2,965 research outputs found
Measurement of the trailing edge of cosmic-ray track signals from a round-tube drift chamber
The trailing edge of tube drift-chamber signals for charged particles is
expected to provide information concerning the particle passage time. This
information may be useful for separating meaningful signals from overlapping
garbage at high-rate experiments, such as the future LHC experiments. We
carried out a cosmic-ray test using a small tube chamber in order to
investigate the feasibility of this idea. We achieved a trailing-edge time
resolution of 12 ns in rms by applying simple pulse shaping to eliminate a
signal tail. A comparison with a Monte Carlo simulation indicates the
importance of well-optimized signal shaping to achieve good resolution. The
resolution may be further improved with better shaping.Comment: 13 pages including 9 figure
q-deformed dynamics and Josephson junction
We define a generalized rate equation for an observable in quantum mechanics,
that involves a parameter q and whose limit gives the standard
Heisenberg equation. The generalized rate equation is used to study dynamics of
current biased Josephson junction. It is observed that this toy model
incorporates diffraction like effects in the critical current. Physical
interpretation for q is provided which is also shown to be q-deformation
parameter.Comment: LaTeX 9 pages, submitted Mod. Phys. Lett. B, e-mail: [email protected]
Non-equivalence between Heisenberg XXZ spin chain and Thirring model
The Bethe ansatz equations for the spin 1/2 Heisenberg XXZ spin chain are
numerically solved, and the energy eigenvalues are determined for the
anti-ferromagnetic case. We examine the relation between the XXZ spin chain and
the Thirring model, and show that the spectrum of the XXZ spin chain is
different from that of the regularized Thirring model.Comment: 10 pages. 2figure
A New Deformed Supersymmetric Oscillator
We construct and discuss the Fock-space representation for a deformed
oscillator with "peculiar" statistics. We show that corresponding algebra
represents deformed supersymmetric oscillator.Comment: LATEX, 10 pages, no figures, to appear in Europhys.Let
Unified View of Deformed Single - Mode Oscillator Algebras
A general framework for the deformation of the single-mode oscillators is
presented and all deformed single-mode oscillators are unified. The extensions
of the Aric-Coon, genon, the para-Bose and the para-Fermi oscillators are
proposed. The generalized harmonic oscillator considered by Brzezinski et al.
is rederived in a simple way.Some remarks on deformation of and
supersymmetry are made.Comment: 12 pages, Latex file, preprint RBI-TH-3/94,PMF-ZTF-3/94, February
1994. (to appear in Phys.Lett. B
On the Vortex-Point Charge Composite: Classical Orbits and Quantum Bound States
The possibility of composite systems arising out of a point charge
interacting with a Nielsen-Olesen vortex in 2+1-dimensions is investigated. It
is shown that classical bounded orbits are possible for certain ranges of
parameters. Long lived metastable states are shown to exist, in a
semi-classical approach, from the study of the effective potential. Loss of
self-adjointness of the Hamiltonian and its subsequent self-adjoint extension
in some cases leads to bound states.Comment: 13 pages, Latex file, For figures e-mail to
"[email protected]
Les Houches Guidebook to Monte Carlo Generators for Hadron Collider Physics
Recently the collider physics community has seen significant advances in the
formalisms and implementations of event generators. This review is a primer of
the methods commonly used for the simulation of high energy physics events at
particle colliders. We provide brief descriptions, references, and links to the
specific computer codes which implement the methods. The aim is to provide an
overview of the available tools, allowing the reader to ascertain which tool is
best for a particular application, but also making clear the limitations of
each tool.Comment: 49 pages Latex. Compiled by the Working Group on Quantum
ChromoDynamics and the Standard Model for the Workshop ``Physics at TeV
Colliders'', Les Houches, France, May 2003. To appear in the proceeding
Generally Deformed Oscillator, Isospectral Oscillator System and Hermitian Phase Operator
The generally deformed oscillator (GDO) and its multiphoton realization as
well as the coherent and squeezed vacuum states are studied. We discuss, in
particular, the GDO depending on a complex parameter q (therefore we call it
q-GDO) together with the finite dimensional cyclic representations. As a
realistic physical system of GDO the isospectral oscillator system is studied
and it is found that its coherent and squeezed vacuum states are closely
related to those of the oscillator. It is pointed out that starting from the
q-GDO with q root of unity one can define the hermitian phase operators in
quantum optics consistently and algebraically. The new creation and
annihilation operators of the Pegg-Barnett type phase operator theory are
defined by using the cyclic representations and these operators degenerate to
those of the ordinary oscillator in the classical limit q->1.Comment: 21 pages, latex, no figure
YAP/TAZ-CDC42 signaling regulates vascular tip cell migration
Angiogenesis and vascular remodeling are essential for the establishment of vascular networks during organogenesis. Here we show that the Hippo signaling pathway effectors YAP and TAZ are required, in a gene dosage-dependent manner, for the proliferation and migration of vascular endothelial cells (ECs) during retinal angiogenesis. Intriguingly, nuclear translocation of YAP and TAZ induced by Lats1/2-deletion blocked endothelial migration and phenocopied Yap/Taz-deficient mutants. Furthermore, overexpression of a cytoplasmic form of YAP (YAPS127D) partially rescued the migration defects caused by loss of YAP and TAZ function. Finally, we found that cytoplasmic YAP positively regulated the activity of the small GTPase CDC42, deletion of which caused severe defects in endothelial migration. These findings uncover a previously unrecognized role of cytoplasmic YAP/TAZ in promoting cell migration by activating CDC42 and provide insight into how Hippo signaling in ECs regulates angiogenesis
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