27,887 research outputs found
Trigger and data acquisition
The lectures address some of the issues of triggering and data acquisition in
large high-energy physics experiments. Emphasis is placed on hadron-collider
experiments that present a particularly challenging environment for event
selection and data collection. However, the lectures also explain how T/DAQ
systems have evolved over the years to meet new challenges. Some examples are
given from early experience with LHC T/DAQ systems during the 2008 single-beam
operations.Comment: 32 pages, Lectures given at the 5th CERN-Latin-American School of
High-Energy Physics, Recinto Quirama, Colombia, 15 - 28 Mar 200
Recommended from our members
Sickle cell anaemia and the experiences of young people living with the condition
This qualitative literature review examines the experiences of young people with Sickle Cell Anaemia (SCA). Sickle cell anaemia (SCA) is a condition acknowledged for its unpredictability, painful episodes and life threatening nature. The aim was to explore the impact SCA has on young people and the experiences they face. After reviewing potential articles found from the EBSCOhost platform, an inclusion and exclusion criteria was used and six appropriate studies were found with the majority of the participants in the 10-25 age range. However, one study had some participants in the early childhood and another had some of the sample in the young adult age range. These articles concentrated on the UK and North America instead of a broader international experience. The critical appraisal skills programme (CASP) was then used to evaluate the articles found. Thematic analysis identified three themes: acceptance, support and unpredictability, with subthemes of spirituality and discrimination. It was clear that SCA affected multiple areas of young peoples’ lives, and health professionals need to consider young people’s views.
The terms Sickle Cell Anaemia and Sickle Cell Disease are used interchangeably throughout this review
High-Energy QCD as a Topological Field Theory
We propose an identification of the conformal field theory underlying
Lipatov's spin-chain model of high-energy scattering in perturbative QCD. It is
a twisted N=2 supersymmetric topological field theory, which arises as the
limiting case of the SL(2,R)/U(1) non-linear sigma model that also plays a role
in describing the Quantum Hall effect and black holes in string theory. The
doubly-infinite set of non-trivial integrals of motion of the high-energy
spin-chain model displayed by Faddeev and Korchemsky are identified as the
Cartan subalgebra of a W_{\infty} \otimes W_{\infty} bosonic sub-symmetry
possessed by this topological theory. The renormalization group and an analysis
of instanton perturbations yield some understanding why this particular
topological spin-chain model emerges in the high-energy limit, and provide a
new estimate of the asymptotic behaviour of multi-Reggeized-gluon exchange.Comment: 24 pages LATEX, one eps figure incorporate
A Liouville String Approach to Microscopic Time and Cosmology
In the non-critical string framework that we have proposed recently, the time
is identified with a dynamical local renormalization group scale, the
Liouville mode, and behaves as a statistical evolution parameter, flowing
irreversibly from an infrared fixed point - which we conjecture to be a
topological string phase - to an ultraviolet one - which corresponds to a
static critical string vacuum. When applied to a toy two-dimensional model of
space-time singularities, this formalism yields an apparent renormalization of
the velocity of light, and a -dependent form of the uncertainty relation for
position and momentum of a test string. We speculate within this framework on a
stringy alternative to conventional field-theoretical inflation, and the decay
towards zero of the cosmological constant in a maximally-symmetric space.Comment: Latex 23 pages, no figures, CERN-TH.7000/93, CTP-TAMU-66/9
Search for Quantum Gravity
A satisfactory theory of quantum gravity may necessitate a drastic
modification of our perception of space-time, by giving it a foamy structure at
distances comparable to the Planck length. It is argued in this essay that the
experimental detection of such structures may be a realistic possibility in the
foreseeable future. After a brief review of different theoretical approaches to
quantum gravity and the relationships between them, we discuss various possible
experimental tests of the quantum nature of space-time. Observations of photons
from distant astrophysical sources such as Gamma-Ray Bursters and laboratory
experiments on neutral kaon decays may be sensitive to quantum-gravitational
effects if they are only minimally suppressed. Experimental limits from the
Whipple Observatory and the CPLEAR Collaboration are already probing close to
the Planck scale, and significant increases in sensitivity are feasible.Comment: 7 pages LATEX, no figures, Awarded First Prize in the Gravity
Research Foundation Essay Competition for 199
Liouville Cosmology
Liouville string theory is a natural framework for discussing the
non-equilibrium evolution of the Universe. It enables non-critical strings to
be treated in mathematically consistent manner, in which target time is
identified with a world-sheet renormalization-group scale parameter, preserving
target-space general coordinate invariance and the existence of an S-matrix. We
review our proposals for a unified treatment of inflation and the current
acceleration of the Universe. We link the current acceleration of the Universe
with the value of the string coupling. In such a scenario, the dilaton plays an
essential background role, driving the acceleration of the Universe during the
present era after decoupling as a constant during inflation.Comment: 23 pages latex, 2 eps figures, contribution to the proceedings of the
Dark 2004 conference, College Station, October 200
Quantum Decoherence in a D-Foam Background
Within the general framework of Liouville string theory, we construct a model
for quantum D-brane fluctuations in the space-time background through which
light closed-string states propagate. The model is based on monopole and vortex
defects on the world sheet, which have been discussed previously in a treatment
of 1+1-dimensional black-hole fluctuations in the space-time background, and
makes use of a T-duality transformation to relate formulations with Neumann and
Dirichlet boundary conditions. In accordance with previous general arguments,
we derive an open quantum-mechanical description of this D-brane foam which
embodies momentum and energy conservation and small mean energy fluctuations.
Quantum decoherence effects appear at a rate consistent with previous
estimates.Comment: 16 pages, Latex, two eps figures include
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