524 research outputs found
Chiral freedom and electroweak symmetry breaking
Antisymmetric tensor fields with chiral couplings to quarks and leptons may
induce spontaneous electroweak symmetry breaking in a model without a
``fundamental'' Higgs scalar. No microscopic local mass term for the chiral
tensors or ``chirons'' is allowed by the symmetries and our model exhibits only
dimensionless couplings. However, the chiral couplings are asymptotically free
and therefore generate a mass scale where they grow large. We argue that at
this scale mass terms for the chiral tensor fields are generated
non-perturbatively - the chirons appear as new massive spin one particles.
Furthermore a scalar top-antitop condensate forms, giving mass to the weak
gauge bosons and fermions. In this scenario the longstanding gauge hierarchy
problem finds a solution similar to the mass generation in QCD. We compute the
general form of the effective action for the chiral tensors and sketch several
possibilities of their detection at LHC or through precision tests of the
electroweak standard model.Comment: 30 pages, 7 figure
PIXEL 2010 - a Resume
The Pixel 2010 conference focused on semiconductor pixel detectors for
particle tracking/vertexing as well as for imaging, in particular for
synchrotron light sources and XFELs. The big LHC hybrid pixel detectors have
impressively started showing their capabilities. X-ray imaging detectors, also
using the hybrid pixel technology, have greatly advanced the experimental
possibilities for diiffraction experiments. Monolithic or semi-monolithic
devices like CMOS active pixels and DEPFET pixels have now reached a state such
that complete vertex detectors for RHIC and superKEKB are being built with
these technologies. Finally, new advances towards fully monolithic active pixel
detectors, featuring full CMOS electronics merged with efficient signal charge
collection, exploiting standard CMOS technologies, SOI and/or 3D integration,
show the path for the future. This r\'esum\'e attempts to extract the main
statements of the results and developments presented at this conference.Comment: 8 pages, 19 figures, conference summar
Readout Concepts for DEPFET Pixel Arrays
Field effect transistors embedded into a depleted silicon bulk (DEPFETs) can
be used as the first amplifying element for the detection of small signal
charges deposited in the bulk by ionizing particles, X-ray photons or visible
light. Very good noise performance at room temperature due to the low
capacitance of the collecting electrode has been demonstrated. Regular two
dimensional arrangements of DEPFETs can be read out by turning on individual
rows and reading currents or voltages in the columns. Such arrangements allow
the fast, low power readout of larger arrays with the possibility of random
access to selected pixels. In this paper, different readout concepts are
discussed as they are required for arrays with incomplete or complete clear and
for readout at the source or the drain. Examples of VLSI chips for the steering
of the gate and clear rows and for reading out the columns are presented.Comment: 8 pages, 9 figures, submitted to Nucl. Instr. and Methods as
proceedings of the 9th European Symposium on Semiconductor Detectors, Elmau,
June 23-27, 200
Exact Solution of Photon Equation in Stationary G\"{o}del-type and G\"{o}del Space-Times
In this work the photon equation (massless Duffin-Kemmer-Petiau equation) is
written expilicitly for general type of stationary G\"{o}del space-times and is
solved exactly for G\"{o}del-type and G\"{o}del space-times. Harmonic
oscillator behaviour of the solutions is discussed and energy spectrum of
photon is obtained.Comment: 9 pages,RevTeX, no figure, revised for publicatio
Pixel Detectors for Charged Particles
Pixel Detectors, as the current technology of choice for the innermost vertex
detection, have reached a stage at which large detectors have been built for
the LHC experiments and a new era of developments, both for hybrid and for
monolithic or semi-monolithic pixel detectors is in full swing. This is largely
driven by the requirements of the upgrade programme for the superLHC and by
other collider experiments which plan to use monolithic pixel detectors for the
first time. A review on current pixel detector developments for particle
tracking and vertexing is given, comprising hybrid pixel detectors for superLHC
with its own challenges in radiation and rate, as well as on monolithic,
so-called active pixel detectors, including MAPS and DEPFET pixels for RHIC and
superBelle.Comment: 19 pages, 23 drawings in 14 figure
Exact Solutions of the Duffin Kemmer Petiau Equation for the Deformed Hulthen Potential
Using the Nikiforov Uvarov method, an application of the relativistic Duffin
Kemmer Petiau equation in the presence of a deformed Hulthen potential is
presented for spin zero particles. We derived the first order coupled
differential radial equations which enable the energy eigenvalues as well as
the full wavefunctions to be evaluated by using of the Nikiforov Uvarov method
that can be written in terms of the hypergeometric polynomials.Comment: 8 pages. submitted to Physica Script
Effects due to a scalar coupling on the particle-antiparticle production in the Duffin-Kemmer-Petiau theory
The Duffin-Kemmer-Petiau formalism with vector and scalar potentials is used
to point out a few misconceptions diffused in the literature. It is explicitly
shown that the scalar coupling makes the DKP formalism not equivalent to the
Klein-Gordon formalism or to the Proca formalism, and that the spin-1 sector of
the DKP theory looks formally like the spin-0 sector. With proper boundary
conditions, scattering of massive bosons in an arbitrary mixed vector-scalar
square step potential is explored in a simple way and effects due to the scalar
coupling on the particle-antiparticle production and localization of bosons are
analyzed in some detail
Comment on ``the Klein-Gordon Oscillator''
The different ways of description of the particle with oscillator-like
interaction are considered. The results are in conformity with the previous
paper of S. Bruce and P. Minning.Comment: LaTeX file, 5p
Status of a DEPFET pixel system for the ILC vertex detector
We have developed a prototype system for the ILC vertex detector based on
DEPFET pixels. The system operates a 128x64 matrix (with ~35x25 square micron
large pixels) and uses two dedicated microchips, the SWITCHER II chip for
matrix steering and the CURO II chip for readout. The system development has
been driven by the final ILC requirements which above all demand a detector
thinned to 50 micron and a row wise read out with line rates of 20MHz and more.
The targeted noise performance for the DEPFET technology is in the range of
ENC=100 e-. The functionality of the system has been demonstrated using
different radioactive sources in an energy range from 6 to 40keV. In recent
test beam experiments using 6GeV electrons, a signal-to-noise ratio of S/N~120
has been achieved with present sensors being 450 micron thick. For improved
DEPFET systems using 50 micron thin sensors in future, a signal-to-noise of 40
is expected.Comment: Invited poster at the International Symposium on the Development of
Detectors for Particle, AstroParticle and Synchrotron Radiation Experiments,
Stanford CA (SNIC06) 6 pages, 12 eps figure
Oxygen consumption in perfused skeletal muscle. Effect of perfusion with aged, fresh and aged-rejuvenated erythrocytes on oxygen consumption, tissue metabolites and inhibition of glucose utilization by acetoacetate
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