presented. Large changes of the breakup cross section in some complete
configurations are found at higher energies. The predicted relativistic
effects, which are mostly of dynamical origin, seem to be supported by existing
data.Comment: 4 pages, 4 figure
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